Sample records for u-2bu subsidence crater

  1. Closure plan for Corrective Action Unit 109: U-2bu subsidence crater, Nevada Test Site, Nevada

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    NONE

    1999-03-01

    The U-2bu subsidence crater, Corrective Action Unit 109, will be closed in accordance with the Resource Conservation and Recovery Act, the Nevada Division of Environmental Protection operational permit, and the Federal Facility Agreement and Consent Order. The U-2bu subsidence crater is located in Area 2 of the Nevada Test Site. It was created in 1971 by an underground nuclear test with the name Miniata. The crater has a diameter of 288 meters (944 feet) and an approximate depth of 35 meters (115 feet). Based on the results of the analyses reported in the site characterization report, the only constituents ofmore » concern in the U-2bu subsidence crater include leachable lead and total petroleum hydrocarbons. Closure activities will include the excavation and disposal of impacted soil from the top of the crater. Upon completion of excavation, verification samples will be collected to show that the leachable lead has been removed to concentrations below the regulatory action level. After sample results show that the lead has been removed, the excavated area will be backfilled and a soil flood diversion berm will be constructed as a best management practice. An independent registered professional engineer will certify the site was closed following the approved Closure Plan. Post-closure care is not warranted for this site because closure activities will involve removal of the Resource Conservation and Recovery Act constituents of concern.« less

  2. Closure Plan for Corrective Action Unit 109: U-2bu Subsidence Crater Nevada Test Site, Nevada

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Shannon Parsons

    1999-03-01

    The U-2bu subsidence crater, Corrective Action Unit 109, will be closed in accordance with the Resource Conservation and Recovery Act, the Nevada Division of Environmental Protection operational permit, and the Federal Facilities Agreement and Consent Order. The U-2bu subsidence crater is located in Area 2 of the Nevada Test Site. It was created in 1971 by an underground nuclear test with the name Miniata. The crater has a diameter of 288 meters (944 feet) and an approximate depth of 35 meters (115 feet). The subsidence crater was used as a land disposal unit for radioactive and hazardous waste from 1973more » to 1988. Site disposal history is supported by memorandums, letters, and personnel who worked at the Nevada Test Site at the time of active disposal. Closure activities will include the excavation and disposal of impacted soil form the tip of the crater. Upon completion of excavation, verification samples will be collected to show that lead has been removed to concentrations be low regulatory action level. The area will then be backfilled and a soil flood diversion berm will be constructed, and certified by an independent professional engineer as to having followed the approved Closure Plan.« less

  3. Recharge from a subsidence crater at the Nevada test site

    USGS Publications Warehouse

    Wilson, G. V.; Ely, D.M.; Hokett, S. L.; Gillespie, D. R.

    2000-01-01

    Current recharge through the alluvial fans of the Nevada Test Site (NTS) is considered to be negligible, but the impact of more than 400 nuclear subsidence craters on recharge is uncertain. Many of the craters contain a playa region, but the impact of these playas has not been addressed. It was hypothesized that a crater playa would focus infiltration through the surrounding coarser-grained material, thereby increasing recharge. Crater U5a was selected because it represented a worst case for runoff into craters. A borehole was instrumented for neutron logging beneath the playa center and immediately outside the crater. Physical and hydraulic properties were measured along a transect in the crater and outside the crater. Particle-size analysis of the 14.6 m of sediment in the crater and morphological features of the crater suggest that a large ponding event of ≈63000 m3 had occurred since crater formation. Water flow simulations with HYDRUS-2D, which were corroborated by the measured water contents, suggest that the wetting front advanced initially by as much as 30 m yr−1 with a recharge rate 32 yr after the event of 2.5 m yr−1Simulations based on the measured properties of the sediments suggest that infiltration will occur preferentially around the playa perimeter. However, these sediments were shown to effectively restrict future recharge by storing water until removal by evapotranspiration (ET). This work demonstrated that subsidence craters may be self-healing.

  4. Crater Floor and Lava Lake Dynamics Measured with T-LIDAR at Pu`u`O`o Crater, Hawai`i

    NASA Astrophysics Data System (ADS)

    Brooks, B. A.; Kauahikaua, J. P.; Foster, J. H.; Poland, M. P.

    2007-12-01

    We used a near-infrared (1.2 micron wavelength) tripod-based scanning LiDAR system (T-LIDAR) to capture crater floor and lava lake dynamics in unprecedented detail at P`u`u `O`o crater on Kilauea volcano, Hawai`i. In the ~40 days following the June 17-19 intrusion/eruption, Pu`u `O`o crater experienced substantial deformation comprising 2 collapse events bracketing rapid filling of the crater by a lava lake. We surveyed the crater floor with centimeter-scale spot-spacings from 3 different vantage points on July 13 and from one vantage point on July 24. Data return was excellent despite heavy fume on July 24 that obscured nearly all of the crater features, including the walls and floor. We formed displacement fields by aligning identical features from different acquisition times in zones on the relatively stable crater walls. From July 13, over a period of several hours, we imaged ~2 m of differential lava lake surface topography from the upwelling (eastern) to downstream (western) portion of the flowing lava lake. From July 13 to July 24, the lava lake level dropped by as much as 20 meters in a zone confined by flanking levees. Our results confirm the utility of T-LiDAR as a new tool for detailed volcano geodesy studies and suggest potential applications in volcano hazards monitoring.

  5. Complex Volcanism at Oppenheimer U Floor-Fractured Crater

    NASA Technical Reports Server (NTRS)

    Gaddis, L. R.; Bennett, K.; Horgan, B.; McBride, Marie; Stopar, J.; Lawrence, S.; Gustafson, J. O.; Giguere, T.

    2017-01-01

    Recent remote sensing studies have identified complex volcanism in the floor-fractured crater (FFC) Oppenheimer U, located in the northwest floor of Oppenheimer crater (35.2degS, 166.3degW, 208 km dia., Figure 1) within the "South Pole - Aitken basin" (SPA) region of the lunar far side. Up to 15 sites of pyroclastic volcanism have been identified in the floor of Oppenheimer crater. Studies of Moon Mineralogy Mapper data (M3, 0.4-3 microns, 86 bands, [5]) indicated that the pyroclastic deposits are comprised of mixtures of clinopyroxene and iron-rich glass, with the Oppenheimer U deposit showing variable composition within the FFC and having the most iron-rich volcanic glass thus far identified on the Moon. Here we examine the floor of Oppenheimer U in more detail and show evidence for possible multiple eruptive vents.

  6. Thermodynamic modelling of the C-U and B-U binary systems

    NASA Astrophysics Data System (ADS)

    Chevalier, P. Y.; Fischer, E.

    2001-02-01

    The thermodynamic modelling of the carbon-uranium (C-U) and boron-uranium (B-U) binary systems is being performed in the framework of the development of a thermodynamic database for nuclear materials, for increasing the basic knowledge of key phenomena which may occur in the event of a severe accident in a nuclear power plant. Applications are foreseen in the nuclear safety field to the physico-chemical interaction modelling, on the one hand the in-vessel core degradation producing the corium (fuel, zircaloy, steel, control rods) and on the other hand the ex-vessel molten corium-concrete interaction (MCCI). The key O-U-Zr ternary system, previously modelled, allows us to describe the first interaction of the fuel with zircaloy cladding. Then, the three binary systems Fe-U, Cr-U and Ni-U were modelled as a preliminary work for modelling the O-U-Zr-Fe-Cr-Ni multicomponent system, allowing us to introduce the steel components in the corium. In the existing database (TDBCR, thermodynamic data base for corium), Ag and In were introduced for modelling AIC (silver-indium-cadmium) control rods which are used in French pressurized water reactors (PWR). Elsewhere, B 4C is also used for control rods. That is why it was agreed to extend in the next years the database with two new components, B and C. Such a work needs the thermodynamic modelling of all the binary and pseudo-binary sub-systems resulting from the combination of B, B 2O 3 and C with the major components of TDBCR, O-U-Zr-Fe-Cr-Ni-Ag-In-Ba-La-Ru-Sr-Al-Ca-Mg-Si + Ar-H. The critical assessment of the very numerous experimental information available for the C-U and B-U binary systems was performed by using a classical optimization procedure and the Scientific Group Thermodata Europe (SGTE). New optimized Gibbs energy parameters are given, and comparisons between calculated and experimental equilibrium phase diagrams or thermodynamic properties are presented. The self-consistency obtained is quite satisfactory.

  7. New superhindered polydentate polyphosphine ligands P(CH2CH2P(t)Bu2)3, PhP(CH2CH2P(t)Bu2)2, P(CH2CH2CH2P(t)Bu2)3, and their ruthenium(II) chloride complexes.

    PubMed

    Gilbert-Wilson, Ryan; Field, Leslie D; Bhadbhade, Mohan M

    2012-03-05

    The synthesis and characterization of the extremely hindered phosphine ligands, P(CH(2)CH(2)P(t)Bu(2))(3) (P(2)P(3)(tBu), 1), PhP(CH(2)CH(2)P(t)Bu(2))(2) (PhP(2)P(2)(tBu), 2), and P(CH(2)CH(2)CH(2)P(t)Bu(2))(3) (P(3)P(3)(tBu), 3) are reported, along with the synthesis and characterization of ruthenium chloro complexes RuCl(2)(P(2)P(3)(tBu)) (4), RuCl(2)(PhP(2)P(2)(tBu)) (5), and RuCl(2)(P(3)P(3)(tBu)) (6). The bulky P(2)P(3)(tBu) (1) and P(3)P(3)(tBu) (3) ligands are the most sterically encumbered PP(3)-type ligands so far synthesized, and in all cases, only three phosphorus donors are able to bind to the metal center. Complexes RuCl(2)(PhP(2)P(2)(tBu)) (5) and RuCl(2)(P(3)P(3)(tBu)) (6) were characterized by crystallography. Low temperature solution and solid state (31)P{(1)H} NMR were used to demonstrate that the structure of RuCl(2)(P(2)P(3)(tBu)) (4) is probably analogous to that of RuCl(2)(PhP(2)P(2)(tBu)) (5) which had been structurally characterized.

  8. Tempest in Vailulu'u Crater

    NASA Astrophysics Data System (ADS)

    Hart, S. R.; Staudigel, H.; Koppers, A.; Young, C.; Baker, E.

    2005-12-01

    The summit crater of the Samoan submarine volcano, Vailulu'u, has been actively erupting since 2001. Based on water chemistry, CTD and temperature logger data from 2000 and 2001, we formulated a model for the hydrothermal system in the crater involving a tidally-modulated "breathing" (Staudigel et al., 2004). During low stands of internal waves (exterior to the crater), the crater exhales warm buoyant hydrothermal water that forms a "halo" around the crater rich in Mn, 3He, and particulates. During "high tides", cold dense external water is inhaled into the crater through the three breaches, and cascades to the crater floor. In April 2005, we used the HURL PISCES V submersible to deploy various temperature and particulate loggers and current meters in and around the crater; these were retrieved by Pisces V in July 2005. In addition, continuous CTD profiling was carried out over 12 hour tidal cycles at one location inside, and one outside, the crater. The accumulated data set fully reinforces our "breathing" model. An ADCP, deployed for 93 days in the NW breach at 752m, showed dominant easterly inflow currents and westerly outflow currents, with maximum velocities of approximately 25 cm/s. The flows were coherent for distances up to 50-60m above the ADCP; the mean inflow velocity and azimuth (20-40 m interval above the ADCP) was 7 cm/s due east; the mean outflow velocity and azimuth was 5 cm/s at 260 degrees. Mean inflows were consistently colder than outflows (5.00 C vs 5.20 C); the maximum observed range in temperature was 1.1 C, correlated with peak flow velocities. The coldest inflows would require very large regional internal wave amplitudes, up to 50-100 meters. A 2-D acoustic current meter was deployed on top of the west crater rim summit (582m) for 90 days, and in the S breach (697m) for 4 days. The summit flows are presumed to represent the regional scale currents; these were largely from the SW quadrant, with typical velocities of 8-15 cm/s, and peaks to

  9. The June-July 2007 collapse and refilling of Puʻu ʻŌʻō Crater, Kilauea Volcano, Hawaiʻi

    USGS Publications Warehouse

    Orr, Tim R.

    2014-01-01

    Episode 57 of Kīlauea’s long-lived east rift zone eruption was characterized by lava effusion and spattering within the crater at Puʻu ʻŌʻō that lasted from July 1 to July 20, 2007. This eruptive episode represented a resumption of activity following a 12-day eruptive hiatus on Kīlauea associated with the episode 56 intrusion and eruption near Kāne Nui o Hamo cone, uprift from Puʻu ʻŌʻō, on June 17–19, 2007. The withdrawal of magma from beneath Puʻu ʻŌʻō led to the collapse of Puʻu ʻŌʻō’s crater floor, forming a concave depression ~85 m deep. After the hiatus, episode 57 lava began to erupt from two vents within Puʻu ʻŌʻō, quickly constructing a lava lake and filling the crater to within 5 m of the precollapse lava level (25 m of the pre-collapse crater floor). Starting July 8, effusion waned as the crater floor began to rise. As uplift progressed, new vents opened along a circumferential fracture that accommodated the displacement. The bulk volume of filling within the Puʻu ʻŌʻō crater and flank pits during episode 57, including both surficial lava accumulation and endogenous growth, is estimated at 1.3×106 m3. This volume equates to a time-averaged dense rock equivalent accumulation rate of 0.6 m3 s-1, which is an order of magnitude less than the supply rate to the volcano at that time, suggesting that most of the magma entering the volcano was being stored. Eruptive activity in Puʻu ʻŌʻō ended late on July 20, and the floor of the crater began to subside rapidly. Shortly afterward, early on July 21, a new fissure eruption started on the northeast flank of Puʻu ʻŌʻō, marking the onset of episode 58. The June–July 2007 collapse and refilling of the Puʻu ʻŌʻō crater, culminating in a new breakout outside of Puʻu ʻŌʻō, illustrates the response of a long-lived eruptive center in Kīlauea’s East Rift Zone to an uprift intrusion. Variations of this pattern occurred several times at Puʻu ʻŌʻō before

  10. Synthesis and structure of the extended phosphazane ligand [(1,4-C6H4){N(μ-PN(t)Bu)2N(t)Bu}2](4).

    PubMed

    Sevilla, Raquel; Less, Robert J; García-Rodríguez, Raúl; Bond, Andrew D; Wright, Dominic S

    2016-02-07

    The reaction of the phenylene-bridged precursor (1,4-C6H4)[N(PCl2)2]2 with (t)BuNH2 in the presence of Et3N gives the new ligand precursor (1,4-C6H4)[N(μ-N(t)Bu)2(PNH(t)Bu)2]2, deprotonation of which with Bu2Mg gives the novel tetraanion [(1,4-C6H4){N(μ-N(t)Bu)2(PN(t)Bu)2}2](4-).

  11. The inverse sandwich complex [(K(18-crown-6))2Cp][CpFe(CO)2]--unpredictable redox reactions of [CpFe(CO)2]I with the silanides Na[SiRtBu2] (R = Me, tBu) and the isoelectronic phosphanyl borohydride K[PtBu2BH3].

    PubMed

    Sänger, Inge; Kückmann, Theresa I; Dornhaus, Franz; Bolte, Michael; Wagner, Matthias; Lerner, Hans-Wolfram

    2012-06-14

    The dimeric iron carbonyl [CpFe(CO)(2)](2) and the iodosilanes tBu(2)RSiI were obtained from the reaction of [CpFe(CO)(2)]I with the silanides Na[SiRtBu(2)] (R = Me, tBu) in THF. By the reactions of [CpFe(CO)(2)]I and Na[SiRtBu(2)] (R = Me, tBu) the disilanes tBu(2)RSiSiRtBu(2) (R = Me, tBu) were additionally formed using more than one equivalent of the silanide. In this context it should be noted that reduction of [CpFe(CO)(2)](2) with Na[SitBu(3)] gives the disilanes tBu(3)SiSitBu(3) along with the sodium ferrate [(Na(18-crown-6))(2)Cp][CpFe(CO)(2)]. The potassium analogue [(K(18-crown-6))(2)Cp][CpFe(CO)(2)] (orthorhombic, space group Pmc2(1)), however, could be isolated as a minor product from the reaction of [CpFe(CO)(2)]I with [K(18-crown-6)][PtBu(2)BH(3)]. The reaction of [CpFe(CO)(2)](2) with the potassium benzophenone ketyl radical and subsequent treatment with 18-crown-6 yielded the ferrate [K(18-crown-6)][CpFe(CO)(2)] in THF at room temperature. The crown ether complex [K(18-crown-6)][CpFe(CO)(2)] was analyzed using X-ray crystallography (orthorhombic, space group Pna2(1)) and its thermal behaviour was investigated.

  12. Bu-2470, a new peptide antibiotic complex. II. Structure determination of Bu-2470 A, B1, B2a and B2b.

    PubMed

    Sugawara, K; Yonemoto, T; Konishi, M; Matsumoto, K; Miyaki, T; Kawaguchi, H

    1983-06-01

    The structures of Bu-2470 A, B1, B2a, and B2b have been determined. Bu-2470 A is a simple octapeptide having no fatty acid moiety, while Bu-2470 B1, B2a and B2b are octapeptides that have been acylated with a beta-hydroxy C11 or C10 fatty acid. The octapeptide structure of Bu-2470 components was found identical with that of octapeptin C1, hence generic names of octapeptin C0, C2, C3 and C4 are proposed for Bu-2470 A, B1, B2a and B2b, respectively.

  13. Traces of warping subsided tectonic blocks on Miranda, Enceladus, Titan

    NASA Astrophysics Data System (ADS)

    Kochemasov, G.

    2007-08-01

    sharp difference between uplifted and subsided blocks presents Miranda having very sharp relief range. Subsided areas (coronas) are strongly folded, uplifted areas strongly degassed what was witnessed by numerous craters of various sizes (not all craters are of impact origin!). Coronas on Miranda present subsided segment and sectors. Typical is a very sharp boundary between risen (+) and fallen (-) blocks. On Enceladus the subsided (squeezed) southern pole area is characterized by "tiger stripes" - traces of contraction, young ice deposits and famous ejections of water vapor and ice. The squeezed area expels 'molten" material from interior - compare with periodically active Hawaiian volcano expelling basalts from constantly under contraction Pacific basin interior. As to the subsided Pacific basin, it is antepodean to uplifted deeply cracked and degassing Africa. On Enceladus to contracted south is opposed expanded north where past degassing is witnessed by numerous craters (not all of them are impacts!). Contraction traces are very impressive on subsided Titan's surfaces - methane filled thinly folded huge areas mainly in near equatorial regions (some scientists think that these folds are eolian dunes but they are parallel, not perpendicular to presumed winds and, besides, winds below ˜60 km in Titan's atmosphere are not detected by "Huygens") [1, 2]. This methane rich area of intensive folding is antepodean to the uplifted and mainly composed of water ice region Xanadu cut by numerous tectonically controlled dry "valleys". So, in spite of many varieties of surface features on icy satellites of the outer Solar system a common main tectonic tendency exists: opposition of subsided contracted and uplifted expanded blocks. References: [1] Kochemasov G.G. (2006)Titan's radar images: crosscutting ripples are dunes or warping surface waves?// Berlin, 22-26 Sept. 2006, EUROPLANET Sci. Conf. 1, EPSC2006-A-00045. [2] Kochemasov G.G. (2006)Planetary plains: subsidence and

  14. Reaction of the thermo-labile triazenide Na[tBu3SiNNNSiMe3] with CO2: formation of the imido carbonate (tBu3SiO)(Me3SiO)C[double bond, length as m-dash]N-SitBu3 and carbamine acid (tBu3SiO)CONH2.

    PubMed

    Lerner, H-W; Bolte, M; Wagner, M

    2017-07-11

    The thermo-labile triazenide Na[tBu 3 SiNNNSiMe 3 ] was prepared by the reaction of Me 3 SiN 3 with Na(thf) 2 [SitBu 3 ] in pentane at -78 °C. Treatment of Na[tBu 3 SiNNNSiMe 3 ] with an excess of carbon dioxide in pentane at -78 °C yielded the imido carbonate (tBu 3 SiO)(Me 3 SiO)C[double bond, length as m-dash]N-SitBu 3 and the carbamine acid (tBu 3 SiO)CONH 2 along with other products. From the reaction solution we could isolate the imido carbonate (tBu 3 SiO)(Me 3 SiO)C[double bond, length as m-dash]N-SitBu 3 and carbamine acid (tBu 3 SiO)CONH 2 . At first single crystals of the carbamine acid (tBu 3 SiO)CONH 2 (triclinic, space group P1[combining macron]) were grown from this solution at room temperature. A second crop of crystals were obtained by concentrating the solution. The second charge consisted of the imido carbonate (tBu 3 SiO)(Me 3 SiO)C[double bond, length as m-dash]N-SitBu 3 (monoclinic, space group P2 1 /n).

  15. Bu-2470, a new peptide antibiotic complex. I. Production, isolation and properties of Bu-2470 A, B1 and B2.

    PubMed

    Konishi, M; Sugawara, K; Tomita, K; Matsumoto, K; Miyaki, T; Fujisawa, K; Tsukiura, H; Kawaguchi, H

    1983-06-01

    A strain of Bacillus circulans produced a complex of basic peptide antibiotics designated Bu-2470, which was found to contain four active components, A, B1, B2a and B2b. Bu-2470 A specifically inhibited various Pseudomonas species including P. aeruginosa, P. maltophilia and P. putida, but otherwise its antibacterial spectrum was limited to certain Gram-negative organisms. Bu-2470 B1 and B2 (B2a + B2b) showed broad antibiotic activity against Gram-positive and Gram-negative bacteria including Pseudomonas species. The physicochemical and biological properties of Bu-2470 B1 and B2 are very similar to those of the octapeptin group of antibiotics.

  16. Synthesis and X-ray structures of dilithium complexes of the phosphonate anions [PhP(E)(N(t)Bu)(2)](2-) (E = O, S, Se, Te) and dimethylaluminum derivatives of [PhP(E)(N(t)Bu)(NH(t)Bu)](-) (E = S, Se).

    PubMed

    Briand, Glen G; Chivers, Tristram; Krahn, Mark; Parvez, Masood

    2002-12-16

    The dilithium salts of the phosphonate dianions [PhP(E)(N(t)Bu)(2)](2-) (E = O, S, Se) are generated by the lithiation of [PhP(E)(NH(t)Bu)(2)] with n-butyllithium. The formation of the corresponding telluride (E = Te) is achieved by oxidation of [Li(2)[PhP(N(t)Bu)(2)

  17. Tritium concentrations in the active Pu'u O'o crater, Kilauea volcano, Hawaii: implications for cold fusion in the Earth's interior

    NASA Astrophysics Data System (ADS)

    Quick, J. E.; Hinkley, T. K.; Reimer, G. M.; Hedge, C. E.

    1991-11-01

    The assertion that deuterium-deuterium fusion may occur at low temperature suggests a potential new source of geothermal heat. If a cold-fusion-like process occurs within the Earth, then a test for its existence would be a search for anomalous tritium in volcanic emissions. The Pu'u O'o crater is the first point at which large amounts of water are degassed from the magma that feeds the Kilauea system. The magma is probably not contaminated by meteoric-source ground water prior to degassing at Pu'u O'o, although mixing of meteoric and magmatic H 2O occurs within the crater. Tritium contents of samples from within the crater are lower than in samples taken simultaneously from the nearby upwind crater rim. These results provide no evidence in support of a cold-fusion-like process in the Earth's interior.

  18. Tritium concentrations in the active Pu'u O'o crater, Kilauea volcano, Hawaii: implications for cold fusion in the Earth's interior

    USGS Publications Warehouse

    Quick, J.E.; Hinkley, T.K.; Reimer, G.M.; Hedge, C.E.

    1991-01-01

    The assertion that deuterium-deuterium fusion may occur at low temperature suggests a potential new source of geothermal heat. If a cold-fusion-like process occurs within the Earth, then a test for its existence would be a search for anomalous tritium in volcanic emissions. The Pu'u O'o crater is the first point at which large amounts of water are degassed from the magma that feeds the Kilauea system. The magma is probably not contaminated by meteoric-source ground water prior to degassing at Pu'u O'o, although mixing of meteoric and magmatic H2O occurs within the crater. Tritium contents of samples from within the crater are lower than in samples taken simultaneously from the nearby upwind crater rim. These results provide no evidence in support of a cold-fusion-like process in the Earth's interior. ?? 1991.

  19. Crater studies: Part A: lunar crater morphometry

    USGS Publications Warehouse

    Pike, Richard J.

    1973-01-01

    Morphometry, the quantitative study of shape, complements the visual observation and photointerpretation in analyzing the most outstanding landforms of the Moon, its craters (refs. 32-1 and 32-2). All three of these interpretative tools, which were developed throughout the long history of telescopic lunar study preceding the Apollo Program, will continue to be applicable to crater analysis until detailed field work becomes possible. Although no large (>17.5 km diameter) craters were examined in situ on any of the Apollo landings, the photographs acquired from the command modules will markedly strengthen results of less direct investigations of the craters. For morphometry, the most useful materials are the orbital metric and panoramic photographs from the final three Apollo missions. These photographs permit preparation of contour maps, topographic profiles, and other numerical data that accurately portray for the first time the surface geometry of lunar craters of all sizes. Interpretations of craters no longer need be compromised by inadequate topographic data. In the pre-Apollo era, hypotheses for the genesis of lunar craters usually were constructed without any numerical descriptive data. Such speculations will have little credibility unless supported by accurate, quantitative data, especially those generated from Apollo orbital photographs. This paper presents a general study of the surface geometry of 25 far-side craters and a more detailed study of rim-crest evenness for 15 near-side and far-side craters. Analysis of this preliminary sample of Apollo 15 and 17 data, which includes craters between 1.5 and 275 km in diameter, suggests that most genetic interpretations of craters made from pre-Apollo topographic measurements may require no drastic revision. All measurements were made from topographic profiles generated on a stereoplotter at the Photogrammetric Unit of the U.S. Geological Survey, Center of Astrogeology, Flagstaff, Arizona.

  20. One-Electron Oxidation of [M(P(t) Bu3 )2 ] (M=Pd, Pt): Isolation of Monomeric [Pd(P(t) Bu3 )2 ](+) and Redox-Promoted C-H Bond Cyclometalation.

    PubMed

    Troadec, Thibault; Tan, Sze-Yin; Wedge, Christopher J; Rourke, Jonathan P; Unwin, Patrick R; Chaplin, Adrian B

    2016-03-07

    Oxidation of zero-valent phosphine complexes [M(P(t) Bu3 )2 ] (M=Pd, Pt) has been investigated in 1,2-difluorobenzene solution using cyclic voltammetry and subsequently using the ferrocenium cation as a chemical redox agent. In the case of palladium, a mononuclear paramagnetic Pd(I) derivative was readily isolated from solution and fully characterized (EPR, X-ray crystallography). While in situ electrochemical measurements are consistent with initial one-electron oxidation, the heavier congener undergoes C-H bond cyclometalation and ultimately affords the 14 valence-electron Pt(II) complex [Pt(κ(2) PC -P(t) Bu2 CMe2 CH2 )(P(t) Bu3 )](+) with concomitant formation of [Pt(P(t) Bu3 )2 H](+) . © 2016 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.

  1. Centrifuge Impact Cratering Experiments

    NASA Technical Reports Server (NTRS)

    Schmidt, R. M.; Housen, K. R.; Bjorkman, M. D.

    1985-01-01

    The kinematics of crater growth, impact induced target flow fields and the generation of impact melt were determined. The feasibility of using scaling relationships for impact melt and crater dimensions to determine impactor size and velocity was studied. It is concluded that a coupling parameter determines both the quantity of melt and the crater dimensions for impact velocities greater than 10km/s. As a result impactor radius, a, or velocity, U cannot be determined individually, but only as a product in the form of a coupling parameter, delta U micron. The melt volume and crater volume scaling relations were applied to Brent crater. The transport of melt and the validity of the melt volume scaling relations are examined.

  2. Coordination polyhedron and chemical vapor deposition of Cu(hfacac)2(t-BuNH2).

    PubMed

    Woo, Kyoungja; Paek, Hojeong; Lee, Wan In

    2003-10-06

    A new pentacoordinate Cu(II) complex, Cu(hfacac)(2)(t-BuNH(2)) [hfacac = CF(3)C(O)CHC(O)CF(3)(-), t-BuNH(2) = tert-butylamine], has been synthesized and structurally characterized. Interestingly, the structure of a single crystal occurred as square pyramidal with one O atom at the apical position and one N and three O atoms at the basal positions, showing a serious degree of distortion. This contrasts with the square-pyramidal structure of Cu(hfacac)(2)L (L = H(2)O and pyrazine), which has the L ligand at the axial position. In the Cu(hfacac)(2)(t-BuNH(2)) complex, the t-BuNH(2) ligand is placed at an equatorial position with a lowered angle by 19.9(2) degrees from the basal plane. This distortion seems to reduce sigma influence and steric hindrance and so stabilizes the square-pyramidal geometry. This precursor has a lower melting point and superior stability to air, moisture, and heat than the Cu(hfacac)(2)(xH(2)O) precursor. The deposition rate of copper oxide film on a Pt layer above 450 degrees C was nearly constant with increasing temperature, indicating a mass transport limited reaction. Therefore it would be a useful metal organic chemical vapor deposition precursor for the fabrication of copper oxide film or superconducting materials. Crystal data for Cu(hfacac)(2)(t-BuNH(2)): 293(2) K, a = 9.6699(4) A, b = 18.0831(10) A, c = 12.8864(11) A, beta = 111.839(5) degrees, monoclinic, space group P2(1)/c, Z = 4.

  3. Controlled Pd(0)/t Bu3P Catalyzed Suzuki Cross-Coupling Polymerization of AB-Type Monomers with ArPd(t Bu3P)X or Pd2(dba)3/t Bu3P/ArX as the Initiator

    DOE PAGES

    Zhang, Honghai; Xing, Chun-Hui; Hu, Qiao-Sheng; ...

    2015-02-05

    The synthesis of well-defined and functionalized conjugated polymers, which are essential in the development of efficient organic electronics, through Suzuki cross-coupling polymerizations has been a challenging task. We developed controlled Pd(0)/t-Bu3P-catalyzed Suzuki cross-coupling polymerizations of AB-type monomers via the chain-growth mechanism with a series of in situ generated ArPd(t-Bu3P)X (X = I, Br, Cl) complexes as initiators. Among them, the combinations of Pd2(dba)3/t-Bu3P/p-BrC6H4I, Pd2(dba)3/t-Bu3P/p-BrC6H4CH2OH and Pd2(dba)3/t-Bu3P/p-PhCOC6H4Br were identified as highly robust initiator systems, resulting in polymers with predictable molecular weight and narrow polydispersity (PDI~1.13-1.20). In addition, Pd2(dba)3/t-Bu3P/p-BrC6H4CH2OH and Pd2(dba)3/t-Bu3P/p-PhCOC6H4Br initiator systems afforded functional polymers with >95% fidelity. Our results pavedmore » the road to access well-defined conjugated polymers, including conjugated polymers with complex polymer architectures such as block copolymers and branch copolymers.« less

  4. Crustal subsidence rate off Hawaii determined from sup 234 U/ sup 238 U ages of drowned coral reefs

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Ludwig, K.R.; Szabo, B.J.; Simmons, K.R.

    1991-02-01

    A series of submerged coral reefs off northwestern Hawaii was formed during (largely glacial) intervals when the rate of local sea-level rise was less than the maximum upward growth rate of the reefs. Mass-spectrometric {sup 234}U/{sup 238}U ages for samples from six such reefs range from 17 to 475 ka and indicate that this part of the Hawaiian Ridge has been subsiding at a roughly uniform rate of 2.6 mm/yr for the past 475 ka. The {sup 234}U/{sup 238}U ages are in general agreement with model ages of reef drowning (based on estimates of paleo-sea-level stands derived from oxygen-isotope ratiosmore » of deep-sea sediments), but there are disagreements in detail. The high attainable precision ({plus minus}10 ka or better on samples younger than {approximately}800 ka), large applicable age range, relative robustness against open-system behavior, and ease of analysis for this technique hold great promise for future applications of dating of 50-1,000 ka coral.« less

  5. Buckets of ash track tephra flux from Halema'uma'u Crater, Hawai'i

    USGS Publications Warehouse

    Swanson, Don; Wooten, Kelly M.; Orr, Tim R.

    2009-01-01

    The 2008–2009 eruption at Kīlauea Volcano's summit made news because of its eight small discrete explosive eruptions and noxious volcanic smog (vog) created from outgassing sulfur dioxide. Less appreciated is the ongoing, weak, but continuous output of tephra, primarily ash, from the new open vent in Halema'uma'u Crater. This tephra holds clues to processes causing the eruption and forming the new crater-in-a-crater, and its flux is important to hazard evaluations.The setting of the vent–easily accessible from the Hawaiian Volcano Observatory (HVO)—is unusually favorable for neardaily tracking of tephra mass flux during this small prolonged basaltic eruption. Recognizing this, scientists from HVO are collecting ash and documenting how ejection masses, components, and chemical compositions vary through time.

  6. A history of the Lonar crater, India: An overview

    NASA Technical Reports Server (NTRS)

    Nayak, V. K.

    1992-01-01

    The origin of the circular structure at Lonar, India, described variously as cauldron, pit, hollow, depression, and crater, has been a controversial subject since the early nineteenth century. A history of its origin and other aspects from 1823 to 1990 are overviewed. The structure in the Deccan Trap Basalt is nearly circular with a breach in the northeast, 1830 m in diameter, 150 m deep, with a saline lake in the crater floor. Over the years, the origin of the Lonar structure has risen from volcanism, subsidence, and cryptovolcanism to an authentic meteorite impact crater. Lonar is unique because it is probably the only terrestrial crater in basalt and is the closest analog with the Moon's craters. Some unresolved questions are suggested. The proposal is made that the young Lonar impact crater, which is less than 50,000 years old, should be considered as the best crater laboratory analogous to those of the Moon, be treated as a global monument, and preserved for scientists to comprehend more about the mysteries of nature and impact cratering, which is now emerging as a fundamental ubiquitous geological process in the evolution of the planets.

  7. Study of the crater deformation of the CODELCO/Andina mine using the satellite and ground data

    NASA Astrophysics Data System (ADS)

    Caverlotti-Silva, M. A.; Arellano-Baeza, A. A.

    2011-12-01

    The correct monitoring of the subsidence of the craters related to the underground mine exploitation is one of the most important endeavors of the satellite remote sensing. The ASTER and LANDSAT satellite images have been used to study the deformation of the crater of the CODELCO/Andina mine, Valparaiso Region, Chile. The high-resolution satellite images were used to detect changes in the lineament patterns related to the subsidence. These results were compared with the ground deformation extracted from the GPS and topography station networks. It was found that sudden changes in the lineament patterns appear when the ground deformation overcomes a definite threshold.

  8. Discriminative stimulus effects of the imidazoline I2 receptor ligands BU224 and phenyzoline in rats.

    PubMed

    Qiu, Yanyan; Zhang, Yanan; Li, Jun-Xu

    2015-02-15

    Although imidazoline I2 receptor ligands have been used as discriminative stimuli, the role of efficacy of I2 receptor ligands as a critical determinant in drug discrimination has not been explored. This study characterized the discriminative stimulus effects of selective imidazoline I2 receptor ligands BU224 (a low-efficacy I2 receptor ligand) and phenyzoline (a higher efficacy I2 receptor ligand) in rats. Two groups of male Sprague-Dawley rats were trained to discriminate 5.6mg/kg BU224 or 32mg/kg phenyzoline (i.p.) from their vehicle in a two-lever food-reinforced drug discrimination procedure, respectively. All rats acquired the discriminations after an average of 18 (BU224) and 56 (phenyzoline) training sessions, respectively. BU224 and phenyzoline completely substituted for one another symmetrically. Several I2 receptor ligands (tracizoline, CR4056, RS45041, and idazoxan) all occasioned>80% drug-associated lever responding in both discriminations. The I2 receptor ligand 2-BFI and a monoamine oxidase inhibitor harmane occasioned>80% drug-associated lever responding in rats discriminating BU224. Other drugs that occasioned partial or less substitution to BU224 cue included clonidine, methamphetamine, ketamine, morphine, methadone and agmatine. Clonidine, methamphetamine and morphine also only produced partial substitution to phenyzoline cue. Naltrexone, dopamine D2 receptor antagonist haloperidol and serotonin (5-HT)2A receptor antagonist MDL100907 failed to alter the discriminative stimulus effects of BU224 or phenyzoline. Combined, these results are the first to demonstrate that BU224 and phenyzoline can serve as discriminative stimuli and that the low-efficacy I2 receptor ligand BU224 shares similar discriminative stimulus effects with higher-efficacy I2 receptor ligands such as phenyzoline and 2-BFI. Copyright © 2015 Elsevier B.V. All rights reserved.

  9. The first five years of Kīlauea’s summit eruption in Halema‘uma‘u Crater, 2008–2013

    USGS Publications Warehouse

    Patrick, Matthew R.; Orr, Tim R.; Sutton, A.J.; Elias, Tamar; Swanson, Donald A.

    2013-01-01

    The eruption in Halema‘uma‘u Crater that began in March 2008 is the longest summit eruption of Kīlauea Volcano, on the Island of Hawai‘i, since 1924. From the time the eruption began, the new "Overlook crater" inside Halema‘uma‘u has exhibited fluctuating lava lake activity, occasional small explosive events, and a persistent gas plume. The beautiful nighttime glow impresses and thrills visitors in Hawai‘i Volcanoes National Park, but the continuous emission of sulfur dioxide gas produces "vog" (volcanic smog) that can severely affect communities and local agriculture downwind. U.S. Geological Survey scientists continue to closely monitor the eruption and assess ongoing hazards.

  10. Geological mapping of lunar highland crater Lalande: Topographic configuration, morphology and cratering process

    NASA Astrophysics Data System (ADS)

    Li, Bo; Ling, Zongcheng; Zhang, Jiang; Chen, Jian; Liu, ChangQing; Bi, Xiangyu

    2018-02-01

    Highland crater Lalande (4.45°S, 8.63°W; D = 23.4 km) is located on the PKT area of the lunar near side, southeast of the Mare Insularum. It is a complex crater in Copernican era and has three distinguishing features: high silicic anomaly, the highest Th abundance and special landforms on its floor. There are some low-relief bulges on the left of Lalande's floor with regular circle or ellipse shapes. They are ∼250-680 m wide and ∼30-91 m high with maximum flank slopes >20°. There are two possible scenarios for the formation of these low-relief bulges which are impact melt products or young silicic volcanic eruptions. We estimated the absolute model ages of the ejecta deposits, several melt ponds and the hummocky floor and determined the ratio of diameter and depth of the crater Lalande. In addition, we found some similar bugle features within other Copernican-aged craters and there were no volcanic source vents on Lalande's floor. Thus, we hypothesized that these low-relief bulges were most consistent with an origin of impact melts during the crater formation instead of small and young volcanic activities occurring on the floor. Based on Kaguya Terrain Camera (TC) ortho-mosaic and Digital Terrain Model (DTM) data produced by TC imagery in stereo, geological units and some linear features on the floor and wall of Lalande have been mapped. Eight geological units are organized by crater floor units: hummocky floor, central peak and low-relief bulges; and crater wall units: terraced walls, channeled and veneered walls, interior walls, mass wasting areas, blocky areas, and melt ponds. These geological units and linear features provided us a chance to understand some details of the cratering process and elevation differences on the floor. We proposed that subsidence due to melt cooling, late-stage wall collapse and rocks uplifted from beneath the surface could be the possible causes of the observed elevation differences on Lalande's floor.

  11. Synthesis of Au38(SCH2CH2Ph)24, Au36(SPh-tBu)24, and Au30(S-tBu)18 Nanomolecules from a Common Precursor Mixture.

    PubMed

    Rambukwella, Milan; Dass, Amala

    2017-10-17

    Phenylethanethiol protected nanomolecules such as Au 25 , Au 38 , and Au 144 are widely studied by a broad range of scientists in the community, owing primarily to the availability of simple synthetic protocols. However, synthetic methods are not available for other ligands, such as aromatic thiol and bulky ligands, impeding progress. Here we report the facile synthesis of three distinct nanomolecules, Au 38 (SCH 2 CH 2 Ph) 24 , Au 36 (SPh-tBu) 24 , and Au 30 (S-tBu) 18 , exclusively, starting from a common Au n (glutathione) m (where n and m are number of gold atoms and glutathiolate ligands) starting material upon reaction with HSCH 2 CH 2 Ph, HSPh-tBu, and HStBu, respectively. The systematic synthetic approach involves two steps: (i) synthesis of kinetically controlled Au n (glutathione) m crude nanocluster mixture with 1:4 gold to thiol molar ratio and (ii) thermochemical treatment of the purified nanocluster mixture with excess thiols to obtain thermodynamically stable nanomolecules. Thermochemical reactions with physicochemically different ligands formed highly monodispersed, exclusively three different core-size nanomolecules, suggesting a ligand induced core-size conversion and structural transformation. The purpose of this work is to make available a facile and simple synthetic method for the preparation of Au 38 (SCH 2 CH 2 Ph) 24 , Au 36 (SPh-tBu) 24 , and Au 30 (S-tBu) 18 , to nonspecialists and the broader scientific community. The central idea of simple synthetic method was demonstrated with other ligand systems such as cyclopentanethiol (HSC 5 H 9 ), cyclohexanethiol(HSC 6 H 11 ), para-methylbenzenethiol(pMBT), 1-pentanethiol(HSC 5 H 11 ), 1-hexanethiol(HSC 6 H 13 ), where Au 36 (SC 5 H 9 ) 24 , Au 36 (SC 6 H 11 ) 24 , Au 36 (pMBT) 24 , Au 38 (SC 5 H 11 ) 24 , and Au 38 (SC 6 H 13 ) 24 were obtained, respectively.

  12. Craters and Granular Jets Generated by Underground Cavity Collapse

    NASA Astrophysics Data System (ADS)

    Loranca-Ramos, F. E.; Carrillo-Estrada, J. L.; Pacheco-Vázquez, F.

    2015-07-01

    We study experimentally the cratering process due to the explosion and collapse of a pressurized air cavity inside a sand bed. The process starts when the cavity breaks and the liberated air then rises through the overlying granular layer and produces a violent eruption; it depressurizes the cavity and, as the gas is released, the sand sinks under gravity, generating a crater. We find that the crater dimensions are totally determined by the cavity volume; the pressure does not affect the morphology because the air is expelled vertically during the eruption. In contrast with impact craters, the rim is flat and, regardless of the cavity shape, it evolves into a circle as the cavity depth increases or if the chamber is located deep enough inside the bed, which could explain why most of the subsidence craters observed in nature are circular. Moreover, for shallow spherical cavities, a collimated jet emerges from the collision of sand avalanches that converge concentrically at the bottom of the depression, revealing that collapse under gravity is the main mechanism driving the jet formation.

  13. Landslide and Land Subsidence Hazards to Pipelines

    USGS Publications Warehouse

    Baum, Rex L.; Galloway, Devin L.; Harp, Edwin L.

    2008-01-01

    Landslides and land subsidence pose serious hazards to pipelines throughout the world. Many existing pipeline corridors and more and more new pipelines cross terrain that is affected by either landslides, land subsidence, or both. Consequently the pipeline industry recognizes a need for increased awareness of methods for identifying and evaluating landslide and subsidence hazard for pipeline corridors. This report was prepared in cooperation with the U.S. Department of Transportation Pipeline and Hazardous Materials Safety Administration, and Pipeline Research Council International through a cooperative research and development agreement (CRADA) with DGH Consulting, Inc., to address the need for up-to-date information about current methods to identify and assess these hazards. Chapters in this report (1) describe methods for evaluating landslide hazard on a regional basis, (2) describe the various types of land subsidence hazard in the United States and available methods for identifying and quantifying subsidence, and (3) summarize current methods for investigating individual landslides. In addition to the descriptions, this report provides information about the relative costs, limitations and reliability of various methods.

  14. Energies and excited-state dynamics of 1Bu+, 1Bu- and 3Ag- states of carotenoids bound to LH2 antenna complexes from purple photosynthetic bacteria

    NASA Astrophysics Data System (ADS)

    Christiana, Rebecca; Miki, Takeshi; Kakitani, Yoshinori; Aoyagi, Shiho; Koyama, Yasushi; Limantara, Leenawaty

    2009-10-01

    Time-resolved pump-probe stimulated-emission and transient-absorption spectra were recorded after excitation with ˜30 fs pulses to the 1Bu+(0) and optically-forbidden diabatic levels of carotenoids, neurosporene, spheroidene and lycopene having n = 9-11 double bonds, bound to LH2 antenna complexes from Rhodobacter sphaeroides G1C, 2.4.1 and Rhodospirillum molischianum. The low-energy shift of stimulated emission from the covalent 1Bu-(0) and 3Ag-(0) levels slightly larger than that from the ionic 1Bu+(0) state suggests the polarization, whereas more efficient triplet generation suggests the twisting of the conjugated chain in Cars bound to the LH2 complexes, when compared to Cars free in solution.

  15. Substitution and Redox Chemistry of [Bu(4)N](2)[Ta(6)Cl(12)(OSO(2)CF(3))(6)].

    PubMed

    Prokopuk, Nicholas; Kennedy, Vance O.; Stern, Charlotte L.; Shriver, Duward F.

    1998-09-21

    Two sequential electrochemical reductions occur for the cluster anion [Ta(6)Cl(12)(OSO(2)CF(3))(6)](2)(-) at 0.89 and 0.29 V vs Ag/AgCl, with the generation [Ta(6)Cl(12)(OSO(2)CF(3))(6)](3)(-) and [Ta(6)Cl(12)(OSO(2)CF(3))(6)](4)(-). Chemical reduction of [Ta(6)Cl(12)(OSO(2)CF(3))(6)](2)(-) by ferrocene produces [Ta(6)Cl(12)(OSO(2)CF(3))(6)](3)(-) with the concomitant shift of the nu(SO(2)) stretch from 1002 to 1018 cm(-)(1). Reaction of [Bu(4)N](2)[Ta(6)Cl(12)(OSO(2)CF(3))(6)] (1) with [Bu(4)N]X (X = Cl, Br, I, NCS) occurs by reduction and substitution, yielding [Bu(4)N](3)[Ta(6)Cl(12)X(6)], where the clusters with X = Br, I, and NCS are new. Spectroscopic (IR and UV-vis) evidence indicates that the reduced cluster core {Ta(6)Cl(12)}(2+) is produced in reaction mixtures of 1 with the halide and pseudohalide ions. Concomitant substitution of the triflate ligands of 1 by X(-) occurs and the rates for the overall reduction and substitution increase in the order X(-) = Cl(-) < Br(-) < NCS(-) < I(-) < CN(-). Reduction of 1 with ferrocene followed by addition of [Bu(4)N]O(2)CCH(3) produces the new cluster [Ta(6)Cl(12)(O(2)CCH(3))(6)](3)(-) isolated as the tetrabutylammonium salt. Cyclic voltammetry and UV-vis spectroscopy on the new clusters [Bu(4)N](3)[Ta(6)Cl(12)X(6)] (X = Br, I, NCS, and O(2)CCH(3)) are reported. Crystal data for [Bu(4)N](3)[Ta(6)Cl(12)(NCS)(6)].CH(2)Cl(2): monoclinic, space group, P2(1)/c (No. 14); a = 25.855(6) Å, b = 21.843(6) Å, c = 16.423(3) Å; beta = 100.03(2) degrees; V = 9133(3) Å(3); Z = 4.

  16. Sub-surface structures and collapse mechanisms of summit pit craters

    NASA Astrophysics Data System (ADS)

    Roche, O.; van Wyk de Vries, B.; Druitt, T. H.

    2001-01-01

    Summit pit craters are found in many types of volcanoes and are generally thought to be the product of collapse into an underpressured reservoir caused by magma withdrawal. We investigate the mechanisms and structures associated with summit pit crater formation by scaled analogue experiments and make comparisons with natural examples. Models use a sand plaster mixture as analogue rock over a cylinder of silicone simulating an underpressured magma reservoir. Experiments are carried out using different roof aspect ratios (roof thickness/roof width) of 0.2-2. They reveal two basic collapse mechanisms, dependant on the roof aspect ratio. One occurs at low aspect ratios (≤1), as illustrated by aspect ratios of 0.2 and 1. Outward dipping reverse faults initiated at the silicone margins propagates through the entire roof thickness and cause subsidence of a coherent block. Collapse along the reverse faults is accommodated by marginal flexure of the block and tension fractures at the surface (aspect ratio of 0.2) or by the creation of inward dipping normal faults delimiting a terrace (aspect ratio of 1). At an aspect ratio of 1, overhanging pit walls are the surface expressions of the reverse faults. Experiments at high aspect ratio (>1.2) reveal a second mechanism. In this case, collapse occurs by stopping, which propagates upwards by a complex pattern of both reverse faults and tension fractures. The initial underground collapse is restricted to a zone above the reservoir and creates a cavity with a stable roof above it. An intermediate mechanism occurs at aspect ratios of 1.1-1.2. In this case, stopping leads to the formation of a cavity with a thin and unstable roof, which collapses suddenly. The newly formed depression then exhibits overhanging walls. Surface morphology and structure of natural examples, such as the summit pit craters at Masaya Volcano, Nicaragua, have many of the features created in the models, indicating that the internal structural geometry of

  17. Secondary Craters

    NASA Image and Video Library

    2016-12-21

    This image of a southern mid-latitude crater was intended to investigate the lineated material on the crater floor. At the higher resolution of HiRISE, the image reveals a landscape peppered by small impact craters. These craters range from about 30 meters in diameter down to the resolution limit (about 2 meter diameter in this image acquired by averaging 2x2 picture elements). Such dense clusters of small craters are frequently formed by secondary craters, caused by the impact of material that was excavated and ejected from the surface of Mars during the creation of a larger nearby crater by the impact of a comet or an asteroid. Secondary impact craters are both interesting and vexing. They are interesting because they show the trajectories of the material that was ejected from the primary impact with the greatest speeds, typically material from near the surface of the blast zone. Secondary craters are often found along the traces of crater rays, linear features that extend radially from fresh impact craters and can reach many crater diameters in length. Secondary craters can be useful when crater rays are visible and the small craters can be associated with a particular primary impact crater. They can be used to constrain the age of the surface where they fell, since the surface must be older than the impact event. The age of the crater can be approximately estimated from the probability of an impact that produced a crater of such a size within a given area of Mars over a given time period. But these secondary craters can also be perplexing when no crater rays are preserved and a source crater is not easily identifiable, as is the case here. The impact that formed these secondary craters took place long enough ago that their association with a particular crater has been erased. They do not appear along the trace of a crater ray that is still apparent in visible or thermal infrared observations. These secondary craters complicate the task of estimating the age of

  18. Geological Mapping of Impact Melt Deposits at Lunar Complex Craters: New Insights into Morphological Diversity, Distribution and the Cratering Process

    NASA Astrophysics Data System (ADS)

    Dhingra, D.; Head, J. W., III; Pieters, C. M.

    2014-12-01

    We have completed high resolution geological mapping of impact melt deposits at the young lunar complex craters (<1 billion years) Copernicus, Jackson and Tycho using data from recent missions. Crater floors being the largest repository of impact melt, we have mapped their morphological diversity expressed in terms of varied surface texture, albedo, character and occurrence of boulder units as well as relative differences in floor elevation. Examples of wall and rim impact melt units and their relation to floor units have also been mapped. Among the distinctive features of these impact melt deposits are: 1) Impact Melt Wave Fronts: These are extensive (sometimes several kilometers in length) and we have documented their occurrence and distribution in different parts of the crater floor at Jackson and Tycho. These features emphasize melt mobility and style of emplacement during the modification stage of the craters. 2) Variations in Floor Elevations: Spatially extensive and coherent sections of crater floors have different elevations at all the three craters. The observed elevation differences could be caused by subsidence due to cooling of melt and/or structural failure, together with a contribution from regional slope. 3) Melt-Covered Megablocks: We also observe large blocks/rock-fragments (megablocks) covered in impact melt, which could be sections of collapsed wall or in some cases, subdued sections of central peaks. 4) Melt-Covered Central Peaks: Impact melt has also been mapped on the central peaks but varies in spatial extent among the craters. The presence of melt on peaks must be taken into account when interpreting peak mineralogy as exposures of deeper crust. 5) Boulder Distribution: Interesting trends are observed in the distribution of boulder units of various sizes; some impact melt units have spatially extensive boulders, while boulder distribution is very scarce in other units on the floor. We interpret these distributions to be influenced by a) the

  19. IR Spectra of n-Bu4M (M = Si, Ge, Sn, Pb), n-BuAuPPh3-d15, and "n-Bu" on a Gold Surface.

    PubMed

    Kaleta, Jiří; Bednárová, Lucie; Čížková, Martina; Wen, Jin; Kaletová, Eva; Michl, Josef

    2017-06-22

    Observed and DFT-calculated IR spectra of n-Bu 4 M (M = Si, Ge, Sn, Pb), (CH 3 CH 2 CH 2 13 CD 2 ) 4 Sn, and n-BuAuPPh 3 -d 15 are reported and assigned. The asymmetric CH stretching vibration of the CH 2 group adjacent to the metal atom appears as a distinct shoulder at ∼2934 cm -1 , whereas for other CH 2 groups it is located at ∼2922 cm -1 . The characteristic peak at ∼2899 cm -1 is attributed to an overtone of a symmetric CH 2 bend at ∼1445 cm -1 . In n-BuAuPPh 3 -d 15 , the CH stretching vibrations of the butyl group are shifted to lower frequencies by ∼10 cm -1 , and two possible rationalizations are offered.

  20. Impact cratering calculations

    NASA Technical Reports Server (NTRS)

    Ahrens, Thomas J.; Okeefe, J. D.; Smither, C.; Takata, T.

    1991-01-01

    In the course of carrying out finite difference calculations, it was discovered that for large craters, a previously unrecognized type of crater (diameter) growth occurred which was called lip wave propagation. This type of growth is illustrated for an impact of a 1000 km (2a) silicate bolide at 12 km/sec (U) onto a silicate half-space at earth gravity (1 g). The von Misses crustal strength is 2.4 kbar. The motion at the crater lip associated with this wave type phenomena is up, outward, and then down, similar to the particle motion of a surface wave. It is shown that the crater diameter has grown d/a of approximately 25 to d/a of approximately 4 via lip propagation from Ut/a = 5.56 to 17.0 during the time when rebound occurs. A new code is being used to study partitioning of energy and momentum and cratering efficiency with self gravity for finite-sized objects rather than the previously discussed planetary half-space problems. These are important and fundamental subjects which can be addressed with smoothed particle hydrodynamic (SPH) codes. The SPH method was used to model various problems in astrophysics and planetary physics. The initial work demonstrates that the energy budget for normal and oblique impacts are distinctly different than earlier calculations for silicate projectile impact on a silicate half space. Motivated by the first striking radar images of Venus obtained by Magellan, the effect of the atmosphere on impact cratering was studied. In order the further quantify the processes of meteor break-up and trajectory scattering upon break-up, the reentry physics of meteors striking Venus' atmosphere versus that of the Earth were studied.

  1. Modeling Recent Subsidence of Mars' Olympus Mons Using Lava Flows as Paleo-Slope Indicators

    NASA Astrophysics Data System (ADS)

    Simpson, M.; Reeves, A.; Chadwick, J.; McGovern, P. J.

    2013-12-01

    Olympus Mons is an enormous volcanic edifice on Mars with a basal diameter over 600 km and a height of 23 km. In spite of this size, no indications of subsidence, such as an obvious topographic moat, have previously been detected around the volcano. In this study, we mapped the orientations of long, thin lava flows on the plains to the south and southeast of Olympus Mons using 100m-resolution imagery from the Thermal Emission Imaging System (THEMIS) on Mars Odyssey, and topography using Mars Orbiter Laser Altimeter (MOLA) data from Mars Global Surveyor. The results show that the flows are no longer oriented in a downhill direction, consistently deviating from modern slope vectors in a counterclockwise direction by 21.4 × 10.8 degrees (n = 65). The configuration of this misalignment between modern and paleo-topography is consistent with subsidence centered on the volcano in the time since the flows were emplaced. Our preliminary geophysical modeling used a range of load volumes, load radii, and lithospheric thicknesses to identify the scenario required to best restore modern topography to match the paleo-topography present when the lava flows were emplaced (i.e. 'uplift' Olympus Mons until the lava flows on the surrounding plains are restored to a downhill direction). The results show that lithospheric subsidence of about 1.2 km due to the magmatic addition of 3.8x10^5 km^3 best fits the observed topographic changes. Load center heights of 1 to 8 km were considered, with best fits generally in the 3-5 km range. Best-fit elastic lithosphere thickness (Te) values were generally 100 km or greater, consistent with estimates for Te from loading models [1,2] and gravity-topography relationships [3,4,5]. Our new crater size-density measurements of the plains in the study area show that the observed subsidence occurred within the past 229 × 26 my. Previous crater counts for Olympus Mons calderas and lower flank flows [6] reveal volcanic activity clustered around 100

  2. Subsidence in tropical peatlands: Estimating CO2 fluxes from peatlands in Southeast Asia

    NASA Astrophysics Data System (ADS)

    Hoyt, A.; Harvey, C. F.; Seppalainen, S. S.; Chaussard, E.

    2017-12-01

    Tropical peatlands of Southeast Asia are an important global carbon stock. However, they are being rapidly deforested and drained. Peatland drainage facilitates peat decomposition, releases sequestered peat carbon to the atmosphere as CO2, and leads to subsidence of the peat surface. As a result, subsidence measurements can be used to monitor peatland carbon loss over time. Until now, subsidence measurements have been primarily limited to ground-based point measurements using subsidence poles. Here we demonstrate a powerful method to measure peatland subsidence rates across much larger areas than ever before. Using remotely sensed InSAR data, we map subsidence rates across thousands of square kilometers in Southeast Asia and validate our results against ground-based subsidence measurements. The method allows us to monitor subsidence in remote locations, providing unprecedented spatial information, and the first comprehensive survey of land uses such as degraded peatlands, burnt and open areas, shrub lands, and smallholder farmlands. Strong spatial patterns emerged, with the highest subsidence rates occurring at the centers of peat domes, where the peat is thickest and drainage depths are likely to be largest. Peatland subsidence rates were also strongly dependent on current and historical land use, with typical subsidence rates ranging from 2-4 cm/yr. Finally, we scaled up our results to calculate total annual emissions from peat decomposition in degraded peatlands.

  3. Imaging the Buried Chicxulub Crater with Gravity Gradients and Cenotes

    NASA Astrophysics Data System (ADS)

    Hildebrand, A. R.; Pilkington, M.; Halpenny, J. F.; Ortiz-Aleman, C.; Chavez, R. E.; Urrutia-Fucugauchi, J.; Connors, M.; Graniel-Castro, E.; Camara-Zi, A.; Vasquez, J.

    1995-09-01

    the other terrestrial planets. A modeled fault of 1.5 km displacement (slightly slumped block exterior and impact breccia interior) reproduces the steepest gradient feature. This model is incompatible with models that place these gradient features inside the collapsed transient cavity. Locations of the karst features of the northern Yucatan region were digitized from 1:50,000 topographic maps, which show most but not all the water-filled sinkholes (locally known as cenotes). A prominent ring of cenotes is visible over the crater that is spatially correlated to the outer steep gravity gradient feature. The mapped cenotes constitute an unbiased sampling of the region's karst surface features of >50 m diameter. The gradient maximum and the cenote ring both meander with amplitudes of up to 2 km. The wiggles in the gradient feature and the cenote distribution probably correspond to the "scalloping" observed at the headwall of terraces in large complex craters. A second partial cenote ring exterior to the southwest side of the main ring corresponds to a less-prominent gravity gradient feature. No concentric structure is observable in the distribution of karst features at radii >90 km. The cenote ring is bounded by the outer peripheral steep gradient feature and must be related to it; the slump faults must have been reactivated sufficiently to create fracturing in the overlying and much younger sediment. Long term subsidence, as found at other terrestrial craters is a possible mechanism for the reactivation. Such long term subsidence may be caused by differential compaction or thermal relaxation. Elevations acquired during gravity surveys show that the cenote ring also corresponds to a topographic low along some of its length that probably reflects preferential erosion.

  4. Late Pleistocene eruptive history of the Mono Craters rhyolites, eastern California, from U-Th dating of explosive and effusive products

    NASA Astrophysics Data System (ADS)

    Marcaida, M.; Vazquez, J. A.; Calvert, A. T.; Miller, J. S.

    2016-12-01

    During late Pleistocene-Holocene time, repeated explosive and effusive eruptions of high-silica rhyolite magma south of Mono Lake, California, have produced a chain of massive domes known as the Mono Craters and a time-series of tephra deposits preserved in sediments of the Wilson Creek formation of ancestral Mono Lake. The record of late Holocene volcanism at Mono Craters is relatively well constrained by tephrostratigraphy and 14C dating, and the timing of late Pleistocene eruptions is similarly well constrained by tephrochronology and magnetostratigraphy of the Wilson Creek formation. However, the chronology of eruptions for the Mono Craters chain, comprising at least 28 individual domes, has thus far been based on age estimates from hydration rind dating of obsidian that is highly dependent on local calibration. We constrain the timing of late Pleistocene dome emplacement by linking independently dated Wilson Creek tephras to their dome equivalents in the Mono Craters using combined titanomagnetite geochemistry and U-Th geochronology. Ion microprobe 238U-230Th dating of unpolished allanite and zircon rims gives isochron dates of ca. 42 ka, ca. 38 ka, ca. 26 ka, and ca. 20 ka for domes 19, 24, 31 (newly recognized), and 11 of the Mono Craters, respectively. These domes are biotite-bearing rhyolites with titanomagnetites that are compositionally identical to those from several Wilson Creek tephras. Specifically, we correlate Ash 15, Ash 7, and Ash 3 of the Wilson Creek formation to domes 19, 31, and 11 of the Mono Craters, respectively, based on matching titanomagnetite compositions and indistinguishable U-Th ages. 40Ar/39Ar dating of single sanidines from domes 19 and 31 yield mean dates that are 10 k.y. older than their corresponding U-Th dates, likely due to excess argon from melt inclusions and/or incompletely re-equilibrated antecrysts. Based on our new U-Th isochron date of ca. 34 ka for allanite-zircon from Ash 8 pumice and the ca. 26-27 ka age of Ash 7

  5. Post-Closure Inspection and Monitoring Report for Corrective Action Unit 110: Area 3 WMD U-3ax/bl Crater, Nevada Test Site, Nevada

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    NSTec Environmental Restoration

    2006-08-01

    This Post-Closure Inspection and Monitoring Report (PCIMR) provides the results of inspections and monitoring for Corrective Action Unit (CAU) 110, Area 3 WMD [Waste Management Division] U-3ax/bl Crater. This PCIMR includes an analysis and summary of the site inspections, repairs and maintenance, meteorological information, and soil moisture monitoring data obtained at CAU 110, for the annual period July 2005 through June 2006. Site inspections of the cover were performed quarterly to identify any significant changes to the site requiring action. The overall condition of the cover, cover vegetation, perimeter fence, and UR warning signs was good. Settling was observed thatmore » exceeded the action level as specified in Section VILB.7 of the Hazardous Waste Permit Number NEV HW009 (Nevada Division of Environmental Protection, 2000). This permit states that cracks or settling greater than 15 centimeters (6 inches) deep that extend 1.0 meter (m) (3 feet [ft]) or more on the cover will be evaluated and repaired within 60 days of detection. Along the east edge of the cover (repaired previously in August 2003, December 2003, May 2004, October 2004), an area of settling was observed during the December 2005 inspection to again be above the action level, and required repair. This area and two other areas of settling on the cover that were first observed during the December 2005 inspection were repaired in February 2006. The semiannual subsidence surveys were done in September 2005 and March 2006. No significant subsidence was observed in the survey data. Monument 5 shows the greatest amount of subsidence (-0.015 m [-0.05 ft] compared to the baseline survey of 2000). This amount is negligible and near the resolution of the survey instruments; it does not indicate that subsidence is occurring on the cover. Soil moisture results obtained to date indicate that the CAU 110 cover is performing as expected. Time Domain Reflectometry (TDR) data indicated an increase in soil

  6. Craters on Crater

    NASA Image and Video Library

    2006-10-10

    Several craters were formed on the rim of this large crater. The movement of material downhill toward the floor of the large crater has formed interesting patterns on the floors of the smaller craters

  7. Synthesis and some coordination chemistry of the PSnP pincer-type stannylene Sn(NCH2PtBu2)2C6H4, attempts to prepare the PSiP analogue, and the effect of the E atom on the molecular structures of E(NCH2PtBu2)2C6H4 (E = C, Si, Ge, Sn).

    PubMed

    Brugos, Javier; Cabeza, Javier A; García-Álvarez, Pablo; Pérez-Carreño, Enrique; Polo, Diego

    2018-03-26

    The non-donor-stabilized PSnP pincer-type stannylene Sn(NCH2PtBu2)2C6H4 (1) has been prepared by treating SnCl2 with Li2(NCH2PtBu2)2C6H4. All attempts to synthesize the analogous PSiP silylene by reduction of the (previously unknown) silanes SiCl2(NCH2PtBu2)2C6H4 (2), SiHCl(NCH2PtBu2)2C6H4 (3) and SiH(HMDS)(NCH2PtBu2)2C6H4 (4; HMDS = N(SiMe3)2) have been unsuccessful. The almost planar (excluding the tert-butyl groups) molecular structure of stannylene 1 (determined by X-ray crystallography) has been rationalized with the help of DFT calculations, which have shown that, in the series of diphosphanetetrylenes E(NCH2PtBu2)2C6H4 (E = C, Si, Ge, Sn), the most stable conformation of the compounds with E = Ge and Sn has both P atoms very close to the EN2C6H4 plane, near (interacting with) the E atom, whereas for the compounds with E = C and Si, both phosphane groups are located at one side of the EN2C6H4 plane and far away from the E atom. The size of the E atom and the strength of stabilizing donor-acceptor PE interactions (both increase on going down in group 14) are key factors in determining the molecular structures of these diphosphanetetrylenes. The syntheses of the chloridostannyl complexes [Rh{κ2Sn,P-SnCl(NCH2PtBu2)2C6H4}(η4-cod)] (5), [RuCl{κ2Sn,P-SnCl(NCH2PtBu2)2C6H4}(η6-cym)] (6) and [IrCl{κ2Sn,P-SnCl(NCH2PtBu2)2C6H4}(η5-C5Me5)] (7) have demonstrated the tendency of stannylene 1 to insert its Sn atom into M-Cl bonds of transition metal complexes and the preference of the resulting PSnP chloridostannyl group to act as a κ2Sn,P-chelating ligand, maintaining an uncoordinated phosphane fragment. X-ray diffraction data (of 6), 31P{1H} NMR data (of 5-7) and DFT calculations (on 6) are consistent with the existence of a weak PSn interaction involving the non-coordinated P atom of complexes 5-7, similar to that found in stannylene 1.

  8. Shallow magma system of Kilauea volcano investigated using L-band synthetic aperture radar data

    NASA Astrophysics Data System (ADS)

    Fukushima, Y.; Sinnett, D. K.; Segall, P.

    2009-12-01

    indicates the followings. Pre-eruption period (9 months): 12 cm/yr of uplift in an area of a few km SW of the summit caldera and 3 cm/yr of subsidence along the ERZ between the summit and Napau craters. Co-eruption period (7 months): 15 cm of subsidence in the summit crater and a few tens of cm of uplift associated with the diking. Post-eruption period (17 months): more than 2 cm/yr of subsidence in the summit area and at least 1 cm/yr of subsidence in the Pu`u `O`o area, where the spatial extensions of the two subsiding areas are comparable. While the obtained subsidence signals can be attributed to lava compactions and to artifacts due to errors in the digital elevation model, our results may indicate a developed shallow magma reservoir under the Pu`u `O`o crater, and also smaller shallow reservoirs distributed along the ERZ between the summit and Pu`u `O`o.

  9. Tetrahalide complexes of the [U(NR)2]2+ ion: synthesis, theory, and chlorine K-edge X-ray absorption spectroscopy.

    PubMed

    Spencer, Liam P; Yang, Ping; Minasian, Stefan G; Jilek, Robert E; Batista, Enrique R; Boland, Kevin S; Boncella, James M; Conradson, Steven D; Clark, David L; Hayton, Trevor W; Kozimor, Stosh A; Martin, Richard L; MacInnes, Molly M; Olson, Angela C; Scott, Brian L; Shuh, David K; Wilkerson, Marianne P

    2013-02-13

    Synthetic routes to salts containing uranium bis-imido tetrahalide anions [U(NR)(2)X(4)](2-) (X = Cl(-), Br(-)) and non-coordinating NEt(4)(+) and PPh(4)(+) countercations are reported. In general, these compounds can be prepared from U(NR)(2)I(2)(THF)(x) (x = 2 and R = (t)Bu, Ph; x = 3 and R = Me) upon addition of excess halide. In addition to providing stable coordination complexes with Cl(-), the [U(NMe)(2)](2+) cation also reacts with Br(-) to form stable [NEt(4)](2)[U(NMe)(2)Br(4)] complexes. These materials were used as a platform to compare electronic structure and bonding in [U(NR)(2)](2+) with [UO(2)](2+). Specifically, Cl K-edge X-ray absorption spectroscopy (XAS) and both ground-state and time-dependent hybrid density functional theory (DFT and TDDFT) were used to probe U-Cl bonding interactions in [PPh(4)](2)[U(N(t)Bu)(2)Cl(4)] and [PPh(4)](2)[UO(2)Cl(4)]. The DFT and XAS results show the total amount of Cl 3p character mixed with the U 5f orbitals was roughly 7-10% per U-Cl bond for both compounds, which shows that moving from oxo to imido has little effect on orbital mixing between the U 5f and equatorial Cl 3p orbitals. The results are presented in the context of recent Cl K-edge XAS and DFT studies on other hexavalent uranium chloride systems with fewer oxo or imido ligands.

  10. Why do complex impact craters have elevated crater rims?

    NASA Astrophysics Data System (ADS)

    Kenkmann, Thomas; Sturm, Sebastian; Krueger, Tim

    2014-05-01

    Most of the complex impact craters on the Moon and on Mars have elevated crater rims like their simple counterparts. The raised rim of simple craters is the result of (i) the deposition of a coherent proximal ejecta blanket at the edge of the transient cavity (overturned flap) and (ii) a structural uplift of the pre-impact surface near the transient cavity rim during the excavation stage of cratering [1]. The latter occurs either by plastic thickening or localized buckling of target rocks, as well as by the emplacement of interthrust wedges [2] or by the injection of dike material. Ejecta and the structural uplift contribute equally to the total elevation of simple crater rims. The cause of elevated crater rims of large complex craters [3] is less obvious, but still, the rim height scales with the final crater diameter. Depending on crater size, gravity, and target rheology, the final crater rim of complex craters can be situated up to 1.5-2.0 transient crater radii distance from the crater center. Here the thickness of the ejecta blanket is only a fraction of that occurring at the rim of simple craters, e.g. [4], and thus cannot account for a strong elevation. Likewise, plastic thickening including dike injection of the underlying target may not play a significant role at this distance any more. We started to systematically investigate the structural uplift and ejecta thickness along the rim of complex impact craters to understand the cause of their elevation. Our studies of two lunar craters (Bessel, 16 km diameter and Euler, 28 km diameter) [5] and one unnamed complex martian crater (16 km diameter) [6] showed that the structural uplift at the final crater rim makes 56-67% of the total rim elevation while the ejecta thickness contributes 33-44%. Thus with increasing distance from the transient cavity rim, the structural uplift seems to dominate. As dike injection and plastic thickening are unlikely at such a distance from the transient cavity, we propose that

  11. Topography and Geomorphology of the Interior of Occator Crater on Ceres

    NASA Astrophysics Data System (ADS)

    Jaumann, Ralf

    2017-04-01

    to the northeast appear to originate from the central region and move slightly uphill. This indicates either a feeding zone that pushes the flows forward by supplying low-viscosity material or an extended subsidence of the crater center, possibly after discharging a subsurface reservoir [1,2], or lateral oscillations of an impact melt sheet during emplacement. The plains material covers an area of about 4750km2 with an average depth of about 250m resulting in a body of plains material of about 1200km3. The plains material is slightly younger than the impact event and the bright deposits are even younger than the plains material. Post impact processes might be due to impact melt, hydrothermal alteration, or cryovolcanic crater filling [1] K. Krohn et al, GRL43, 11994, (2016). [2] R. Jaumann et al., LPSC47, 1455 (2016). [3] N. Schmedemann et al, GRL43, 11987. (2016) [4] A. Neesemann, et al., Icarus, in prep. [5] P. Schenk, et al., LPSC47 (2016).

  12. Meteor Crater (Barringer Meteorite Crater), Arizona: Summary of Impact Conditions

    NASA Astrophysics Data System (ADS)

    Roddy, D. J.; Shoemaker, E. M.

    1995-09-01

    Meteor Crater in northern Arizona represents the most abundant type of impact feature in our Solar System, i.e., the simple bowl-shaped crater. Excellent exposures and preservation of this large crater and its ejecta blanket have made it a critical data set in both terrestrial and planetary cratering research. Recognition of the value of the crater was initiated in the early 1900's by Daniel Moreau Barringer, whose 27 years of exploration championed its impact origin [1]. In 1960, Shoemaker presented information that conclusively demonstrated that Meteor Crater was formed by hypervelocity impact [2]. This led the U.S. Geological Survey to use the crater extensively in the 1960-70's as a prime training site for the Apollo astronauts. Today, Meteor Crater continues to serve as an important research site for the international science community, as well as an educational site for over 300,000 visitors per year. Since the late 1950's, studies of this crater have presented an increasingly clearer view of this impact and its effects and have provided an improved view of impact cratering in general. To expand on this data set, we are preparing an upgraded summary on the Meteor Crater event following the format in [3], including information and interpretations on: 1) Inferred origin and age of the impacting body, 2) Inferred ablation and deceleration history in Earth's atmosphere, 3) Estimated speed, trajectory, angle of impact, and bow shock conditions, 4) Estimated coherence, density, size, and mass of impacting body, 5) Composition of impacting body (Canyon Diablo meteorite), 6) Estimated kinetic energy coupled to target rocks and atmosphere, 7) Terrain conditions at time of impact and age of impact, 8) Estimated impact dynamics, such as pressures in air, meteorite, and rocks, 9) Inferred and estimated material partitioning into vapor, melt, and fragments, 10) Crater and near-field ejecta parameters, 11) Rock unit distributions in ejecta blanket, 12) Estimated far

  13. U.S. Geological Survey Subsidence Interest Group conference, Edwards Air Force Base, Antelope Valley, California, November 18-19, 1992; abstracts and summary

    USGS Publications Warehouse

    Prince, Keith R.; Galloway, Devin L.; Leake, Stanley A.

    1995-01-01

    Land subsidence, the loss of surface elevation as a result of the removal of subsurface support, affects every state in the United States. More than 17,000 mi2 of land in the United States has been lowered by the various processes that produce land subsidence with annual costs from resulting flooding and structural damage that exceed $125 million. It is estimated that an additional $400 million is spent nationwide in attempts to control subsidence. Common causes of land subsidence include the removal of oil, gas, and water from underground reservoirs; dissolution of limestone aquifers (sinkholes); underground mining activities; drainage of organic soils; and hydrocompaction (the initial wetting of dry soils). Overdrafting of aquifers is the major cause of areally extensive land subsidence, and as ground-water pumping increases, land subsidence also will increase. Land subsidence and its effects on engineering structures have been recognized for centuries, but it was not until this century that the processes that produce land subsidence were identified and understood. In 1928, while working with field data from a test of the Dakota Sandstone aquifer, O.E. Meinzer of the U.S. Geological Survey recognized the compressibility of aquifers. Around the same time, Karl Terzaghi, a soil scientist working at Harvard University, developed the one-dimensional consolidation theory that provided a quantitative means of predicting soil compaction resulting from the drainage of compressible soils. Thus, with the recognition of the compressibility of aquifers (Meinzer), and the development of a quantitative means of predicting soil compaction as a consequence of the reduction of intergranular pore pressure (Terzaghi), the theory of aquifer-system compaction was formed. With the widespread availa- bility of electric power in rural areas, and the advent of the deep turbine pump, ground-water withdrawals increased dramatically throughout the country in the 1940's and 1950's. Along

  14. Land Subsidence Monitoring by InSAR Time Series Technique Derived From ALOS-2 PALSAR-2 over Surabaya City, Indonesia

    NASA Astrophysics Data System (ADS)

    Aditiya, A.; Takeuchi, W.; Aoki, Y.

    2017-12-01

    Surabaya is the second largest city in Indonesia and the capital of East Java Province with rapid population and industrialization. The impact of urbanization in the big city can suffer potential disasters either nature or anthropogenic such as land subsidence and flood. The pattern of land subsidence need to be mapped for the purposes of planning and structuring the city as well as taking appropriate policy in anticipating and mitigating the impact. This research has used interferometric Synthetic Aperture Radar (InSAR) Small Baseline Subset (SBAS) technique and applied time series analysis to investigate land subsidence occured. The technique includes the process of focusing the SAR data, incorporating the precise orbit, generating interferogram and phase unwrapping using SNAPHU algorithms. The results showed land subsidence has been detected during 2014-2017 over Surabaya city area using ALOS-2/PALSAR-2 images data. These results reveal the subsidence has observed in several area in Surabaya in particular northern part reach up to ∼2 cm/year. The fastest subsidence occurs in highly populated areas suffer vulnerable to flooding and sea level rise impact. In urban areas we found a correlation between land subsidence with residential or industrial land use. It concludes that land subsidence is mainly caused by ground water consumption for industrial and residential use respectively.

  15. Standardizing the nomenclature of Martian impact crater ejecta morphologies

    USGS Publications Warehouse

    Barlow, Nadine G.; Boyce, Joseph M.; Costard, Francois M.; Craddock, Robert A.; Garvin, James B.; Sakimoto, Susan E.H.; Kuzmin, Ruslan O.; Roddy, David J.; Soderblom, Laurence A.

    2000-01-01

    The Mars Crater Morphology Consortium recommends the use of a standardized nomenclature system when discussing Martian impact crater ejecta morphologies. The system utilizes nongenetic descriptors to identify the various ejecta morphologies seen on Mars. This system is designed to facilitate communication and collaboration between researchers. Crater morphology databases will be archived through the U.S. Geological Survey in Flagstaff, where a comprehensive catalog of Martian crater morphologic information will be maintained.

  16. Singlet internal conversion processes in the order of 1Bu+→3Ag-→1Bu-→2Ag-→1Ag- in all- trans-spheroidene and lycopene as revealed by subpicosecond time-resolved Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Rondonuwu, Ferdy S.; Kakitani, Yoshinori; Tamura, Hiroshi; Koyama, Yasushi

    2006-09-01

    Key Raman lines ascribable to the 1Bu+, 3Ag-, 1Bu- and 2Ag- states were identified in the subpicosecond time-resolved Raman spectra of spheroidene and lycopene having 10 and 11 conjugated double bonds, respectively. The sequential rise-and-decay of the key Raman lines showed the internal conversion processes of 1Bu+→3Ag-→1Bu-→2Ag-→1Ag- (ground). The time constant in each step of internal conversion reflects the energy gap between the relevant states that had been determined by measurement of resonance - Raman excitation profiles [K. Furuichi, T. Sashima, Y. Koyama, Chem. Phys. Lett. 356 (2002) 547].

  17. Flexural subsidence and basement tectonics of the Cretaceous Western Interior basin, United States

    NASA Astrophysics Data System (ADS)

    Pang, Ming; Nummedal, Dag

    1995-02-01

    The flexural subsidence history recorded in Cenomanian to early Campanian (97 to 80 Ma) strata in the Cretaceous U.S. Western Interior basin was studied with two-dimensional flexural backstripping techniques. Results indicate that the flexural subsidence resulting from thrust loading was superimposed on epeirogenic subsidence in the foreland basin. The flexural component exhibits significant spatial and temporal variations along both the strike and dip relative to the Sevier thrust belt. The greatest cumulative subsidence occurred in southwestern Wyoming and northern Utah. Concurrent subsidence in northwestern Montana and southern Utah was insignificant. Temporal trends in subsidence also show a distinct regional pattern. From the Cenomanian to late Turonian (97 to 90 Ma), subsidence rates were high in Utah and much lower in Wyoming and Montana. In contrast, during the Coniacian and Santonian (90 to 85 Ma) subsidence accelerated rapidly in Wyoming, increased slightly in Montana, and decreased in Utah. We suggest that these spatially and temporally varying subsidence patterns reflect the interplay of several geodynamic factors, including: (1) temporal and spatial variation in emplacement of the thrust loads, (2) segmentation of the basement into adjacent blocks with different rheological properties, (3) reactivation of basement fault trends, and (4) regional dynamic topographic effects.

  18. Geologic Mapping of the Martian Impact Crater Tooting

    NASA Technical Reports Server (NTRS)

    Mouginis-Mark, Peter; Boyce, Joseph M.

    2008-01-01

    Tooting crater is approximately 29 km in diameters, is located at 23.4 deg N, 207.5 deg E and is classified as a multi-layered ejecta crater. Tooting crater is a very young crater, with an estimated age of 700,000 to 2M years. The crater formed on virtually flat lava flows within Amazonis Planitia where there appears to have been no major topographic features prior to the impact, so that we can measure ejecta thickness and cavity volume. In the past 12 months, the authors have: published their first detailed analysis of the geometry of the crater cavity and the distribution of the ejecta layers; refined the geologic map of the interior of Tooting crater through mapping of the cavity at a scale of 1:1100K; and continued the analysis of an increasing number of high resolution images obtained by the CTX and HiRISE instruments. Currently the authors seek to resolve several science issues that have been identified during this mapping, including: what is the origin of the lobate flows on the NW and SW rims of the crater?; how did the ejecta curtain break apart during the formation of the crater, and how uniform was the emplacement process for the ejecta layers; and, can we infer physical characteristics about the ejecta? Future study plans include the completion of a draft geologic map of Tooting crater and submission of it to the U.S. Geological survey for a preliminary review, publishing a second research paper on the detailed geology of the crater cavity and the distribution of the flows on the crater rim, and completing the map text for the 1:100K geologic map description of units at Tooting crater.

  19. Lunar Cratering Chronology: Calibrating Degree of Freshness of Craters to Absolute Ages

    NASA Astrophysics Data System (ADS)

    Trang, D.; Gillis-Davis, J.; Boyce, J. M.

    2013-12-01

    The use of impact craters to age-date surfaces of and/or geomorphological features on planetary bodies is a decades old practice. Various dating techniques use different aspects of impact craters in order to determine ages. One approach is based on the degree of freshness of primary-impact craters. This method examines the degradation state of craters through visual inspection of seven criteria: polygonality, crater ray, continuous ejecta, rim crest sharpness, satellite craters, radial channels, and terraces. These criteria are used to rank craters in order of age from 0.0 (oldest) to 7.0 (youngest). However, the relative decimal scale used in this technique has not been tied to a classification of absolute ages. In this work, we calibrate the degree of freshness to absolute ages through crater counting. We link the degree of freshness to absolute ages through crater counting of fifteen craters with diameters ranging from 5-22 km and degree of freshness from 6.3 to 2.5. We use the Terrain Camera data set on Kaguya to count craters on the continuous ejecta of each crater in our sample suite. Specifically, we divide the crater's ejecta blanket into quarters and count craters between the rim of the main crater out to one crater radii from the rim for two of the four sections. From these crater counts, we are able to estimate the absolute model age of each main crater using the Craterstats2 tool in ArcGIS. Next, we compare the degree of freshness for the crater count-derived age of our main craters to obtain a linear inverse relation that links these two metrics. So far, for craters with degree of freshness from 6.3 to 5.0, the linear regression has an R2 value of 0.7, which corresponds to a relative uncertainty of ×230 million years. At this point, this tool that links degree of freshness to absolute ages cannot be used with craters <8km because this class of crater degrades quicker than larger craters. A graphical solution exists for correcting the degree of

  20. Coordination chemistry of 2,2'-biphenylenedithiophosphinate and diphenyldithiophosphinate with U, Np, and Pu

    DOE PAGES

    Macor, Joseph A.; Brown, Jessie L.; Cross, Justin Neil; ...

    2015-01-01

    New members of the dithiophosphinic acid family of potential actinide extractants were prepared: heterocyclic 2,2'-biphenylenedithiophosphinic acids of stoichiometry HS 2P(R 2C 12H 6) (R = H or tBu). The time- and atom-efficient syntheses afforded multigram quantities of pure HS 2P(R 2C 12H 6) in reasonable yields (~60%). These compounds differed from other diaryldithiophosphinic acid extractants in that the two aryl groups were connected to one another at the ortho positions to form a 5-membered dibenzophosphole ring. These 2,2'-biphenylenedithiophosphinic acids were readily deprotonated to form S 2P(R 2C 12H 6) 1- anions, which were crystallized as salts with tetraphenylpnictonium cations (ZPhmore » 4 1+; Z = P or As). Coordination chemistry between [S 2P( tBu 2C 12H 6)] 1- and [S 2P(C 6H 5)2] 1- with U, Np, and Pu was comparatively investigated. The results showed that dithiophosphinate complexes of UIV and NpIV were redox stable relative to those of UIII, whereas reactions involving PuIV gave intractable material. For instance, reactions involving UIV and NpIV generated An[S 2P( tBu 2C 12H 6)] 4 and An[S 2P(C 6H 5) 2] 4 whereas reactions between PuIV and [S 2P(C 6H 5) 2] 1- generated a mixture of products from which we postulated a transient PuIII species based on UV-Vis spectroscopy. However, the trivalent Pu[S 2P(C 6H 5) 2] 3(NC 5H 5) 2 compound is stable and could be isolated from reactions between [S 2P(C 6H 5) 2] 1- and the trivalent PuI 3(NC 5H 5) 4 starting material. Attempts to synthesize analogous trivalent compounds with UIII provided the tetravalent U[S 2P(C 6H 5 )2] 4 oxidation product.« less

  1. Constraints on the geomorphological evolution of the nested summit craters of Láscar volcano from high spatio-temporal resolution TerraSAR-X interferometry

    NASA Astrophysics Data System (ADS)

    Richter, Nicole; Salzer, Jacqueline Tema; de Zeeuw-van Dalfsen, Elske; Perissin, Daniele; Walter, Thomas R.

    2018-03-01

    Small-scale geomorphological changes that are associated with the formation, development, and activity of volcanic craters and eruptive vents are often challenging to characterize, as they may occur slowly over time, can be spatially localized, and difficult, or dangerous, to access. Using high-spatial and high-temporal resolution synthetic aperture radar (SAR) imagery collected by the German TerraSAR-X (TSX) satellite in SpotLight mode in combination with precise topographic data as derived from Pléiades-1A satellite data, we investigate the surface deformation within the nested summit crater system of Láscar volcano, Chile, the most active volcano of the central Andes. Our aim is to better understand the structural evolution of the three craters that comprise this system, to assess their physical state and dynamic behavior, and to link this to eruptive activity and associated hazards. Using multi-temporal SAR interferometry (MT-InSAR) from ascending and descending orbital geometries, we retrieve the vertical and east-west components of the displacement field. This time series indicates constant rates of subsidence and asymmetric horizontal displacements of all summit craters between June 2012 and July 2014, as well as between January 2015 and March 2017. The vertical and horizontal movements that we observe in the central crater are particularly complex and cannot be explained by any single crater formation mechanism; rather, we suggest that short-term activities superimposed on a combination of ongoing crater evolution processes, including gravitational slumping, cooling and compaction of eruption products, as well as possible piston-like subsidence, are responsible for the small-scale geomorphological changes apparent in our data. Our results demonstrate how high-temporal resolution synthetic aperture radar interferometry (InSAR) time series can add constraints on the geomorphological evolution and structural dynamics of active crater and vent systems at

  2. Approaching Endeavour Crater, Sol 2,680

    NASA Image and Video Library

    2011-10-10

    This image from the navigation camera on NASA Mars Exploration Rover Opportunity shows the view ahead on the day before the rover reached the rim of Endeavour crater. It was taken during the 2,680th Martian day, or sol, of the rover work on Mars.

  3. Presence and absence of electronic mixing in shorter-chain and longer-chain carotenoids: Assignment of the symmetries of 1Bu- and 3Ag- states located just below the 1Bu+ state

    NASA Astrophysics Data System (ADS)

    Sutresno, Adita; Kakitani, Yoshinori; Zuo, Ping; Li, Chunyong; Koyama, Yasushi; Nagae, Hiroyoshi

    2007-10-01

    In spheroidene (having the number of conjugated double bonds n = 10), stimulated emission was observed from the mixed vibronic levels of 1Bu+(0)+1Bu-(2) and 1Bu+(1)+1Bu-(3), whereas in lycopene, anhydrorhodovibrin and spirilloxanthin ( n = 11-13), stimulated emission, from the pure vibronic levels of 1Bu+(0) and 1Bu+(1). Thus, the 1Bu+ state can mix with the 1Bu- state but not with the 3Ag- state, both being located just below the 1Bu+ state. The presence and absence of the mixing of the neighboring diabatic states support the symmetries of the next low-lying 1Bu- and 3Ag- states.

  4. How old is Autolycus crater?

    NASA Astrophysics Data System (ADS)

    Hiesinger, Harald; Pasckert, Jan Henrik; van der Bogert, Carolyn H.; Robinson, Mark S.

    2016-04-01

    Accurately determining the lunar cratering chronology is prerequisite for deriving absolute model ages (AMAs) across the lunar surface and throughout the Solar System [e.g., 1]. However, the lunar chronology is only constrained by a few data points over the last 1 Ga and there are no calibration data available between 1 and 3 Ga and beyond 3.9 Ga [2]. Rays from Autolycus and Aristillus cross the Apollo 15 landing site and presumably transported material to this location [3]. [4] proposed that at the Apollo 15 landing site about 32% of any exotic material would come from Autolycus crater and 25% would come from Aristillus crater. [5,6] proposed that the 39Ar-40Ar age of 2.1 Ga derived from three petrologically distinct, shocked Apollo 15 KREEP basalt samples, date Autolycus crater. Grier et al. [7] reported that the optical maturity (OMAT) characteristics of these craters are indistinguishable from the background values despite the fact that both craters exhibit rays that were used to infer relatively young, i.e., Copernican ages [8,9]. Thus, both OMAT characteristics and radiometric ages of 2.1 Ga and 1.29 Ga for Autolycus and Aristillus, respectively, suggest that these two craters are not Copernican in age. [10] interpreted newer U-Pb ages of 1.4 and 1.9 Ga from sample 15405 as the formation ages of Aristillus and Autolycus. If Autolycus is indeed the source of the dated exotic material collected at the Apollo 15 landing site, than performing crater size frequency distribution (CSFD) measurements for Autolycus offers the possibility to add a new calibration point to the lunar chronology, particularly in an age range that was previously unconstrained. We used calibrated and map-projected LRO NAC images to perform CSFD measurements within ArcGIS, using CraterTools [11]. CSFDs were then plotted with CraterStats [12], using the production and chronology functions of [13]. We determined ages of 3.72 and 3.85 Ga for the interior (Ai1) and ejecta area Ae3, which we

  5. Infrasonic tremor wavefield of the Pu`u `Ō`ō crater complex and lava tube system, Hawaii, in April 2007

    NASA Astrophysics Data System (ADS)

    Matoza, Robin S.; Fee, David; GarcéS, Milton A.

    2010-12-01

    Long-lived effusive volcanism at the Pu`u `Ō`ō crater complex, Kilauea Volcano, Hawaii produces persistent infrasonic tremor that has been recorded almost continuously for months to years. Previous studies showed that this infrasonic tremor wavefield can be recorded at a range of >10 km. However, the low signal power of this tremor relative to ambient noise levels results in significant propagation effects on signal detectability at this range. In April 2007, we supplemented a broadband infrasound array at ˜12.5 km from Pu`u `Ō`ō (MENE) with a similar array at ˜2.4 km from the source (KIPU). The additional closer-range data enable further evaluation of tropospheric propagation effects and provide higher signal-to-noise ratios for studying volcanic source processes. The infrasonic tremor source appears to consist of at least two separate physical processes. We suggest that bubble cloud oscillation in a roiling magma conduit beneath the crater complex may produce a broadband component of the tremor. Low-frequency sound sourced in a shallow magma conduit may radiate infrasound efficiently into the atmosphere due to the anomalous transparency of the magma-air interface. We further propose that more sharply peaked tones with complex temporal evolution may result from oscillatory interactions of a low-velocity gas jet with solid vent boundaries in a process analogous to the hole tone or whistler nozzle. The infrasonic tremor arrives with a median azimuth of ˜67° at KIPU. Additional infrasonic signals and audible sounds originating from the extended lava tube system to the south of the crater complex (median azimuth ˜77°) coincided with turbulent degassing activity at a new lava tube skylight. Our observations indicate that acoustic studies may aid in understanding persistent continuous degassing and unsteady flow dynamics at Kilauea Volcano.

  6. Radioprotection of the Brain White Matter by Mn(III) N-Butoxyethylpyridylporphyrin-Based Superoxide Dismutase Mimic MnTnBuOE-2-PyP5+

    PubMed Central

    Weitzel, Douglas H.; Tovmasyan, Artak; Ashcraft, Kathleen A.; Rajic, Zrinka; Weitner, Tin; Liu, Chunlei; Li, Wei; Buckley, Anne F.; Prasad, Mark R.; Young, Kenneth H.; Rodriguiz, Ramona M.; Wetsel, William C.; Peters, Katherine B.; Spasojevic, Ivan; Herndon, James E.; Batinic-Haberle, Ines; Dewhirst, Mark W.

    2015-01-01

    Cranial irradiation is a standard therapy for primary and metastatic brain tumors. A major drawback of radiotherapy (RT), however, is long-term cognitive loss that affects quality of life. Radiation-induced oxidative stress in normal brain tissue is thought to contribute to cognitive decline. We evaluated the effectiveness of a novel mimic of superoxide dismutase enzyme (SOD), MnTnBuOE-2-PyP5+ (Mn(III) meso-tetrakis(N-n-butoxyethylpyridinium-2-yl)porphyrin), to provide long-term neuroprotection following 8 Gy of whole brain irradiation. Long-term RT damage can only be assessed by brain imaging and neurocognitive studies. C57BL/6J mice were treated with MnTnBuOE-2-PyP5+ before and after RT and evaluated three months later. At this time point, drug concentration in the brain was 25 nmol/L. Mice treated with MnTnBuOE-2-PyP5+/RT exhibited MRI evidence for myelin preservation in the corpus callosum compared with saline/RT treatment. Corpus callosum histology demonstrated a significant loss of axons in the saline/RT group that was rescued in the MnTnBuOE-2-PyP5+/RT group. In addition, the saline/RT groups exhibited deficits in motor proficiency as assessed by the rotorod test and running wheel tests. These deficits were ameliorated in groups treated with MnTnBuOE-2-PyP5+/RT. Our data demonstrate that MnTnBuOE-2-PyP5+ is neuroprotective for oxidative stress damage caused by radiation exposure. In addition, glioblastoma cells were not protected by MnTnBuOE-2-PyP5+ combination with radiation in vitro. Likewise, the combination of MnTnBuOE-2-PyP5+ with radiation inhibited tumor growth more than RT alone in flank tumors. In summary, MnTnBuOE-2-PyP5+ has dual activity as a neuroprotector and a tumor radiosensitizer. Thus, it is an attractive candidate for adjuvant therapy with RT in future studies with patients with brain cancer. PMID:25319393

  7. Houston-Galveston Bay area, Texas, from space; a new tool for mapping land subsidence

    USGS Publications Warehouse

    Stork, Sylvia V.; Sneed, Michelle

    2002-01-01

    Interferometric Synthetic Aperture Radar (InSAR) is a powerful new tool that uses radar signals to measure displacement (subsidence and uplift) of the Earth's crust at an unprecedented level of spatial detail and high degree of measurement resolution.The Houston-Galveston Bay area, possibly more than any other metropolitan area in the United States, has been adversely affected by land subsidence. Extensive subsidence, caused mainly by ground-water pumping but also by oil and gas extraction, has increased the frequency of flooding, caused extensive damage to industrial and transportation infrastructure, motivated major investments in levees, reservoirs, and surfacewater distribution facilities, and caused substantial loss of wetland habitat. Ongoing patterns of subsidence in the Houston area have been carefully monitored using borehole extensometers, Global Positioning System (GPS) and conventional spirit-leveling surveys, and more recently, an emerging technology—Interferometric Synthetic Aperture Radar (InSAR)—which enables development of spatially-detailed maps of land-surface displacement over broad areas. This report, prepared by the U.S. Geological Survey (USGS) in cooperation with the U.S. Fish and Wildlife Service, briefly summarizes the history of subsidence in the area and the local consequences of subsidence and describes the use of InSAR as one of several tools in an integrated subsidence-monitoring program in the area.

  8. Methyl transfer from Fe (and Mo) to Sn: formation of (eta(5)-C(5)H(5))M(CO)(n)Sn(t)Bu(2)Me (M = Fe, n = 2; M = Mo, n = 3) complexes from photochemical irradiation of (eta(5)-C(5)H(5))M(CO)(n)Me and (t)Bu(2)SnH(2).

    PubMed

    Sharma, Hemant K; Arias-Ugarte, Renzo; Metta-Magana, Alejandro; Pannell, Keith H

    2010-07-07

    Formation of an Sn-CH(3) bond, concomitantly with an Sn-M (M = Fe, Mo), is readily achieved from the photochemical reactions of (t)Bu(2)SnH(2) with (eta(5)-C(5)H(5))M(CO)(n)Me (M = Fe, n = 2; M = Mo, n = 3) via the intermediacy of (eta(5)-C(5)H(5))M(CO)(n)Sn(t)Bu(2)H.

  9. Phobos - Surface density of impact craters

    NASA Technical Reports Server (NTRS)

    Thomas, P.; Veverka, J.

    1977-01-01

    Revised crater counts for Phobos are presented which are based on uniform Mariner 9 imagery and Duxbury's (1974) map of the satellite. The contiguous portion of the satellite's surface on which all craters down to the limiting resolution of 0.2 to 0.3 km in diameter would be expected to be identified is delineated and found to contain 87 identifiable craters larger than 0.2 km in diameter. Analysis of the crater size distribution shows that the surface appears to be saturated for craters exceeding 1 km in diameter but the crater counts definitely fall below the saturation curve for smaller craters. Reasons for this fall-off are considered, and it is noted that too few craters are visible in Mariner 9 images of Deimos to permit meaningful crater counts on that satellite's surface. It is concluded that, contrary to a previous assertion, the surfaces of Phobos and Deimos are not known to be saturated with craters larger than 0.2 km in diameter.

  10. Gully formation in terrestrial simple craters: Meteor Crater, USA and Lonar Crater, India

    NASA Astrophysics Data System (ADS)

    Kumar, P.; Head, J. W.; Kring, D. A.

    2007-12-01

    Geomorphic features such as gullies, valley networks, and channels on Mars have been used as a proxy to understand the climate and landscape evolution of Mars. Terrestrial analogues provide significant insight as to how the various exogenic and endogenic processes might contribute to the evolution of these martian landscapes. We describe here a terrestrial example from Meteor Crater, which shows a spectacular development of gullies throughout the inner wall in response to rainwater precipitation, snow melting and groundwater discharge. As liquid water has been envisaged as one of the important agents of landscape sculpturing, Meteor Crater remains a useful landmark, where planetary geologists can learn some lessons. We also show here how the lithology and structural framework of this crater controls the gully distribution. Like many martian impact craters, it was emplaced in layered sedimentary rocks with an exceptionally well-developed centripetal drainage pattern consisting of individual alcoves, channels and fans. Some of the gullies originate from the rim crest and others from the middle crater wall, where a lithologic transition occurs. Deeply incised alcoves are well-developed on the soft sandstones of the Coconino Formation exposed on the middle crater wall, beneath overlying dolomite. In general, the gully locations are along crater wall radial fractures and faults, which are favorable locales of groundwater flow and discharge; these structural discontinuities are also the locales where the surface runoff from rain precipitation and snow melting can preferentially flow, causing degradation. Like martian craters, channels are well developed on the talus deposits and alluvial fans on the periphery of the crater floor. In addition, lake sediments on the crater floor provide significant evidence of a past pluvial climate, when groundwater seeped from springs on the crater wall. Caves exposed on the lower crater level may point to percolation of surface runoff

  11. Meteor Crater, AZ

    NASA Technical Reports Server (NTRS)

    2002-01-01

    The Barringer Meteorite Crater (also known as 'Meteor Crater') is a gigantic hole in the middle of the arid sandstone of the Arizona desert. A rim of smashed and jumbled boulders, some of them the size of small houses, rises 50 m above the level of the surrounding plain. The crater itself is nearly a 1500 m wide, and 180 m deep. When Europeans first discovered the crater, the plain around it was covered with chunks of meteoritic iron - over 30 tons of it, scattered over an area 12 to 15 km in diameter. Scientists now believe that the crater was created approximately 50,000 years ago. The meteorite which made it was composed almost entirely of nickel-iron, suggesting that it may have originated in the interior of a small planet. It was 50 m across, weighed roughly 300,000 tons, and was traveling at a speed of 65,000 km per hour. This ASTER 3-D perspective view was created by draping an ASTER bands 3-2-1image over a digital elevation model from the US Geological Survey National Elevation Dataset.

    This image was acquired on May 17, 2001 by the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) on NASA's Terra satellite. With its 14 spectral bands from the visible to the thermal infrared wavelength region, and its high spatial resolution of 15 to 90 meters (about 50 to 300 feet), ASTER will image Earth for the next 6 years to map and monitor the changing surface of our planet.

    ASTER is one of five Earth-observing instruments launched December 18,1999, on NASA's Terra satellite. The instrument was built by Japan's Ministry of Economy, Trade and Industry. A joint U.S./Japan science team is responsible for validation and calibration of the instrument and the data products. Dr. Anne Kahle at NASA's Jet Propulsion Laboratory, Pasadena, California, is the U.S. Science team leader; Bjorn Eng of JPL is the project manager. ASTER is the only high resolution imaging sensor on Terra. The Terra mission is part of NASA's Earth Science Enterprise, along

  12. Tektite-like bodies at Lonar Crater, India - Implications for the origin of tektites

    NASA Technical Reports Server (NTRS)

    Murali, A. V.; Zolensky, M. E.; Blanchard, D. P.

    1987-01-01

    Homogeneous dense glass bodies (both irregular and splash form) with high silica contents (about 67 pct SiO2) occur in the vicinity of Lonar Crater, India. Their lack of microlites and mineral remnants and their uniform chemical composition virtually preclude a volcanic origin. They are similar to tektites reported in the literature. While such a close association of tektite-like bodies with impact craters is already known (Aouelloul Crater, Mauritania; Zhamanshin Crater, U.S.S.R.), the tektite-like bodies at Lonar Crater are unique in that they occur in an essentially basaltic terrain. Present geochemical data are consistent with these high silica glass bodies being impact melt products of two-thirds basalt and one-third local intertrappean sediment (chert). The tektite-like bodies of the impact craters Lonar, Zhamanshin, and Aouelloul are generally similar. Strong terrestrial geochemical signatures reflect the target rock REE patterns and abundance ratios and demonstrate their terrestrial origin resulting from meteorite impact, as has been suggested by earlier workers.

  13. Correlating the subsidence pattern and land use in Bandung, Indonesia with both Sentinel-1/2 and ALOS-2 satellite images

    NASA Astrophysics Data System (ADS)

    Du, Zheyuan; Ge, Linlin; Ng, Alex Hay-Man; Zhu, Qinggaozi; Yang, Xihua; Li, Liyuan

    2018-05-01

    Continuous research has been conducted in Bandung City, West Java province, Indonesia over the past two decades. Previous studies carried out in a regional-scale might be useful for estimating the correlation between land subsidence and groundwater extraction, but inadequate for local safety management as subsidence may vary over different areas with detailed characters. This study is focused primarily on subsidence phenomenon in local, patchy and village scales, respectively, with Sentinel-1 and ALOS-2 dataset acquired from September 2014 to July 2017. The Sentinel-1 derived horizontal movement map confirmed that the vertical displacement is dominant of the Line-of-Sight (LoS) subsidence. Moreover, both Sentinel-1 and ALOS-2 derived InSAR measurements were cross-validated with each other. In order to understand the subsidence in a more systematic way, six 10-cm subsidence zones have been selected known as Zone A-F. Further analyses conducted over multiple scales show that industrial usage of groundwater is not always the dominant factor that causes the land subsidence and indeed it does not always create large land subsidence either. Regions experiencing subsidence is due to a combined impact of a number of factors, e.g., residential, industrial or agricultural activities. The outcome of this work not only contributes to knowledge on efficient usage of the satellite-based monitoring networks, but also assists developing the best hazard mitigation plans. In the future work, as we cannot draw the conclusion which is the dominant factor within each sub-zone due to the lack of statistical data, e.g., the groundwater consumption rates per square kilometre for different land types, further datasets are still needed to examine the core factor.

  14. Crater Impacts on Vesta

    NASA Image and Video Library

    2012-05-10

    This graphic shows the global distribution of craters that hit the giant asteroid Vesta, based on data from NASA Dawn mission. The yellow circles indicate craters of 2 miles or wider, with the size of the circles indicating the size of the crater.

  15. Paradigm lost: Venus crater depths and the role of gravity in crater modification

    NASA Technical Reports Server (NTRS)

    Sharpton, Virgil L.

    1992-01-01

    Previous to Magellan, a convincing case had been assembled that predicted that complex impact craters on Venus were considerably shallower than their counterparts on Mars, Mercury, the Moon, and perhaps even Earth. This was fueled primarily by the morphometric observation that, for a given diameter (D), crater depth (d) seems to scale inversely with surface gravity for the other planets in the inner solar system. The unpredicted depth of fresh impact craters on Venus argues against a simple inverse relationship between surface gravity and crater depth. Factors that could contribute to deep craters on Venus include (1) more efficient excavation on Venus, possibly reflecting rheological effects of the hot venusian environment; (2) more melting and efficient removal of melt from the crater cavity; and (3) enhanced ejection of material out of the crater, possibly as a result of entrainment in an atmosphere set in motion by the passage of the projectile. The broader issue raised by the venusian crater depths is whether surface gravity is the predominant influence on crater depths on any planet. While inverse gravity scaling of crater depths has been a useful paradigm in planetary cratering, the venusian data do not support this model and the terrestrial data are equivocal at best. The hypothesis that planetary gravity is the primary influence over crater depths and the paradigm that terrestrial craters are shallow should be reevaluated.

  16. MnTnBuOE-2-PyP protects normal colorectal fibroblasts from radiation damage and simultaneously enhances radio/chemotherapeutic killing of colorectal cancer cells

    PubMed Central

    Kosmacek, Elizabeth A.; Chatterjee, Arpita; Tong, Qiang; Lin, Chi; Oberley, Rebecca E.

    2016-01-01

    Manganese porphyrins have been shown to be potent radioprotectors in a variety of cancer models. However, the mechanism as to how these porphyrins protect normal tissues from radiation damage still remains largely unknown. In the current study, we determine the effects of the manganese porphyrin, MnTnBuOE-2-PyP, on primary colorectal fibroblasts exposed to irradiation. We found that 2 Gy of radiation enhances the fibroblasts' ability to contract a collagen matrix, increases cell size and promotes cellular senesence. Treating fibroblasts with MnTnBuOE-2-PyP significantly inhibited radiation-induced collagen contraction, preserved cell morphology and also inhibited cellular senescence. We further showed that MnTnBuOE-2-PyP enhanced the overall viability of the fibroblasts following exposure to radiation but did not protect colorectal cancer cell viability. Specifically, MnTnBuOE-2-PyP in combination with irradiation, caused a significant decrease in tumor clonogenicity. Since locally advanced rectal cancers are treated with chemoradiation therapy followed by surgery and non-metastatic anal cancers are treated with chemoradiation therapy, we also investigated the effects of MnTnBuOE-2-PyP in combination with radiation, 5-fluorouracil with and without Mitomycin C. We found that MnTnBuOE-2-PyP in combination with Mitomycin C or 5-fluorouracil further enhances those compounds' ability to suppress tumor cell growth. When MnTnBuOE-2-PyP was combined with the two chemotherapeutics and radiation, we observed the greatest reduction in tumor cell growth. Therefore, these studies indicate that MnTnBuOE-2-PyP could be used as a potent radioprotector for normal tissue, while at the same time enhancing radiation and chemotherapy treatment for rectal and anal cancers. PMID:27119354

  17. MnTnBuOE-2-PyP protects normal colorectal fibroblasts from radiation damage and simultaneously enhances radio/chemotherapeutic killing of colorectal cancer cells.

    PubMed

    Kosmacek, Elizabeth A; Chatterjee, Arpita; Tong, Qiang; Lin, Chi; Oberley-Deegan, Rebecca E

    2016-06-07

    Manganese porphyrins have been shown to be potent radioprotectors in a variety of cancer models. However, the mechanism as to how these porphyrins protect normal tissues from radiation damage still remains largely unknown. In the current study, we determine the effects of the manganese porphyrin, MnTnBuOE-2-PyP, on primary colorectal fibroblasts exposed to irradiation. We found that 2 Gy of radiation enhances the fibroblasts' ability to contract a collagen matrix, increases cell size and promotes cellular senesence. Treating fibroblasts with MnTnBuOE-2-PyP significantly inhibited radiation-induced collagen contraction, preserved cell morphology and also inhibited cellular senescence. We further showed that MnTnBuOE-2-PyP enhanced the overall viability of the fibroblasts following exposure to radiation but did not protect colorectal cancer cell viability. Specifically, MnTnBuOE-2-PyP in combination with irradiation, caused a significant decrease in tumor clonogenicity. Since locally advanced rectal cancers are treated with chemoradiation therapy followed by surgery and non-metastatic anal cancers are treated with chemoradiation therapy, we also investigated the effects of MnTnBuOE-2-PyP in combination with radiation, 5-fluorouracil with and without Mitomycin C. We found that MnTnBuOE-2-PyP in combination with Mitomycin C or 5-fluorouracil further enhances those compounds' ability to suppress tumor cell growth. When MnTnBuOE-2-PyP was combined with the two chemotherapeutics and radiation, we observed the greatest reduction in tumor cell growth. Therefore, these studies indicate that MnTnBuOE-2-PyP could be used as a potent radioprotector for normal tissue, while at the same time enhancing radiation and chemotherapy treatment for rectal and anal cancers.

  18. Martian subsurface properties and crater formation processes inferred from fresh impact crater geometries

    NASA Astrophysics Data System (ADS)

    Stewart, Sarah T.; Valiant, Gregory J.

    2006-10-01

    The geometry of simple impact craters reflects the properties of the target materials, and the diverse range of fluidized morphologies observed in Martian ejecta blankets are controlled by the near-surface composition and the climate at the time of impact. Using the Mars Orbiter Laser Altimeter (MOLA) data set, quantitative information about the strength of the upper crust and the dynamics of Martian ejecta blankets may be derived from crater geometry measurements. Here, we present the results from geometrical measurements of fresh craters 3-50 km in rim diameter in selected highland (Lunae and Solis Plana) and lowland (Acidalia, Isidis, and Utopia Planitiae) terrains. We find large, resolved differences between the geometrical properties of the freshest highland and lowland craters. Simple lowland craters are 1.5-2.0 times deeper (≥5σo difference) with >50% larger cavities (≥2σo) compared to highland craters of the same diameter. Rim heights and the volume of material above the preimpact surface are slightly greater in the lowlands over most of the size range studied. The different shapes of simple highland and lowland craters indicate that the upper ˜6.5 km of the lowland study regions are significantly stronger than the upper crust of the highland plateaus. Lowland craters collapse to final volumes of 45-70% of their transient cavity volumes, while highland craters preserve only 25-50%. The effective yield strength of the upper crust in the lowland regions falls in the range of competent rock, approximately 9-12 MPa, and the highland plateaus may be weaker by a factor of 2 or more, consistent with heavily fractured Noachian layered deposits. The measured volumes of continuous ejecta blankets and uplifted surface materials exceed the predictions from standard crater scaling relationships and Maxwell's Z model of crater excavation by a factor of 3. The excess volume of fluidized ejecta blankets on Mars cannot be explained by concentration of ejecta through

  19. Martian Central Pit Craters

    NASA Technical Reports Server (NTRS)

    Hillman, E.; Barlow, N. G.

    2005-01-01

    Impact craters containing central pits are rare on the terrestrial planets but common on icy bodies. Mars is the exception among the terrestrial planets, where central pits are seen on crater floors ( floor pits ) as well as on top of central peaks ( summit pits ). Wood et al. [1] proposed that degassing of subsurface volatiles during crater formation produced central pits. Croft [2] argued instead that central pits might form during the impact of volatile-rich comets. Although central pits are seen in impact craters on icy moons such as Ganymede, they do show some significant differences from their martian counterparts: (a) only floor pits are seen on Ganymede, and (b) central pits begin to occur at crater diameters where the peak ring interior morphology begins to appear in terrestrial planet craters [3]. A study of craters containing central pits was conducted by Barlow and Bradley [4] using Viking imagery. They found that 28% of craters displaying an interior morphology on Mars contain central pits. Diameters of craters containing central pits ranged from 16 to 64 km. Barlow and Bradley noted that summit pit craters tended to be smaller than craters containing floor pits. They also noted a correlation of central pit craters with the proposed rings of large impact basins. They argued that basin ring formation fractured the martian crust and allowed subsurface volatiles to concentrate in these locations. They favored the model that degassing of the substrate during crater formation was responsible for central pit formation due to the preferential location of central pit craters along these basin rings.

  20. Transformation of Au144(SCH2CH2Ph)60 to Au133(SPh-tBu)52 Nanomolecules: Theoretical and Experimental Study.

    PubMed

    Nimmala, Praneeth Reddy; Theivendran, Shevanuja; Barcaro, Giovanni; Sementa, Luca; Kumara, Chanaka; Jupally, Vijay Reddy; Apra, Edoardo; Stener, Mauro; Fortunelli, Alessandro; Dass, Amala

    2015-06-04

    Ultrastable gold nanomolecule Au144(SCH2CH2Ph)60 upon etching with excess tert-butylbenzenethiol undergoes a core-size conversion and compositional change to form an entirely new core of Au133(SPh-tBu)52. This conversion was studied using high-resolution electrospray mass spectrometry which shows that the core size conversion is initiated after 22 ligand exchanges, suggesting a relatively high stability of the Au144(SCH2CH2Ph)38(SPh-tBu)22 intermediate. The Au144 → Au133 core size conversion is surprisingly different from the Au144 → Au99 core conversion reported in the case of thiophenol, -SPh. Theoretical analysis and ab initio molecular dynamics simulations show that rigid p-tBu groups play a crucial role by reducing the cluster structural freedom, and protecting the cluster from adsorption of exogenous and reactive species, thus rationalizing the kinetic factors that stabilize the Au133 core size. This 144-atom to 133-atom nanomolecule's compositional change is reflected in optical spectroscopy and electrochemistry.

  1. Seismic Shaking Removal of Craters 0.2-0.5 km in Diameter on Asteroid 433 Eros

    NASA Technical Reports Server (NTRS)

    Thomas, P. C.; Robinson, M. S.

    2005-01-01

    Impact cratering acts in a variety of ways to create a surprising range of scenery on small satellites and asteroids. The visible crater population is a self-modifying characteristic of these airless objects, and determining the various ways younger craters can add or subtract from the population is an important aspect of small body "geology." Asteroid 433 Eros, the most closely studied of any small body, has two aspects of its crater population that have attracted attention: a fall-off of crater densities below approx.100 m diameter relative to an expected equilibrium population [1] and regions of substantially lower large crater densities [2, 3, 4]. In this work we examine the global variation of the density of craters on Eros larger than 0.177 km, a size range above that involved in small crater depletion hypotheses [1, 5]. We counted all craters on Eros to a size range somewhat below 0.177 km diameter (and different from data used in [3]). The primary metric for this study is the number of craters between 0.177 and 1.0 km within a set radius of each grid point on the 2deg x 2deg shape model of Eros. This number can be expressed as an R-value [6], provided that it is remembered that the large bin size makes individual R values slightly different from those obtained in the usual root-2 bins.

  2. Demonstration of subsidence monitoring system

    NASA Astrophysics Data System (ADS)

    Conroy, P. J.; Gyarmaty, J. H.; Pearson, M. L.

    1981-06-01

    Data on coal mine subsidence were studied as a basis for the development of subsidence control technology. Installation, monitoring, and evaluation of three subsidence monitoring instrument systems were examined: structure performance, performance of supported systems, and performance of caving systems. Objectives of the instrument program were: (1) to select, test, assemble, install, monitor, and maintain all instrumentation required for implementing the three subsidence monitoring systems; and (2) to evaluate performance of each instrument individually and as part of the appropriate monitoring system or systems. The use of an automatic level and a rod extensometer for measuring structure performance, and the automatic level, steel tape extensometer, FPBX, FPBI, USBM borehole deformation gauge, and vibrating wire stressmeters for measuring the performance of caving systems are recommended.

  3. Planetary geological studies. [MARS crater morphology and ejecta deposit topography

    NASA Technical Reports Server (NTRS)

    Blasius, K. R.

    1981-01-01

    A global data base was assembled for the study of Mars crater ejecta morphology. The craters were classified as to morhology using individual photographic prints of Viking orbiter frames. Positional and scale information were derived by fitting digitized mosaic coordinates to lattitude-longitude coordinates of surface features from the Mars geodetic control net and feature coordinates from the U.S.G.S. series of 1:5,00,000 scale shaded relief maps. Crater morphology characteristics recorded are of two classes - attributes of each ejecta deposit and other crater charactersitics. Preliminary efforts to check the data base with findings of other workers are described.

  4. Large Crater Clustering tool

    NASA Astrophysics Data System (ADS)

    Laura, Jason; Skinner, James A.; Hunter, Marc A.

    2017-08-01

    In this paper we present the Large Crater Clustering (LCC) tool set, an ArcGIS plugin that supports the quantitative approximation of a primary impact location from user-identified locations of possible secondary impact craters or the long-axes of clustered secondary craters. The identification of primary impact craters directly supports planetary geologic mapping and topical science studies where the chronostratigraphic age of some geologic units may be known, but more distant features have questionable geologic ages. Previous works (e.g., McEwen et al., 2005; Dundas and McEwen, 2007) have shown that the source of secondary impact craters can be estimated from secondary impact craters. This work adapts those methods into a statistically robust tool set. We describe the four individual tools within the LCC tool set to support: (1) processing individually digitized point observations (craters), (2) estimating the directional distribution of a clustered set of craters, back projecting the potential flight paths (crater clusters or linearly approximated catenae or lineaments), (3) intersecting projected paths, and (4) intersecting back-projected trajectories to approximate the local of potential source primary craters. We present two case studies using secondary impact features mapped in two regions of Mars. We demonstrate that the tool is able to quantitatively identify primary impacts and supports the improved qualitative interpretation of potential secondary crater flight trajectories.

  5. Evidence for rapid topographic evolution and crater degradation on Mercury from simple crater morphometry

    NASA Astrophysics Data System (ADS)

    Fassett, Caleb I.; Crowley, Malinda C.; Leight, Clarissa; Dyar, M. Darby; Minton, David A.; Hirabayashi, Masatoshi; Thomson, Bradley J.; Watters, Wesley A.

    2017-06-01

    Examining the topography of impact craters and their evolution with time is useful for assessing how fast planetary surfaces evolve. Here, new measurements of depth/diameter (d/D) ratios for 204 craters of 2.5 to 5 km in diameter superposed on Mercury's smooth plains are reported. The median d/D is 0.13, much lower than expected for newly formed simple craters ( 0.21). In comparison, lunar craters that postdate the maria are much less modified, and the median crater in the same size range has a d/D ratio that is nearly indistinguishable from the fresh value. This difference in crater degradation is remarkable given that Mercury's smooth plains and the lunar maria likely have ages that are comparable, if not identical. Applying a topographic diffusion model, these results imply that crater degradation is faster by a factor of approximately two on Mercury than on the Moon, suggesting more rapid landform evolution on Mercury at all scales.Plain Language SummaryMercury and the Moon are both airless bodies that have experienced numerous impact events over billions of years. These impacts form <span class="hlt">craters</span> in a geologic instant. The question examined in this manuscript is how fast these <span class="hlt">craters</span> erode after their formation. To simplify the problem, we examined <span class="hlt">craters</span> of a particular size (<span class="hlt">2</span>.5 to 5 km in diameter) on a particular geologic terrain type (volcanic smooth plains) on both the Moon and Mercury. We then measured the topography of hundreds of <span class="hlt">craters</span> on both bodies that met these criteria. Our results suggest that <span class="hlt">craters</span> on Mercury become shallower much more quickly than <span class="hlt">craters</span> on the Moon. We estimate that Mercury's topography erodes at a rate at least a factor of two faster than the Moon's.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.sciencedirect.com/science/article/pii/S0019103509003753','USGSPUBS'); return false;" href="http://www.sciencedirect.com/science/article/pii/S0019103509003753"><span>Impact <span class="hlt">craters</span> on Titan</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Wood, Charles A.; Lorenz, Ralph; Kirk, Randy; Lopes, Rosaly; Mitchell, Karl; Stofan, Ellen; ,</p> <p>2010-01-01</p> <p>Five certain impact <span class="hlt">craters</span> and 44 additional nearly certain and probable ones have been identified on the 22% of Titan's surface imaged by Cassini's high-resolution radar through December 2007. The certain <span class="hlt">craters</span> have morphologies similar to impact <span class="hlt">craters</span> on rocky planets, as well as two with radar bright, jagged rims. The less certain <span class="hlt">craters</span> often appear to be eroded versions of the certain ones. Titan's <span class="hlt">craters</span> are modified by a variety of processes including fluvial erosion, mass wasting, burial by dunes and submergence in seas, but there is no compelling evidence of isostatic adjustments as on other icy moons, nor draping by thick atmospheric deposits. The paucity of <span class="hlt">craters</span> implies that Titan's surface is quite young, but the modeled age depends on which published <span class="hlt">crater</span> production rate is assumed. Using the model of Artemieva and Lunine (2005) suggests that <span class="hlt">craters</span> with diameters smaller than about 35 km are younger than 200 million years old, and larger <span class="hlt">craters</span> are older. <span class="hlt">Craters</span> are not distributed uniformly; Xanadu has a <span class="hlt">crater</span> density <span class="hlt">2</span>-9 times greater than the rest of Titan, and the density on equatorial dune areas is much lower than average. There is a small excess of <span class="hlt">craters</span> on the leading hemisphere, and <span class="hlt">craters</span> are deficient in the north polar region compared to the rest of the world. The youthful age of Titan overall, and the various erosional states of its likely impact <span class="hlt">craters</span>, demonstrate that dynamic processes have destroyed most of the early history of the moon, and that multiple processes continue to strongly modify its surface. The existence of 24 possible impact <span class="hlt">craters</span> with diameters less than 20 km appears consistent with the Ivanov, Basilevsky and Neukum (1997) model of the effectiveness of Titan's atmosphere in destroying most but not all small projectiles.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70037384','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70037384"><span>Impact <span class="hlt">craters</span> on Titan</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Wood, C.A.; Lorenz, R.; Kirk, R.; Lopes, R.; Mitchell, Ken; Stofan, E.</p> <p>2010-01-01</p> <p>Five certain impact <span class="hlt">craters</span> and 44 additional nearly certain and probable ones have been identified on the 22% of Titan's surface imaged by Cassini's high-resolution radar through December 2007. The certain <span class="hlt">craters</span> have morphologies similar to impact <span class="hlt">craters</span> on rocky planets, as well as two with radar bright, jagged rims. The less certain <span class="hlt">craters</span> often appear to be eroded versions of the certain ones. Titan's <span class="hlt">craters</span> are modified by a variety of processes including fluvial erosion, mass wasting, burial by dunes and submergence in seas, but there is no compelling evidence of isostatic adjustments as on other icy moons, nor draping by thick atmospheric deposits. The paucity of <span class="hlt">craters</span> implies that Titan's surface is quite young, but the modeled age depends on which published <span class="hlt">crater</span> production rate is assumed. Using the model of Artemieva and Lunine (2005) suggests that <span class="hlt">craters</span> with diameters smaller than about 35 km are younger than 200 million years old, and larger <span class="hlt">craters</span> are older. <span class="hlt">Craters</span> are not distributed uniformly; Xanadu has a <span class="hlt">crater</span> density <span class="hlt">2</span>-9 times greater than the rest of Titan, and the density on equatorial dune areas is much lower than average. There is a small excess of <span class="hlt">craters</span> on the leading hemisphere, and <span class="hlt">craters</span> are deficient in the north polar region compared to the rest of the world. The youthful age of Titan overall, and the various erosional states of its likely impact <span class="hlt">craters</span>, demonstrate that dynamic processes have destroyed most of the early history of the moon, and that multiple processes continue to strongly modify its surface. The existence of 24 possible impact <span class="hlt">craters</span> with diameters less than 20 km appears consistent with the Ivanov, Basilevsky and Neukum (1997) model of the effectiveness of Titan's atmosphere in destroying most but not all small projectiles. ?? 2009 Elsevier Inc.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014Icar..239..186B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014Icar..239..186B"><span>Martian Low-Aspect-Ratio Layered Ejecta (LARLE) <span class="hlt">craters</span>: Distribution, characteristics, and relationship to pedestal <span class="hlt">craters</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Barlow, Nadine G.; Boyce, Joseph M.; Cornwall, Carin</p> <p>2014-09-01</p> <p>Low-Aspect-Ratio Layered Ejecta (LARLE) <span class="hlt">craters</span> are a unique landform found on Mars. LARLE <span class="hlt">craters</span> are characterized by a <span class="hlt">crater</span> and normal layered ejecta pattern surrounded by an extensive but thin outer deposit which terminates in a sinuous, almost flame-like morphology. We have conducted a survey to identify all LARLE <span class="hlt">craters</span> ⩾1-km-diameter within the ±75° latitude zone and to determine their morphologic and morphometric characteristics. The survey reveals 140 LARLE <span class="hlt">craters</span>, with the majority (91%) located poleward of 40°S and 35°N and all occurring within thick mantles of fine-grained deposits which are likely ice-rich. LARLE <span class="hlt">craters</span> range in diameter from the cut-off limit of 1 km up to 12.<span class="hlt">2</span> km, with 83% being smaller than 5 km. The radius of the outer LARLE deposit displays a linear trend with the <span class="hlt">crater</span> radius and is greatest at higher polar latitudes. The LARLE deposit ranges in length between <span class="hlt">2</span>.56 and 14.81 <span class="hlt">crater</span> radii in average extent, with maximum length extending up to 21.4 <span class="hlt">crater</span> radii. The LARLE layer is very sinuous, with lobateness values ranging between 1.45 and 4.35. LARLE <span class="hlt">craters</span> display a number of characteristics in common with pedestal <span class="hlt">craters</span> and we propose that pedestal <span class="hlt">craters</span> are eroded versions of LARLE <span class="hlt">craters</span>. The distribution and characteristics of the LARLE <span class="hlt">craters</span> lead us to propose that impact excavation into ice-rich fine-grained deposits produces a dusty base surge cloud (like those produced by explosion <span class="hlt">craters</span>) that deposits dust and ice particles to create the LARLE layers. Salts emplaced by upward migration of water through the LARLE deposit produce a surficial duricrust layer which protects the deposit from immediate removal by eolian processes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://images.nasa.gov/#/details-as10-34-5173.html','SCIGOVIMAGE-NASA'); return false;" href="https://images.nasa.gov/#/details-as10-34-5173.html"><span>Apollo 10 photograph of the lunar farside near IAU <span class="hlt">crater</span> No. 300</span></a></p> <p><a target="_blank" href="https://images.nasa.gov/">NASA Image and Video Library</a></p> <p></p> <p>1969-05-18</p> <p>AS10-34-5173 (18-26 May 1969) --- An Apollo 10 photograph of the lunar farside showing an area in the vicinity of International Astronomical Union (I.A.<span class="hlt">U</span>.) <span class="hlt">crater</span> No. 300, taken from the Command and Service Modules. This view is looking south over typical rugged lunar terrain. I.A.<span class="hlt">U</span>. <span class="hlt">crater</span> No. 300 is located at 155 degrees east longitude and 10 degrees south latitude.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/22225017-pressure-build-up-during-fire-test-type-packages-containing-water','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22225017-pressure-build-up-during-fire-test-type-packages-containing-water"><span>Pressure Build-Up During the Fire Test in Type <span class="hlt">B(U</span>) Packages Containing Water - 13280</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Feldkamp, Martin; Nehrig, Marko; Bletzer, Claus</p> <p></p> <p>The safety assessment of packages for the transport of radioactive materials with content containing liquids requires special consideration. The main focus is on water as supplementary liquid content in Type <span class="hlt">B(U</span>) packages. A typical content of a Type <span class="hlt">B(U</span>) package is ion exchange resin, waste of a nuclear power plant, which is not dried, normally only drained. Besides the saturated ion exchange resin, a small amount of free water can be included in these contents. Compared to the safety assessment of packages with dry content, attention must be paid to some more specific issues. An overview of these issues ismore » provided. The physical and chemical compatibility of the content itself and the content compatibility with the packages materials must be demonstrated for the assessment. Regarding the mechanical resistance the package has to withstand the forces resulting from the freezing liquid. The most interesting point, however, is the pressure build-up inside the package due to vaporization. This could for example be caused by radiolysis of the liquid and must be taken into account for the storage period. If the package is stressed by the total inner pressure, this pressure leads to mechanical loads to the package body, the lid and the lid bolts. Thus, the pressure is the driving force on the gasket system regarding the activity release and a possible loss of tightness. The total pressure in any calculation is the sum of partial pressures of different gases which can be caused by different effects. The pressure build-up inside the package caused by the regulatory thermal test (30 min at 800 deg. C), as part of the cumulative test scenario under accident conditions of transport is discussed primarily. To determine the pressure, the temperature distribution in the content must be calculated for the whole period from beginning of the thermal test until cooling-down. In this case, while calculating the temperature distribution, conduction and radiation as well as</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2840173','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2840173"><span>A model for the CO-inhibited form of [NiFe] hydrogenase: synthesis of (CO)3Fe(μ-St<span class="hlt">Bu</span>)3Ni{SC6H3-<span class="hlt">2</span>,6-(mesityl)<span class="hlt">2</span>} and reversible CO addition at the Ni site</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Ohki, Yasuhiro; Yasumura, Kazunari; Ando, Masaru; Shimokata, Satoko; Tatsumi, Kazuyuki</p> <p>2010-01-01</p> <p>A [NiFe] hydrogenase model compound having a distorted trigonal-pyramidal nickel center, (CO)3Fe(μ-St<span class="hlt">Bu</span>)3Ni(SDmp), 1 (Dmp = C6H3-<span class="hlt">2</span>,6-(mesityl)<span class="hlt">2</span>), was synthesized from the reaction of the tetranuclear Fe-Ni-Ni-Fe complex [(CO)3Fe(μ-St<span class="hlt">Bu</span>)3Ni]<span class="hlt">2</span>(μ-Br)<span class="hlt">2</span>, <span class="hlt">2</span> with NaSDmp at -40 °C. The nickel site of complex 1 was found to add CO or CNt<span class="hlt">Bu</span> at -40 °C to give (CO)3Fe(St<span class="hlt">Bu)(μ-StBu</span>)<span class="hlt">2</span>Ni(CO)(SDmp), 3, or (CO)3Fe(St<span class="hlt">Bu)(μ-StBu</span>)<span class="hlt">2</span>Ni(CNt<span class="hlt">Bu</span>)(SDmp), 4, respectively. One of the CO bands of 3, appearing at 2055 cm-1 in the infrared spectrum, was assigned as the Ni-CO band, and this frequency is comparable to those observed for the CO-inhibited forms of [NiFe] hydrogenase. Like the CO-inhibited forms of [NiFe] hydrogenase, the coordination of CO at the nickel site of 1 is reversible, while the CNt<span class="hlt">Bu</span> adduct 4 is more robust. PMID:20147622</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2010-title46-vol8/pdf/CFR-2010-title46-vol8-sec381-8.pdf','CFR'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2010-title46-vol8/pdf/CFR-2010-title46-vol8-sec381-8.pdf"><span>46 CFR 381.8 - <span class="hlt">Subsidized</span> vessel participation.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2010&page.go=Go">Code of Federal Regulations, 2010 CFR</a></p> <p></p> <p>2010-10-01</p> <p>... from MARAD an amount for the operating-differential subsidy (ODS) likely to be paid for the carriage of... <span class="hlt">subsidized</span> bidders; (<span class="hlt">2</span>) Deriving “augmented bids” for the <span class="hlt">subsidized</span> operators by adding the ODS amount to... on MARAD's calculation of anticipated costs (less ODS in the case of a <span class="hlt">subsidized</span> vessel) for the...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.usgs.gov/of/1974/1064/report.pdf','USGSPUBS'); return false;" href="https://pubs.usgs.gov/of/1974/1064/report.pdf"><span>Preliminary <span class="hlt">subsidence</span> investigation of Sacramento Valley, California</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Lofgren, B.E.; Ireland, R.L.</p> <p>1973-01-01</p> <p>Although a number of agencies have made leveling surveys in Sacramento Valley and a valleywide network of first- and second-order control exists, few areas have sufficient control for determining whether land <span class="hlt">subsidence</span> has occurred and if so, how much, within the time span of vertical control. Available data suggest that 0.<span class="hlt">2</span> to 0.9 foot (0.06 to 0.3 m) of <span class="hlt">subsidence</span> probably has occurred from 1935-42 to 1964 in an extensive agricultural area of heavy ground-water pumping between Zamora and Davis, and that as much as <span class="hlt">2</span> feet (0.6 m) of <span class="hlt">subsidence</span> has occurred in at least two areas of pumping overdraft--east of Zamora, and west of Arbuckle. A comparison of maps showing long-term water-level decline and average annual ground-water pumpage indicates several other areas of probable <span class="hlt">subsidence</span>. In six general areas--northwest of Sacramento; northeast of Sacramento; southeast of Yuba City; 10 miles (16 km) north of Willows; 20 miles (32 km) north of Willows; and especially in the Arbuckle area,ground-water declines have quite probably produced significant <span class="hlt">subsidence</span>. In two areas of most intensive pumping, no long-term water-level declines have occurred, and no <span class="hlt">subsidence</span> is indicated. If problems of land <span class="hlt">subsidence</span> are of concern in Sacramento Valley, and if estimates of historic <span class="hlt">subsidence</span> or <span class="hlt">subsidence</span> potential are needed, serious consideration should be given to a field program of basic-data collection. Second-order leveling along a few carefully selected lines of existing control, and the installation and operation of two or three compaction recorders in areas of continuing water-level decline, would provide helpful data for estimating .past and future <span class="hlt">subsidence</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://images.nasa.gov/#/details-PIA21454.html','SCIGOVIMAGE-NASA'); return false;" href="https://images.nasa.gov/#/details-PIA21454.html"><span>A Dragonfly-Shaped <span class="hlt">Crater</span></span></a></p> <p><a target="_blank" href="https://images.nasa.gov/">NASA Image and Video Library</a></p> <p></p> <p>2017-02-10</p> <p>The broader scene for this image is the fluidized ejecta from Bakhuysen <span class="hlt">Crater</span> to the southwest, but there's something very interesting going on here on a much smaller scale. A small impact <span class="hlt">crater</span>, about 25 meters in diameter, with a gouged-out trench extends to the south. The ejecta (rocky material ejected from the <span class="hlt">crater</span>) mostly extends to the east and west of the <span class="hlt">crater</span>. This "butterfly" ejecta is very common for <span class="hlt">craters</span> formed at low impact angles. Taken together, these observations suggest that the <span class="hlt">crater</span>-forming impactor came in at a low angle from the north, hit the ground and ejected material to the sides. The top of the impactor may have sheared off ("decapitating" the impactor) and continued downrange, forming the trench. We can't prove that's what happened, but this explanation is consistent with the observations. Regardless of how it formed, it's quite an interesting-looking "dragonfly" <span class="hlt">crater</span>. The map is projected here at a scale of 50 centimeters (19.69 inches) per pixel. [The original image scale is 55.7 centimeters (21.92 inches) per pixel (with <span class="hlt">2</span> x <span class="hlt">2</span> binning); objects on the order of 167 centimeters (65.7 inches) across are resolved.] North is up. http://photojournal.jpl.nasa.gov/catalog/PIA21454</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1435519-reactivity-silanes-tbuponop-ruthenium-dichloride-facile-synthesis-chloro-silyl-ruthenium-compounds-formic-acid-decomposition','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1435519-reactivity-silanes-tbuponop-ruthenium-dichloride-facile-synthesis-chloro-silyl-ruthenium-compounds-formic-acid-decomposition"><span>Reactivity of Silanes with ( t<span class="hlt">Bu</span>PONOP)Ruthenium Dichloride: Facile Synthesis of Chloro-Silyl Ruthenium Compounds and Formic Acid Decomposition</span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Anderson, Nickolas H.; Boncella, James M.; Tondreau, Aaron M.</p> <p>2017-08-15</p> <p>The coordination of t<span class="hlt">Bu</span>PONOP ( t<span class="hlt">Bu</span>PONOP=<span class="hlt">2</span>,6-bis(ditert-butylphosphinito)pyridine) to different ruthenium starting materials, to generate ( t<span class="hlt">Bu</span>PONOP)RuCl <span class="hlt">2</span>, was investigated in this paper. The resultant ( t<span class="hlt">Bu</span>PONOP)RuCl <span class="hlt">2</span> reactivity with three different silanes was then investigated and contrasted dramatically with the reactivity of ( iPrPONOP)RuCl <span class="hlt">2</span>(DMSO) ( iPrPONOP=<span class="hlt">2</span>,6-bis(diisopropylphosphinito)pyridine) with the same silanes. The 16-electron species ( t<span class="hlt">Bu</span>PONOP)Ru(H)Cl was produced from the reaction of triethylsilane with ( t<span class="hlt">Bu</span>PONOP)RuCl <span class="hlt">2</span>. Reactions of ( t<span class="hlt">Bu</span>PONOP)RuCl <span class="hlt">2</span> with both phenylsilane or diphenylsilane afforded the 16-electron hydrido-silyl species ( t<span class="hlt">Bu</span>PONOP)Ru(H)(PhSiCl <span class="hlt">2</span>) and ( t<span class="hlt">Bu</span>PONOP)Ru(H)(Ph <span class="hlt">2</span>SiCl), respectively. Reactions of all three of these complexes with silver triflate affordedmore » the simple salt metathesis products of ( t<span class="hlt">Bu</span>PONOP)Ru(H)(OTf), ( t<span class="hlt">Bu</span>PONOP)Ru(H)(PhSiCl(OTf)), and ( t<span class="hlt">Bu</span>PONOP)Ru(H)(Ph <span class="hlt">2</span>Si(OTf)). Formic acid dehydrogenation was performed in the presence of triethylamine (TEA), and each species proved competent for gas-pressure generation of CO <span class="hlt">2</span> and H <span class="hlt">2</span>. Finally, the hydride species ( t<span class="hlt">Bu</span>PONOP)Ru(H)Cl, ( t<span class="hlt">Bu</span>PONOP)Ru(H)(OTf), and ( t<span class="hlt">Bu</span>PONOP)Ru(H)(PhSiCl <span class="hlt">2</span>) exhibited faster catalytic activity than the other compounds tested.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA471743','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA471743"><span>Laboratory and Field Investigations of Small <span class="hlt">Crater</span> Repair Technologies</span></a></p> <p><a target="_blank" href="http://www.dtic.mil/">DTIC Science & Technology</a></p> <p></p> <p>2007-09-01</p> <p>caps over debris backfill or specially placed or compacted backfill, structural systems to bridge <span class="hlt">craters</span>, foamed <span class="hlt">crater</span> backfills, and structural ...Jeb S. Tingle, and Timothy J. McCaffrey Geotechnical and Structures Laboratory <span class="hlt">U</span>.S. Army Engineer Research and Development Center 3909 Halls Ferry...Engineer Research and Development Center (ERDC), Geotechnical and Structures Laboratory (GSL), Vicksburg, MS. The findings and recommendations presented</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014P%26SS...96...71M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014P%26SS...96...71M"><span>Impact <span class="hlt">cratering</span> experiments in brittle targets with variable thickness: Implications for deep pit <span class="hlt">craters</span> on Mars</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Michikami, T.; Hagermann, A.; Miyamoto, H.; Miura, S.; Haruyama, J.; Lykawka, P. S.</p> <p>2014-06-01</p> <p>High-resolution images reveal that numerous pit <span class="hlt">craters</span> exist on the surface of Mars. For some pit <span class="hlt">craters</span>, the depth-to-diameter ratios are much greater than for ordinary <span class="hlt">craters</span>. Such deep pit <span class="hlt">craters</span> are generally considered to be the results of material drainage into a subsurface void space, which might be formed by a lava tube, dike injection, extensional fracturing, and dilational normal faulting. Morphological studies indicate that the formation of a pit <span class="hlt">crater</span> might be triggered by the impact event, and followed by collapse of the ceiling. To test this hypothesis, we carried out laboratory experiments of impact <span class="hlt">cratering</span> into brittle targets with variable roof thickness. In particular, the effect of the target thickness on the <span class="hlt">crater</span> formation is studied to understand the penetration process by an impact. For this purpose, we produced mortar targets with roof thickness of 1-6 cm, and a bulk density of 1550 kg/m3 by using a mixture of cement, water and sand (0.<span class="hlt">2</span> mm) in the ratio of 1:1:10, by weight. The compressive strength of the resulting targets is 3.<span class="hlt">2</span>±0.9 MPa. A spherical nylon projectile (diameter 7 mm) is shot perpendicularly into the target surface at the nominal velocity of 1.<span class="hlt">2</span> km/s, using a two-stage light-gas gun. <span class="hlt">Craters</span> are formed on the opposite side of the impact even when no target penetration occurs. Penetration of the target is achieved when <span class="hlt">craters</span> on the opposite sides of the target connect with each other. In this case, the cross section of <span class="hlt">crater</span> somehow attains a flat hourglass-like shape. We also find that the <span class="hlt">crater</span> diameter on the opposite side is larger than that on the impact side, and more fragments are ejected from the <span class="hlt">crater</span> on the opposite side than from the <span class="hlt">crater</span> on the impact side. This result gives a qualitative explanation for the observation that the Martian deep pit <span class="hlt">craters</span> lack a raised rim and have the ejecta deposit on their floor instead. <span class="hlt">Craters</span> are formed on the opposite impact side even when no penetration</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014acm..conf..564V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014acm..conf..564V"><span><span class="hlt">Craters</span> on comets</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Vincent, J.; Oklay, N.; Marchi, S.; Höfner, S.; Sierks, H.</p> <p>2014-07-01</p> <p>This paper reviews the observations of <span class="hlt">crater</span>-like features on cometary nuclei. ''Pits'' have been observed on almost all cometary nuclei but their origin is not fully understood [1,<span class="hlt">2</span>,3,4]. It is currently assumed that they are created mainly by the cometary activity with a pocket of volatiles erupting under a dust crust, leaving a hole behind. There are, however, other features which cannot be explained in this way and are interpreted alternatively as remnants of impact <span class="hlt">craters</span>. This work focusses on the second type of pit features: impact <span class="hlt">craters</span>. We present an in-depth review of what has been observed previously and conclude that two main types of <span class="hlt">crater</span> morphologies can be observed: ''pit-halo'' and ''sharp pit''. We extend this review by a series of analysis of impact <span class="hlt">craters</span> on cometary nuclei through different approaches [5]: (1) Probability of impact: We discuss the chances that a Jupiter Family Comet like 9P/Tempel 1 or the target of Rosetta 67P/Churyumov-Gerasimenko can experience an impact, taking into account the most recent work on the size distribution of small objects in the asteroid Main Belt [6]. (<span class="hlt">2</span>) <span class="hlt">Crater</span> morphology from scaling laws: We present the status of scaling laws for impact <span class="hlt">craters</span> on cometary nuclei [7] and discuss their strengths and limitations when modeling what happens when a rocky projectile hits a very porous material. (3) Numerical experiments: We extend the work on scaling laws by a series of hydrocode impact simulations, using the iSALE shock physics code [8,9,10] for varying surface porosity and impactor velocity (see Figure). (4) Surface processes and evolution: We discuss finally the fate of the projectile and the effects of the impact-induced surface compaction on the activity of the nucleus. To summarize, we find that comets do undergo impacts although the rapid evolution of the surface erases most of the features and make <span class="hlt">craters</span> difficult to detect. In the case of a collision between a rocky body and a highly porous</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017IJAEO..61...92N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017IJAEO..61...92N"><span>Satellite radar interferometry for monitoring <span class="hlt">subsidence</span> induced by longwall mining activity using Radarsat-<span class="hlt">2</span>, Sentinel-1 and ALOS-<span class="hlt">2</span> data</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ng, Alex Hay-Man; Ge, Linlin; Du, Zheyuan; Wang, Shuren; Ma, Chao</p> <p>2017-09-01</p> <p>This paper describes the simulation and real data analysis results from the recently launched SAR satellites, ALOS-<span class="hlt">2</span>, Sentinel-1 and Radarsat-<span class="hlt">2</span> for the purpose of monitoring <span class="hlt">subsidence</span> induced by longwall mining activity using satellite synthetic aperture radar interferometry (InSAR). Because of the enhancement of orbit control (pairs with shorter perpendicular baseline) from the new satellite SAR systems, the mine <span class="hlt">subsidence</span> detection is now mainly constrained by the phase discontinuities due to large deformation and temporal decorrelation noise. This paper investigates the performance of the three satellite missions with different imaging modes for mapping longwall mine <span class="hlt">subsidence</span>. The results show that the three satellites perform better than their predecessors. The simulation results show that the Sentinel-1A/B constellation is capable of mapping rapid mine <span class="hlt">subsidence</span>, especially the Sentinel-1A/B constellation with stripmap (SM) mode. Unfortunately, the Sentinel-1A/B SM data are not available in most cases and hence real data analysis cannot be conducted in this study. Despite the Sentinel-1A/B SM data, the simulation and real data analysis suggest that ALOS-<span class="hlt">2</span> is best suited for mapping mine <span class="hlt">subsidence</span> amongst the three missions. Although not investigated in this study, the X-band satellites TerraSAR-X and COSMO-SkyMed with short temporal baseline and high spatial resolution can be comparable with the performance of the Radarsat-<span class="hlt">2</span> and Sentinel-1 C-band data over the dry surface with sparse vegetation. The potential of the recently launched satellites (e.g. ALOS-<span class="hlt">2</span> and Sentinel-1A/B) for mapping longwall mine <span class="hlt">subsidence</span> is expected to be better than the results of this study, if the data acquired from the ideal acquisition modes are available.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA440232','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA440232"><span>MODFLOW-2000 Ground-Water Model--User Guide to the <span class="hlt">Subsidence</span> and Aquifer-System Compaction (SUB) Package</span></a></p> <p><a target="_blank" href="http://www.dtic.mil/">DTIC Science & Technology</a></p> <p></p> <p>2003-01-01</p> <p>compaction and water -level changes (Epstein, 1987 ; Hanson, 1989). More recent efforts have focused on incorporating <span class="hlt">subsidence</span> calculations in widely...Horizontal aquifer movement in a Theis-Thiem confined system: Water Resources Research, v. 30, no. 4, p. 953–964. Heywood, C.E., 1997, Piezometric ...<span class="hlt">U</span>.S. DEPARTMENT OF THE INTERIOR <span class="hlt">U</span>.S. GEOLOGICAL SURVEY MODFLOW-2000 Ground- Water Model—User Guide to the <span class="hlt">Subsidence</span> and Aquifer-System Compaction</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_3");'>3</a></li> <li><a href="#" onclick='return showDiv("page_4");'>4</a></li> <li class="active"><span>5</span></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_5 --> <div id="page_6" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_4");'>4</a></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li class="active"><span>6</span></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="101"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70012230','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70012230"><span>Small impact <span class="hlt">craters</span> in the lunar regolith - Their morphologies, relative ages, and rates of formation</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Moore, H.J.; Boyce, J.M.; Hahn, D.A.</p> <p>1980-01-01</p> <p>Apparently, there are two types of size-frequency distributions of small lunar <span class="hlt">craters</span> (???1-100 m across): (1) <span class="hlt">crater</span> production distributions for which the cumulative frequency of <span class="hlt">craters</span> is an inverse function of diameter to power near <span class="hlt">2</span>.8, and (<span class="hlt">2</span>) steady-state distributions for which the cumulative frequency of <span class="hlt">craters</span> is inversely proportional to the square of their diameters. According to theory, cumulative frequencies of <span class="hlt">craters</span> in each morphologic category within the steady-state should also be an inverse function of the square of their diameters. Some data on frequency distribution of <span class="hlt">craters</span> by morphologic types are approximately consistent with theory, whereas other data are inconsistent with theory. A flux of <span class="hlt">crater</span> producing objects can be inferred from size-frequency distributions of small <span class="hlt">craters</span> on the flanks and ejecta of <span class="hlt">craters</span> of known age. <span class="hlt">Crater</span> frequency distributions and data on the <span class="hlt">craters</span> Tycho, North Ray, Cone, and South Ray, when compared with the flux of objects measured by the Apollo Passive Seismometer, suggest that the flux of objects has been relatively constant over the last 100 m.y. (within 1/3 to 3 times of the flux estimated for Tycho). Steady-state frequency distributions for <span class="hlt">craters</span> in several morphologic categories formed the basis for estimating the relative ages of <span class="hlt">craters</span> and surfaces in a system used during the Apollo landing site mapping program of the <span class="hlt">U</span>.S. Geological Survey. The relative ages in this system are converted to model absolute ages that have a rather broad range of values. The range of values of the absolute ages are between about 1/3 to 3 times the assigned model absolute age. ?? 1980 D. Reidel Publishing Co.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=PIA04678&hterms=under+armor&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dunder%2Barmor','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=PIA04678&hterms=under+armor&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dunder%2Barmor"><span>Pedestal <span class="hlt">Crater</span> and Yardangs</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>2003-01-01</p> <p>MGS MOC Release No. MOC<span class="hlt">2</span>-444, 6 August 2003<p/>This April 2003 Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a small meteor impact <span class="hlt">crater</span> that has been modified by wind erosion. Two things happened after the <span class="hlt">crater</span> formed. First, the upper few meters of surface material into which the meteor impacted was later eroded away by wind. The <span class="hlt">crater</span> ejecta formed a protective armor that kept the material under the ejecta from been blown away. This caused the <span class="hlt">crater</span> and ejecta to appear as if standing upon a raised platform--a feature that Mars geologists call a <i>pedestal <span class="hlt">crater</span>.</i> Next, the pedestal <span class="hlt">crater</span> was buried beneath several meters of new sediment, and then this material was eroded away by wind to form the array of sharp ridges that run across the pedestal <span class="hlt">crater</span>'s surface. These small ridges are known as <i>yardangs</i>. This picture is illuminated by sunlight from the upper left; it is located in west Daedalia Planum near 14.6oS, 131.9oW.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFM.P23C2741W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFM.P23C2741W"><span>Using THEMIS thermal infrared observations of rays from Corinto <span class="hlt">crater</span> to study secondary <span class="hlt">crater</span> formation on Mars</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Williams, J. P.</p> <p>2017-12-01</p> <p>Corinto <span class="hlt">crater</span> (16.95°N, 141.72°E), a 13.8 km diameter <span class="hlt">crater</span> in Elysium Planitia, displays dramatic rays in Mars Odyssey's Thermal Emission Imaging System (THEMIS) nighttime infrared imagery where high concentrations of secondary <span class="hlt">craters</span> have altered the thermophysical properties of the martian surface. The THEMIS observations provide a record of secondary <span class="hlt">crater</span> formation in the region and ray segments are identified up to 2000 km ( 145 <span class="hlt">crater</span> radii) distance [1][<span class="hlt">2</span>]. Secondary <span class="hlt">craters</span> are likely to have the largest influence on model surfaces ages between 0.1 to a few Myr as there is the potential for one or two sizeable <span class="hlt">craters</span> to project secondary <span class="hlt">craters</span> onto those surfaces and thus alter the <span class="hlt">crater</span> size-frequency distribution (CSFD) with an instantaneous spike in <span class="hlt">crater</span> production [3]. Corinto <span class="hlt">crater</span> is estimated to be less than a few Ma [4] placing the formation of its secondaries within this formative time period. Secondary <span class="hlt">craters</span> superposed on relatively young impact <span class="hlt">craters</span> that predate Corinto provide observations of the secondary <span class="hlt">crater</span> populations. <span class="hlt">Crater</span> counts at 520 and 660 km distance from Corinto (38 and 48 <span class="hlt">crater</span> radii respectively), were conducted. Higher <span class="hlt">crater</span> densities were observed within ray segments, however secondary <span class="hlt">craters</span> still influenced the CSFD where ray segments were not apparent, resulting in steepening in the CSFD. Randomness analysis confirms an increase in clustering as diameters decrease suggesting an increasing fraction of secondary <span class="hlt">craters</span> at smaller diameters, both within the ray and outside. The counts demonstrate that even at nearly 50 <span class="hlt">crater</span> radii, Corinto secondaries still influence the observed CSFD, even outside of any obvious rays. <span class="hlt">Crater</span> populations used to derive model ages on many geologically young regions on Mars, such as glacial and periglacial landforms related to obliquity excursions that occur on 106 - 107 yr cycles, should be used cautiously and analyzed for any evidence, either morphologic or</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20140004932','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20140004932"><span>LU60645GT and MA132843GT Catalogues of Lunar and Martian Impact <span class="hlt">Craters</span> Developed Using a <span class="hlt">Crater</span> Shape-based Interpolation <span class="hlt">Crater</span> Detection Algorithm for Topography Data</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Salamuniccar, Goran; Loncaric, Sven; Mazarico, Erwan Matias</p> <p>2012-01-01</p> <p>For Mars, 57,633 <span class="hlt">craters</span> from the manually assembled catalogues and 72,668 additional <span class="hlt">craters</span> identified using several <span class="hlt">crater</span> detection algorithms (CDAs) have been merged into the MA130301GT catalogue. By contrast, for the Moon the most complete previous catalogue contains only 14,923 <span class="hlt">craters</span>. Two recent missions provided higher-quality digital elevation maps (DEMs): SELENE (in 1/16° resolution) and Lunar Reconnaissance Orbiter (we used up to 1/512°). This was the main motivation for work on the new <span class="hlt">Crater</span> Shape-based interpolation module, which improves previous CDA as follows: (1) it decreases the number of false-detections for the required number of true detections; (<span class="hlt">2</span>) it improves detection capabilities for very small <span class="hlt">craters</span>; and (3) it provides more accurate automated measurements of <span class="hlt">craters</span>' properties. The results are: (1) LU60645GT, which is currently the most complete (up to D>=8 km) catalogue of Lunar <span class="hlt">craters</span>; and (<span class="hlt">2</span>) MA132843GT catalogue of Martian <span class="hlt">craters</span> complete up to D>=<span class="hlt">2</span> km, which is the extension of the previous MA130301GT catalogue. As previously achieved for Mars, LU60645GT provides all properties that were provided by the previous Lunar catalogues, plus: (1) correlation between morphological descriptors from used catalogues; (<span class="hlt">2</span>) correlation between manually assigned attributes and automated measurements; (3) average errors and their standard deviations for manually and automatically assigned attributes such as position coordinates, diameter, depth/diameter ratio, etc; and (4) a review of positional accuracy of used datasets. Additionally, surface dating could potentially be improved with the exhaustiveness of this new catalogue. The accompanying results are: (1) the possibility of comparing a large number of Lunar and Martian <span class="hlt">craters</span>, of e.g. depth/diameter ratio and <span class="hlt">2</span>D profiles; (<span class="hlt">2</span>) utilisation of a method for re-projection of datasets and catalogues, which is very useful for <span class="hlt">craters</span> that are very close to poles; and (3) the extension of the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70030612','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70030612"><span><span class="hlt">Crater</span> gradation in Gusev <span class="hlt">crater</span> and Meridiani Planum, Mars</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Grant, J. A.; Arvidson, R. E.; Crumpler, L.S.; Golombek, M.P.; Hahn, B.; Haldemann, A.F.C.; Li, R.; Soderblom, L.A.; Squyres, S. W.; Wright, S.P.; Watters, W.A.</p> <p>2006-01-01</p> <p>The Mars Exploration Rovers investigated numerous <span class="hlt">craters</span> in Gusev <span class="hlt">crater</span> and Meridiani Planum during the first ???400 sols of their missions. <span class="hlt">Craters</span> vary in size and preservation state but are mostly due to secondary impacts at Gusev and primary impacts at Meridiani. <span class="hlt">Craters</span> at both locations are modified primarily by eolian erosion and infilling and lack evidence for modification by aqueous processes. Effects of gradation on <span class="hlt">crater</span> form are dependent on size, local lithology, slopes, and availability of mobile sediments. At Gusev, impacts into basaltic rubble create shallow <span class="hlt">craters</span> and ejecta composed of resistant rocks. Ejecta initially experience eolian stripping, which becomes weathering-limited as lags develop on ejecta surfaces and sediments are trapped within <span class="hlt">craters</span>. Subsequent eolian gradation depends on the slow production of fines by weathering and impacts and is accompanied by minor mass wasting. At Meridiani the sulfate-rich bedrock is more susceptible to eolian erosion, and exposed <span class="hlt">crater</span> rims, walls, and ejecta are eroded, while lower interiors and low-relief surfaces are increasingly infilled and buried by mostly basaltic sediments. Eolian processes outpace early mass wasting, often produce meters of erosion, and mantle some surfaces. Some small <span class="hlt">craters</span> were likely completely eroded/buried. <span class="hlt">Craters</span> >100 m in diameter on the Hesperian-aged floor of Gusev are generally more pristine than on the Amazonian-aged Meridiani plains. This conclusion contradicts interpretations from orbital views, which do not readily distinguish <span class="hlt">crater</span> gradation state at Meridiani and reveal apparently subdued <span class="hlt">crater</span> forms at Gusev that may suggest more gradation than has occurred. Copyright 2006 by the American Geophysical Union.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006JGRE..111.2S08G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006JGRE..111.2S08G"><span><span class="hlt">Crater</span> gradation in Gusev <span class="hlt">crater</span> and Meridiani Planum, Mars</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Grant, J. A.; Arvidson, R. E.; Crumpler, L. S.; Golombek, M. P.; Hahn, B.; Haldemann, A. F. C.; Li, R.; Soderblom, L. A.; Squyres, S. W.; Wright, S. P.; Watters, W. A.</p> <p>2006-01-01</p> <p>The Mars Exploration Rovers investigated numerous <span class="hlt">craters</span> in Gusev <span class="hlt">crater</span> and Meridiani Planum during the first ~400 sols of their missions. <span class="hlt">Craters</span> vary in size and preservation state but are mostly due to secondary impacts at Gusev and primary impacts at Meridiani. <span class="hlt">Craters</span> at both locations are modified primarily by eolian erosion and infilling and lack evidence for modification by aqueous processes. Effects of gradation on <span class="hlt">crater</span> form are dependent on size, local lithology, slopes, and availability of mobile sediments. At Gusev, impacts into basaltic rubble create shallow <span class="hlt">craters</span> and ejecta composed of resistant rocks. Ejecta initially experience eolian stripping, which becomes weathering-limited as lags develop on ejecta surfaces and sediments are trapped within <span class="hlt">craters</span>. Subsequent eolian gradation depends on the slow production of fines by weathering and impacts and is accompanied by minor mass wasting. At Meridiani the sulfate-rich bedrock is more susceptible to eolian erosion, and exposed <span class="hlt">crater</span> rims, walls, and ejecta are eroded, while lower interiors and low-relief surfaces are increasingly infilled and buried by mostly basaltic sediments. Eolian processes outpace early mass wasting, often produce meters of erosion, and mantle some surfaces. Some small <span class="hlt">craters</span> were likely completely eroded/buried. <span class="hlt">Craters</span> >100 m in diameter on the Hesperian-aged floor of Gusev are generally more pristine than on the Amazonian-aged Meridiani plains. This conclusion contradicts interpretations from orbital views, which do not readily distinguish <span class="hlt">crater</span> gradation state at Meridiani and reveal apparently subdued <span class="hlt">crater</span> forms at Gusev that may suggest more gradation than has occurred.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/939120','SCIGOV-STC'); return false;" href="https://www.osti.gov/servlets/purl/939120"><span>Post-Closure Inspection and Monitoring Report for Corrective Action Unit 110: Area 3 WMD <span class="hlt">U</span>-3ax/bl <span class="hlt">Crater</span>, Nevada Test Site, Nevada, For the Period July 2007-June 2008</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>NSTec Environmental Restoration</p> <p>2008-08-01</p> <p>This Post-Closure Inspection and Monitoring Report (PCIMR) provides the results of inspections and monitoring for Corrective Action Unit (CAU) 110, Area 3 WMD [Waste Management Division] <span class="hlt">U</span>-3ax/bl <span class="hlt">Crater</span>. This PCIMR includes an analysis and summary of the site inspections, repairs and maintenance, meteorological information, and soil moisture monitoring data obtained at CAU 110 for the period July 2007 through June 2008. Site inspections of the cover were performed quarterly to identify any significant changes to the site requiring action. The overall condition of the cover, perimeter fence, and use restriction (UR) warning signs was good. However, settling was observed thatmore » exceeded the action level as specified in Section VII.B.7 of the Hazardous Waste Permit Number NEV HW021 (Nevada Division of Environmental Protection, 2005). This permit states that cracks or settling greater than 15 centimeters (6 inches) deep that extend 1.0 meter (m) (3 feet [ft]) or more on the cover will be evaluated and repaired within 60 days of detection. Two areas of settling and cracks were observed on the south and east edges of the cover during the September 2007 inspection that exceeded the action level and required repair. The areas were repaired in October 2007. Additional settling and cracks were observed along the east side of the cover during the December 2007 inspection that exceeded the action level, and the area was repaired in January 2008. Significant animal burrows were also observed during the March 2008 inspection, and small mammal trapping and relocation was performed in April 2008. The semiannual <span class="hlt">subsidence</span> surveys were performed in September 2007 and March 2008. No significant <span class="hlt">subsidence</span> was observed in the survey data. Monument 5 shows the greatest amount of <span class="hlt">subsidence</span> (-0.02 m [-0.08 ft] compared to the baseline survey of 2000). This amount is negligible and near the resolution of the survey instruments; it does not indicate that <span class="hlt">subsidence</span> is occurring</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2003icbg.conf...20D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003icbg.conf...20D"><span>WIRGO in TIC's? [What (on Earth) is Really Going On in Terrestrial Impact <span class="hlt">Craters</span>?</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Dence, Michael R.</p> <p>2003-02-01</p> <p>Canada is well endowed with impact <span class="hlt">craters</span> formed in crystalline rocks with relatively homogeneous physical properties. They exhibit all the main morphological-structural variations with <span class="hlt">crater</span> size seen in <span class="hlt">craters</span> on other rocky planets, from small simple bowl to large peak and ring forms. Lacking stratigraphy, analysis is based on the imprint of shock melting and metamorphism, the position of the GPL (limit of initial Grady-Kipp fracturing due to shock wave reverberations) relative to shock level, the geometry of late stage shears and breccias and the volume of shocked material beyond the GPL. Simple <span class="hlt">craters</span>, exemplified by Brent (D = 3.7 km) allow direct comparison with models and experimental data. Results of interest include: 1. The central pool of impact melt and underlying breccia at the base of the <span class="hlt">crater</span> fill is interpreted as the remnant of the transient <span class="hlt">crater</span> lining; <span class="hlt">2</span>. The overlying main mass of breccias filling the final apparent <span class="hlt">crater</span> results from latestage slumping of large slabs bounded by a primary shear surface that conforms to a sphere segment of radius, rs approx. = <span class="hlt">2</span>dtc, where dtc is the transient <span class="hlt">crater</span> depth; 3. The foot of the primary shear intersects above the GPL at the centre of the melt pool and the rapid emplacement of slumped slabs produces further brecciation while suppressing any tendency for the centre to rise. In the autochthonous breccias below the melt and in the underlying para-allochthone below the GPL, shock metamorphism weakens with depth. The apparent attenuation of the shock pulse can be compared with experimentally derived rates of attenuation to give a measure of displacements down axis and estimates of the size of a nominal bolide of given velocity, the volume of impact melt and the energy released on impact. In larger complex <span class="hlt">craters</span> (e.g. Charlevoix, D = 52 km) apparent shock attenuation is low near the centre but is higher towards the margin. The inflection point marks the change from uplift of deep material in the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19920019775&hterms=graduation+rates&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dgraduation%2Brates','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19920019775&hterms=graduation+rates&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dgraduation%2Brates"><span>Styles of <span class="hlt">crater</span> gradation in Southern Ismenius Lacus, Mars: Clues from Meteor <span class="hlt">Crater</span>, Arizona</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Grant, J. A.; Schultz, P. H.</p> <p>1992-01-01</p> <p>Impact <span class="hlt">craters</span> on the Earth and Mars provide a unique opportunity to quantify the gradational evolution of instantaneously created landforms in a variety of geologic settings. Unlike most landforms, the initial morphology associated with impact <span class="hlt">craters</span> on both planets is uncomplicated by competition between construction and degradation during formation. Furthermore, pristine morphologies are both well-constrained and similar to a first order. The present study compares styles of graduation at Meteor <span class="hlt">Crater</span> with those around selected <span class="hlt">craters</span> (greater than 1-<span class="hlt">2</span> km in diameter) in southern Ismenius Lacus. Emphasis is placed on features visible in images near LANDSAT TM resolution (30-50 m/pixel) which is available for both areas. In contrast to Mars, vegetation on the Earth can modify gradation, but appears to influence overall rates and styles by <span class="hlt">2</span>X-3X rather than orders of magnitude. Further studies of additional <span class="hlt">craters</span> in differing settings will refine the effects of this and other factors (e.g., substrate). Finally, by analogy with results from other terrestrial gradational surfaces this study should help provide constraints on climate over <span class="hlt">crater</span> histories.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFM.P41D2864R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFM.P41D2864R"><span>Impact <span class="hlt">Craters</span>: Size-Dependent Degration Rates</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ravi, S.; Mahanti, P.; Meyer, H. M.; Robinson, M. S.</p> <p>2017-12-01</p> <p>From superposition relations, Shoemaker and Hackman (1) devised the lunar geologic timescale with Copernican and Eratosthenian as the most recent periods. Classifying <span class="hlt">craters</span> into the two periods is key to understanding impactor flux and regolith maturation rates over the last 3 Ga. Both Copernican and Eratosthenian <span class="hlt">craters</span> exhibit crisp morphologies (sharp rims, steep slopes), however, only the former exhibit high reflectance rays and ejecta (1). Based on the Optical Maturity Parameter (OMAT; <span class="hlt">2</span>), Grier et al. (3) classified 50 fresh <span class="hlt">craters</span> (D >20 km) into 3 categories - young (OMAT >0.22), intermediate, and old (OMAT <0.16). In our previous work, Copernican <span class="hlt">craters</span> (D > 10) were identified (4) from a catalogue of 11,875 <span class="hlt">craters</span> (5). In this work; we compare two size ranges (D: 5 km - 10 km and 10 km to 15 km) of 177 Copernican <span class="hlt">craters</span> based on the average OMAT, measured near the <span class="hlt">crater</span> rim (3). OMAT is measured at the <span class="hlt">crater</span> rim (as opposed to further away from the <span class="hlt">crater</span>) to minimize the influence of spatial variation of OMAT (6) in our investigation. We found that OMAT values are typically lower for smaller <span class="hlt">craters</span> (5km < D < 10km) in comparison to larger <span class="hlt">craters</span> (10km < D < 15km). However, when compared against morphological freshness (as determined by d/D for simpler <span class="hlt">craters</span>), the smaller <span class="hlt">craters</span> were fresher (higher d/D value). Since the OMAT value decreases with age, <span class="hlt">craters</span> with higher d/D value (morphologically fresher) should have higher OMAT, but this is not the case. We propose that quicker loss of OMAT (over time) for smaller <span class="hlt">craters</span> compared to decrease in d/D with <span class="hlt">crater</span> ageing, is responsible for the observed decreased OMAT for smaller <span class="hlt">craters</span>. (1) Shoemaker and Hackman, 1962 (<span class="hlt">2</span>) Lucey et al., 2000 (3) Grier et al., 2001 (4) Ravi et al., 2016 (5) Reinhold et al., 2015 (6) Mahanti et al., 2016</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014EPSC....9..454R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014EPSC....9..454R"><span>The Variability of <span class="hlt">Crater</span> Identification Among Expert and Community <span class="hlt">Crater</span> Analysts</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Robbins, S. J.; Antonenko, I.; Kirchoff, M. R.; Chapman, C. R.; Fassett, C. I.; Herrick, R. R.; Singer, K.; Zanetti, M.; Lehan, C.; Huang, D.; Gay, P.</p> <p>2014-04-01</p> <p>Statistical studies of impact <span class="hlt">crater</span> populations have been used to model ages of planetary surfaces for several decades [1]. This assumes that <span class="hlt">crater</span> counts are approximately invariant and a "correct" population will be identified if the analyst is skilled and diligent. However, the reality is that <span class="hlt">crater</span> identification is somewhat subjective, so variability between analysts, or even a single analyst's variation from day-to-day, is expected [e.g., <span class="hlt">2</span>, 3]. This study was undertaken to quantify that variability within an expert analyst population and between experts and minimally trained volunteers.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20000113023&hterms=sedimentation+channels&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dsedimentation%2Bchannels','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20000113023&hterms=sedimentation+channels&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dsedimentation%2Bchannels"><span>Gale <span class="hlt">Crater</span>: An Amazonian Impact <span class="hlt">Crater</span> Lake at the Plateau/Plain Boundary</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Cabrol, N. A.; Grin, E. A.</p> <p>1998-01-01</p> <p>Gale is a 140-km diameter impact <span class="hlt">crater</span> located at the plateau/plain boundary in the Aeolis Northeast subquadrangle of Mars (5S/223W). The <span class="hlt">crater</span> is bordered in the northward direction by the Elysium Basin, and in eastward direction by Hesperian channels and the Aeolis Mensae <span class="hlt">2</span>. The <span class="hlt">crater</span> displays a rim with two distinct erosion stages: (a) though eroded, the south rim of Gale has an apparent crest line visible from the north to the southwest (b) the west and northwest rims are characterized by a strong erosion that, in some places, partially destroyed the rampart, leaving remnant pits embayed in smooth-like deposits. The same type of deposits is observed north, outside Gale, it also borders the Aeolis Mensae, covers the bottom of the plateau scarp, and the <span class="hlt">crater</span> floor. The central part of Gale shows a 6400 km<span class="hlt">2</span> subround and asymmetrical deposit: (a) the south part is composed of smooth material, (b) the north part shows spectacular terraces, streamlines, and channels. The transition between the two parts of the deposit is characterized by a scarp ranging from 200 to 2000 in high. The highest point of the scarp is at the center of the <span class="hlt">crater</span>, and probably corresponds to a central peak. Gale <span class="hlt">crater</span> does not show a major channel directly inflowing. However, several large fluvi systems are bordering the <span class="hlt">crater</span>, and could be at the origin of the flooding of the <span class="hlt">crater</span>, or have contributed to. One fluvial system is entering the <span class="hlt">crater</span> by the southwest rim but cannot be accounted alone for the volume of sediment deposited in the <span class="hlt">crater</span>. This channel erodes the <span class="hlt">crater</span> floor deposit, and ends in a irregular-shaped and dark albedo feature. Gale <span class="hlt">crater</span> shows the morphology of a <span class="hlt">crater</span> filled during sedimentation episodes, and then eroded Part of the lower sediment deposition contained in Gale might be ancient and not only aqueous in origin. According to the regional geologic history, the sedimentary deposit could be a mixture of aeolian and pyroclastic material, and aqueous</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=PIA10947&hterms=slump&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dslump','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=PIA10947&hterms=slump&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dslump"><span>Oudemans <span class="hlt">Crater</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>2008-01-01</p> <p><p/> This image of the interior of Oudemans <span class="hlt">Crater</span> was taken by the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) at 1800 UTC (1:00 p.m. EDT) on October <span class="hlt">2</span>, 2006, near 9.8 degrees south latitude, 268.5 degrees east longitude. CRISM's image was taken in 544 colors covering 0.36-3.92 micrometers, and shows features as small as 20 meters (66 feet) across. <p/> Oudemans <span class="hlt">Crater</span> is located at the extreme western end of Valles Marineris in the Sinai Planum region of Mars. The <span class="hlt">crater</span> measures some 124 kilometers (77 miles) across and sports a large central peak. <p/> Complex <span class="hlt">craters</span> like Oudemans are formed when an object, such as an asteroid or comet, impacts the planet. The size, speed and angle at which the object hits all determine the type of <span class="hlt">crater</span> that forms. The initial impact creates a bowl-shaped <span class="hlt">crater</span> and flings material (known as ejecta) out in all directions along and beyond the margins of the bowl forming an ejecta blanket. As the initial <span class="hlt">crater</span> cavity succumbs to gravity, it rebounds to form a central peak while material along the bowl's rim slumps back into the <span class="hlt">crater</span> forming terraces along the inner wall. If the force of the impact is strong enough, a central peak forms and begins to collapse back into the <span class="hlt">crater</span> basin, forming a central peak ring. <p/> The uppermost image in the montage above shows the location of CRISM data on a mosaic taken by the Mars Odyssey spacecraft's Thermal Emission Imaging System (THEMIS). The CRISM data was taken inside the <span class="hlt">crater</span>, on the northeast slope of the central peak. <p/> The lower left image is an infrared false-color image that reveals several distinctive deposits. The center of the image holds a ruddy-brown deposit that appears to correlates with a ridge running southwest to northeast. Lighter, buff-colored deposits occupy low areas interspersed within the ruddy-brown deposit. The southeast corner holds small hills that form part of the central peak complex. <p/> The lower right image shows spectral</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008AGUFM.P23B1374K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008AGUFM.P23B1374K"><span>Cataloging of <span class="hlt">Craters</span> on Enceladus</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Karpes, B. A.; Stoddard, P. R.</p> <p>2008-12-01</p> <p>The surface of Saturn's satellite Enceladus is unique in terms of the amount of geologic activity that is taking place on what many had once assumed would be a cold and dead icy moon. Instead of a cold, <span class="hlt">cratered</span> surface we have found a surface scarred with signs of tectonic activity in the form of numerous long rifts and fractures and we have seen cryovolcanic activity emanating from the south polar region. Using mostly Cassini images (a few of the map images are from Voyager), we are currently in the process of creating a comprehensive catalog of <span class="hlt">craters</span> that, we believe, will be an invaluable tool in aiding our understanding of this enigmatic moon. The catalog will give the location of all <span class="hlt">craters</span> measuring at least one-half degree (~<span class="hlt">2.2</span> km) in diameter. In addition to location and size, the catalog will also note deformation of the <span class="hlt">craters</span>, both in terms of rifting and ellipticity. The deformations can give us insight to the tectonic history (i.e. many of the <span class="hlt">craters</span> show post impact rifting) as well as giving us a further tool to study tectonic stresses across the surface. Areas of differing resolution are highlighted as they are an important limiting factor in determining <span class="hlt">crater</span> densities. It is for this reason that <span class="hlt">crater</span> sizes of one-half degree were chosen as they are more identifiable in lower resolution areas than <span class="hlt">craters</span> that are much smaller. We intend to study <span class="hlt">crater</span> distribution and have so far noted high <span class="hlt">crater</span> densities between 216° W and 144° W and between 10° S and 10° N approximately centered around 180° longitude (the antipode to the sub-Saturnian point). In addition to our study of <span class="hlt">crater</span> distribution we believe this catalog, upon completion, will be useful in the study of surface processes and surface heating of Enceladus.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19740047045&hterms=genetic+data+analysis&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dgenetic%2Bdata%2Banalysis','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19740047045&hterms=genetic+data+analysis&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dgenetic%2Bdata%2Banalysis"><span>Multivariate analyses of <span class="hlt">crater</span> parameters and the classification of <span class="hlt">craters</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Siegal, B. S.; Griffiths, J. C.</p> <p>1974-01-01</p> <p>Multivariate analyses were performed on certain linear dimensions of six genetic types of <span class="hlt">craters</span>. A total of 320 <span class="hlt">craters</span>, consisting of laboratory fluidization <span class="hlt">craters</span>, <span class="hlt">craters</span> formed by chemical and nuclear explosives, terrestrial maars and other volcanic <span class="hlt">craters</span>, and terrestrial meteorite impact <span class="hlt">craters</span>, authenticated and probable, were analyzed in the first data set in terms of their mean rim crest diameter, mean interior relief, rim height, and mean exterior rim width. The second data set contained an additional 91 terrestrial <span class="hlt">craters</span> of which 19 were of experimental percussive impact and 28 of volcanic collapse origin, and which was analyzed in terms of mean rim crest diameter, mean interior relief, and rim height. Principal component analyses were performed on the six genetic types of <span class="hlt">craters</span>. Ninety per cent of the variation in the variables can be accounted for by two components. Ninety-nine per cent of the variation in the <span class="hlt">craters</span> formed by chemical and nuclear explosives is explained by the first component alone.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19790055295&hterms=functional+structure&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3Dfunctional%2Bstructure','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19790055295&hterms=functional+structure&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3Dfunctional%2Bstructure"><span>Lunar <span class="hlt">crater</span> volumes - Interpretation by models of impact <span class="hlt">cratering</span> and upper crustal structure</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Croft, S. K.</p> <p>1978-01-01</p> <p>Lunar <span class="hlt">crater</span> volumes can be divided by size into two general classes with distinctly different functional dependence on diameter. <span class="hlt">Craters</span> smaller than approximately 12 km in diameter are morphologically simple and increase in volume as the cube of the diameter, while <span class="hlt">craters</span> larger than about 20 km are complex and increase in volume at a significantly lower rate implying shallowing. Ejecta and interior volumes are not identical and their ratio, Schroeters Ratio (SR), increases from about 0.5 for simple <span class="hlt">craters</span> to about 1.5 for complex <span class="hlt">craters</span>. The excess of ejecta volume causing the increase, can be accounted for by a discontinuity in lunar crust porosity at 1.5-<span class="hlt">2</span> km depth. The diameter range of significant increase in SR corresponds with the diameter range of transition from simple to complex <span class="hlt">crater</span> morphology. This observation, combined with theoretical rebound calculation, indicates control of the transition diameter by the porosity structure of the upper crust.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70018513','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70018513"><span>Coral ages and island <span class="hlt">subsidence</span>, Hilo drill hole</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Moore, J.G.; Ingram, B.L.; Ludwig, K. R.; Clague, D.A.</p> <p>1996-01-01</p> <p>A 25.8-m-thick sedimentary section containing coral fragments occurs directly below a surface lava flow (the ???1340 year old Panaewa lava flow) at the Hilo drill hole. Ten coral samples from this section dated by accelerator mass spectrometry (AMS) radiocarbon and five by thermal infrared multispectral scanner (TIMS) 230Th/<span class="hlt">U</span> methods show good agreement. The calcareous unit is 9790 years old at the bottom and 1690 years old at the top and was deposited in a shallow lagoon behind an actively growing reef. This sedimentary unit is underlain by a 34-m-thick lava flow which in turn overlies a thin volcaniclastic silt with coral fragments that yield a single 14C date of 10,340 years. The age-depth relations of the dated samples can be compared with proposed eustatic sea level curves after allowance for island <span class="hlt">subsidence</span> is taken. Island <span class="hlt">subsidence</span> averages <span class="hlt">2.2</span> mm/yr for the last 47 years based on measurements from a tide gage near the drill hole or <span class="hlt">2.5-2</span>.6 mm/yr for the last 500,000 years based on the ages and depths of a series of drowned coral reefs offshore from west Hawaii. The age-depth measurements of coral fragments are more consistent with eustatic sea levels as determined by coral dating at Barbados and Albrolhos Islands than those based on oxygen isotopic data from deep sea cores. The Panaewa lava flow entered a lagoon underlain by coral debris and covered the drill site with 30.9 m of lava of which 11 m was above sea level. This surface has now <span class="hlt">subsided</span> to 4.<span class="hlt">2</span> m above sea level, but it demonstrates how a modern lava flow entering Hilo Bay would not only change the coastline but could extensively modify the offshore shelf.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5928493','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5928493"><span>Gold(I) Complexes of the Geminal Phosphinoborane t<span class="hlt">Bu</span><span class="hlt">2</span>PCH<span class="hlt">2</span>BPh<span class="hlt">2</span></span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p></p> <p>2018-01-01</p> <p>In this work, we explored the coordination properties of the geminal phosphinoborane t<span class="hlt">Bu</span><span class="hlt">2</span>PCH<span class="hlt">2</span>BPh<span class="hlt">2</span> (<span class="hlt">2</span>) toward different gold(I) precursors. The reaction of <span class="hlt">2</span> with an equimolar amount of the sulfur-based complex (Me<span class="hlt">2</span>S)AuCl resulted in displacement of the SMe<span class="hlt">2</span> ligand and formation of linear phosphine gold(I) chloride 3. Using an excess of ligand <span class="hlt">2</span>, bisligated complex 4 was formed and showed dynamic behavior at room temperature. Changing the gold(I) metal precursor to the phosphorus-based complex, (Ph3P)AuCl impacted the coordination behavior of ligand <span class="hlt">2</span>. Namely, the reaction of ligand <span class="hlt">2</span> with (Ph3P)AuCl led to the heterolytic cleavage of the gold–chloride bond, which is favored over PPh3 ligand displacement. To the best of our knowledge, <span class="hlt">2</span> is the first example of a P/B-ambiphilic ligand capable of cleaving the gold–chloride bond. The coordination chemistry of <span class="hlt">2</span> was further analyzed by density functional theory calculations. PMID:29732451</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/29732451','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/29732451"><span>Gold(I) Complexes of the Geminal Phosphinoborane t<span class="hlt">Bu</span><span class="hlt">2</span>PCH<span class="hlt">2</span>BPh<span class="hlt">2</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Boom, Devin H A; Ehlers, Andreas W; Nieger, Martin; Devillard, Marc; Bouhadir, Ghenwa; Bourissou, Didier; Slootweg, J Chris</p> <p>2018-04-30</p> <p>In this work, we explored the coordination properties of the geminal phosphinoborane t <span class="hlt">Bu</span> <span class="hlt">2</span> PCH <span class="hlt">2</span> BPh <span class="hlt">2</span> ( <span class="hlt">2</span> ) toward different gold(I) precursors. The reaction of <span class="hlt">2</span> with an equimolar amount of the sulfur-based complex (Me <span class="hlt">2</span> S)AuCl resulted in displacement of the SMe <span class="hlt">2</span> ligand and formation of linear phosphine gold(I) chloride 3 . Using an excess of ligand <span class="hlt">2</span> , bisligated complex 4 was formed and showed dynamic behavior at room temperature. Changing the gold(I) metal precursor to the phosphorus-based complex, (Ph 3 P)AuCl impacted the coordination behavior of ligand <span class="hlt">2</span> . Namely, the reaction of ligand <span class="hlt">2</span> with (Ph 3 P)AuCl led to the heterolytic cleavage of the gold-chloride bond, which is favored over PPh 3 ligand displacement. To the best of our knowledge, <span class="hlt">2</span> is the first example of a P/B-ambiphilic ligand capable of cleaving the gold-chloride bond. The coordination chemistry of <span class="hlt">2</span> was further analyzed by density functional theory calculations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26808253','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26808253"><span>Antifungal activity of rimocidin and a new rimocidin derivative <span class="hlt">BU</span>16 produced by Streptomyces mauvecolor <span class="hlt">BU</span>16 and their effects on pepper anthracnose.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Jeon, B J; Kim, J D; Han, J W; Kim, B S</p> <p>2016-05-01</p> <p>The objective of this study was to explore antifungal metabolites targeting fungal cell envelope and to evaluate the control efficacy against anthracnose development in pepper plants. A natural product library comprising 3000 microbial culture extracts was screened via an adenylate kinase (AK)-based cell lysis assay to detect antifungal metabolites targeting the cell envelope of plant-pathogenic fungi. The culture extract of Streptomyces mauvecolor strain <span class="hlt">BU</span>16 displayed potent AK-releasing activity. Rimocidin and a new rimocidin derivative, <span class="hlt">BU</span>16, were identified from the extract as active constituents. <span class="hlt">BU</span>16 is a tetraene macrolide containing a six-membered hemiketal ring with an ethyl group side chain instead of the propyl group in rimocidin. Rimocidin and <span class="hlt">BU</span>16 showed broad-spectrum antifungal activity against various plant-pathogenic fungi and demonstrated potent control efficacy against anthracnose development in pepper plants. Antifungal metabolites produced by S. mauvecolor strain <span class="hlt">BU</span>16 were identified to be rimocidin and <span class="hlt">BU</span>16. The compounds displayed potent control efficacy against pepper anthracnose. Rimocidin and <span class="hlt">BU</span>16 would be active ingredients of disease control agents disrupting cell envelope of plant-pathogenic fungi. The structure and antifungal activity of rimocidin derivative <span class="hlt">BU</span>16 is first described in this study. © 2016 The Society for Applied Microbiology.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_4");'>4</a></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li class="active"><span>6</span></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_6 --> <div id="page_7" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li class="active"><span>7</span></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="121"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/98655-avian-utilization-subsidence-wetlands','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/98655-avian-utilization-subsidence-wetlands"><span>Avian utilization of <span class="hlt">subsidence</span> wetlands</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Nawrot, J.R.; Conley, P.S.; Smout, C.L.</p> <p>1995-09-01</p> <p>Diverse and productive wetlands have resulted from coal mining in the midwest. The trend from surface to underground mining has increased the potential for <span class="hlt">subsidence</span>. Planned <span class="hlt">subsidence</span> of longwall mining areas provides increased opportunities for wetland habitat establishment. Planned <span class="hlt">subsidence</span> over a 180 meter (590 foot) deep longwall mine in southern Illinois during 1984 to 1986 produced three <span class="hlt">subsidence</span> wetlands totaling 15 hectares (38 acres). The resulting palustrine emergent wetlands enhanced habitat diversity within the surrounding palustrine forested unsubsided area. Habitat assessments and evaluations of avian utilization of the <span class="hlt">subsidence</span> wetlands were conducted during February 1990 through October 1991. Avianmore » utilization was greatest within the <span class="hlt">subsided</span> wetlands. Fifty-three bird species representing seven foraging guilds utilized the <span class="hlt">subsidence</span> wetlands. Wading/fishing, dabbling waterfowl, and insectivorous avian guilds dominated the <span class="hlt">subsidence</span> wetlands. The <span class="hlt">subsidence</span> wetlands represented ideal habitat for wood ducks and great blue herons which utilized snags adjacent to and within the wetlands for nesting (19 great blue heron nests produced 25 young). Dense cover and a rich supply of macroinvertebrates provide excellent brood habitat for wood ducks, while herpetofauna and ichthyofauna provided abundant forage in shallow water zones for great blue herons and other wetland wading birds. The diversity of game and non-game avifauna utilizing the <span class="hlt">subsidence</span> areas demonstrated the unique value of these wetlands. Preplanned <span class="hlt">subsidence</span> wetlands can help mitigate loss of wetland habitats in the midwest.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19920033269&hterms=slump&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dslump','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19920033269&hterms=slump&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dslump"><span>Terrace width variations in complex Mercurian <span class="hlt">craters</span> and the transient strength of <span class="hlt">cratered</span> Mercurian and lunar crust</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Leith, Andrew C.; Mckinnon, William B.</p> <p>1991-01-01</p> <p>The effective cohesion of the <span class="hlt">cratered</span> region during <span class="hlt">crater</span> collapse is determined via the widths of slump terraces of complex <span class="hlt">craters</span>. Terrace widths are measured for complex <span class="hlt">craters</span> on Mercury; these generally increase outward toward the rim for a given <span class="hlt">crater</span>, and the width of the outermost major terrace is generally an increasing function of <span class="hlt">crater</span> diameter. The terrace widths on Mercury and a gravity-driven slump model are used to estimate the strength of the <span class="hlt">cratered</span> region immediately after impact (about 1-<span class="hlt">2</span> MPa). A comparison with the previous study of lunar complex <span class="hlt">craters</span> by Pearce and Melosh (1986) indicates that the transient strength of <span class="hlt">cratered</span> Mercurian crust is no greater than that of the moon. The strength estimates vary only slightly with the geometric model used to restore the outermost major terrace to its precollapse configuration and are consistent with independent strength estimates from the simple-to-complex <span class="hlt">crater</span> depth/diameter transition.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19850015257&hterms=mass+wasting&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Dmass%2Bwasting','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19850015257&hterms=mass+wasting&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Dmass%2Bwasting"><span>Morphologic Evolution of the Mount St. Helens <span class="hlt">Crater</span> Area, Washington</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Beach, G. L.</p> <p>1985-01-01</p> <p>The large rockslide-avalanche that preceded the eruption of Mount St. Helens on 18 May 1980 removed approximately <span class="hlt">2</span>.8 cubic km of material from the summit and north flank of the volcano, forming a horseshoe-shaped <span class="hlt">crater</span> <span class="hlt">2</span>.0 km wide and 3.9 km long. A variety of erosional and depositional processes, notably mass wasting and gully development, acted to modify the topographic configuration of the <span class="hlt">crater</span> area. To document this morphologic evolution, a series of annual large-scale topographic maps is being produced as a base for comparitive geomorphic analysis. Four topographic maps of the Mount St. Helens <span class="hlt">crater</span> area at a scale of 1:4000 were produced by the National Mapping Division of the <span class="hlt">U</span>. S. Geological Survey. Stereo aerial photography for the maps was obtained on 23 October 1980, 10 September 1981, 1 September 1982, and 17 August 1983. To quantify topographic changes in the study area, each topographic map is being digitized and corresponding X, Y, and Z values from successive maps are being computer-compared.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010cosp...38..532S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010cosp...38..532S"><span>Method for evaluation of laboratory <span class="hlt">craters</span> using <span class="hlt">crater</span> detection algorithm for digital topography data</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Salamunićcar, Goran; Vinković, Dejan; Lončarić, Sven; Vučina, Damir; Pehnec, Igor; Vojković, Marin; Gomerčić, Mladen; Hercigonja, Tomislav</p> <p></p> <p>In our previous work the following has been done: (1) the <span class="hlt">crater</span> detection algorithm (CDA) based on digital elevation model (DEM) has been developed and the GT-115225 catalog has been assembled [GRS, 48 (5), in press, doi:10.1109/TGRS.2009.2037750]; and (<span class="hlt">2</span>) the results of comparison between explosion-induced laboratory <span class="hlt">craters</span> in stone powder surfaces and GT-115225 have been presented using depth/diameter measurements [41stLPSC, Abstract #1428]. The next step achievable using the available technology is to create 3D scans of such labo-ratory <span class="hlt">craters</span>, in order to compare different properties with simple Martian <span class="hlt">craters</span>. In this work, we propose a formal method for evaluation of laboratory <span class="hlt">craters</span>, in order to provide objective, measurable and reproducible estimation of the level of achieved similarity between these laboratory and real impact <span class="hlt">craters</span>. In the first step, the section of MOLA data for Mars (or SELENE LALT for Moon) is replaced with one or several 3D-scans of laboratory <span class="hlt">craters</span>. Once embedment was done, the CDA can be used to find out whether this laboratory <span class="hlt">crater</span> is similar enough to real <span class="hlt">craters</span>, as to be recognized as a <span class="hlt">crater</span> by the CDA. The CDA evaluation using ROC' curve represents how true detection rate (TDR=TP/(TP+FN)=TP/GT) depends on the false detection rate (FDR=FP/(TP+FP)). Using this curve, it is now possible to define the measure of similarity between laboratory and real impact <span class="hlt">craters</span>, as TDR or FDR value, or as a distance from the bottom-right origin of the ROC' curve. With such an approach, the reproducible (formally described) method for evaluation of laboratory <span class="hlt">craters</span> is provided.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016cosp...41E1981V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016cosp...41E1981V"><span>Identification of <span class="hlt">craters</span> on Moon using <span class="hlt">Crater</span> Density Parameter</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Vandana, Vandana</p> <p>2016-07-01</p> <p>Lunar <span class="hlt">craters</span> are the most noticeable features on the face of the moon. They take up 40.96% of the lunar surface and, their accumulated area is approximately three times as much as the lunar surface area. There are many myths about the moon. Some says moon is made of cheese. The moon and the sun chase each other across the sky etc. but scientifically the moon are closest and are only natural satellite of earth. The orbit plane of the moon is tilted by 5° and orbit period around the earth is 27-3 days. There are two eclipse i.e. lunar eclipse and solar eclipse which always comes in pair. Moon surface has 3 parts i.e. highland, Maria, and <span class="hlt">crater</span>. For <span class="hlt">crater</span> diagnostic <span class="hlt">crater</span> density parameter is one of the means for measuring distance can be easily identity the density between two <span class="hlt">craters</span>. <span class="hlt">Crater</span> size frequency distribution (CSFD) is being computed for lunar surface using TMC and MiniSAR image data and hence, also the age for the selected test sites of mars is also determined. The GIS-based program uses the density and orientation of individual <span class="hlt">craters</span> within LCCs (as vector points) to identify potential source <span class="hlt">craters</span> through a series of cluster identification and ejection modeling analyses. JMars software is also recommended and operated only the time when connected with server but work can be done in Arc GIS with the help of Arc Objects and Model Builder. The study plays a vital role to determine the lunar surface based on <span class="hlt">crater</span> (shape, size and density) and exploring affected <span class="hlt">craters</span> on the basis of height, weight and velocity. Keywords: Moon; <span class="hlt">Crater</span>; MiniSAR.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19940011922','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19940011922"><span>Galileo SSI lunar observations: Copernican <span class="hlt">craters</span> and soils</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Mcewen, A. S.; Greeley, R.; Head, James W.; Pieters, C. M.; Fischer, E. M.; Johnson, T. V.; Neukum, G.</p> <p>1993-01-01</p> <p>The Galileo spacecraft completed its first Earth-Moon flyby (EMI) in December 1990 and its second flyby (EM<span class="hlt">2</span>) in December 1992. Copernican-age <span class="hlt">craters</span> are among the most prominent features seen in the SSI (Solid-State Imaging) multispectral images of the Moon. The interiors, rays, and continuous ejecta deposits of these youngest <span class="hlt">craters</span> stand out as the brightest features in images of albedo and visible/1-micron color ratios (except where impact melts are abundant). <span class="hlt">Crater</span> colors and albedos (away from impact melts) are correlated with their geologic emplacement ages as determined from counts of superposed <span class="hlt">craters</span>; these age-color relations can be used to estimate the emplacement age (time since impact event) for many Copernican-age <span class="hlt">craters</span> on the near and far sides of the Moon. The spectral reflectivities of lunar soils are controlled primarily by (1) soil maturity, resulting from the soil's cumulative age of exposure to the space environment; (<span class="hlt">2</span>) steady-state horizontal and vertical mixing of fresh crystalline materials ; and (3) the mineralogy of the underlying bedrock or megaregolith. Improved understanding of items (1) and (<span class="hlt">2</span>) above will improve our ability to interpret item (3), especially for the use of <span class="hlt">crater</span> compositions as probes of crustal stratigraphy. We have examined the multispectral and superposed <span class="hlt">crater</span> frequencies of large isolated <span class="hlt">craters</span>, mostly of Eratosthenian and Copernican ages, to avoid complications due to (1) secondaries (as they affect superposed <span class="hlt">crater</span> counts) and (<span class="hlt">2</span>) spatially and temporally nonuniform regolith mixing from younger, large, and nearby impacts. <span class="hlt">Crater</span> counts are available for 11 mare <span class="hlt">craters</span> and 9 highlands <span class="hlt">craters</span> within the region of the Moon imaged during EM1. The EM<span class="hlt">2</span> coverage provides multispectral data for 10 additional <span class="hlt">craters</span> with superposed <span class="hlt">crater</span> counts. Also, the EM<span class="hlt">2</span> data provide improved spatial resolution and signal-to-noise ratios over the western nearside.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008DPS....40.6109S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008DPS....40.6109S"><span>Comparison of the Production Size-frequency Distribution (SFD) of <span class="hlt">Craters</span> on Saturnian Satellites With the Lunar <span class="hlt">Crater</span> SFD and Asteroid Diameter SFD</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Schmedemann, Nico; Neukum, G.; Denk, T.; Wagner, R.; Hartmann, O.; Michael, G.</p> <p>2008-09-01</p> <p>Introduction: The understanding of the geologic history of the saturnian satellites (and hence of the history of the solar system) is a major goal for us as part of the Cassini imaging experiment (ISS) team. For this reason, the SFDs of <span class="hlt">craters</span> on Saturn's medium-sized moons have been analyzed and compared with the goal to determine the sources of the primary impactors on the saturnian satellites. Comparison of SFDs: The lunar SFD was derived by Neukum (1983). Multiple measurements of the <span class="hlt">crater</span> production SFD on the saturnian satellites have shown a high similarity to the lunar curve (Neukum et al., 2006). From measurements on Iapetus, <span class="hlt">crater</span> counts over 4 orders of magnitude in <span class="hlt">crater</span> diameter are available now. Those measurements fit nicely to the velocity-corrected lunar curve for <span class="hlt">crater</span> diameters below 60 km. By analyzing the body-diameter SFD of main-belt asteroids (data source: MPC web site, http://cfa-www.harvard.edu/iau/mpc.html, July 2008), a strong similarity with respect to the lunar curve is found as well. Hence, there are good reasons for the conclusion that asteroidal impactors captured by Saturn are responsible for the <span class="hlt">cratering</span> record measured on the saturnian satellites. References and notes: Magnitude-to-diameter conversion of asteroids: D<span class="hlt">2</span>=1/Pv*106.247-0.4*H H: absolute magnitude; Pv: geometric albedo; (Fowler & Chillemi, 1992) Neukum, G. (1983): Meteoritenbombardement und Datierung planetarer Oberflächen. Habilitation Dissertation for Faculty Membership, Ludwig-Maximilians Univ. München, Munich, Germany, 186 pp. Neukum, G.; Wagner, R.; Wolf, <span class="hlt">U</span>.; Denk, T. (2006): The <span class="hlt">Cratering</span> Record and <span class="hlt">Cratering</span> Chronologies of the Saturnian Satellites and the Origin of Impactors: Results from Cassini ISS Data. European Planetary Science Congress (EPSC) 2006, Berlin, Germany, 18-22 September 2006, p.610. Fowler, J.W.; Chillemi, J.R. (1992): IRAS asteroid data processing. In: Tedesco, E.F., Veeder, G.J., Fowler, J.W., Chillemi, J.R. (eds.): The IRAS Minor</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010EGUGA..12.4044K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010EGUGA..12.4044K"><span>Well known outstanding geoid and relief depressions as regular wave woven features on Eartg (Indian geoid minimum), Moon (SPA basin), Phobos (Stickney <span class="hlt">crater</span>), and Miranda (an ovoid).</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kochemasov, Gennady G.</p> <p>2010-05-01</p> <p> by the sector highest elevation. Procellarum Ocean is filled with basalts and Ti-basalts. The SPA basin must be filled with even denser rocks. One expects here feldspar-free, pyroxene enriched rocks with some admixture of Fe metal and troilite. The spectral observations of Carle Pieters [4] confirm orthopyroxene enrichment and absence of feldspar. Enigmatic large and deep depression of <span class="hlt">crater</span> Stickney on Phobos with an appropriate scale adjustment to much larger Earth and Moon occupies a similar structural position to the Indian geoid minimum and the SPA basin. Such situation cannot be random and proves a common origin of these remarkable tectonic features at so different celestial bodies. This conclusion is reinforced by taking for a comparison another small heavenly body- Uranus satellite Miranda. Imaged by Voyager <span class="hlt">2</span> spacecraft in 1986 it shows two kinds of terrains (PIA01980 & others). <span class="hlt">Subsided</span> provinces (ovoids) characterized by intensive curvilinear folding and faulting interrupt uplifted densely <span class="hlt">cratered</span> old provinces. One of the deeply <span class="hlt">subsided</span> ovoids with curvilinear folds pattern (compression under <span class="hlt">subsidence</span>) perfectly fits into a sector boundary. References: [1] Kochemasov G. (1999) Theorems of wave planetary tectonics // Geophys. Res. Abstr., V.1, #3, 700. [<span class="hlt">2</span>] Kochemasov G.G. (1998) The Moon: Earth-type sectoral tectonics, relief and relevant chemical features // The 3rd International Confernce on Exploration and Utilization of the Moon, Oct. 11-14, 1998, Moscow, Russia, Abstracts, p. 29. [3] Kochemasov G.G. (1998) Moon-Earth: similarity of sectoral organization // 32nd COSPAR Scientific Assembly, Nagoya, Japan, 12-19 July 1998, Abstracts, p. 77. [4] Pieters C. (1997) Annales Geophys., v. 15, pt. III, p. 792.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012EGUGA..14.5200D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012EGUGA..14.5200D"><span>Experimental impact <span class="hlt">crater</span> morphology</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Dufresne, A.; Poelchau, M. H.; Hoerth, T.; Schaefer, F.; Thoma, K.; Deutsch, A.; Kenkmann, T.</p> <p>2012-04-01</p> <p>The research group MEMIN (Multidisciplinary Experimental and Impact Modelling Research Network) is conducting impact experiments into porous sandstones, examining, among other parameters, the influence of target pore-space saturation with water, and projectile velocity, density and mass, on the <span class="hlt">cratering</span> process. The high-velocity (<span class="hlt">2</span>.5-7.8 km/s) impact experiments were carried out at the two-stage light-gas gun facilities of the Fraunhofer Institute EMI (Germany) using steel, iron meteorite (Campo del Cielo IAB), and aluminium projectiles with Seeberg Sandstone as targets. The primary objectives of this study within MEMIN are to provide detailed morphometric data of the experimental <span class="hlt">craters</span>, and to identify trends and characteristics specific to a given impact parameter. Generally, all <span class="hlt">craters</span>, regardless of impact conditions, have an inner depression within a highly fragile, white-coloured centre, an outer spallation (i.e. tensile failure) zone, and areas of arrested spallation (i.e. spall fragments that were not completely dislodged from the target) at the <span class="hlt">crater</span> rim. Within this general morphological framework, distinct trends and differences in <span class="hlt">crater</span> dimensions and morphological characteristics are identified. With increasing impact velocity, the volume of <span class="hlt">craters</span> in dry targets increases by a factor of ~4 when doubling velocity. At identical impact conditions (steel projectiles, ~5km/s), <span class="hlt">craters</span> in dry and wet sandstone targets differ significantly in that "wet" <span class="hlt">craters</span> are up to 76% larger in volume, have depth-diameter ratios generally below 0.19 (whereas dry <span class="hlt">craters</span> are almost consistently above this value) at significantly larger diameters, and their spallation zone morphologies show very different characteristics. In dry <span class="hlt">craters</span>, the spall zone surfaces dip evenly at 10-20° towards the <span class="hlt">crater</span> centre. In wet <span class="hlt">craters</span>, on the other hand, they consist of slightly convex slopes of 10-35° adjacent to the inner depression, and of sub-horizontal tensile</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70188637','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70188637"><span><span class="hlt">Crater</span> density differences: Exploring regional resurfacing, secondary <span class="hlt">crater</span> populations, and <span class="hlt">crater</span> saturation equilibrium on the moon</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Povilaitis, R Z; Robinson, M S; van der Bogert, C H; Hiesinger, Harald; Meyer, H M; Ostrach, Lillian</p> <p>2017-01-01</p> <p>The global population of lunar <span class="hlt">craters</span> >20 km in diameter was analyzed by Head et al., (2010) to correlate <span class="hlt">crater</span> distribution with resurfacing events and multiple impactor populations. The work presented here extends the global <span class="hlt">crater</span> distribution analysis to smaller <span class="hlt">craters</span> (5–20 km diameters, n = 22,746). Smaller <span class="hlt">craters</span> form at a higher rate than larger <span class="hlt">craters</span> and thus add granularity to age estimates of larger units and can reveal smaller and younger areas of resurfacing. An areal density difference map generated by comparing the new dataset with that of Head et al., (2010) shows local deficiencies of 5–20 km diameter <span class="hlt">craters</span>, which we interpret to be caused by a combination of resurfacing by the Orientale basin, infilling of intercrater plains within the nearside highlands, and partial mare flooding of the Australe region. Chains of 5–30 km diameter secondaries northwest of Orientale and possible 8–22 km diameter basin secondaries within the farside highlands are also distinguishable. Analysis of the new database indicates that <span class="hlt">craters</span> 57–160 km in diameter across much of the lunar highlands are at or exceed relative <span class="hlt">crater</span> densities of R = 0.3 or 10% geometric saturation, but nonetheless appear to fit the lunar production function. Combined with the observation that small <span class="hlt">craters</span> on old surfaces can reach saturation equilibrium at 1% geometric saturation (Xiao and Werner, 2015), this suggests that saturation equilibrium is a size-dependent process, where large <span class="hlt">craters</span> persist because of their resistance to destruction, degradation, and resurfacing.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70012224','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70012224"><span>Low-velocity impact <span class="hlt">craters</span> in ice and ice-saturated sand with implications for Martian <span class="hlt">crater</span> count ages.</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Croft, S.K.; Kieffer, S.W.; Ahrens, T.J.</p> <p>1979-01-01</p> <p>We produced a series of decimeter-sized impact <span class="hlt">craters</span> in blocks of ice near 0oC and -70oC and in ice-saturated sand near -70oC as a preliminary investigation of <span class="hlt">cratering</span> in materials analogous to those found on Mars and the outer solar satellites. <span class="hlt">Crater</span> diameters in the ice-saturated sand were <span class="hlt">2</span> times larger than <span class="hlt">craters</span> in the same energy and velocity range in competent blocks of granite, basalt and cement. <span class="hlt">Craters</span> in ice were c.3 times larger. Martian impact <span class="hlt">crater</span> energy versus diameter scaling may thus be a function of latitude. -from Authors</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=PIA04904&hterms=Northeast&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3DNortheast','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=PIA04904&hterms=Northeast&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3DNortheast"><span>Exhuming <span class="hlt">Crater</span> in Northeast Arabia</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>2003-01-01</p> <p>MGS MOC Release No. MOC<span class="hlt">2</span>-563, 3 December 2003<p/>The upper crust of Mars is layered, and interbedded with these layers are old, filled and buried meteor impact <span class="hlt">craters</span>. In a few places on Mars, such as Arabia Terra, erosion has re-exposed some of the filled and buried <span class="hlt">craters</span>. This October 2003 Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows an example. The larger circular feature was once a meteor <span class="hlt">crater</span>. It was filled with sediment, then buried beneath younger rocks. The smaller circular feature is a younger impact <span class="hlt">crater</span> that formed in the surface above the rocks that buried the large <span class="hlt">crater</span>. Later, erosion removed all of the material that covered the larger, buried <span class="hlt">crater</span>, except in the location of the small <span class="hlt">crater</span>. This pair of martian landforms is located near 17.6oN, 312.8oW. The image covers an area 3 km (1.9 mi) wide and is illuminated from the lower left.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016GeoRL..43.7424X','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016GeoRL..43.7424X"><span>The self-secondary <span class="hlt">crater</span> population of the Hokusai <span class="hlt">crater</span> on Mercury</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Xiao, Zhiyong; Prieur, Nils C.; Werner, Stephanie C.</p> <p>2016-07-01</p> <p>Whether or not self-secondaries dominate small <span class="hlt">crater</span> populations on continuous ejecta deposits and floors of fresh impact <span class="hlt">craters</span> has long been a controversy. This issue potentially affects the age determination technique using <span class="hlt">crater</span> statistics. Here the self-secondary <span class="hlt">crater</span> population on the continuous ejecta deposits of the Hokusai <span class="hlt">crater</span> on Mercury is unambiguously recognized. Superposition relationships show that this population was emplaced after both the ballistic sedimentation of excavation flows and the subsequent veneering of impact melt, but it predated the settlement and solidification of melt pools on the <span class="hlt">crater</span> floor. Fragments that formed self-secondaries were launched via impact spallation with large angles. Complex <span class="hlt">craters</span> on the Moon, Mercury, and Mars probably all have formed self-secondaries populations. Dating young <span class="hlt">craters</span> using <span class="hlt">crater</span> statistics on their continuous ejecta deposits can be misleading. Impact melt pools are less affected by self-secondaries. Overprint by subsequent <span class="hlt">crater</span> populations with time reduces the predominance of self-secondaries.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2003JChPh.119.1373C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003JChPh.119.1373C"><span>On the inversion of the 1 <span class="hlt">Bu</span> and <span class="hlt">2</span> Ag electronic states in α,ω-diphenylpolyenes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Catalán, J.</p> <p>2003-07-01</p> <p>An alternative model to that of the inversion of the states 1<span class="hlt">Bu</span> and <span class="hlt">2</span>Ag is proposed for interpreting the photophysics of the α,ω-diphenylpolyenes. This model is based upon the existence of two chemical structures with <span class="hlt">Bu</span> symmetry, which may be ascribed to the same excited electronic state 1<span class="hlt">Bu</span>. One of the two chemical structures corresponds to the Franck-Condon structure with conjugated single and double bonds for the polyene chain, and another consists of a nearly equivalent series of partial double bonds along the polyene chain. The latter relaxed structure is consistent with the observation of high torsional energy barriers and low photoisomerization quantum yields for diphenylhexatriene in the singlet excited state manifold. Interestingly, such a simple quantum model as that of the particle in a one-dimensional box provides quite an accurate description of the absorption spectroscopic properties of these major compounds. This is partly the result of the most stable structures for these compounds being of the all-trans type; such structures increase in length as additional ethylene units are added, which makes them very similar to a one-dimensional box becoming increasingly longer.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015JGRB..120.6141S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015JGRB..120.6141S"><span>Scaling multiblast <span class="hlt">craters</span>: General approach and application to volcanic <span class="hlt">craters</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sonder, I.; Graettinger, A. H.; Valentine, G. A.</p> <p>2015-09-01</p> <p>Most volcanic explosions leave a <span class="hlt">crater</span> in the surface around the center of the explosions. Such <span class="hlt">craters</span> differ from products of single events like meteorite impacts or those produced by military testing because they typically result from multiple, rather than single, explosions. Here we analyze the evolution of experimental <span class="hlt">craters</span> that were created by several detonations of chemical explosives in layered aggregates. An empirical relationship for the scaled <span class="hlt">crater</span> radius as a function of scaled explosion depth for single blasts in flat test beds is derived from experimental data, which differs from existing relations and has better applicability for deep blasts. A method to calculate an effective explosion depth for nonflat topography (e.g., for explosions below existing <span class="hlt">craters</span>) is derived, showing how multiblast <span class="hlt">crater</span> sizes differ from the single-blast case: Sizes of natural caters (radii and volumes) are not characteristic of the number of explosions, nor therefore of the total acting energy, that formed a <span class="hlt">crater</span>. Also, the <span class="hlt">crater</span> size is not simply related to the largest explosion in a sequence but depends upon that explosion and the energy of that single blast and on the cumulative energy of all blasts that formed a <span class="hlt">crater</span>. The two energies can be combined to form an effective number of explosions that is characteristic for the <span class="hlt">crater</span> evolution. The multiblast <span class="hlt">crater</span> size evolution has implications on the estimates of volcanic eruption energies, indicating that it is not correct to estimate explosion energy from <span class="hlt">crater</span> size using previously published relationships that were derived for single-blast cases.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008P%26SS...56.1992S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008P%26SS...56.1992S"><span>GT-57633 catalogue of Martian impact <span class="hlt">craters</span> developed for evaluation of <span class="hlt">crater</span> detection algorithms</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Salamunićcar, Goran; Lončarić, Sven</p> <p>2008-12-01</p> <p><span class="hlt">Crater</span> detection algorithms (CDAs) are an important subject of the recent scientific research. A ground truth (GT) catalogue, which contains the locations and sizes of known <span class="hlt">craters</span>, is important for the evaluation of CDAs in a wide range of CDA applications. Unfortunately, previous catalogues of <span class="hlt">craters</span> by other authors cannot be easily used as GT. In this paper, we propose a method for integration of several existing catalogues to obtain a new <span class="hlt">craters</span> catalogue. The methods developed and used during this work on the GT catalogue are: (1) initial screening of used catalogues; (<span class="hlt">2</span>) evaluation of self-consistency of used catalogues; (3) initial registration from three different catalogues; (4) cross-evaluation of used catalogues; (5) additional registrations and registrations from additional catalogues; and (6) fine-tuning and registration with additional data-sets. During this process, all <span class="hlt">craters</span> from all major currently available manually assembled catalogues were processed, including catalogues by Barlow, Rodionova, Boyce, Kuzmin, and our previous work. Each <span class="hlt">crater</span> from the GT catalogue contains references to <span class="hlt">crater(s</span>) that are used for its registration. This provides direct access to all properties assigned to <span class="hlt">craters</span> from the used catalogues, which can be of interest even to those scientists that are not directly interested in CDAs. Having all these <span class="hlt">craters</span> in a single catalogue also provides a good starting point for searching for <span class="hlt">craters</span> still not catalogued manually, which is also expected to be one of the challenges of CDAs. The resulting new GT catalogue contains 57,633 <span class="hlt">craters</span>, significantly more than any previous catalogue. From this point of view, GT-57633 catalogue is currently the most complete catalogue of large Martian impact <span class="hlt">craters</span>. Additionally, each <span class="hlt">crater</span> from the resulting GT-57633 catalogue is aligned with MOLA topography and, during the final review phase, additionally registered/aligned with 1/256° THEMIS-DIR, 1/256° MDIM and 1/256° MOC</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://images.nasa.gov/#/details-PIA22371.html','SCIGOVIMAGE-NASA'); return false;" href="https://images.nasa.gov/#/details-PIA22371.html"><span>Bonestell <span class="hlt">Crater</span></span></a></p> <p><a target="_blank" href="https://images.nasa.gov/">NASA Image and Video Library</a></p> <p></p> <p>2018-04-17</p> <p>Bonestell <span class="hlt">Crater</span> is a relatively young <span class="hlt">crater</span> located in Acidalia Planitia. The grooved surface of the ejecta blanket is evident in this VIS image. Dust blown into the <span class="hlt">crater</span> and the downslope movement of fine materials from the rim are slowly modifying the <span class="hlt">crater</span> features. Orbit Number: 71230 Latitude: 36.398 Longitude: 329.708 Instrument: VIS Captured: 2018-01-04 05:31 https://photojournal.jpl.nasa.gov/catalog/PIA22371</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017Icar..288...69H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017Icar..288...69H"><span>Spatial distribution of impact <span class="hlt">craters</span> on Deimos</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hirata, Naoyuki</p> <p>2017-05-01</p> <p>Deimos, one of the Martian moons, has numerous impact <span class="hlt">craters</span>. However, it is unclear whether <span class="hlt">crater</span> saturation has been reached on this satellite. To address this issue, we apply a statistical test known as nearest-neighbor analysis to analyze the <span class="hlt">crater</span> distribution of Deimos. When a planetary surface such as the Moon is saturated with impact <span class="hlt">craters</span>, the spatial distribution of <span class="hlt">craters</span> is generally changed from random to more ordered. We measured impact <span class="hlt">craters</span> on Deimos from Viking and HiRISE images and found (1) that the power law of the size-frequency distribution of the <span class="hlt">craters</span> is approximately -1.7, which is significantly shallower than those of potential impactors, and (<span class="hlt">2</span>) that the spatial distribution of <span class="hlt">craters</span> over 30 m in diameter cannot be statistically distinguished from completely random distribution, which indicates that the surface of Deimos is inconsistent with a surface saturated with impact <span class="hlt">craters</span>. Although a <span class="hlt">crater</span> size-frequency distribution curve with a slope of -<span class="hlt">2</span> is generally interpreted as indicating saturation equilibrium, it is here proposed that two competing mechanisms, seismic shaking and ejecta emplacement, have played a major role in erasing <span class="hlt">craters</span> on Deimos and are therefore responsible for the shallow slope of this curve. The observed <span class="hlt">crater</span> density may have reached steady state owing to the obliterations induced by the two competing mechanisms. Such an occurrence indicates that the surface is saturated with impact <span class="hlt">craters</span> despite the random distribution of <span class="hlt">craters</span> on Deimos. Therefore, this work proposes that the age determined by the current <span class="hlt">craters</span> on Deimos reflects neither the age of Deimos itself nor that of the formation of the large concavity centered at its south pole because <span class="hlt">craters</span> should be removed by later impacts. However, a few of the largest <span class="hlt">craters</span> on Deimos may be indicative of the age of the south pole event.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.usgs.gov/imap/2790/pdf/i2790.pdf','USGSPUBS'); return false;" href="https://pubs.usgs.gov/imap/2790/pdf/i2790.pdf"><span><span class="hlt">Crater</span> Lake revealed</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Ramsey, David W.; Dartnell, Peter; Bacon, Charles R.; Robinson, Joel E.; Gardner, James V.</p> <p>2003-01-01</p> <p>Around 500,000 people each year visit <span class="hlt">Crater</span> Lake National Park in the Cascade Range of southern Oregon. Volcanic peaks, evergreen forests, and <span class="hlt">Crater</span> Lake’s incredibly blue water are the park’s main attractions. <span class="hlt">Crater</span> Lake partially fills the caldera that formed approximately 7,700 years ago by the eruption and subsequent collapse of a 12,000-foot volcano called Mount Mazama. The caldera-forming or climactic eruption of Mount Mazama drastically changed the landscape all around the volcano and spread a blanket of volcanic ash at least as far away as southern Canada.Prior to the climactic event, Mount Mazama had a 400,000 year history of cone building activity like that of other Cascade volcanoes such as Mount Shasta. Since the climactic eruption, there have been several less violent, smaller postcaldera eruptions within the caldera itself. However, relatively little was known about the specifics of these eruptions because their products were obscured beneath <span class="hlt">Crater</span> Lake’s surface. As the <span class="hlt">Crater</span> Lake region is still potentially volcanically active, understanding past eruptive events is important to understanding future eruptions, which could threaten facilities and people at <span class="hlt">Crater</span> Lake National Park and the major transportation corridor east of the Cascades.Recently, the lake bottom was mapped with a high-resolution multibeam echo sounder. The new bathymetric survey provides a <span class="hlt">2</span>m/pixel view of the lake floor from its deepest basins virtually to the shoreline. Using Geographic Information Systems (GIS) applications, the bathymetry data can be visualized and analyzed to shed light on the geology, geomorphology, and geologic history of <span class="hlt">Crater</span> Lake.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://images.nasa.gov/#/details-PIA21591.html','SCIGOVIMAGE-NASA'); return false;" href="https://images.nasa.gov/#/details-PIA21591.html"><span>Secondary <span class="hlt">Craters</span> in Bas Relief</span></a></p> <p><a target="_blank" href="https://images.nasa.gov/">NASA Image and Video Library</a></p> <p></p> <p>2017-04-17</p> <p>NASA's Mars Reconnaissance Orbiter (MRO) captured this region of Mars, sprayed with secondary <span class="hlt">craters</span> from 10-kilometer Zunil <span class="hlt">Crater</span> to the northwest. Secondary <span class="hlt">craters</span> form from rocks ejected at high speed from the primary <span class="hlt">crater</span>, which then impact the ground at sufficiently high speed to make huge numbers of much smaller <span class="hlt">craters</span> over a large region. In this scene, however, the secondary <span class="hlt">crater</span> ejecta has an unusual raised-relief appearance like bas-relief sculpture. How did that happen? One idea is that the region was covered with a layer of fine-grained materials like dust or pyroclastics about 1 to <span class="hlt">2</span> meters thick when the Zunil impact occurred (about a million years ago), and the ejecta served to harden or otherwise protect the fine-grained layer from later erosion by the wind. https://photojournal.jpl.nasa.gov/catalog/PIA21591</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li class="active"><span>7</span></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_7 --> <div id="page_8" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li class="active"><span>8</span></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="141"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009APS..DFD.PK009C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009APS..DFD.PK009C"><span>Granular <span class="hlt">Crater</span> Formation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Clark, Abe; Behringer, Robert; Brandenburg, John</p> <p>2009-11-01</p> <p>This project characterizes <span class="hlt">crater</span> formation in a granular material by a jet of gas impinging on a granular material, such as a retro-rocket landing on the moon. We have constructed a <span class="hlt">2</span>D model of a planetary surface, which consists of a thin, clear box partially filled with granular materials (sand, lunar and Mars simulants...). A metal pipe connected to a tank of nitrogen gas via a solenoid valve is inserted into the top of the box to model the rocket. The results are recorded using high-speed video. We process these images and videos in order to test existing models and develop new ones for describing <span class="hlt">crater</span> formation. A similar set-up has been used by Metzger et al.footnotetextP. T. Metzger et al. Journal of Aerospace Engineering (2009) We find that the long-time shape of the <span class="hlt">crater</span> is consistent with a predicted catenary shape (Brandenburg). The depth and width of the <span class="hlt">crater</span> both evolve logarithmically in time, suggesting an analogy to a description in terms of an activated process: dD/dt = A (-aD) (D is the <span class="hlt">crater</span> depth, a and A constants). This model provides a useful context to understand the role of the jet speed, as characterized by the pressure used to drive the flow. The box width also plays an important role in setting the width of the <span class="hlt">crater</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://images.nasa.gov/#/details-PIA04448.html','SCIGOVIMAGE-NASA'); return false;" href="https://images.nasa.gov/#/details-PIA04448.html"><span>Cydonia <span class="hlt">Craters</span></span></a></p> <p><a target="_blank" href="https://images.nasa.gov/">NASA Image and Video Library</a></p> <p></p> <p>2003-03-22</p> <p>In this image from NASA Mars Odyssey, eroded mesas and secondary <span class="hlt">craters</span> dot the landscape in an area of Cydonia Mensae. The single oval-shaped <span class="hlt">crater</span> displays a butterfly ejecta pattern, indicating that the <span class="hlt">crater</span> formed from a low-angle impact.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006AGUFM.P51E1236G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006AGUFM.P51E1236G"><span>Electron Microscopy Studies of Comet Wild-<span class="hlt">2</span> Particulate Residue Preserved in the Stardust Metallic Foil <span class="hlt">Craters</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Graham, G. A.; Kearsley, A. T.; Dai, Z.; Leroux, H.; Teslich, N. E.; Stroud, R.; Borg, J.; Bradley, J. P.; Horz, F. P.; Zolensky, M.</p> <p>2006-12-01</p> <p>The study of comets is fundamental to the understanding of early solar system processes. Much of the current knowledge of cometary compositions comes from `fly-by' missions or remote sensing studies but not, until now, from the laboratory analyses of samples. The Stardust spacecraft (NASA's 4th Discovery mission) was launched in 1999 and in January 2004 had a successful fly-by close to the nucleus of comet Wild <span class="hlt">2</span>. During the encounter, the collector tray assembly containing the principle particle capture technology of low- density silica aerogel was deployed. In addition, the metallic foils (1100 series Aluminum) wrapped around the collector frame also picked up material from the 6.1 km/s cometary particle collisions. Since the retrieval of the sample return capsule in January 2006, and as part of the preliminary examination, a selected number of foils have been scanned using SEM-EDX to locate cometary dust derived impact <span class="hlt">craters</span>. <span class="hlt">Craters</span> ranging from 100 nanometers to several hundreds of micrometers in diameter, containing both monomineralic and polymineralic projectile melts, have been identified, measured and analyzed. Focused ion beam microscopy techniques have been used to take cross-section slices of either individual <span class="hlt">craters</span> or specific residue fragments, and thin them to electron transparency. TEM-EDX analysis of these slices shows that crystalline grains are occasionally preserved, despite the high shock pressures and temperatures that caused most of the particle to melt. Observations from the <span class="hlt">crater</span> residues make a useful addition to studies of the composition and mineralogy of the cometary particulates preserved within the impact tracks in the silica aerogel. This work was in part performed under the auspices of the <span class="hlt">U</span>.S. Department of Energy, National Nuclear Security Administration by the University of California, Lawrence Livermore National Laboratory under contract No. W-7405-Eng-48.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/16237437','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/16237437"><span>Secondary <span class="hlt">craters</span> on Europa and implications for <span class="hlt">cratered</span> surfaces.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Bierhaus, Edward B; Chapman, Clark R; Merline, William J</p> <p>2005-10-20</p> <p>For several decades, most planetary researchers have regarded the impact <span class="hlt">crater</span> populations on solid-surfaced planets and smaller bodies as predominantly reflecting the direct ('primary') impacts of asteroids and comets. Estimates of the relative and absolute ages of geological units on these objects have been based on this assumption. Here we present an analysis of the comparatively sparse <span class="hlt">crater</span> population on Jupiter's icy moon Europa and suggest that this assumption is incorrect for small <span class="hlt">craters</span>. We find that 'secondaries' (<span class="hlt">craters</span> formed by material ejected from large primary impact <span class="hlt">craters</span>) comprise about 95 per cent of the small <span class="hlt">craters</span> (diameters less than 1 km) on Europa. We therefore conclude that large primary impacts into a solid surface (for example, ice or rock) produce far more secondaries than previously believed, implying that the small <span class="hlt">crater</span> populations on the Moon, Mars and other large bodies must be dominated by secondaries. Moreover, our results indicate that there have been few small comets (less than 100 m diameter) passing through the jovian system in recent times, consistent with dynamical simulations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19780060127&hterms=TNT&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3DTNT','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19780060127&hterms=TNT&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3DTNT"><span>Tabular comparisons of the Flynn Creek impact <span class="hlt">crater</span>, United States, Steinheim impact <span class="hlt">crater</span>, Germany and Snowball explosion <span class="hlt">crater</span>, Canada</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Roddy, D. J.</p> <p>1977-01-01</p> <p>A tabular outline of comparative data is presented for 340 basic dimensional, morphological, and structural parameters and related aspects for three <span class="hlt">craters</span> of the flat-floored, central uplift type, two of which are natural terrestrial impact <span class="hlt">craters</span> and one is a large-scale experimental explosion <span class="hlt">crater</span>. The three <span class="hlt">craters</span> are part of a general class, in terms of their morphology and structural deformation that is represented on each of the terrestrial planets including the moon. One of the considered <span class="hlt">craters</span>, the Flynn Creek <span class="hlt">Crater</span>, was formed by a hypervelocity impact event approximately 360 m.y. ago in what is now north central Tennessee. The impacting body appears to have been a carbonaceous chondrite or a cometary mass. The second <span class="hlt">crater</span>, the Steinheim <span class="hlt">Crater</span>, was formed by an impact event approximately 14.7 m.y. ago in what is now southwestern Germany. The Snowball <span class="hlt">Crater</span> was formed by the detonation of a 500-ton TNT hemisphere on flat-lying, unconsolidated alluvium in Alberta, Canada.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25551728','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25551728"><span>Synthesis, spectral and antifungal analysis of diaryldithiophosphates of mono- and dibutyltin(IV): x-ray structure of [{(3,5-CH3)<span class="hlt">2</span>C6H3O)<span class="hlt">2</span>PS<span class="hlt">2}2</span>Sn(n<span class="hlt">Bu</span>)<span class="hlt">2</span>].</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Syed, Atiya; Khajuria, Ruchi; Kumar, Sandeep; Jassal, Amanpreet Kaur; Hundal, Maninder S; Pandey, Sushil K</p> <p>2014-01-01</p> <p>Diaryldithiophosphate complexes of mono- and dibutyltin(IV) corresponding to [(ArO)(<span class="hlt">2</span>)PS(<span class="hlt">2</span>)(n)Sn(n<span class="hlt">Bu</span>)xCl(4-x-n)] (Ar = o-CH(3)C(6)H(4), m-CH(3)C(6)H(4), p-CH(3)C(6)H(4), 4-Cl-3-CH(3)C(6)H(3), (3,5-CH(3))(<span class="hlt">2</span>)C(6)H(3); n = 1, <span class="hlt">2</span> for x = 1 and n = <span class="hlt">2</span> for x = <span class="hlt">2</span>) were successfully isolated and characterized by elemental analyses, IR, multinuclear NMR ((1)H, (13)C, (31)P and (119)Sn) spectroscopy and X-ray analysis. The thermal properties of the complex [(3,5-CH(3))(<span class="hlt">2</span>)C(6)H(3)O(<span class="hlt">2</span>)PS(<span class="hlt">2)](2</span>)Sn(n<span class="hlt">Bu</span>)(<span class="hlt">2</span>) (12) have been examined by combined DTA/ DTG thermal analyses. Single crystal X-ray analysis of [(3,5-CH(3))(<span class="hlt">2</span>)C(6)H(3)O(<span class="hlt">2</span>)PS(<span class="hlt">2)](2</span>)S(n)(n<span class="hlt">Bu</span>)(<span class="hlt">2</span>) (12) revealed that two diaryldithiophosphate ions are coordinated to tin atom in an anisobidentate fashion through the sulfur atoms of each dithiophosphate moiety leading to distorted skew-trapezoidal bipyramidal geometry. The antifungal activity depicts that these complexes are active against fungus Penicillium chrysogenium.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20030068028','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20030068028"><span>Russian-US Partnership to Study the 23-km-diameter El'gygtgyn Impact <span class="hlt">Crater</span>, Northeast Russia</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Sharpton, Virgil L.; Minyuk, Pavel S.; Brigham-Grette, Julie; Glushkova, Olga; Layer, Paul; Raikevich, Mikhail; Stone, David; Smirnov, Valdimir</p> <p>2002-01-01</p> <p>El'gygytgyn <span class="hlt">crater</span>, located within Eastern Siberia, is a Pliocene-aged (3.6 Ma), well-preserved impact <span class="hlt">crater</span> with a rim diameter of roughly 23 km. The target rocks are a coherent assemblage of crystalline rocks ranging from andesite to basalt. At the time of impact the region was forested and the Arctic Ocean was nearly ice-free. A 15-km lake fills the center of the feature and water depths are approximately 175 m. Evidence of shock metamorphism, -- including coesite, fused mineral glasses, and planar deformation features in quartz -- has been reported. This feature is one of the youngest and best preserved complex <span class="hlt">craters</span> on Earth. Because of its remote Arctic setting, however, El gygytgyn <span class="hlt">crater</span> remains poorly investigated. The objectives of this three-year project are to establish and maintain a research partnership between scientists from Russia and the United States interested in the El gygytgyn <span class="hlt">crater</span>. The principal institutions in the <span class="hlt">U</span>.S. will be the Geophysical Institute, University of Alaska Fairbanks and the University of Massachusetts Amherst. The principal institution in Russia will be the North East Interdisciplinary Scientific Research Institute (NEISRI), which is the Far-East Branch of the Russian Academy of Science. Three science tasks are identified for the exchange program: (1) Evaluate impactite samples collected during previous field excursions for evidence of and level of shock deformation. (<span class="hlt">2</span>) Build a high-resolution digital elevation model for the <span class="hlt">crater</span> and its surroundings using interferometric synthetic aperture radar techniques on JERS-1, ERS-1, ERS-<span class="hlt">2</span>, and/or RadarSat range-doppler data. (3) Gather all existing surface data available from Russian and <span class="hlt">U</span>.S. institutions (DEM, remote sensing image data, field-based lithological and sample maps, and existing geophysical data) and assemble into a Geographic Information Systems database.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20150021036','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20150021036"><span>Processes Modifying <span class="hlt">Cratered</span> Terrains on Pluto</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Moore, J. M.</p> <p>2015-01-01</p> <p>The July encounter with Pluto by the New Horizons spacecraft permitted imaging of its <span class="hlt">cratered</span> terrains with scales as high as approximately 100 m/pixel, and in stereo. In the initial download of images, acquired at <span class="hlt">2.2</span> km/pixel, widely distributed impact <span class="hlt">craters</span> up to 260 km diameter are seen in the near-encounter hemisphere. Many of the <span class="hlt">craters</span> appear to be significantly degraded or infilled. Some <span class="hlt">craters</span> appear partially destroyed, perhaps by erosion such as associated with the retreat of scarps. Bright ice-rich deposits highlight some <span class="hlt">crater</span> rims and/or floors. While the <span class="hlt">cratered</span> terrains identified in the initial downloaded images are generally seen on high-to-intermediate albedo surfaces, the dark equatorial terrain informally known as Cthulhu Regio is also densely <span class="hlt">cratered</span>. We will explore the range of possible processes that might have operated (or still be operating) to modify the landscape from that of an ancient pristinely <span class="hlt">cratered</span> state to the present terrains revealed in New Horizons images. The sequence, intensity, and type of processes that have modified ancient landscapes are, among other things, the record of climate and volatile evolution throughout much of the Pluto's existence. The deciphering of this record will be discussed. This work was supported by NASA's New Horizons project.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFMEP53B1699E','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFMEP53B1699E"><span>Towards a Global Land <span class="hlt">Subsidence</span> Map</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Erkens, G.; Kooi, H.; Sutanudjaja, E.</p> <p>2017-12-01</p> <p>Land <span class="hlt">subsidence</span> is a global problem, but a global land <span class="hlt">subsidence</span> map is not available yet. Such map is crucial to raise global awareness of land <span class="hlt">subsidence</span>, as land <span class="hlt">subsidence</span> causes extensive damage (probably in the order of billions of dollars annually). Insights in the rates of <span class="hlt">subsidence</span> are particularly relevant for low lying deltas and coastal zones, for which any further loss in elevation is unwanted. With the global land <span class="hlt">subsidence</span> map relative sea level rise predictions may be improved, contributing to global flood risk calculations. In this contribution, we discuss the approach and progress we have made so far in making a global land <span class="hlt">subsidence</span> map. The first results will be presented and discussed, and we give an outlook on the work needed to derive a global land <span class="hlt">subsidence</span> map.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EGUGA..1919573S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..1919573S"><span>How to deal with <span class="hlt">subsidence</span> in the Dutch delta?</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Stouthamer, Esther; Erkens, Gilles</p> <p>2017-04-01</p> <p>In many deltas worldwide <span class="hlt">subsidence</span> still is an underestimated problem, while the threat posed by land <span class="hlt">subsidence</span> to low-lying urbanizing and urbanized deltas exceeds the threat of sea-level rise induced by climate change. Human-induced <span class="hlt">subsidence</span> is driven by the extraction of hydrocarbons and groundwater, drainage of phreatic groundwater, and loading by buildings and infrastructure. The consequences of <span class="hlt">subsidence</span> are increased flood risk and flood water depth, rising groundwater levels relative to the land surface, land loss, damage to buildings and infrastructure, and salinization of ground and surface water.. The Netherlands has a long history of <span class="hlt">subsidence</span>. Large-scale drainage of the extensive peatlands in the western and northern parts of the Netherlands started approximately 1000 years ago as a result of rapid population growth. <span class="hlt">Subsidence</span> is still ongoing due to (1) continuous drainage of the former peatland, which is now mainly in use as agricultural land and built-up area, (<span class="hlt">2</span>) expansion of the built-up area and the infrastructural network, (3) salt mining and the extraction of gas in the northern Netherlands. Mitigating <span class="hlt">subsidence</span> and its negative impacts requires understanding of the relative contribution of the drivers contributing to total <span class="hlt">subsidence</span>, accurate predictions of land <span class="hlt">subsidence</span> under different management scenarios, and its impacts. Such understanding enables the development of effective and sustainable management strategies. In the Netherlands, a lot of effort is put into water management aiming at amongst others the protection against floods and the ensuring agricultural activities, but a specific policy focusing on <span class="hlt">subsidence</span> is lacking. The development of strategies to cope with <span class="hlt">subsidence</span> is very challenging, because (1) the exact contribution of different drivers of <span class="hlt">subsidence</span> to total <span class="hlt">subsidence</span> is spatially different within the Netherlands, (<span class="hlt">2</span>) there is no single problem owner, which makes it difficult to recognize this a common</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19920001654','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19920001654"><span>Characteristics of ejecta and alluvial deposits at Meteor <span class="hlt">Crater</span>, Arizona and Odessa <span class="hlt">Craters</span>, Texas: Results from ground penetrating radar</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Grant, J. A.; Schultz, P. H.</p> <p>1991-01-01</p> <p>Previous ground penetrating radar (GRP) studies around 50,000 year old Meteor <span class="hlt">Crater</span> revealed the potential for rapid, inexpensive, and non-destructive sub-surface investigations for deep reflectors (generally greater than 10 m). New GRP results are summarized focusing the shallow sub-surfaces (1-<span class="hlt">2</span> m) around Meteor <span class="hlt">Crater</span> and the main <span class="hlt">crater</span> at Odessa. The following subject areas are covered: (1) the thickness, distribution, and nature of the contact between surrounding alluvial deposits and distal ejecta; and (<span class="hlt">2</span>) stratigraphic relationships between both the ejecta and alluvium derived from both pre and post <span class="hlt">crater</span> drainages. These results support previous conclusions indicating limited vertical lowering (less than 1 m) of the distal ejecta at Meteor <span class="hlt">Crater</span> and allow initial assessment of the gradational state if the Odessa <span class="hlt">craters</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011AGUFM.H23H1397C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011AGUFM.H23H1397C"><span><span class="hlt">Subsidence</span> due to Excessive Groundwater Withdrawal in the San Joaquin Valley, California</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Corbett, F.; Harter, T.; Sneed, M.</p> <p>2011-12-01</p> <p>Francis Corbett1, Thomas Harter1 and Michelle Sneed<span class="hlt">2</span> 1Department of Land Air and Water Resources, University of California, Davis. <span class="hlt">2</span><span class="hlt">U</span>.S. Geological Survey Western Remote Sensing and Visualization Center, Sacramento. Abstract: Groundwater development within the Central Valley of California began approximately a century ago. Water was needed to supplement limited surface water supplies for the burgeoning population and agricultural industries, especially within the arid but fertile San Joaquin Valley. Groundwater levels have recovered only partially during wet years from drought-induced lows creating long-term groundwater storage overdraft. Surface water deliveries from Federal and State sources led to a partial alleviation of these pressure head declines from the late 1960s. However, in recent decades, surface water deliveries have declined owing to increasing environmental pressures, whilst water demands have remained steady. Today, a large portion of the San Joaquin Valley population, and especially agriculture, rely upon groundwater. Groundwater levels are again rapidly declining except in wet years. There is significant concern that <span class="hlt">subsidence</span> due to groundwater withdrawal, first observed at a large scale in the middle 20th century, will resume as groundwater resources continue to be depleted. Previous <span class="hlt">subsidence</span> has led to problems such as infrastructure damage and flooding. To provide a support tool for groundwater management on a naval air station in the southern San Joaquin Valley (Tulare Lake Basin), a one-dimensional MODFLOW <span class="hlt">subsidence</span> model covering the period 1925 to 2010 was developed incorporating extensive reconstruction of historical <span class="hlt">subsidence</span> and water level data from various sources. The stratigraphy used for model input was interpreted from geophysical logs and well completion reports. Gaining good quality data proved problematic, and often values needed to be estimated. In part, this was due to the historical lack of awareness/understanding of</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFM.H41A1205H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFM.H41A1205H"><span>Land <span class="hlt">subsidence</span> in Yunlin, Taiwan, due to Agricultural and Domestic Water Use</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hsu, K.; Lin, P.; Lin, Z.</p> <p>2013-12-01</p> <p><span class="hlt">Subsidence</span> in a layered aquifer is caused by groundwater excess extraction and results in complicated problems in Taiwan. Commonly, responsibility to <span class="hlt">subsidence</span> for agricultural and domestic water users is difficulty to identify due to the lack of quantitative evidences. An integrated model was proposed to analyze <span class="hlt">subsidence</span> problem. The flow field utilizes analytical solution for pumping in a layered system from Neuman and Witherspoon (1969) to calculate the head drawdown variation. The <span class="hlt">subsidence</span> estimation applies Terzaghi (1943) one-dimensional consolidation theory to calculate the deformation in each layer. The proposed model was applied to estimate land <span class="hlt">subsidence</span> and drawdown variation at the Yuanchang Township of Yunlin County in Taiwan. Groundwater data for dry-season periods were used for calibration and validation. Seasonal effect in groundwater variation was first filtered out. Dry-season pumping effect on land <span class="hlt">subsidence</span> was analyzed. The results show that multi-layer pumping contributes more in <span class="hlt">subsidence</span> than single-layer pumping on the response of drawdown and land <span class="hlt">subsidence</span> in aquifer <span class="hlt">2</span> with a contribution of 97% total change at Yuanchang station. Pumping in aquifer <span class="hlt">2</span> contributes more significant than pumping in aquifer 3 to cause change in drawdown and land <span class="hlt">subsidence</span> in aquifer <span class="hlt">2</span> with a contribution of 70% total change at Yuanchang station. Larger area of <span class="hlt">subsidence</span> in Yuanchang Township was attributed pumping at aquifer <span class="hlt">2</span> while pumping at aquifer 3 results in significant <span class="hlt">subsidence</span> near the well field. The single-layer user contributes most area of <span class="hlt">subsidence</span> but the multi-layer user generates more serious <span class="hlt">subsidence</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20060041245&hterms=permeability+distribution&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dpermeability%2Bdistribution','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20060041245&hterms=permeability+distribution&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dpermeability%2Bdistribution"><span>Rapid <span class="hlt">subsidence</span> over oil fields measured by SAR</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Fielding, E. J.; Blom, R. G.; Goldstein, R. M.</p> <p>1998-01-01</p> <p>The Lost Hills and Belridge oil felds are in the San Joaquin Valley, California. The major oil reservoir is high porosity and low permeability diatomite. Extraction of large volumes from shallow depths causes reduction in pore pressure and subsequent compaction, forming a surface <span class="hlt">subsidence</span> bowl. We measure this <span class="hlt">subsidence</span> from space using interferometric analysis of SAR (Synthetic Aperture Radar) data collected by the European Space Agency Remote Sensing Satellites (ERS-1 and ERS-<span class="hlt">2</span>). Maximum <span class="hlt">subsidence</span> rates are as high as 40 mm in 35 days or > 400 mm/yr, measured from interferograms with time separations ranging from one day to 26 months. The 8- and 26-month interferograms contain areas where the <span class="hlt">subsidence</span> gradient exceeds the measurement possible with ERS SAR, but shows increased detail in areas of less rapid <span class="hlt">subsidence</span>. Synoptic mapping of <span class="hlt">subsidence</span> distribution from satellite data powerfully complements ground-based techniques, permits measurements where access is difficult, and aids identification of underlying causes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70032716','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70032716"><span>Degradation of Victoria <span class="hlt">crater</span>, Mars</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Grant, J. A.; Wilson, S.A.; Cohen, B. A.; Golombek, M.P.; Geissler, P.E.; Sullivan, R.J.; Kirk, R.L.; Parker, T.J.</p> <p>2008-01-01</p> <p>The ???750 m diameter and ???75 m deep Victoria <span class="hlt">crater</span> in Meridiani Planum, Mars, is a degraded primary impact structure retaining a ???5 m raised rim consisting of 1-<span class="hlt">2</span> m of uplifted rocks overlain by ???3 m of ejecta at the rim crest. The rim is 120-220 m wide and is surrounded by a dark annulus reaching an average of 590 m beyond the raised rim. Comparison between observed morphology and that expected for pristine <span class="hlt">craters</span> 500-750 m across indicates that the original, pristine <span class="hlt">crater</span> was close to 600 m in diameter. Hence, the <span class="hlt">crater</span> has been erosionally widened by ???150 m and infilled by ???50 m of sediments. Eolian processes are responsible for most <span class="hlt">crater</span> modification, but lesser mass wasting or gully activity contributions cannot be ruled out. Erosion by prevailing winds is most significant along the exposed rim and upper walls and accounts for ???50 m widening across a WNW-ESE diameter. The volume of material eroded from the <span class="hlt">crater</span> walls and rim is ???20% less than the volume of sediments partially filling the <span class="hlt">crater</span>, indicating eolian infilling from sources outside the <span class="hlt">crater</span> over time. The annulus formed when ???1 m deflation of the ejecta created a lag of more resistant hematite spherules that trapped <10-20 cm of darker, regional basaltic sands. Greater relief along the rim enabled meters of erosion. Comparison between Victoria and regional <span class="hlt">craters</span> leads to definition of a <span class="hlt">crater</span> degradation sequence dominated by eolian erosion and infilling over time. Copyright 2008 by the American Geophysical Union.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009CPL...477..194K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009CPL...477..194K"><span>Vibrational relaxation and internal conversion in the overlapped optically-allowed 1<span class="hlt">Bu</span>+ and optically-forbidden 1<span class="hlt">Bu</span>- or 3Ag- vibronic levels of carotenoids: Effects of diabatic mixing as determined by Kerr-gate fluorescence spectroscopy</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kakitani, Yoshinori; Miki, Takeshi; Koyama, Yasushi; Nagae, Hiroyoshi; Nakamura, Ryosuke; Kanematsu, Yasuo</p> <p>2009-07-01</p> <p>The time constants of the vibrational relaxation, υ = <span class="hlt">2</span> → υ = 1 and υ = 1 → υ = 0, in the 1<span class="hlt">Bu</span>+ manifold and those of internal conversion from the 1<span class="hlt">Bu</span>+(0) level, which is isoenergetic (so-called 'diabatic') with the 1<span class="hlt">Bu</span>- vibronic levels in neurosporene and spheroidene and with the 3Ag- vibronic levels in lycopene and anhydrorhodovibrin, were determined by Kerr-gate fluorescence spectroscopy. The time constants of the vibrational relaxation were in the ˜1:<span class="hlt">2</span> ratio, and those of internal conversion agreed with the lifetimes of the diabatic counterparts, i.e., the 1<span class="hlt">Bu</span>- and 3Ag- electronic states, respectively.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70027122','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70027122"><span>Marine-target <span class="hlt">craters</span> on Mars? An assessment study</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Ormo, J.; Dohm, J.M.; Ferris, J.C.; Lepinette, A.; Fairen, A.G.</p> <p>2004-01-01</p> <p>Observations of impact <span class="hlt">craters</span> on Earth show that a water column at the target strongly influences lithology and morphology of the resultant <span class="hlt">crater</span>. The degree of influence varies with the target water depth and impactor diameter. Morphological features detectable in satellite imagery include a concentric shape with an inner <span class="hlt">crater</span> inset within a shallower outer <span class="hlt">crater</span>, which is cut by gullies excavated by the resurge of water. In this study, we show that if oceans, large seas, and lakes existed on Mars for periods of time, marine-target <span class="hlt">craters</span> must have formed. We make an assessment of the minimum and maximum amounts of such <span class="hlt">craters</span> based on published data on water depths, extent, and duration of putative oceans within "contacts 1 and <span class="hlt">2</span>," <span class="hlt">cratering</span> rate during the different oceanic phases, and computer modeling of minimum impactor diameters required to form long-lasting <span class="hlt">craters</span> in the seafloor of the oceans. We also discuss the influence of erosion and sedimentation on the preservation and exposure of the <span class="hlt">craters</span>. For an ocean within the smaller "contact <span class="hlt">2</span>" with a duration of 100,000 yr and the low present <span class="hlt">crater</span> formation rate, only ???1-<span class="hlt">2</span> detectable marine-target <span class="hlt">craters</span> would have formed. In a maximum estimate with a duration of 0.8 Gyr, as many as 1400 <span class="hlt">craters</span> may have formed. An ocean within the larger "contact 1-Meridiani," with a duration of 100,000 yr, would not have received any seafloor <span class="hlt">craters</span> despite the higher <span class="hlt">crater</span> formation rate estimated before 3.5 Gyr. On the other hand, with a maximum duration of 0.8 Gyr, about 160 seafloor <span class="hlt">craters</span> may have formed. However, terrestrial examples show that most marine-target <span class="hlt">craters</span> may be covered by thick sediments. Ground penetrating radar surveys planned for the ESA Mars Express and NASA 2005 missions may reveal buried <span class="hlt">craters</span>, though it is uncertain if the resolution will allow the detection of diagnostic features of marine-target <span class="hlt">craters</span>. The implications regarding the discovery of marine-target <span class="hlt">craters</span> on</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://rosap.ntl.bts.gov/view/dot/30687','DOTNTL'); return false;" href="https://rosap.ntl.bts.gov/view/dot/30687"><span>Cost-benefit analysis : substituting ground transportation for <span class="hlt">subsidized</span> essential air services.</span></a></p> <p><a target="_blank" href="http://ntlsearch.bts.gov/tris/index.do">DOT National Transportation Integrated Search</a></p> <p></p> <p>2015-12-01</p> <p>Since the Airline Deregulation Act of 1978, the <span class="hlt">U</span>.S. Department of Transportation (DOT) has been <span class="hlt">subsidizing</span> air service to : small rural communities through the Essential Air Service (EAS) program. The original intent of the program was to maintain ...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://images.nasa.gov/#/details-PIA18384.html','SCIGOVIMAGE-NASA'); return false;" href="https://images.nasa.gov/#/details-PIA18384.html"><span>Large, Fresh <span class="hlt">Crater</span> Surrounded by Smaller <span class="hlt">Craters</span></span></a></p> <p><a target="_blank" href="https://images.nasa.gov/">NASA Image and Video Library</a></p> <p></p> <p>2014-05-22</p> <p>The largest <span class="hlt">crater</span> associated with a March 2012 impact on Mars has many smaller <span class="hlt">craters</span> around it, revealed in this image from the High Resolution Imaging Science Experiment HiRISE camera on NASA Mars Reconnaissance Orbiter.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFMNH31B0229G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFMNH31B0229G"><span><span class="hlt">Subsidence</span> driving forces in large Delta Plain</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Grall, C.; Steckler, M. S.</p> <p>2017-12-01</p> <p>Recent studies show large variability in <span class="hlt">subsidence</span> rates among large delta plains that directly impact coastal management of these highly vulnerable environments. Observations show both significant spatial variation in <span class="hlt">subsidence</span> across each delta, as well as large differences in magnitude between different deltas. This variability raises the question of what are the driving forces that control <span class="hlt">subsidence</span> in large delta plains that this study aims to address. <span class="hlt">Subsidence</span> and sediment compaction is studied in 4 end-member large Delta Plains: the Ganges-Brahmaputra, the Mekong, the Mississippi and the Nile. Those large delta plains drastically contrast in <span class="hlt">subsidence</span> rates (from values to several mm/yr to several cm/yr), in the nature of the sediment (notably in clay and organic matter content), and in the volume of sediment supplied by the large rivers that feed those coastal environments. The volume of sediment deposited in each delta plain during the Holocene is estimated and the compaction of the underlying sedimentary column is computed by using a backstripping approach. Sediment compaction behaviors are defined accordingly to the observed clay, silt and organic contents, and the rate of <span class="hlt">subsidence</span> associated with compaction is determined. Results suggest that about <span class="hlt">2</span>/3 of observed Holocene <span class="hlt">subsidence</span> may be associated with the mechanical and chemical compaction of the underlying sedimentary column due to the load of sediment deposited. The compaction appears to be significantly higher in delta plains characterized by a high sediment input and a high organic matter and clay content. Thus, the observed <span class="hlt">subsidence</span> rates in the (muddy) Mekong delta appear to be one order of magnitude higher than other delta plains. In contrast, <span class="hlt">subsidence</span> rates are modest in the Ganges-Brahmaputra, the Mississippi and the Nile delta plains, except away from the major rivers where deposits are muddier.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li class="active"><span>8</span></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_8 --> <div id="page_9" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li class="active"><span>9</span></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="161"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://images.nasa.gov/#/details-PIA04018.html','SCIGOVIMAGE-NASA'); return false;" href="https://images.nasa.gov/#/details-PIA04018.html"><span>Buried <span class="hlt">Crater</span></span></a></p> <p><a target="_blank" href="https://images.nasa.gov/">NASA Image and Video Library</a></p> <p></p> <p>2002-12-04</p> <p>With a location roughly equidistant between two of the largest volcanic constructs on the planet, the fate of the approximately 50 km 31 mile impact <span class="hlt">crater</span> in this image from NASA Mars Odyssey was sealed. It has been buried to the rim by lava flows. The MOLA context image shows pronounced flow lobes surrounding the <span class="hlt">crater</span>, a clear indication of the most recent episode of volcanism that could have contributed to its infilling. Breaches in the rim are clearly evident in the image and suggest locations through which lavas could have flowed. These openings appear to be limited to the west side of the <span class="hlt">crater</span>. Other <span class="hlt">craters</span> in the area are nearly obliterated by the voluminous lava flows, further demonstrating one of the means by which Mars renews its surface. The MOLA context image shows pronounced flow lobes surrounding the <span class="hlt">crater</span>, a clear indication of the most recent episode of volcanism that could have contributed to its infilling. Breaches in the rim are clearly evident in the image and suggest locations through which lavas could have flowed. These openings appear to be limited to the west side of the <span class="hlt">crater</span>. Other <span class="hlt">craters</span> in the area are nearly obliterated by the voluminous lava flows, further demonstrating one of the means by which Mars renews its surface. http://photojournal.jpl.nasa.gov/catalog/PIA04018</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017M%26PS...52..493H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017M%26PS...52..493H"><span>Martian <span class="hlt">cratering</span> 11. Utilizing decameter scale <span class="hlt">crater</span> populations to study Martian history</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hartmann, W. K.; Daubar, I. J.</p> <p>2017-03-01</p> <p>New information has been obtained in recent years regarding formation rates and the production size-frequency distribution (PSFD) of decameter-scale primary Martian <span class="hlt">craters</span> formed during recent orbiter missions. Here we compare the PSFD of the currently forming small primaries (P) with new data on the PSFD of the total small <span class="hlt">crater</span> population that includes primaries and field secondaries (P + fS), which represents an average over longer time periods. The two data sets, if used in a combined manner, have extraordinary potential for clarifying not only the evolutionary history and resurfacing episodes of small Martian geological formations (as small as one or few km<span class="hlt">2</span>) but also possible episodes of recent climatic change. In response to recent discussions of statistical methodologies, we point out that <span class="hlt">crater</span> counts do not produce idealized statistics, and that inherent uncertainties limit improvements that can be made by more sophisticated statistical analyses. We propose three mutually supportive procedures for interpreting <span class="hlt">crater</span> counts of small <span class="hlt">craters</span> in this context. Applications of these procedures support suggestions that topographic features in upper meters of mid-latitude ice-rich areas date only from the last few periods of extreme Martian obliquity, and associated predicted climate excursions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20090033478','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20090033478"><span><span class="hlt">Cratering</span> Equations for Zinc Orthotitanate Coated Aluminum</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Hyde, James; Christiansen, Eric; Liou, Jer-Chyi; Ryan, Shannon</p> <p>2009-01-01</p> <p>The final STS-125 servicing mission (SM4) to the Hubble Space Telescope (HST) in May of 2009 saw the return of the <span class="hlt">2</span>nd Wide Field Planetary Camera (WFPC<span class="hlt">2</span>) aboard the shuttle Discovery. This hardware had been in service on HST since it was installed during the SM1 mission in December of 1993 yielding one of the longest low Earth orbit exposure times (15.4 years) of any returned space hardware. The WFPC<span class="hlt">2</span> is equipped with a 0.8 x <span class="hlt">2.2</span> m radiator for thermal control of the camera electronics (Figure 1). The space facing surface of the 4.1 mm thick aluminum radiator is coated with Z93 zinc orthotitanate thermal control paint with a nominal thickness of 0.1 0.<span class="hlt">2</span> mm. Post flight inspections of the radiator panel revealed hundreds of micrometeoroid/orbital debris (MMOD) impact <span class="hlt">craters</span> ranging in size from less than 300 to nearly 1000 microns in diameter. The Z93 paint exhibited large spall areas around the larger impact sites (Figure <span class="hlt">2</span>) and the <span class="hlt">craters</span> observed in the 6061-T651 aluminum had a different shape than those observed in uncoated aluminum. Typical hypervelocity impact <span class="hlt">craters</span> in aluminum have raised lips around the impact site. The <span class="hlt">craters</span> in the HST radiator panel had suppressed <span class="hlt">crater</span> lips, and in some cases multiple <span class="hlt">craters</span> were present instead of a single individual <span class="hlt">crater</span>. Humes and Kinard observed similar behavior after the WFPC1 post flight inspection and assumed the Z93 coating was acting like a bumper in a Whipple shield. Similar paint behavior (spall) was also observed by Bland<span class="hlt">2</span> during post flight inspection of the International Space Station (ISS) S-Band Antenna Structural Assembly (SASA) in 2008. The SASA, with similar Z93 coated aluminum, was inspected after nearly 4 years of exposure on the ISS. The multi-<span class="hlt">crater</span> phenomena could be a function of the density, composition, or impact obliquity angle of the impacting particle. For instance, a micrometeoroid particle consisting of loosely bound grains of material could be responsible for creating the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19870006229','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19870006229"><span><span class="hlt">Cratering</span> mechanics</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Ivanov, B. A.</p> <p>1986-01-01</p> <p>Main concepts and theoretical models which are used for studying the mechanics of <span class="hlt">cratering</span> are discussed. Numerical two-dimensional calculations are made of explosions near a surface and high-speed impact. Models are given for the motion of a medium during <span class="hlt">cratering</span>. Data from laboratory modeling are given. The effect of gravitational force and scales of <span class="hlt">cratering</span> phenomena is analyzed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006epsc.conf..625P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006epsc.conf..625P"><span>An assessment of <span class="hlt">crater</span> erosional histories on the Earth and Mars using digital terrain models.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Paul, R. L.; Muller, J.-P.; Murray, J. B.</p> <p></p> <p> ICEDS. These are: Barringer, Arizona, <span class="hlt">U</span>.S.A; Goat Paddock, West Australia; Ouarkziz, Algeria; Roter Kamm, Namibia; Talemzane, Algeria; Tenoumer, Mauritania; Tswaing, South Africa 1 and Upheaval Dome, Utah, <span class="hlt">U</span>.S.A. Comparable Martian <span class="hlt">craters</span> are in the process of being chosen using the USGS PIGWAD database and the Morphological Catalogue of the <span class="hlt">Craters</span> of Mars. Digital Terrain Models of each <span class="hlt">crater</span> using SRTM DEMs and data from the recent Mars Express HRSC will be used at various resolutions (30m upwards) to provide three dimensional models to assess the capabilities of measuring erosional effects. There is also available ASTER DEMs and ASTER Level 1A for terrestrial <span class="hlt">craters</span> and MOLA tracks for Martian <span class="hlt">craters</span>. Both laboratory and theoretical models of <span class="hlt">crater</span> shape and erosion features will provide a better understanding of the processes observed. This will enable us to develop a better explanation of why <span class="hlt">craters</span> are the shape they are. References. Barlow N., 1987, <span class="hlt">Crater</span> Size-Frequency Distribution and a Revised Martian Relative Chronology, Icarus, 75, 285-305. Barlow, N., 1995, The degradation of impact <span class="hlt">craters</span> in Maja Valles and Arabia Mars, Journal GeoPhys. Res., 100, 23307-23316. Earth Impact Database http://www.unb.ca/passc/ImpactDatabase/ Earth PIGWAD database http://webgis.wr.usgs.gov/website/mars%5Fcrater%5Fhtml/viewer.htm ICEDS http://iceds.ge.ucl.ac.uk/ Morphology Catalogue of the <span class="hlt">Craters</span> of Mars http://selena.sai.msu.ru/Home/Mars_Cat/Mars_Cat.htm Murray J.B, Guest J.E, 1970, Circularities of <span class="hlt">craters</span> and related structures on Earth and Moon, Modern Geology, 1, 149-159. Forsberg-Taylor N., Howard A.D., 2004, <span class="hlt">Crater</span> degradation in the Martian Highlands: Morphometric Analysis of the Sinus Sabaeus region and simulation modelling suggest fluvial processes, Journal GeoPhys Res., 109, E05002. <span class="hlt">2</span></p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70013564','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70013564"><span>Land <span class="hlt">subsidence</span> near oil and gas fields, Houston, Texas.</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Holzer, T.L.; Bluntzer, R.L.</p> <p>1984-01-01</p> <p><span class="hlt">Subsidence</span> profiles across 29 oil and gas fields in the 12 200 km<span class="hlt">2</span> Houston, Texas, regional <span class="hlt">subsidence</span> area, which is caused by the decline of ground-water level, suggest that the contribution of petroleum withdrawal to local land <span class="hlt">subsidence</span> is small. In addition to land <span class="hlt">subsidence</span>, faults with an aggregate length of more than 240 km have offset the land surface in historical time. Natural geologic deformation, ground-water pumping, and petroleum withdrawal have all been considered as potential causes of the historical offset across these faults. The minor amount of localized land <span class="hlt">subsidence</span> associated with oil and gas fields, suggests that petroleum withdrawal is not a major cause of the historical faulting. -from Authors</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27781357','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27781357"><span>[Cu13 {S<span class="hlt">2</span> CNn <span class="hlt">Bu</span><span class="hlt">2</span> }6 (acetylide)4 ]+ : A Two-Electron Superatom.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Chakrahari, Kiran Kumarvarma; Liao, Jian-Hong; Kahlal, Samia; Liu, Yu-Chiao; Chiang, Ming-Hsi; Saillard, Jean-Yves; Liu, C W</p> <p>2016-11-14</p> <p>The first structurally characterized copper cluster with a Cu 13 centered cuboctahedral arrangement, a model of the bulk copper fcc structure, was observed in [Cu 13 (S <span class="hlt">2</span> CN n <span class="hlt">Bu</span> <span class="hlt">2</span> ) 6 (C≡CR) 4 ](PF 6 ) (R=C(O)OMe, C 6 H 4 F) nanoclusters. Four of the eight triangular faces of the cuboctahedron are capped by acetylide groups in μ 3  fashion, and each of the six square faces is bridged by a dithiolate ligand in μ <span class="hlt">2</span> ,μ <span class="hlt">2</span> fashion, which leads to a truncated tetrahedron of twelve sulfur atoms. DFT calculations are fully consistent with the description of these Cu 13 clusters as two-electron superatoms, that is, a [Cu 13 ] 11+ core passivated by ten monoanionic ligands, with an a 1 HOMO containing two 1S jellium electrons. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009AGUFMNH43C1338B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009AGUFMNH43C1338B"><span>Hazards of Gulf Coast <span class="hlt">Subsidence</span>: Crustal Loading, Geodesy, InSAR and UAVSAR Observations</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Blom, R. G.; Chapman, B. D.; Dokka, R. K.; Fielding, E. J.; Hensley, S.; Ivins, E. R.; Lohman, R. B.</p> <p>2009-12-01</p> <p>Hurricanes Katrina and Rita focused attention on the vulnerability of the <span class="hlt">U</span>.S. Gulf Coast. Significant improvement in geophysical understanding of <span class="hlt">subsidence</span> rates, temporal variability, and geographic distribution is not only an interesting scientific challenge, it is necessary for long term protection of lives and property. An integrated geophysical approach using precise and accurate geodetic measurements is the only way to gain physical insight into the myriad of possible processes at work and provide accurate predictions of future <span class="hlt">subsidence</span> rates. In particular, southeast Louisiana is a Holocene landscape built on a coastal delta created by the Mississippi River during the past ~8,000 years as sea level rise slowed. Prior to human intervention natural <span class="hlt">subsidence</span> was offset by sediment deposition by the Mississippi River during floods, and in situ organic sediment production in marshes. Currently, several processes have been documented to contribute to <span class="hlt">subsidence</span>, including wetland loss due to lack of present day sediment flux, land <span class="hlt">subsidence</span> due to sediment compaction, sediment oxidation, fluid withdrawal, salt evacuation, tectonics, and also crustal loading. One of the least studied <span class="hlt">subsidence</span> driving phenomena is the effect of crustal loading due to Mississippi River sediments, and the geologically recent ~130 m (427 ft.) rise in sea level. We model <span class="hlt">subsidence</span> rates expected from these loads using geophysical methods developed for post-glacial rebound. Our model predicted, and geodetically observed, vertical <span class="hlt">subsidence</span> rates vary between <span class="hlt">2</span> - 8 mm per year over areas of 30,000 to 750 square kilometers, respectively. This viscoelastic flexure is the background crustal deformation field, upon which larger amplitude, but smaller spatial scale, <span class="hlt">subsidence</span> occurs due to other factors. We are extending <span class="hlt">subsidence</span> measurements from traditional geodetic techniques (including GPS), to geographically comprehensive measurements derived from synthetic aperture radar</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=PIA06865&hterms=Football&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DFootball','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=PIA06865&hterms=Football&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DFootball"><span>'Endurance <span class="hlt">Crater</span>' Overview</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>2004-01-01</p> <p><p/> This overview of 'Endurance <span class="hlt">Crater</span>' traces the path of the Mars Exploration Rover Opportunity from sol 94 (April 29, 2004) to sol 205 (August 21, 2004). The route charted to enter the <span class="hlt">crater</span> was a bit circuitous, but well worth the extra care engineers took to ensure the rover's safety. On sol 94, Opportunity sat on the edge of this impressive, football field-sized <span class="hlt">crater</span> while rover team members assessed the scene. After traversing around the 'Karatepe' region and past 'Burns Cliff,' the rover engineering team assessed the possibility of entering the <span class="hlt">crater</span>. Careful analysis of the angles Opportunity would face, including testing an Earth-bound model on simulated martian terrain, led the team to decide against entering the <span class="hlt">crater</span> at that particular place. Opportunity then backed up before finally dipping into the <span class="hlt">crater</span> on its 130th sol (June 5, 2004). The rover has since made its way down the <span class="hlt">crater</span>'s inner slope, grinding, trenching and examining fascinating rocks and soil targets along the way. The rover nearly made it to the intriguing dunes at the bottom of the <span class="hlt">crater</span>, but when it got close, the terrain did not look safe enough to cross.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018SoSyR..52....1I','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018SoSyR..52....1I"><span>Size-Frequency Distribution of Small Lunar <span class="hlt">Craters</span>: Widening with Degradation and <span class="hlt">Crater</span> Lifetime</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ivanov, B. A.</p> <p>2018-01-01</p> <p>The review and new measurements are presented for depth/diameter ratio and slope angle evolution during small ( D < 1 km) lunar impact <span class="hlt">craters</span> aging (degradation). Comparative analysis of available data on the areal <span class="hlt">cratering</span> density and on the <span class="hlt">crater</span> degradation state for selected <span class="hlt">craters</span>, dated with returned Apollo samples, in the first approximation confirms Neukum's chronological model. The uncertainty of <span class="hlt">crater</span> retention age due to <span class="hlt">crater</span> degradational widening is estimated. The collected and analyzed data are discussed to be used in the future updating of mechanical models for lunar <span class="hlt">crater</span> aging.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=PIA08784&hterms=duck&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dduck','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=PIA08784&hterms=duck&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dduck"><span>'Victoria <span class="hlt">Crater</span>' from 'Duck Bay' (Stereo)</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>2006-01-01</p> <p><p/> [figure removed for brevity, see original site] Figure 1 <p/> [figure removed for brevity, see original site] Figure <span class="hlt">2</span> <p/> NASA's Mars rover Opportunity edged 3.7 meters (12 feet) closer to the top of the 'Duck Bay' alcove along the rim of 'Victoria <span class="hlt">Crater</span>' during the rover's 952nd Martian day, or sol (overnight Sept. 27 to Sept. 28), and gained this vista of the <span class="hlt">crater</span>. The rover's navigation camera took the seven exposures combined into this mosaic view of the <span class="hlt">crater</span>'s interior. This <span class="hlt">crater</span> has been the mission's long-term destination for the past 21 Earth months. <p/> The far side of the <span class="hlt">crater</span> is about 800 meters (one-half mile) away. The rim of the <span class="hlt">crater</span> is composed of alternating promontories, rocky points towering approximately 70 meters (230 feet) above the <span class="hlt">crater</span> floor, and recessed alcoves, such as Duck Bay. The bottom of the <span class="hlt">crater</span> is covered by sand that has been shaped into ripples by the Martian wind. The rocky cliffs in the foreground have been informally named 'Cape Verde,' on the left, and 'Cabo Frio,' on the right. <p/> Victoria <span class="hlt">Crater</span> is about five times wider than 'Endurance <span class="hlt">Crater</span>,' which Opportunity spent six months examining in 2004, and about 40 times wider than 'Eagle <span class="hlt">Crater</span>,' where Opportunity first landed. The great lure of Victoria is an expectation that the thick stack of geological layers exposed in the <span class="hlt">crater</span> walls could reveal the record of past environmental conditions over a much greater span of time than Opportunity has read from rocks examined earlier in the mission. <p/> The stereo-anaglyph view presented here is a cylindrical projection with geometric seam correction.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://images.nasa.gov/#/details-PIA20036.html','SCIGOVIMAGE-NASA'); return false;" href="https://images.nasa.gov/#/details-PIA20036.html"><span>The Youngest <span class="hlt">Crater</span> on Charon?</span></a></p> <p><a target="_blank" href="https://images.nasa.gov/">NASA Image and Video Library</a></p> <p></p> <p>2015-10-29</p> <p>NASA's New Horizons scientists have discovered a striking contrast between one of the fresh <span class="hlt">craters</span> on Pluto's largest moon Charon and a neighboring <span class="hlt">crater</span> dotting the moon's Pluto-facing hemisphere. The <span class="hlt">crater</span>, informally named Organa, caught scientists' attention as they were studying New Horizons' highest-resolution infrared compositional scan of Charon. Organa and portions of the surrounding material ejected from it show infrared absorption at wavelengths of about <span class="hlt">2.2</span> microns, indicating that the <span class="hlt">crater</span> is rich in frozen ammonia -- and, from what scientists have seen so far, unique on Pluto's largest moon. The infrared spectrum of nearby Skywalker <span class="hlt">crater</span>, for example, is similar to the rest of Charon's <span class="hlt">craters</span> and surface, with features dominated by ordinary water ice. This composite image is based on observations from the New Horizons Ralph/LEISA instrument made at 10:25 UT (6:25 a.m. EDT) on July 14, 2015, when New Horizons was 50,000 miles (81,000 kilometers) from Charon. The spatial resolution is 3 miles (5 kilometers) per pixel. The LEISA data were downlinked Oct. 1-4, 2015, and processed into a map of Charon's <span class="hlt">2.2</span> micron ammonia-ice absorption band. Long Range Reconnaissance Imager (LORRI) panchromatic images used as the background in this composite were taken about 8:33 UT (4:33 a.m. EDT) July 14 at a resolution of 0.6 miles (0.9 kilometers) per pixel and downlinked Oct. 5-6. The ammonia absorption map from LEISA is shown in green on the LORRI image. The region covered by the yellow box is 174 miles across (280 kilometers). http://photojournal.jpl.nasa.gov/catalog/PIA20036</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://dx.doi.org/10.1023/A:1009904816246','USGSPUBS'); return false;" href="http://dx.doi.org/10.1023/A:1009904816246"><span>Vertical accretion and shallow <span class="hlt">subsidence</span> in a mangrove forest of southwestern Florida, <span class="hlt">U</span>.S.A</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Cahoon, D.R.; Lynch, J.C.</p> <p>1997-01-01</p> <p> surface and subsurface processes and the procces controlling soil elevation differed among forest types. The mangrove ecosystem at Rookery Bay has remained stable as sea level has risen during the past 70 years. Yet, lead-210 accretion data suggest a substantial accretion deficit has occurred in the past century (accretion was 10-20 cm < sea-level rise from 1930 to 1990) in the fringe and island forests at Rookery Bay. In contrast, our measures of elevation change mostly equalled the estimates of sea-level rise and shallow <span class="hlt">subsidence</span>. These data suggest that (1) vertical accretion in this system is driven by local sea-level rise and shallow <span class="hlt">subsidence</span>, and (<span class="hlt">2</span>) the mangrove forests are mostly keeping pace with sea-level rise. Thus, the vulnerability of this mangrove ecosystem to sea-level rise is best described in terms of an elevation deficit (elevation change minus sea-level rise) based on annual measures rather than an accretion deficit (accretion minus sea-level rise) based on decadal measures.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70010404','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70010404"><span>Moon-Mercury: Relative preservation states of secondary <span class="hlt">craters</span></span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Scott, D.H.</p> <p>1977-01-01</p> <p>Geologic mapping of the Kuiper quadrangle of Mercury and other geologic studies of the planet indicate that secondary <span class="hlt">craters</span> are much better preserved than those on the moon around primary <span class="hlt">craters</span> of similar size and morphology. Among the oldest recognized secondary <span class="hlt">craters</span> on the moon associated with <span class="hlt">craters</span> 100 km across or less are those of Posidonius, Atlas and Plato; these <span class="hlt">craters</span> have been dated as middle to late Imbrian in age. Many <span class="hlt">craters</span> on Mercury with dimensions, morphologies and superposed <span class="hlt">crater</span> densities similar to these lunar <span class="hlt">craters</span> have fields and clusters of fresher appearing secondary <span class="hlt">craters</span>. The apparent differences between secondary-<span class="hlt">crater</span> morphology and parent <span class="hlt">crater</span> may be due in part to: (1) rapid isostatic adjustment of the parent <span class="hlt">crater</span>; (<span class="hlt">2</span>) different impact fluxes between the two planets; and (or) (3) to the greater concentration of Mercurian secondaries around impact areas, thereby accentuating <span class="hlt">crater</span> forms. Another factor which may contribute to the better state of preservation of Mercurian secondaries relative to the moon is the difference in <span class="hlt">crater</span> ejecta velocities on both bodies. These velocities have been calculated for fields of secondary <span class="hlt">craters</span> at about equal ranges from lunar and Mercurian parent <span class="hlt">craters</span>. Results show that ejection velocities of material producing most of the secondary <span class="hlt">craters</span> are rather low (<1 km/s) but velocities on Mercury are about 50% greater than those on the moon for equivalent ranges. Higher velocities may produce morphologically enhanced secondary <span class="hlt">craters</span> which may account for their better preservation with time. ?? 1977.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017DPS....4910003B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017DPS....4910003B"><span>What Really Happened to Earth's Older <span class="hlt">Craters</span>?</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bottke, William; Mazrouei, Sara; Ghent, Rebecca; Parker, Alex</p> <p>2017-10-01</p> <p>Most assume the Earth’s <span class="hlt">crater</span> record is heavily biased, with erosion/tectonics destroying older <span class="hlt">craters</span>. This matches expectations, but is it actually true? To test this idea, we compared Earth’s <span class="hlt">crater</span> record, where nearly all D ≥ 20 km <span class="hlt">craters</span> are < 650 Myr old, to the Moon’s. Here lunar <span class="hlt">crater</span> ages were computed using a new method employing LRO-Diviner temperature data. Large lunar rocks have high thermal inertia and remain warm through the night relative to the regolith. Analysis shows young <span class="hlt">craters</span> with numerous meter-sized fragments are easy to pick out from older <span class="hlt">craters</span> with eroded fragments. Moreover, an inverse relationship between rock abundance (RA) and <span class="hlt">crater</span> age exists. Using measured RA values, we computed ages for 111 rocky <span class="hlt">craters</span> with D ≥ 10 km that formed between 80°N and 80°S over the last 1 Gyr.We found several surprising results. First, the production rate of D ≥ 10 km lunar <span class="hlt">craters</span> increased by a factor of <span class="hlt">2.2</span> [-0.9, +4.4; 95% confidence limits] over the past 250 Myr compared to the previous 750 Myr. Thus, the NEO population is higher now than it has been for the last billion years. Second, the size and age distributions of lunar and terrestrial <span class="hlt">craters</span> for D ≥ 20 km over the last 650 Myr have similar shapes. This implies that <span class="hlt">crater</span> erasure must be limited on stable terrestrial terrains; in an average sense, for a given region, the Earth either keeps all or loses all of its D ≥ 20 <span class="hlt">craters</span> at the same rate, independent of size. It also implies the observed deficit of large terrestrial <span class="hlt">craters</span> between 250-650 Myr is not preservation bias but rather reflects a distinctly lower impact flux. We predict 355 ± 86 D ≥ 20 km <span class="hlt">craters</span> formed on Earth over the last 650 Myr. Only 38 ± 6 are known, so the ratio, 10.7 ± 3.1%, is a measure of the Earth’s surface that is reasonably stable to large <span class="hlt">crater</span> formation over 650 Myr. If erosion had dominated, the age distribution of terrestrial <span class="hlt">craters</span> would be strongly skewed toward</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://images.nasa.gov/#/details-PIA21754.html','SCIGOVIMAGE-NASA'); return false;" href="https://images.nasa.gov/#/details-PIA21754.html"><span>Juling <span class="hlt">Crater</span></span></a></p> <p><a target="_blank" href="https://images.nasa.gov/">NASA Image and Video Library</a></p> <p></p> <p>2017-08-25</p> <p>This high-resolution image of Juling <span class="hlt">Crater</span> on Ceres reveals, in exquisite detail, features on the rims and <span class="hlt">crater</span> floor. The <span class="hlt">crater</span> is about 1.6 miles (<span class="hlt">2</span>.5 kilometers) deep and the small mountain, seen left of the center of the <span class="hlt">crater</span>, is about 0.6 miles (1 kilometers) high. The many features indicative of the flow of material suggest the subsurface is rich in ice. The geological structure of this region also generally suggests that ice is involved. The origin of the small depression seen at the top of the mountain is not fully understood but might have formed as a consequence of a landslide, visible on the northeastern flank. Dawn took this image during its extended mission on August 25, 2016, from its low-altitude mapping orbit at a distance of about 240 miles (385 kilometers) above the surface. The center coordinates of this image are 36 degrees south latitude, 167 degrees east longitude. Juling is named after the Sakai/Orang Asli spirit of the crops from Malaysia. NASA's Dawn spacecraft acquired this picture on August 24, 2016. The image was taken during Dawn's extended mission, from its low altitude mapping orbit at about 240 miles (385 kilometers) above the surface. The center coordinates of this image are 38 degrees south latitude, 165 degrees east longitude. https://photojournal.jpl.nasa.gov/catalog/PIA21754</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19810041820&hterms=evolution+rock&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Devolution%2Brock','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19810041820&hterms=evolution+rock&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Devolution%2Brock"><span>Infrared and radar signatures of lunar <span class="hlt">craters</span> - Implications about <span class="hlt">crater</span> evolution</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Thompson, T. W.; Cutts, J. A.; Shorthill, R. W.; Zisk, S. H.</p> <p>1980-01-01</p> <p>Geological models accounting for the strongly <span class="hlt">crater</span> size-dependent IR and radar signatures of lunar <span class="hlt">crater</span> floors are examined. The simplest model involves the formation and subsequent 'gardening' of an impact melt layer on the <span class="hlt">crater</span> floor, but while adequate in accounting for the gradual fading of IR temperatures and echo strengths in <span class="hlt">craters</span> larger than 30 km in diameter, it is inadequate for smaller ones. It is concluded that quantitative models of the evolution of rock populations in regoliths and of the interaction of microwaves with regoliths are needed in order to understand <span class="hlt">crater</span> evolutionary processes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://images.nasa.gov/#/details-PIA04930.html','SCIGOVIMAGE-NASA'); return false;" href="https://images.nasa.gov/#/details-PIA04930.html"><span>Clouds Near Mie <span class="hlt">Crater</span></span></a></p> <p><a target="_blank" href="https://images.nasa.gov/">NASA Image and Video Library</a></p> <p></p> <p>2003-12-13</p> <p>Mie <span class="hlt">Crater</span>, a large basin formed by asteroid or comet impact in Utopia Planitia, lies at the center of this Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) red wide angle image. The <span class="hlt">crater</span> is approximately 104 km (65 mi) across. To the east and southeast (toward the lower right) of Mie, in this 5 December 2003 view, are clouds of dust and water ice kicked up by local dust storm activity. It is mid-winter in the northern hemisphere of Mars, a time when passing storms are common on the northern plains of the red planet. Sunlight illuminates this image from the lower left; Mie <span class="hlt">Crater</span> is located at 48.5°N, 220.3°W. Viking <span class="hlt">2</span> landed west/southwest of Mie <span class="hlt">Crater</span>, off the left edge of this image, in September 1976. http://photojournal.jpl.nasa.gov/catalog/PIA04930</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=PIA04516&hterms=polygons&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dpolygons','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=PIA04516&hterms=polygons&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dpolygons"><span>Polygons on <span class="hlt">Crater</span> Floor</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>2003-01-01</p> <p>MGS MOC Release No. MOC<span class="hlt">2</span>-357, 11 May 2003<p/>This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) picture shows a pattern of polygons on the floor of a northern plains impact <span class="hlt">crater</span>. These landforms are common on <span class="hlt">crater</span> floors at high latitudes on Mars. Similar polygons occur in the arctic and antarctic regions of Earth, where they indicate the presence and freeze-thaw cycling of ground ice. Whether the polygons on Mars also indicate water ice in the ground is uncertain. The image is located in a <span class="hlt">crater</span> at 64.8oN, 292.7oW. Sunlight illuminates the scene from the lower left.<p/></p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017ISPAr62W1...23B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017ISPAr62W1...23B"><span>Small <span class="hlt">Craters</span> and Their Diagnostic Potential</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bugiolacchi, R.</p> <p>2017-07-01</p> <p>I analysed and compared the size-frequency distributions of <span class="hlt">craters</span> in the Apollo 17 landing region, comprising of six mare terrains with varying morphologies and <span class="hlt">cratering</span> characteristics, along with three other regions allegedly affected by the same secondary event (Tycho secondary surge). I propose that for the smaller <span class="hlt">crater</span> sizes (in this work 9-30 m), a] an exponential curve of power -0.18D can approximate Nkm-<span class="hlt">2</span> <span class="hlt">crater</span> densities in a regime of equilibrium, while b] a power function D-3 closely describes the factorised representation of <span class="hlt">craters</span> by size (1 m). The saturation level within the Central Area suggests that c] either the modelled rates of <span class="hlt">crater</span> erosion on the Moon should be revised, or that the Tycho event occurred much earlier in time than the current estimate. We propose that d] the size-frequency distribution of small secondary <span class="hlt">craters</span> may bear the signature (in terms of size-frequency distribution of debris/surge) of the source impact and that this observation should be tested further.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li class="active"><span>9</span></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_9 --> <div id="page_10" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li class="active"><span>10</span></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="181"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://cfpub.epa.gov/si/si_public_record_report.cfm?direntryid=336758','PESTICIDES'); return false;" href="https://cfpub.epa.gov/si/si_public_record_report.cfm?direntryid=336758"><span>Impacts of 25 years of groundwater extraction on <span class="hlt">subsidence</span> ...</span></a></p> <p><a target="_blank" href="http://www.epa.gov/pesticides/search.htm">EPA Pesticide Factsheets</a></p> <p></p> <p></p> <p>Many major river deltas in the world are <span class="hlt">subsiding</span> and consequently become increasingly vulnerable to flooding and storm surges, salinization and permanent inundation. For the Mekong Delta, annual <span class="hlt">subsidence</span> rates up to several centimetres have been reported. Excessive groundwater extraction is suggested as the main driver. As groundwater levels drop, <span class="hlt">subsidence</span> is induced through aquifer compaction. Over the past 25 years, groundwater exploitation has increased dramatically, transforming the delta from an almost undisturbed hydrogeological state to a situation with increasing aquifer depletion. Yet the exact contribution of groundwater exploitation to <span class="hlt">subsidence</span> in the Mekong delta has remained unknown. In this study we deployed a delta-wide modelling approach, comprising a 3D hydrogeological model with an integrated <span class="hlt">subsidence</span> module. This provides a quantitative spatially-explicit assessment of groundwater extraction-induced <span class="hlt">subsidence</span> for the entire Mekong delta since the start of widespread overexploitation of the groundwater reserves. We find that <span class="hlt">subsidence</span> related to groundwater extraction has gradually increased in the past decades with highest sinking rates at present. During the past 25 years, the delta sank on average ~18 cm as a consequence of groundwater withdrawal. Current average <span class="hlt">subsidence</span> rates due to groundwater extraction in our best estimate model amount to 1.1 cm yr−1, with areas <span class="hlt">subsiding</span> over <span class="hlt">2</span>.5 cm yr−1, outpacing global sea level ri</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=PIA09369&hterms=block+chain&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dblock%2Bchain','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=PIA09369&hterms=block+chain&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dblock%2Bchain"><span>Rayed Gratteri <span class="hlt">Crater</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>2006-01-01</p> <p><p/> [figure removed for brevity, see original site] Click on image for larger version <p/> This HiRISE image covers the western portion of the primary cavity of Gratteri <span class="hlt">crater</span> situated in the Memnonia Fossae region. Gratteri <span class="hlt">crater</span> is one of five definitive large rayed <span class="hlt">craters</span> on Mars. Gratteri <span class="hlt">crater</span> has a diameter of approximately 6.9 kilometers. <span class="hlt">Crater</span> rays are long, linear features formed from the high-velocity ejection of blocks of material that re-impact the surface in linear clusters or chains that appear to emanate from the main or primary cavity. Such <span class="hlt">craters</span> have been long recognized as the 'brightest' and 'freshest' <span class="hlt">craters</span> on the Moon. However, Martian rays differ from lunar rays in that they are not 'bright,' but best recognized by their thermal signature (at night) in 100 meter/pixel THEMIS thermal infrared images. The HiRISE image shows that Gratteri <span class="hlt">crater</span> has well-developed and sharp <span class="hlt">crater</span> morphologic features with no discernable superimposed impact <span class="hlt">craters</span>. The HiRISE sub-image shows that this is true for the ejecta and <span class="hlt">crater</span> floor up to the full resolution of the image. Massive slumped blocks of materials on the <span class="hlt">crater</span> floor and the 'spur and gully' morphology with the <span class="hlt">crater</span> wall may suggest that the subsurface in this area may be thick and homogenous. Gratteri <span class="hlt">crater</span>'s ejecta blanket (as seen in THEMIS images) can be described as 'fluidized,' which may be suggestive of the presence of ground-ice that may have helped to 'liquefy' the ejecta as it was deposited near the <span class="hlt">crater</span>. Gratteri's ejecta can be observed to have flowed in and around obstacles including an older, degraded <span class="hlt">crater</span> lying immediately to the SW of Gratteri's primary cavity. <p/> Image PSP_001367_1620 was taken by the High Resolution Imaging Science Experiment (HiRISE) camera onboard the Mars Reconnaissance Orbiter spacecraft on November 10, 2006. The complete image is centered at -17.7 degrees latitude, 199.9 degrees East longitude. The range to the target site was 257.1 km</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19750027106&hterms=future+implications&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dfuture%2Bimplications','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19750027106&hterms=future+implications&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dfuture%2Bimplications"><span><span class="hlt">Cratering</span> on Mars. I - <span class="hlt">Cratering</span> and obliteration history. II Implications for future <span class="hlt">cratering</span> studies from Mariner 4 reanalysis</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Chapman, C. R.</p> <p>1974-01-01</p> <p>It is pointed out that Mars is especially well adapted to statistical studies of <span class="hlt">crater</span> morphologies for deciphering its geological history. A framework for understanding planetary geomorphological histories from the diameter-frequency relations of different morphological classes of <span class="hlt">craters</span> described by Chapmam et al. (1970) is extended in order to understand Martian <span class="hlt">cratering</span>, erosional, and depositional history. The <span class="hlt">cratering</span>-obliteration history derived is compared with global interpretations considered by Hartman (1973) and Soderblom et al. (1974). An idealized dust-filling model is employed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2005Geomo..71..389D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2005Geomo..71..389D"><span>Land <span class="hlt">subsidence</span> and caprock dolines caused by subsurface gypsum dissolution and the effect of <span class="hlt">subsidence</span> on the fluvial system in the Upper Tigris Basin (between Bismil Batman, Turkey)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Doğan, Uğur</p> <p>2005-11-01</p> <p>Karstification-based land <span class="hlt">subsidence</span> was found in the Upper Tigris Basin with dimensions not seen anywhere else in Turkey. The area of land <span class="hlt">subsidence</span>, where there are secondary and tertiary <span class="hlt">subsidence</span> developments, reaches 140 km <span class="hlt">2</span>. <span class="hlt">Subsidence</span> depth ranges between 40 and 70 m. The <span class="hlt">subsidence</span> was formed as a result of subsurface gypsum dissolution in Lower Miocene formation. Although there are limestones together with gypsum and Eocene limestone below them in the area, a <span class="hlt">subsidence</span> with such a large area is indicative of karstification in the gypsum. The stratigraphical cross-sections taken from the wells and the water analyses also verify this fact. The Lower Miocene gypsum, which shows confined aquifer features, was completely dissolved by the aggressive waters injected from the top and discharged through by Zellek Fault. This resulted in the development of <span class="hlt">subsidence</span> and formation of caprock dolines on loosely textured Upper Miocene-Pliocene cover formations. The Tigris River runs through the <span class="hlt">subsidence</span> area between Batman and Bismil. There are four terrace levels as T1 (40 m), T<span class="hlt">2</span> (30 m), T3 (10 m) and T4 (4-5 m) in the Tigris River valley. It was also found that there were some movements of the levels of the terraces in the valley by <span class="hlt">subsidence</span>. The <span class="hlt">subsidence</span> developed gradually throughout the Quaternary; however no terrace was formed purely because of <span class="hlt">subsidence</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018JGRE..123..113S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018JGRE..123..113S"><span><span class="hlt">Crater</span> Mound Formation by Wind Erosion on Mars</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Steele, L. J.; Kite, E. S.; Michaels, T. I.</p> <p>2018-01-01</p> <p>Most of Mars' ancient sedimentary rocks by volume are in wind-eroded sedimentary mounds within impact <span class="hlt">craters</span> and canyons, but the connections between mound form and wind erosion are unclear. We perform mesoscale simulations of different <span class="hlt">crater</span> and mound morphologies to understand the formation of sedimentary mounds. As <span class="hlt">crater</span> depth increases, slope winds produce increased erosion near the base of the <span class="hlt">crater</span> wall, forming mounds. Peak erosion rates occur when the <span class="hlt">crater</span> depth is ˜<span class="hlt">2</span> km. Mound evolution depends on the size of the host <span class="hlt">crater</span>. In smaller <span class="hlt">craters</span> mounds preferentially erode at the top, becoming more squat, while in larger <span class="hlt">craters</span> mounds become steeper sided. This agrees with observations where smaller <span class="hlt">craters</span> tend to have proportionally shorter mounds and larger <span class="hlt">craters</span> have mounds encircled by moats. If a large-scale sedimentary layer blankets a <span class="hlt">crater</span>, then as the layer recedes across the <span class="hlt">crater</span> it will erode more toward the edges of the <span class="hlt">crater</span>, resulting in a crescent-shaped moat. When a 160 km diameter mound-hosting <span class="hlt">crater</span> is subject to a prevailing wind, the surface wind stress is stronger on the leeward side than on the windward side. This results in the center of the mound appearing to "march upwind" over time and forming a "bat-wing" shape, as is observed for Mount Sharp in Gale <span class="hlt">crater</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=PIA10006&hterms=duck+hazard&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dduck%2Bhazard','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=PIA10006&hterms=duck+hazard&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dduck%2Bhazard"><span>At Bright Band Inside Victoria <span class="hlt">Crater</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>2007-01-01</p> <p><p/> A layer of light-toned rock exposed inside Victoria <span class="hlt">Crater</span> in the Meridiani Planum region of Mars appears to mark where the surface was at the time, many millions of years ago, when an impact excavated the <span class="hlt">crater</span>. NASA's Mars Exploration Rover Opportunity drove to this bright band as the science team's first destination for the rover during investigations inside the <span class="hlt">crater</span>. <p/> Opportunity's left front hazard-identification camera took this image just after the rover finished a drive of <span class="hlt">2</span>.25 meters (7 feet, 5 inches) during the rover's 1,305th Martian day, or sol, (Sept. 25, 2007). The rocks beneath the rover and its extended robotic arm are part of the bright band. <p/> Victoria <span class="hlt">Crater</span> has a scalloped shape of alternating alcoves and promontories around the <span class="hlt">crater</span>'s circumference. Opportunity descended into the <span class="hlt">crater</span> two weeks earlier, within an alcove called 'Duck Bay.' Counterclockwise around the rim, just to the right of the arm in this image, is a promontory called 'Cabo Frio.'</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=PIA03829&hterms=DIRT&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3DDIRT','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=PIA03829&hterms=DIRT&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3DDIRT"><span>Impact <span class="hlt">Crater</span> with Peak</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>2002-01-01</p> <p>(Released 14 June 2002) The Science This THEMIS visible image shows a classic example of a martian impact <span class="hlt">crater</span> with a central peak. Central peaks are common in large, fresh <span class="hlt">craters</span> on both Mars and the Moon. This peak formed during the extremely high-energy impact <span class="hlt">cratering</span> event. In many martian <span class="hlt">craters</span> the central peak has been either eroded or buried by later sedimentary processes, so the presence of a peak in this <span class="hlt">crater</span> indicates that the <span class="hlt">crater</span> is relatively young and has experienced little degradation. Observations of large <span class="hlt">craters</span> on the Earth and the Moon, as well as computer modeling of the impact process, show that the central peak contains material brought from deep beneath the surface. The material exposed in these peaks will provide an excellent opportunity to study the composition of the martian interior using THEMIS multi-spectral infrared observations. The ejecta material around the <span class="hlt">crater</span> can is well preserved, again indicating relatively little modification of this landform since its initial creation. The inner walls of this approximately 18 km diameter <span class="hlt">crater</span> show complex slumping that likely occurred during the impact event. Since that time there has been some downslope movement of material to form the small chutes and gullies that can be seen on the inner <span class="hlt">crater</span> wall. Small (50-100 m) mega-ripples composed of mobile material can be seen on the floor of the <span class="hlt">crater</span>. Much of this material may have come from the walls of the <span class="hlt">crater</span> itself, or may have been blown into the <span class="hlt">crater</span> by the wind. The Story When a meteor smacked into the surface of Mars with extremely high energy, pow! Not only did it punch an 11-mile-wide <span class="hlt">crater</span> in the smoother terrain, it created a central peak in the middle of the <span class="hlt">crater</span>. This peak forms kind of on the 'rebound.' You can see this same effect if you drop a single drop of milk into a glass of milk. With <span class="hlt">craters</span>, in the heat and fury of the impact, some of the land material can even liquefy. Central peaks like the one</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25510329','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25510329"><span>Radical anionic versus neutral <span class="hlt">2,2</span>'-bipyridyl coordination in uranium complexes supported by amide and ketimide ligands.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Diaconescu, Paula L; Cummins, Christopher C</p> <p>2015-02-14</p> <p>The synthesis and characterization of (bipy)(<span class="hlt">2</span>)<span class="hlt">U(N[t-Bu</span>]Ar)(<span class="hlt">2</span>) (1-(bipy)(<span class="hlt">2</span>), bipy = <span class="hlt">2,2</span>'-bipyridyl, Ar = 3,5-C(6)H(3)Me(<span class="hlt">2</span>)), (bipy)<span class="hlt">U</span>(N[(1)Ad]Ar)(3) (<span class="hlt">2</span>-bipy), (bipy)(<span class="hlt">2</span>)<span class="hlt">U(NC[t-Bu</span>]Mes)(3) (3-(bipy)(<span class="hlt">2</span>), Mes = <span class="hlt">2</span>,4,6-C(6)H(<span class="hlt">2</span>)Me(3)), and IU(bipy)(NC[t-<span class="hlt">Bu</span>]Mes)(3) (3-I-bipy) are reported. X-ray crystallography studies indicate that bipy coordinates as a radical anion in 1-(bipy)(<span class="hlt">2</span>) and <span class="hlt">2</span>-bipy, and as a neutral ligand in 3-I-bipy. In 3-(bipy)(<span class="hlt">2</span>), one of the bipy ligands is best viewed as a radical anion, the other as a neutral ligand. The electronic structure assignments are supported by NMR spectroscopy studies of exchange experiments with 4,4'-dimethyl-<span class="hlt">2,2</span>'-bipyridyl and also by optical spectroscopy. In all complexes, uranium was assigned a +4 formal oxidation state.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFM.P43A2871F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFM.P43A2871F"><span>Investigations of Ceres's <span class="hlt">Craters</span> with Straightened Rim</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Frigeri, A.; De Sanctis, M. C.; Ammannito, E.; Raponi, A.; Formisano, M.; Ciarniello, M.; Magni, G.; Combe, J. P.; Marchi, S.; Raymond, C. A.; Schwartz, S. J.</p> <p>2017-12-01</p> <p>Dwarf planet Ceres hosts some geological features that are unique in the solar system because its composition, rich in aqueously-altered silicates, is usually found on full-size planets, whereas its mean radius is smaller than most natural satellites in the solar system. For example, the local high-albedo, carbonate-rich areas or faculaeare specific to Ceres; also, the absence of big impact <span class="hlt">crater</span> structures is key to understand the overall mechanical behaviour of the Cerean crust. After the first findings of water ice occurring in the shadowed areas of <span class="hlt">craters</span> on Ceres by the NASA/Dawn mission (1, <span class="hlt">2</span>), we analyzed the morphology of <span class="hlt">craters</span> looking for features similar to the ones where the water ice composition has been detected analyzing the data from the VIR spectrometer (3). These <span class="hlt">craters</span> fall outside of the family of polygonal <span class="hlt">craters</span> which are mainly related to regional or global scale tectonics (4). We analyzed the morphology on the base of the global mosaic, the digital terrain model derived by using the stereo photogrammetry method and the single data frames of the Framing Camera. Our investigation started from <span class="hlt">crater</span> Juling, which is characterized by a portion of the rim which forms a straight segment instead of a portion of a circle. This linear <span class="hlt">crater</span> wall is also steep enough that it forms a cliff that is in the shadowed area in all images acquired by Dawn. Very smooth and bright deposits lay at the foot of this <span class="hlt">crater</span>-wall cliff. Then, we identified several other <span class="hlt">craters</span>, relatively fresh, with radius of <span class="hlt">2</span> to 10 kilometers, showing one or two sectors of the <span class="hlt">crater</span>-rim being truncated by a mass-wasting process, probably a rockfall. Our first analysis show that in the selected <span class="hlt">craters</span>, the truncated sectors are always in the north-eastern sector of the rim for the <span class="hlt">craters</span> in the southern hemisphere. Conversely, the <span class="hlt">craters</span> on the northern hemisphere exhibit a truncated rim in their south-eastern sector. Although a more detailed analysis is mandatory</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://images.nasa.gov/#/details-PIA21652.html','SCIGOVIMAGE-NASA'); return false;" href="https://images.nasa.gov/#/details-PIA21652.html"><span>A Triple <span class="hlt">Crater</span></span></a></p> <p><a target="_blank" href="https://images.nasa.gov/">NASA Image and Video Library</a></p> <p></p> <p>2017-06-01</p> <p>This image from NASA's Mars Reconnaissance Orbiter shows an elongated depression from three merged <span class="hlt">craters</span>. The raised rims and ejecta indicate that these are impact <span class="hlt">craters</span> rather than collapse or volcanic landforms. The pattern made by the ejecta and the <span class="hlt">craters</span> suggest this was a highly oblique (low angle to the surface) impact, probably coming from the west. There may have been three major pieces flying in close formation to make this triple <span class="hlt">crater</span>. https://photojournal.jpl.nasa.gov/catalog/PIA21652</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3995079','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3995079"><span><span class="hlt">Bu</span>GZ is required for Bub3 stability, Bub1 kinetochore function, and chromosome alignment</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Toledo, Chad M.; Herman, Jacob A.; Olsen, Jonathan B.; Ding, Yu; Corrin, Philip; Girard, Emily J.; Olson, James M.; Emili, Andrew; DeLuca, Jennifer G.; Paddison, Patrick J.</p> <p>2014-01-01</p> <p>Summary During mitosis, the spindle assembly checkpoint (SAC) monitors the attachment of kinetochores (KTs) to the plus ends of spindle microtubules (MTs) and prevents anaphase onset until chromosomes are aligned and KTs are under proper tension. Here, we identify a SAC component, <span class="hlt">Bu</span>GZ/ZNF207, from an RNAi viability screen in human Glioblastoma multiforme (GBM) brain tumor stem cells. <span class="hlt">Bu</span>GZ binds to and stabilizes Bub3 during interphase and mitosis through a highly conserved GLE<span class="hlt">2</span>p-binding sequence (GLEBS) domain. Inhibition of <span class="hlt">Bu</span>GZ results in loss of both Bub3 and its binding partner Bub1 from KTs, reduction of Bub1-dependent phosphorylation of centromeric histone H<span class="hlt">2</span>A, attenuation of KT-based Aurora kinase B activity, and lethal chromosome congression defects in cancer cells. Phylogenetic analysis indicates that <span class="hlt">Bu</span>GZ orthologs are highly conserved among eukaryotes, but are conspicuously absent from budding and fission yeasts. These findings suggest <span class="hlt">Bu</span>GZ has evolved to facilitate Bub3 activity and chromosome congression in higher eukaryotes. PMID:24462187</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://images.nasa.gov/#/details-PIA03912.html','SCIGOVIMAGE-NASA'); return false;" href="https://images.nasa.gov/#/details-PIA03912.html"><span>Frosted <span class="hlt">Crater</span></span></a></p> <p><a target="_blank" href="https://images.nasa.gov/">NASA Image and Video Library</a></p> <p></p> <p>2002-08-05</p> <p>This image from NASA Mars Odyssey spacecraft displays a frosted <span class="hlt">crater</span> in the Martian northern hemisphere. It was taken during the northern spring, when the CO<span class="hlt">2</span> ice cap starts to sublimate and recede.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://images.nasa.gov/#/details-PIA21402.html','SCIGOVIMAGE-NASA'); return false;" href="https://images.nasa.gov/#/details-PIA21402.html"><span>Inamahari <span class="hlt">Crater</span></span></a></p> <p><a target="_blank" href="https://images.nasa.gov/">NASA Image and Video Library</a></p> <p></p> <p>2017-04-13</p> <p>Inamahari <span class="hlt">Crater</span> on Ceres, the large well-defined <span class="hlt">crater</span> at the center of this image, is one of the sites where scientists have discovered evidence for organic material. The <span class="hlt">crater</span>, 42 miles (68 kilometers) in diameter, presents other interesting attributes. It has a polygonal shape and an association with another <span class="hlt">crater</span> of similar size and geometry called Homshuk (center right), although the latter appears eroded and is likely older. Future studies of Inamahari <span class="hlt">crater</span> and surroundings may help uncover the mechanisms involved in the exposure of organic material onto Ceres' surface. Inamahari was named for a pair of male and female deities from the ancient Siouan tribe of South Carolina, invoked for a successful sowing season. Homshuk refers to the spirit of corn (maize) from the Popoluca peoples of southern Mexico. Inamahari is located at 14 degrees north latitude, 89 degrees east longitude. This picture was taken by NASA's Dawn on September 25, 2015 from an altitude of about 915 miles (1,470 kilometers). It has a resolution of 450 feet (140 meters) per pixel. https://photojournal.jpl.nasa.gov/catalog/PIA21402</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://images.nasa.gov/#/details-GSFC_20171208_Archive_e001873.html','SCIGOVIMAGE-NASA'); return false;" href="https://images.nasa.gov/#/details-GSFC_20171208_Archive_e001873.html"><span>Tycho <span class="hlt">Crater</span>'s Peak</span></a></p> <p><a target="_blank" href="https://images.nasa.gov/">NASA Image and Video Library</a></p> <p></p> <p>2011-06-29</p> <p>NASA image release June 30, 2011 On June 10, 2011, NASA's Lunar Reconnaissance Orbiter captured a dramatic sunrise view of Tycho <span class="hlt">crater</span>. A very popular target with amateur astronomers, Tycho is located at 43.37°S, 348.68°E, and is about 51 miles (82 km) in diameter. The summit of the central peak is 1.24 miles (<span class="hlt">2</span> km) above the <span class="hlt">crater</span> floor. The distance from Tycho's floor to its rim is about <span class="hlt">2</span>.92 miles (4.7 km). Tycho <span class="hlt">crater</span>'s central peak complex, shown here, is about 9.3 miles (15 km) wide, left to right (southeast to northwest in this view). › More information and related images › NASA's LRO website Credit: NASA Goddard/Arizona State University NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Like us on Facebook Find us on Instagram</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2888259','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2888259"><span>Characterization of the Terminal Iron(IV) Imides {[PhBPt<span class="hlt">Bu</span><span class="hlt">2</span>(pz’)]FeIV≡NAd}+</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Thomas, Christine M.; Mankad, Neal P.; Peters, Jonas C.</p> <p>2008-01-01</p> <p>New hybrid bis(phosphine)(pyrazole)borate tripodal ligands ([PhBPt<span class="hlt">Bu</span><span class="hlt">2</span>(pz’)]−) are reported that support pseudotetrahedral iron in the oxidation states +1, +<span class="hlt">2</span>, +3, and +4. The higher oxidation states are stabilized by a terminal Fe≡NR linkage. Of particular interest is the generation and thorough characterization of an S = 1 FeIV≡NR+ imide cation using this new ligand system. The latter species can be observed electrochemically and spectroscopically, and its solid-state crystal structure is reported. PMID:16608321</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://eric.ed.gov/?q=organic+AND+electronics&id=EJ1062153','ERIC'); return false;" href="https://eric.ed.gov/?q=organic+AND+electronics&id=EJ1062153"><span>NMR Kinetics of the S[subscript N]<span class="hlt">2</span> Reaction between <span class="hlt">Bu</span>Br and I[superscript -]: An Introductory Organic Chemistry Laboratory Exercise</span></a></p> <p><a target="_blank" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p>Mobley, T. Andrew</p> <p>2015-01-01</p> <p>A simple organic chemistry experiment is described that investigates the kinetics of the reaction between 1-bromobutane (<span class="hlt">Bu</span>Br) and iodide (I[superscript -]) as followed by observing the disappearance of <span class="hlt">Bu</span>Br and the appearance of 1-iodobutane (<span class="hlt">Bu</span>I) using [superscript 1]H NMR spectroscopy. In small groups of three to four, students acquire data to…</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70016809','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70016809"><span><span class="hlt">Subsidence</span> of Surtsey volcano, 1967-1991</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Moore, J.G.; Jakobsson, S.; Holmjarn, J.</p> <p>1992-01-01</p> <p>The Surtsey marine volcano was built on the southern insular shelf of Iceland, along the seaward extension of the east volcanic zone, during episodic explosive and effusive activity from 1963 to 1967. A 1600-m-long, east-west line of 42 bench marks was established across the island shortly after volcanic activity stopped. From 1967 to 1991 a series of leveling surveys measured the relative elevation of the original bench marks, as well as additional bench marks installed in 1979, 1982 and 1985. Concurrent measurements were made of water levels in a pit dug on the north coast, in a drill hole, and along the coastline exposed to the open ocean. These surveys indicate that the dominant vertical movement of Surtsey is a general <span class="hlt">subsidence</span> of about 1.1??0.3 m during the 24-year period of observations. The rate of <span class="hlt">subsidence</span> decreased from 15-20 cm/year for 1967-1968 to 1-<span class="hlt">2</span> cm/year in 1991. Greatest <span class="hlt">subsidence</span> is centered about the eastern vent area. Through 1970, <span class="hlt">subsidence</span> was locally greatest where the lava plain is thinnest, adjacent to the flanks of the eastern tephra cone. From 1982 onward, the region closest to the hydrothermal zone, which is best developed in the vicinity of the eastern vent, began showing less <span class="hlt">subsidence</span> relative to the rest of the surveyed bench marks. The general <span class="hlt">subsidence</span> of the island probably results from compaction of the volcanic material comprising Surtsey, compaction of the sea-floor sediments underlying the island, and possibly downwarping of the lithosphere due to the laod of Surtsey. The more localized early downwarping near the eastern tephra cone is apparently due to greater compaction of tephra relative to lava. The later diminished local <span class="hlt">subsidence</span> near the hydrothermal zone is probably due to a minor volume increase caused by hydrous alteration of glassy tephra. However, this volume increase is concentrated at depth beneath the bottom of the 176-m-deep cased drillhole. ?? 1992 Springer-Verlag.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017RAA....17...24J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017RAA....17...24J"><span>Physical properties of lunar <span class="hlt">craters</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Joshi, Maitri P.; Bhatt, Kushal P.; Jain, Rajmal</p> <p>2017-02-01</p> <p>The surface of the Moon is highly <span class="hlt">cratered</span> due to impacts of meteorites, asteroids, comets and other celestial objects. The origin, size, structure, age and composition vary among <span class="hlt">craters</span>. We study a total of 339 <span class="hlt">craters</span> observed by the Lunar Reconnaissance Orbiter Camera (LROC). Out of these 339 <span class="hlt">craters</span>, 214 <span class="hlt">craters</span> are known (named <span class="hlt">craters</span> included in the IAU Gazetteer of Planetary Nomenclature) and 125 <span class="hlt">craters</span> are unknown (<span class="hlt">craters</span> that are not named and objects that are absent in the IAU Gazetteer). We employ images taken by LROC at the North and South Poles and near side of the Moon. We report for the first time the study of unknown <span class="hlt">craters</span>, while we also review the study of known <span class="hlt">craters</span> conducted earlier by previous researchers. Our study is focused on measurements of diameter, depth, latitude and longitude of each <span class="hlt">crater</span> for both known and unknown <span class="hlt">craters</span>. The diameter measurements are based on considering the Moon to be a spherical body. The LROC website also provides a plot which enables us to measure the depth and diameter. We found that out of 214 known <span class="hlt">craters</span>, 161 <span class="hlt">craters</span> follow a linear relationship between depth (d) and diameter (D), but 53 <span class="hlt">craters</span> do not follow this linear relationship. We study physical dimensions of these 53 <span class="hlt">craters</span> and found that either the depth does not change significantly with diameter or the depths are extremely high relative to diameter (conical). Similarly, out of 125 unknown <span class="hlt">craters</span>, 78 <span class="hlt">craters</span> follow the linear relationship between depth (d) and diameter (D) but 47 <span class="hlt">craters</span> do not follow the linear relationship. We propose that the <span class="hlt">craters</span> following the scaling law of depth and diameter, also popularly known as the linear relationship between d and D, are formed by the impact of meteorites having heavy metals with larger dimension, while those with larger diameter but less depth are formed by meteorites/celestial objects having low density material but larger diameter. The <span class="hlt">craters</span> with very high depth and with very small</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19720012222','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19720012222"><span>Simultaneous impact and lunar <span class="hlt">craters</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Oberbeck, V. R.</p> <p>1972-01-01</p> <p>The existence of large terrestrial impact <span class="hlt">crater</span> doublets and <span class="hlt">crater</span> doublets that have been inferred to be impact <span class="hlt">craters</span> on Mars suggests that simultaneous impact of two or more bodies can occur at nearly the same point on planetary surfaces. An experimental study of simultaneous impact of two projectiles near one another shows that doublet <span class="hlt">craters</span> with ridges perpendicular to the bilateral axis of symmetry result when separation between impact points relative to individual <span class="hlt">crater</span> diameter is large. When separation is progressively less, elliptical <span class="hlt">craters</span> with central ridges and peaks, and circular <span class="hlt">craters</span> with deep round bottoms are produced. These <span class="hlt">craters</span> are similar in structure to many of the large lunar <span class="hlt">craters</span>. Results suggest that the simultaneous impact of meteoroids near one another may be an important mechanism for the production of central peaks in large lunar <span class="hlt">craters</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013E%26PSL.383...37S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013E%26PSL.383...37S"><span>Paleo-elevation and <span class="hlt">subsidence</span> of ˜145Ma Shatsky Rise inferred from CO<span class="hlt">2</span> and H<span class="hlt">2</span>O in fresh volcanic glass</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Shimizu, Kenji; Shimizu, Nobumichi; Sano, Takashi; Matsubara, Noritaka; Sager, William</p> <p>2013-12-01</p> <p>Shatsky Rise, a large Mesozoic oceanic plateau in the northwest Pacific, consists of three massifs (Tamu, Ori, and Shirshov) that formed near a mid-ocean-ridge triple junction. Published depth estimates imply that Shatsky Rise has not <span class="hlt">subsided</span> normally, like typical oceanic lithosphere. We estimated paleo-eruption depths of Shatsky Rise massifs on the basis of dissolved CO<span class="hlt">2</span> and H<span class="hlt">2</span>O in volcanic glass and descriptions of cores recovered from five sites of Integrated Ocean Drilling Program Expedition 324. Initial maximum elevations of Shatsky Rise are estimated to be 2500-3500 m above the surrounding seafloor and the ensuing <span class="hlt">subsidence</span> of Shatsky Rise is estimated to be 2600-3400 m. We did not observe the anomalously low <span class="hlt">subsidence</span> that has been reported for both Shatsky Rise and the Ontong Java Plateau. Although we could not resolve whether Shatsky Rise originated from a hot mantle plume or non-plume fusible mantle, uplift and <span class="hlt">subsidence</span> histories of Shatsky Rise for the both cases are constrained based on the <span class="hlt">subsidence</span> trend from the center of Tamu Massif (˜2600 m) toward the flank of Ori Massif (˜3400 m). In the case of a hot mantle plume origin, Shatsky Rise may have formed on young (˜5 Ma) pre-existing oceanic crust with a total crustal thickness of ˜20 km. For this scenario, the center of Shatsky Rise is subsequently uplifted by later (prolonged) crustal growth, forming the observed ˜30 km thickness crust. For a non-plume origin, Shatsky Rise may have formed at the spreading ridge center as initially thick crust (˜30 km thickness), with later reduced <span class="hlt">subsidence</span> caused by the emplacement of a buoyant mass-perhaps a refractory mantle residuum-beneath the center of Shatsky Rise.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li class="active"><span>10</span></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_10 --> <div id="page_11" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li class="active"><span>11</span></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="201"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFM.P33B4033B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFM.P33B4033B"><span>Modeling Low Velocity Impacts: Predicting <span class="hlt">Crater</span> Depth on Pluto</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bray, V. J.; Schenk, P.</p> <p>2014-12-01</p> <p>The New Horizons mission is due to fly-by the Pluto system in Summer 2015 and provides the first opportunity to image the Pluto surface in detail, allowing both the appearance and number of its <span class="hlt">crater</span> population to be studied for the first time. Bray and Schenk (2014) combined previous <span class="hlt">cratering</span> studies and numerical modeling of the impact process to predict <span class="hlt">crater</span> morphology on Pluto based on current understanding of Pluto's composition, structure and surrounding impactor population. Predictions of how the low mean impact velocity (~<span class="hlt">2</span>km/s) of the Pluto system will influence <span class="hlt">crater</span> formation is a complex issue. Observations of secondary <span class="hlt">cratering</span> (low velocity, high angle) and laboratory experiments of impact at low velocity are at odds regarding how velocity controls depth-diameter ratios: Observations of secondary <span class="hlt">craters</span> show that these low velocity <span class="hlt">craters</span> are shallower than would be expected for a hyper-velocity primary. Conversely, gas gun work has shown that relative <span class="hlt">crater</span> depth increases as impact velocity decreases. We have investigated the influence of impact velocity further with iSALE hydrocode modeling of comet impact into Pluto. With increasing impact velocity, a projectile will produce wider and deeper <span class="hlt">craters</span>. The depth-diameter ratio (d/D) however has a more complex progression with increasing impact velocity: impacts faster than <span class="hlt">2</span>km/s lead to smaller d/D ratios as impact velocity increases, in agreement with gas-gun studies. However, decreasing impact velocity from <span class="hlt">2</span>km/s to 300 m/s produced smaller d/D as impact velocity was decreased. This suggests that on Pluto the deepest <span class="hlt">craters</span> would be produced by ~ <span class="hlt">2</span>km/s impacts, with shallower <span class="hlt">craters</span> produced by velocities either side of this critical point. Further simulations to investigate whether this effect is connected to the sound speed of the target material are ongoing. The complex relationship between impact velocity and <span class="hlt">crater</span> depth for impacts occurring between 300m/s and 10 km/s suggests</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://images.nasa.gov/#/details-PIA15382.html','SCIGOVIMAGE-NASA'); return false;" href="https://images.nasa.gov/#/details-PIA15382.html"><span>Successive Formation of Impact <span class="hlt">Craters</span></span></a></p> <p><a target="_blank" href="https://images.nasa.gov/">NASA Image and Video Library</a></p> <p></p> <p>2012-02-16</p> <p>This image from NASA Dawn spacecraft shows two overlapping impact <span class="hlt">craters</span> on asteroid Vesta. The rims of the <span class="hlt">craters</span> are both reasonably fresh but the larger <span class="hlt">crater</span> must be older because the smaller <span class="hlt">crater</span> cuts across the larger <span class="hlt">crater</span> rim.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/6141924-sinkhole-type-subsidence-over-abandoned-coal-mines-st-david-illinois-mine-subsidence-report-st-david-illinois-field-survey-analysis-mine-subsidence-abandoned-coal-mines-st-david-illinois','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/6141924-sinkhole-type-subsidence-over-abandoned-coal-mines-st-david-illinois-mine-subsidence-report-st-david-illinois-field-survey-analysis-mine-subsidence-abandoned-coal-mines-st-david-illinois"><span>Sinkhole-type <span class="hlt">subsidence</span> over abandoned coal mines in St. David, Illinois. Mine <span class="hlt">subsidence</span> report, St. David, Illinois. A field survey and analysis of mine <span class="hlt">subsidence</span> of abandoned coal mines in St. David, Illinois</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Wildanger, E.G.; Mahar, J.; Nieto, A.</p> <p>1980-01-01</p> <p>This study examined the geologic data, mining history, and <span class="hlt">subsidence</span> trends of the St. David region. Mine <span class="hlt">subsidence</span> has occurred due to collapse of the abandoned mine workings. The known <span class="hlt">subsidence</span> areas have been mapped and described. Results of the study include: (1) St. David has been undermined by both large shipping mines and smaller local mines; (<span class="hlt">2</span>) sinkholes will continue to develop in this area in response to rock failure and roof collapse above the abandoned mine workings; (3) some primary factors that contribute to the sinkhole problems are the undermining and roof rock composition; (4) sinkholes will bemore » smaller in the future; (5) ten of the 63 sinkholes occurred close enough to structures to cause damage, and only six sinkholes caused damage; (6) ways to minimize potential damage to future homes from sinkhole <span class="hlt">subsidence</span> are manageable; (7) threats to residents lie in the collapse of heavy walls, brick chimneys, breaks in gas, water, or electrical lines; and (8) location of future <span class="hlt">subsidence</span> is not predictable. (DP)« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27021613','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27021613"><span>Searching for the Source <span class="hlt">Crater</span> of Nakhlite Meteorites.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Kereszturi, A; Chatzitheodoridis, E</p> <p>2016-11-01</p> <p>We surveyed the Martian surface in order to identify possible source <span class="hlt">craters</span> of the nakhlite Martian meteorites. We investigated rayed <span class="hlt">craters</span> that are assumed to be younger than 11 Ma, on lava surfaces with a solidification age around 1.<span class="hlt">2</span> Ga. An area of 17.3 million km <span class="hlt">2</span> Amazonian lava plains was surveyed and 53 rayed <span class="hlt">craters</span> were identified. Although most of them are smaller than the threshold limit that is estimated as minimum of launching fragments to possible Earth crossing trajectories, their observed size frequency distribution agrees with the expected areal density from <span class="hlt">cratering</span> models characteristic for <span class="hlt">craters</span> that are less than few tens of Ma old. We identified 6 <span class="hlt">craters</span> larger than 3 km diameter constituting the potentially best source <span class="hlt">craters</span> for nakhlites. These larger candidates are located mostly on a smooth lava surface, and in some cases, on the earlier fluvial-like channels. In three cases they are associated with fluidized ejecta lobes and rays - although the rays are faint in these <span class="hlt">craters</span>, thus might be older than the other <span class="hlt">craters</span> with more obvious rays. More work is therefore required to accurately estimate ages based on ray system for this purpose. A more detailed search should further link remote sensing Martian data with the in-situ laboratory analyses of Martian meteorites, especially in case of high altitude, steep terrains, where the <span class="hlt">crater</span> rays seems to rarely survive several Ma.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.usgs.gov/sir/2007/5190/','USGSPUBS'); return false;" href="https://pubs.usgs.gov/sir/2007/5190/"><span>Land <span class="hlt">Subsidence</span> and Aquifer-System Compaction in the Tucson Active Management Area, South-Central Arizona, 1987-2005</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Carruth, Rob; Flynn, Pool; Donald, R.; Anderson, Carl E.</p> <p>2007-01-01</p> <p>The <span class="hlt">U</span>.S. Geological Survey monitors land <span class="hlt">subsidence</span> and aquifer-system compaction caused by ground-water depletion in Tucson Basin and Avra Valley - two of the three alluvial basins within the Tucson Active Management Area. In spring 1987, the Global Positioning System was used to measure horizontal and vertical positions for bench marks at 43 sites to establish a network for monitoring land <span class="hlt">subsidence</span> in Tucson Basin and Avra Valley. Between 1987 and 2005, the original number of <span class="hlt">subsidence</span> monitoring stations was gradually increased to more than 100 stations to meet the need for information in the growing metropolitan area. Data from approximately 60 stations common to the Global Positioning System surveys done after an initial survey in 1987 are used to document land <span class="hlt">subsidence</span>. For the periods of comparison, average land-surface deformation generally is less than the maximum <span class="hlt">subsidence</span> at an individual station and takes into account land-surface recovery from elastic aquifer-system compaction. Between 1987 and 1998, as much as 3.<span class="hlt">2</span> inches of <span class="hlt">subsidence</span> occurred in Tucson Basin and as much as 4 inches of <span class="hlt">subsidence</span> occurred in Avra Valley. For the 31 stations that are common to both the 1987 and 1998 Global Positioning System surveys, the average <span class="hlt">subsidence</span> during the 11-year period was about 0.5 inch in Tucson Basin and about 1.<span class="hlt">2</span> inches in Avra Valley. For the approximately 60 stations that are common to both the 1998 and 2002 Global Positioning System surveys, the data indicate that as much as 3.5 inches of <span class="hlt">subsidence</span> occurred in Tucson Basin and as much as 1.1 inches of <span class="hlt">subsidence</span> occurred in Avra Valley. The average <span class="hlt">subsidence</span> for the 4-year period is about 0.4 inch in Tucson Basin and 0.6 inch in Avra Valley. Between the 2002 and the 2005 Global Positioning System surveys, the data indicate that as much as 0.<span class="hlt">2</span> inch of <span class="hlt">subsidence</span> occurred in Tucson Basin and as much as <span class="hlt">2.2</span> inches of <span class="hlt">subsidence</span> occurred in Avra Valley. The average <span class="hlt">subsidence</span> for the 3-year</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://images.nasa.gov/#/details-PIA15591.html','SCIGOVIMAGE-NASA'); return false;" href="https://images.nasa.gov/#/details-PIA15591.html"><span>Canuleia <span class="hlt">Crater</span></span></a></p> <p><a target="_blank" href="https://images.nasa.gov/">NASA Image and Video Library</a></p> <p></p> <p>2012-04-24</p> <p>This image from NASA Dawn spacecraft of asteroid Vesta shows Canuleia <span class="hlt">crater</span>, a large, irregularly shaped <span class="hlt">crater</span>. Other interesting features of Canuleia include the diffuse bright material that is both inside and outside of its rim.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=PIA03961&hterms=Butterfly&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3DButterfly','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=PIA03961&hterms=Butterfly&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3DButterfly"><span>Small Impact <span class="hlt">Crater</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>2005-01-01</p> <p><p/> 22 June 2005 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a small impact <span class="hlt">crater</span> with a 'butterfly' ejecta pattern. The butterfly pattern results from an oblique impact. Not all oblique impacts result in an elliptical <span class="hlt">crater</span>, but they can result in a non-radial pattern of ejecta distribution. The two-toned nature of the ejecta -- with dark material near the <span class="hlt">crater</span> and brighter material further away -- might indicate the nature of subsurface materials. Below the surface, there may be a layer of lighter-toned material, underlain by a layer of darker material. The impact throws these materials out in a pattern that reflects the nature of the underlying layers. <p/> <i>Location near</i>: 3.7oN, 348.<span class="hlt">2</span>oW <i>Image width</i>: 3 km (1.9 mi) <i>Illumination from</i>: lower left <i>Season</i>: Northern Autumn</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20150005819&hterms=AGEs&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3DAGEs','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20150005819&hterms=AGEs&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3DAGEs"><span>Small Rayed <span class="hlt">Crater</span> Ejecta Retention Age Calculated from Current <span class="hlt">Crater</span> Production Rates on Mars</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Calef, F. J. III; Herrick, R. R.; Sharpton, V. L.</p> <p>2011-01-01</p> <p>Ejecta from impact <span class="hlt">craters</span>, while extant, records erosive and depositional processes on their surfaces. Estimating ejecta retention age (Eret), the time span when ejecta remains recognizable around a <span class="hlt">crater</span>, can be applied to estimate the timescale that surface processes operate on, thereby obtaining a history of geologic activity. However, the abundance of sub-kilometer diameter (D) <span class="hlt">craters</span> identifiable in high resolution Mars imagery has led to questions of accuracy in absolute <span class="hlt">crater</span> dating and hence ejecta retention ages (Eret). This research calculates the maximum Eret for small rayed impact <span class="hlt">craters</span> (SRC) on Mars using estimates of the Martian impactor flux adjusted for meteorite ablation losses in the atmosphere. In addition, we utilize the diameter-distance relationship of secondary <span class="hlt">cratering</span> to adjust <span class="hlt">crater</span> counts in the vicinity of the large primary <span class="hlt">crater</span> Zunil.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70032685','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70032685"><span>Update on <span class="hlt">subsidence</span> at the Wairakei-Tauhara geothermal system, New Zealand</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Allis, R.; Bromley, C.; Currie, S.</p> <p>2009-01-01</p> <p>The total <span class="hlt">subsidence</span> at the Wairakei field as a result of 50 years of geothermal fluid extraction is 15 ?? 0.5 m. <span class="hlt">Subsidence</span> rates in the center of the <span class="hlt">subsidence</span> bowl have decreased from over 450 mm/year during the 1970s to 80-90 mm/year during 2000-2007. The location of the bowl, adjacent to the original liquid outflow zone of the field, has not changed significantly. <span class="hlt">Subsidence</span> at the Tauhara field due to Wairakei production was not as well documented in the early years but appeared later and has been less intense than at Wairakei. Total <span class="hlt">subsidence</span> of <span class="hlt">2</span>.6 ?? 0.5 m has also occurred close to the original liquid outflow zone of this field, and maximum <span class="hlt">subsidence</span> rates in this area today are in the 80-100 mm/year range. In the western part of the Wairakei field, near the area of hot upflow, <span class="hlt">subsidence</span> rates have approximately doubled during the last 20 years to 30-50 mm/year. This increase appears to be have been caused by declining pressure in the underlying steam zone in this area, which is tapped by some production wells. At Tauhara field, two areas of <span class="hlt">subsidence</span> have developed since the 1990s with rates of 50-65 mm/year. Although less well-determined, this <span class="hlt">subsidence</span> may also be caused by declining pressure in shallow steam zones. The cause of the main <span class="hlt">subsidence</span> bowls in the Wairakei-Tauhara geothermal system is locally high-compressibility rocks within the Huka Falls Formation (HFF), which are predominantly lake sediments and an intervening layer of pumice breccia. At Wairakei, casing deformation suggests the greatest compaction is at 150-200 m depth. The cause of the large compressibility is inferred to be higher clay content in the HFF due to intense hydrothermal alteration close to the natural fluid discharge areas. Future <span class="hlt">subsidence</span> is predicted to add an additional <span class="hlt">2</span>-4 m to the Wairakei bowl, and 1-<span class="hlt">2</span> m elsewhere, but these estimates depend on the assumed production-injection scenarios.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://images.nasa.gov/#/details-PIA03490.html','SCIGOVIMAGE-NASA'); return false;" href="https://images.nasa.gov/#/details-PIA03490.html"><span>Meteor <span class="hlt">Crater</span>, AZ</span></a></p> <p><a target="_blank" href="https://images.nasa.gov/">NASA Image and Video Library</a></p> <p></p> <p>2002-03-12</p> <p>The Barringer Meteorite <span class="hlt">Crater</span> (also known as "Meteor <span class="hlt">Crater</span>") is a gigantic hole in the middle of the arid sandstone of the Arizona desert. A rim of smashed and jumbled boulders, some of them the size of small houses, rises 50 m above the level of the surrounding plain. The <span class="hlt">crater</span> itself is nearly a 1500 m wide, and 180 m deep. When Europeans first discovered the <span class="hlt">crater</span>, the plain around it was covered with chunks of meteoritic iron - over 30 tons of it, scattered over an area 12 to 15 km in diameter. Scientists now believe that the <span class="hlt">crater</span> was created approximately 50,000 years ago. The meteorite which made it was composed almost entirely of nickel-iron, suggesting that it may have originated in the interior of a small planet. It was 50 m across, weighed roughly 300,000 tons, and was traveling at a speed of 65,000 km per hour. This ASTER 3-D perspective view was created by draping an ASTER bands 3-<span class="hlt">2</span>-1image over a digital elevation model from the US Geological Survey National Elevation Dataset. This image was acquired on May 17, 2001 by the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) on NASA's Terra satellite. With its 14 spectral bands from the visible to the thermal infrared wavelength region, and its high spatial resolution of 15 to 90 meters (about 50 to 300 feet), ASTER will image Earth for the next 6 years to map and monitor the changing surface of our planet. http://photojournal.jpl.nasa.gov/catalog/PIA03490</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFM.V52C..04P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFM.V52C..04P"><span>Controls on lava lake level at Halema`uma`<span class="hlt">u</span> <span class="hlt">Crater</span>, Kilauea Volcano</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Patrick, M. R.; Orr, T. R.</p> <p>2013-12-01</p> <p>Lava level is a fundamental measure of lava lake activity, but very little continuous long-term data exist worldwide to explore this aspect of lava lake behavior. The ongoing summit eruption at Kilauea Volcano began in 2008 and is characterized by an active lava lake within the eruptive vent. Lava level has been measured nearly continuously at Kilauea for several years using a combination of webcam images, laser rangefinder, and terrestrial LIDAR. Fluctuations in lava level have been a common aspect of the eruption and occur over several timescales. At the shortest timescale, the lava lake level can change over seconds to hours owing to two observed shallow gas-related processes. First, gas pistoning is common and is driven by episodic gas accumulation and release from the surface of the lava lake, causing the lava level to rise and fall by up to 20 m. Second, rockfalls into the lake trigger abrupt gas release, and lava level may drop as much as 10 m as a result. Over days, cyclic changes in lava level closely track cycles of deflation-inflation (DI) deformation events at the summit, leading to level changes up to 50 m. Rift zone intrusions have caused large (up to 140 m) drops in lava level over several days. On the timescale of weeks to months, the lava level follows the long-term inflation and deflation of the summit region, resulting in level changes up to 140 m. The remarkable correlation between lava level and deflation-inflation cycles, as well as the long-term deformation of the summit region, indicates that the lava lake acts as a reliable 'piezometer' (a measure of liquid pressure in the magma plumbing system); therefore, assessments of summit pressurization (and rift zone eruption potential) can now be carried out with the naked eye. The summit lava lake level is closely mirrored by the lava level within Pu`<span class="hlt">u</span> `O`o <span class="hlt">crater</span>, the vent area for the 30-year-long eruption on Kilauea's east rift zone, which is 20 km downrift of the summit. The coupling of these</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19840011716','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19840011716"><span>Centrifuge impact <span class="hlt">cratering</span> experiment 5</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>1984-01-01</p> <p>Transient crates motions, <span class="hlt">cratering</span> flow fields, crates dynamics, determining impact conditions from total <span class="hlt">crater</span> welt, centrifuge quarter-space <span class="hlt">cratering</span>, and impact <span class="hlt">cratering</span> mechanics research is documented.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017DPS....4921406W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017DPS....4921406W"><span>Ganymede’s stratigraphy and <span class="hlt">crater</span> distributions in Voyager and Galileo SSI images: results from the anti-jovian hemisphere</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wagner, Roland Josef; Schmedemann, Nico; Stephan, Katrin; Werner, Stephanie; Ivanov, Boris A.; Roatsch, Thomas; Jaumann, Ralf; Palumbo, Pasquale</p> <p>2017-10-01</p> <p><span class="hlt">Crater</span> size distributions are a valuable tool in planetary stratigraphy to derive the sequence of geologic events. In this study, we extend our previous work [1] in Ganymede’s sub-jovian hemisphere to the anti-jovian hemisphere. For geologic mapping, the map by [<span class="hlt">2</span>] is used as a reference. Our study provides groundwork for the upcoming imaging by the JANUS camera aboard ESA’s JUICE mission [3]. Voyager-<span class="hlt">2</span> images are reprocessed using a map scale of 700 m/pxl achieved for parts of the anti-jovian hemisphere. To obtain relative ages from <span class="hlt">crater</span> frequencies, we apply an updated <span class="hlt">crater</span> scaling law for <span class="hlt">cratering</span> into icy targets in order to derive a <span class="hlt">crater</span> production function for Ganymede [1]. Also, we adopt the Poisson timing analysis method discussed and implemented recently [4] to obtain relative (and absolute model) ages. Results are compared to those from the sub-jovian hemisphere [1] as well as to support and/or refine the global stratigraphic system by [<span class="hlt">2</span>]. Further emphasis is placed on local target areas in the anti-jovian hemisphere imaged by Galileo SSI at regional map scales of 100 to 300 m/pxl in order to study local geologic effects and processes. These areas incorporate (1) dark and (<span class="hlt">2</span>) light tectonized materials, and (3) impact <span class="hlt">crater</span> materials including an area with numerous secondaries from ray <span class="hlt">crater</span> Osiris. References: [1] Wagner R. et al. (2014), DPS meeting #46, abstract 418.09. [<span class="hlt">2</span>] Collins G. et al. (2013), <span class="hlt">U</span>.S.G.S. Sci. Inv. Map 3237. [3] Della Corte V. et al. (2014), Proc. SPIE 9143, doi:10.1117/12.2056353. [4] Michael G. et al. (2016), Icarus 277, 279-285.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/8974','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/8974"><span>Artificial recharge for <span class="hlt">subsidence</span> abatement at the NASA-Johnson Space Center, Phase I</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Garza, Sergio</p> <p>1977-01-01</p> <p>Regional decline of aquifer head due to ground-water withdrawal in the Houston area has caused extensive land-surface <span class="hlt">subsidence</span>. The NASA-Johnson Space Center (NASA-JSC) in southeastern Harris County, Texas, was about 13 to 19 feet above mean sea level in 1974 and sinking at a rate of more than 0.<span class="hlt">2</span> foot per year. NASA-JSC officials, concerned about the hurricane flooding hazard, requested the <span class="hlt">U</span>.S. Geological Survey to study the feasibility of artificially recharging the aquifers for <span class="hlt">subsidence</span> abatement. Hydrologic digital models were developed for theoretical determinations of quantities of water needed, under various well-array plans, for artificial recharge of the Chicot and Evangeline aquifers in order to halt the local <span class="hlt">subsidence</span> at NASA-JSC. The programs for the models were developed for analysis of three-dimensional ground-water flow. Total injection rates of between <span class="hlt">2</span>,000 and 14,000 gallons per minute under three general well-array plans were determined for a range of residual clay pore pressures of 10 to 70 feet of hydraulic head. The space distributions of the resultant hydraulic heads, illustrated for injection rates of 3,600 and 8 ,400 gallons per minute, indicated that, for the same rate, increasing the number and spread of the injection locations reduces the head gradients within NASA-JSC. (Woodard-USGS)</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012CG.....48..228P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012CG.....48..228P"><span>Application of an adaptive neuro-fuzzy inference system to ground <span class="hlt">subsidence</span> hazard mapping</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Park, Inhye; Choi, Jaewon; Jin Lee, Moung; Lee, Saro</p> <p>2012-11-01</p> <p>We constructed hazard maps of ground <span class="hlt">subsidence</span> around abandoned underground coal mines (AUCMs) in Samcheok City, Korea, using an adaptive neuro-fuzzy inference system (ANFIS) and a geographical information system (GIS). To evaluate the factors related to ground <span class="hlt">subsidence</span>, a spatial database was constructed from topographic, geologic, mine tunnel, land use, and ground <span class="hlt">subsidence</span> maps. An attribute database was also constructed from field investigations and reports on existing ground <span class="hlt">subsidence</span> areas at the study site. Five major factors causing ground <span class="hlt">subsidence</span> were extracted: (1) depth of drift; (<span class="hlt">2</span>) distance from drift; (3) slope gradient; (4) geology; and (5) land use. The adaptive ANFIS model with different types of membership functions (MFs) was then applied for ground <span class="hlt">subsidence</span> hazard mapping in the study area. Two ground <span class="hlt">subsidence</span> hazard maps were prepared using the different MFs. Finally, the resulting ground <span class="hlt">subsidence</span> hazard maps were validated using the ground <span class="hlt">subsidence</span> test data which were not used for training the ANFIS. The validation results showed 95.12% accuracy using the generalized bell-shaped MF model and 94.94% accuracy using the Sigmoidal<span class="hlt">2</span> MF model. These accuracy results show that an ANFIS can be an effective tool in ground <span class="hlt">subsidence</span> hazard mapping. Analysis of ground <span class="hlt">subsidence</span> with the ANFIS model suggests that quantitative analysis of ground <span class="hlt">subsidence</span> near AUCMs is possible.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://images.nasa.gov/#/details-PIA04454.html','SCIGOVIMAGE-NASA'); return false;" href="https://images.nasa.gov/#/details-PIA04454.html"><span>Flooded <span class="hlt">Crater</span></span></a></p> <p><a target="_blank" href="https://images.nasa.gov/">NASA Image and Video Library</a></p> <p></p> <p>2003-04-04</p> <p>This image from NASA Mars Odyssey spacecraft shows a flooded <span class="hlt">crater</span> in Amazonis Planitia. This <span class="hlt">crater</span> has been either flooded with mud and or lava. The fluid then ponded up, dried and formed the surface textures we see today.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://images.nasa.gov/#/details-PIA00462.html','SCIGOVIMAGE-NASA'); return false;" href="https://images.nasa.gov/#/details-PIA00462.html"><span>Venus - Multiple-Floored, Irregular Impact <span class="hlt">Crater</span></span></a></p> <p><a target="_blank" href="https://images.nasa.gov/">NASA Image and Video Library</a></p> <p></p> <p>1996-09-26</p> <p>NASA' sMagellan imaged this multiple-floored, irregular impact <span class="hlt">crater</span> at latitude 16.4 degrees north, longitude 352.1 degrees east, during orbits 481 and 482 on 27 September 1990. This <span class="hlt">crater</span>, about 9.<span class="hlt">2</span> kilometers in maximum diameter, was formed on what appears to be a slightly fractured, radar-dark (smooth) plain. The abundant, low viscosity flows associated with this <span class="hlt">cratering</span> event have, however, filled local, fault-controlled troughs (called graben). These shallow graben are well portrayed on this Magellan image but would be unrecognizable but for their coincidental infilling by the radar-bright <span class="hlt">crater</span> flows. This fortuitous enhancement by the <span class="hlt">crater</span> flows of fault structures that are below the resolution of the Magellan synthetic aperture radar is providing the Magellan Science Team with valuable geologic information. The flow deposits from the <span class="hlt">craters</span> are thought to consist primarily of shock melted rock and fragmented debris resulting from the nearly simultaneous impacts of two projectile fragments into the hot (800 degrees Fahrenheit) surface rocks of Venus. The presence of the various floors of this irregular <span class="hlt">crater</span> is interpreted to be the result of crushing, fragmentation, and eventual aerodynamic dispersion of a single entry projectile during passage through the dense Venusian atmosphere. http://photojournal.jpl.nasa.gov/catalog/PIA00462</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://images.nasa.gov/#/details-PIA13738.html','SCIGOVIMAGE-NASA'); return false;" href="https://images.nasa.gov/#/details-PIA13738.html"><span>Doublet <span class="hlt">Crater</span></span></a></p> <p><a target="_blank" href="https://images.nasa.gov/">NASA Image and Video Library</a></p> <p></p> <p>2010-12-22</p> <p>This image from NASA Mars Odyssey is of a doublet <span class="hlt">crater</span> located in Utopia Planitia, near the Elysium Volcanic region. Doublet <span class="hlt">craters</span> are formed by simultaneous impact of a meteor that broke into two pieces prior to hitting the surface.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20050172168','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20050172168"><span>Hydrothermal Alteration at Lonar <span class="hlt">Crater</span>, India and Elemental Variations in Impact <span class="hlt">Crater</span> Clays</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Newsom, H. E.; Nelson, M. J.; Shearer, C. K.; Misra, S.; Narasimham, V.</p> <p>2005-01-01</p> <p>The role of hydrothermal alteration and chemical transport involving impact <span class="hlt">craters</span> could have occurred on Mars, the poles of Mercury and the Moon, and other small bodies. We are studying terrestrial <span class="hlt">craters</span> of various sizes in different environments to better understand aqueous alteration and chemical transport processes. The Lonar <span class="hlt">crater</span> in India (1.8 km diameter) is particularly interesting being the only impact <span class="hlt">crater</span> in basalt. In January of 2004, during fieldwork in the ejecta blanket around the rim of the Lonar <span class="hlt">crater</span> we discovered alteration zones not previously described at this <span class="hlt">crater</span>. The alteration of the ejecta blanket could represent evidence of localized hydrothermal activity. Such activity is consistent with the presence of large amounts of impact melt in the ejecta blanket. Map of one area on the north rim of the <span class="hlt">crater</span> containing highly altered zones at least 3 m deep is shown.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20100003189','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20100003189"><span>Creation of High Resolution Terrain Models of Barringer Meteorite <span class="hlt">Crater</span> (Meteor <span class="hlt">Crater</span>) Using Photogrammetry and Terrestrial Laser Scanning Methods</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Brown, Richard B.; Navard, Andrew R.; Holland, Donald E.; McKellip, Rodney D.; Brannon, David P.</p> <p>2010-01-01</p> <p>Barringer Meteorite <span class="hlt">Crater</span> or Meteor <span class="hlt">Crater</span>, AZ, has been a site of high interest for lunar and Mars analog <span class="hlt">crater</span> and terrain studies since the early days of the Apollo-Saturn program. It continues to be a site of exceptional interest to lunar, Mars, and other planetary <span class="hlt">crater</span> and impact analog studies because of its relatively young age (est. 50 thousand years) and well-preserved structure. High resolution (<span class="hlt">2</span> meter to 1 decimeter) digital terrain models of Meteor <span class="hlt">Crater</span> in whole or in part were created at NASA Stennis Space Center to support several lunar surface analog modeling activities using photogrammetric and ground based laser scanning techniques. The dataset created by this activity provides new and highly accurate 3D models of the inside slope of the <span class="hlt">crater</span> as well as the downslope rock distribution of the western ejecta field. The data are presented to the science community for possible use in furthering studies of Meteor <span class="hlt">Crater</span> and impact <span class="hlt">craters</span> in general as well as its current near term lunar exploration use in providing a beneficial test model for lunar surface analog modeling and surface operation studies.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li class="active"><span>11</span></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_11 --> <div id="page_12" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li class="active"><span>12</span></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="221"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70190499','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70190499"><span>Viscous relaxation of Ganymede's impact <span class="hlt">craters</span>: Constraints on heat flux</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Bland, Michael T.; Singer, Kelsi N.; McKinnon, William B.; Schenk, Paul M.</p> <p>2017-01-01</p> <p>Measurement of <span class="hlt">crater</span> depths in Ganymede’s dark terrain have revealed substantial numbers of unusually shallow <span class="hlt">craters</span> indicative of viscous relaxation [see companion paper: Singer, K.N., Schenk, P. M., Bland, M.T., McKinnon, W.B., (2017). Relaxed impact <span class="hlt">craters</span> on Ganymede: Regional variations and high heat flow. Icarus, submitted]. These viscously relaxed <span class="hlt">craters</span> provide insight into the thermal history of the dark terrain: the rate of relaxation depends on the size of the <span class="hlt">crater</span> and the thermal structure of the lithosphere. Here we use finite element simulations of <span class="hlt">crater</span> relaxation to constrain the heat flux within the dark terrain when relaxation occurred. We show that the degree of viscous relaxation observed cannot be achieved through radiogenic heating alone, even if all of the relaxed <span class="hlt">craters</span> are ancient and experienced the high radiogenic fluxes present early in the satellite’s history. For <span class="hlt">craters</span> with diameter ≥ 10 km, heat fluxes of 40–50 mW m-<span class="hlt">2</span>−<span class="hlt">2</span>"> can reproduce the observed <span class="hlt">crater</span> depths, but only if the fluxes are sustained for ∼1 Gyr. These <span class="hlt">craters</span> can also be explained by shorter-lived “heat pulses” with magnitudes of ∼100 mW m-<span class="hlt">2</span>−<span class="hlt">2</span>"> and timescales of 10–100 Myr. At small <span class="hlt">crater</span> diameters (4 km) the observed shallow depths are difficult to achieve even when heat fluxes as high as 150 mW m-<span class="hlt">2</span>−<span class="hlt">2</span>"> are sustained for 1 Gyr. The extreme thermal conditions required to viscously relax small <span class="hlt">craters</span> may indicate that mechanisms other than viscous relaxation, such as topographic degradation, are also in play at small <span class="hlt">crater</span> diameters. The timing of the relaxation event(s) is poorly constrained due to the sparsity of adequate topographic information, though it likely occurred in Ganymede’s middle history (neither recently, nor shortly after satellite formation). The consistency between the timing and magnitude of the heat fluxes derived here and those inferred from other tectonic features suggests that a single event</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=PIA04049&hterms=sputnik&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dsputnik','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=PIA04049&hterms=sputnik&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dsputnik"><span>Impact <span class="hlt">Crater</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>2002-01-01</p> <p><p/> [figure removed for brevity, see original site] <p/>Today marks the 45th anniversary of the dawn of the Space Age (October 4, 1957). On this date the former Soviet Union launched the world's first satellite, Sputnik 1. Sputnik means fellow traveler. For comparison Sputnik 1 weighed only 83.6 kg (184 pounds) while Mars Odyssey weighs in at 758 kg (1,671 pounds).<p/>This scene shows several interesting geologic features associated with impact <span class="hlt">craters</span> on Mars. The continuous lobes of material that make up the ejecta blanket of the large impact <span class="hlt">crater</span> are evidence that the <span class="hlt">crater</span> ejecta were fluidized upon impact of the meteor that formed the <span class="hlt">crater</span>. Volatiles within the surface mixed with the ejecta upon impact thus creating the fluidized form. Several smaller impact <span class="hlt">craters</span> are also observed within the ejecta blanket of the larger impact <span class="hlt">crater</span> giving a relative timing of events. Layering of geologic units is also observed within the large impact <span class="hlt">crater</span> walls and floor and may represent different compositional units that erode at variable rates. Cliff faces, dissected gullies, and heavily eroded impact <span class="hlt">craters</span> are observed in the bottom half of the image at the terminus of a flat-topped plateau.<p/>Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.<p/>NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19940011827','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19940011827"><span>Implications of <span class="hlt">crater</span> distributions on Venus</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Kaula, W. M.</p> <p>1993-01-01</p> <p>The horizontal locations of <span class="hlt">craters</span> on Venus are consistent with randomness. However, (1) randomness does not make <span class="hlt">crater</span> counts useless for age indications; (<span class="hlt">2</span>) consistency does not imply necessity or optimality; and (3) horizontal location is not the only reference frame against which to test models. Re (1), the apparent smallness of resurfacing areas means that a region on the order of one percent of the planet with a typical number of <span class="hlt">craters</span>, 5-15, will have a range of feature ages of several 100 My. Re (<span class="hlt">2</span>), models of resurfacing somewhat similar to Earth's can be found that are also consistent and more optimal than random: i.e., resurfacing occurring in clusters, that arise and die away in lime intervals on the order of 50 My. These agree with the observation that there are more areas of high <span class="hlt">crater</span> density, and fewer of moderate density, than optimal for random. Re (3), 799 <span class="hlt">crater</span> elevations were tested; there are more at low elevations and fewer at high elevations than optimal for random: i.e., 54.6 percent below the median. Only one of 40 random sets of 799 was as extreme.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://images.nasa.gov/#/details-PIA08457.html','SCIGOVIMAGE-NASA'); return false;" href="https://images.nasa.gov/#/details-PIA08457.html"><span>Filled <span class="hlt">Craters</span></span></a></p> <p><a target="_blank" href="https://images.nasa.gov/">NASA Image and Video Library</a></p> <p></p> <p>2006-05-11</p> <p>This MOC image shows adjacent impact <span class="hlt">craters</span> located north-northwest of the Acheron Fossae region of Mars. The two <span class="hlt">craters</span> are of similar size and formed by meteor impacts. However, one is much more filled than the other, indicating that it is older</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://images.nasa.gov/#/details-PIA03849.html','SCIGOVIMAGE-NASA'); return false;" href="https://images.nasa.gov/#/details-PIA03849.html"><span>Spallanzani <span class="hlt">Crater</span></span></a></p> <p><a target="_blank" href="https://images.nasa.gov/">NASA Image and Video Library</a></p> <p></p> <p>2002-07-17</p> <p>The <span class="hlt">craters</span> on Mars display a variety of interior deposits, one of which is shown in this image from NASA Mars Odyssey. Spallanzani <span class="hlt">Crater</span> is located far enough south that it probably experiences the seasonal growth and retreat of the south polar cap.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70020209','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70020209"><span>Impact <span class="hlt">cratering</span> through geologic time</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Shoemaker, E.M.; Shoemaker, C.S.</p> <p>1998-01-01</p> <p>New data on lunar <span class="hlt">craters</span> and recent discoveries about <span class="hlt">craters</span> on Earth permit a reassessment of the bombardment history of Earth over the last 3.<span class="hlt">2</span> billion years. The combined lunar and terrestrial <span class="hlt">crater</span> records suggest that the long-term average rate of production of <span class="hlt">craters</span> larger than 20 km in diameter has increased, perhaps by as much as 60%, in the last 100 to 200 million years. Production of <span class="hlt">craters</span> larger than 70 km in diameter may have increased, in the same time interval, by a factor of five or more over the average for the preceding three billion years. A large increase in the flux of long-period comets appears to be the most likely explanation for such a long-term increase in the <span class="hlt">cratering</span> rate. Two large <span class="hlt">craters</span>, in particular, appear to be associated with a comet shower that occurred about 35.5 million years ago. The infall of cosmic dust, as traced by 3He in deep sea sediments, and the ages of large <span class="hlt">craters</span>, impact glass horizons, and other stratigraphic markers of large impacts seem to be approximately correlated with the estimated times of passage of the Sun through the galactic plane, at least for the last 65 million years. Those are predicted times for an increased near-Earth flux of comets from the Oort Cloud induced by the combined effects of galactic tidal perturbations and encounters of the Sun with passing stars. Long-term changes in the average comet flux may be related to changes in the amplitude of the z-motion of the Sun perpendicular to the galactic plane or to stripping of the outer Oort cloud by encounters with large passing stars, followed by restoration from the inner Oort cloud reservoir.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19810013459','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19810013459"><span>An investigation of the <span class="hlt">cratering</span>-induced motions occurring during the formation of bowl-shaped <span class="hlt">craters</span>. [using high explosive charges as the <span class="hlt">cratering</span> source</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Piekutowski, A. J.</p> <p>1980-01-01</p> <p>The effects of the dynamic processes which occur during <span class="hlt">crater</span> formation were examined using small hemispherical high-explosive charges detonated in a tank which had one wall constructed of a thick piece of clear plexiglas. <span class="hlt">Crater</span> formation and the motions of numerous tracer particles installed in the <span class="hlt">cratering</span> medium at the medium-wall interface were viewed through the wall of this quarter-space tank and recorded with high-speed cameras. Subsequent study and analysis of particle motions and events recorded on the film provide data needed to develop a time-sequence description of the formation of a bowl-shaped <span class="hlt">crater</span>. Tables show the dimensions of <span class="hlt">craters</span> produced in a quarter-space tank compared with dimensions of <span class="hlt">craters</span> produced in normal half-space tanks. <span class="hlt">Crater</span> growth rate summaries are also tabulated.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/1016194','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/1016194"><span>Unusual bacterioplankton community structure in ultra-oligotrophic <span class="hlt">Crater</span> Lake</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Urbach, Ena; Vergin, Kevin L.; Morse, Ariel</p> <p>2001-01-01</p> <p>The bacterioplankton assemblage in <span class="hlt">Crater</span> Lake, Oregon (<span class="hlt">U</span>.S.A.), is different from communities found in other oxygenated lakes, as demonstrated by four small subunit ribosomal ribonucleic acid (SSU rRNA) gene clone libraries and oligonucleotide probe hybridization to RNA from lake water. Populations in the euphotic zone of this deep (589 m), oligotrophic caldera lake are dominated by two phylogenetic clusters of currently uncultivated bacteria: CL120-10, a newly identified cluster in the verrucomicrobiales, and ACK4 actinomycetes, known as a minor constituent of bacterioplankton in other lakes. Deep-water populations at 300 and 500 m are dominated by a different pair of uncultivated taxa: CL500-11, a novel cluster in the green nonsulfur bacteria, and group I marine crenarchaeota. b-Proteobacteria, dominant in most other freshwater environments, are relatively rare in <span class="hlt">Crater</span> Lake (<=16% of nonchloroplast bacterial rRNA at all depths). Other taxa identified in <span class="hlt">Crater</span> Lake libraries include a newly identified candidate bacterial division, ABY1, and a newly identified subcluster, CL0-1, within candidate division OP10. Probe analyses confirmed vertical stratification of several microbial groups, similar to patterns observed in open-ocean systems. Additional similarities between <span class="hlt">Crater</span> Lake and ocean microbial populations include aphotic zone dominance of group I marine crenarchaeota and green nonsulfur bacteria. Comparison of <span class="hlt">Crater</span> Lake to other lakes studied by rRNA methods suggests that selective factors structuring <span class="hlt">Crater</span> Lake bacterioplankton populations may include low concentrations of available trace metals and dissolved organic matter, chemistry of infiltrating hydrothermal waters, and irradiation by high levels of ultraviolet light.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://images.nasa.gov/#/details-PIA19263.html','SCIGOVIMAGE-NASA'); return false;" href="https://images.nasa.gov/#/details-PIA19263.html"><span>Crumpled <span class="hlt">Crater</span></span></a></p> <p><a target="_blank" href="https://images.nasa.gov/">NASA Image and Video Library</a></p> <p></p> <p>2015-03-30</p> <p>It is no secret that Mercury's surface is scarred by abundant tectonic deformation, the vast majority of which is due to the planet's history of cooling and contraction through time. Yet Mercury is also heavily <span class="hlt">cratered</span>, and hosts widespread volcanic plains. So it's perhaps unsurprising that these three types of landform often intersect-literally-as shown in this scene. Here, an unnamed <span class="hlt">crater</span>, about 7.5 km (4.7 mi.) in diameter was covered, and almost fully buried, by lava. At some point after, compression of the surface formed scarps and ridges in the area that, when they reached the buried <span class="hlt">crater</span>, came to describe its curved outline. Many arcuate ridges on Mercury formed this way. In this high-resolution view, we can also see the younger, later population of smaller <span class="hlt">craters</span> that pock-mark the surface. http://photojournal.jpl.nasa.gov/catalog/PIA19263</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20030018897&hterms=geology&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dgeology','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20030018897&hterms=geology&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dgeology"><span>Geology of Lofn <span class="hlt">Crater</span>, Callisto</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Greeley, Ronald; Heiner, Sarah; Klemaszewski, James E.</p> <p>2001-01-01</p> <p>Lofn <span class="hlt">crater</span> is a 180-km-diameter impact structure in the southern <span class="hlt">cratered</span> plains of Callisto and is among the youngest features seen on the surface. The Lofn area was imaged by the Galileo spacecraft at regional-scale resolutions (875 m/pixel), which enable the general geology to be investigated. The morphology of Lofn <span class="hlt">crater</span> suggests that (1) it is a class of impact structure intermediate between complex <span class="hlt">craters</span> and palimpsests or (<span class="hlt">2</span>) it formed by the impact of a projectile which fragmented before reaching the surface, resulting in a shallow <span class="hlt">crater</span> (even for Callisto). The asymmetric pattern of the rim and ejecta deposits suggests that the impactor entered at a low angle from the northwest. The albedo and other characteristics of the ejecta deposits from Lofn also provide insight into the properties of the icy lithosphere and subsurface configuration at the time of impact. The "target" for the Lofn impact is inferred to have included layered materials associated with the Adlinda multiring structure northwest of Loh and ejecta deposits from the Heimdall <span class="hlt">crater</span> area to the southeast. The Lofn impact might have penetrated through these materials into a viscous substrate of ductile ice or possibly liquid water. This interpretation is consistent with models of the current interior of Callisto based on geophysical information obtained from the Galileo spacecraft.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20050167756&hterms=lithology&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3Dlithology','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20050167756&hterms=lithology&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3Dlithology"><span>Visible-Near Infrared Imaging Spectrometer Data of Explosion <span class="hlt">Craters</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Farr, T. G.</p> <p>2005-01-01</p> <p>In a continuing study to capture a realistic terrain applicable to studies of <span class="hlt">cratering</span> processes and landing hazards on Mars, we have obtained new high resolution visible-near infrared images of several explosion <span class="hlt">craters</span> at the Nevada Test Site. We used the Airborne Visible-Infrared Imaging Spectrometer (AVIRIS) to obtain images in 224 spectral bands from 0.4-<span class="hlt">2</span>.5 microns [1]. The main <span class="hlt">craters</span> that were imaged were Sedan, Scooter, Schooner, Buggy, and Danny Boy [<span class="hlt">2</span>]. The 390 m diameter Sedan <span class="hlt">crater</span>, located on Yucca Flat, is the largest and freshest explosion <span class="hlt">crater</span> on Earth that was formed under conditions similar to hypervelocity impact <span class="hlt">cratering</span>. As such, it is effectively pristine, having been formed in 1962 as a result of the detonation of a 104 kiloton thermonuclear device, buried at the appropriate equivalent depth of burst required to make a "simple" <span class="hlt">crater</span> [<span class="hlt">2</span>]. Sedan was formed in alluvium of mixed lithology [3] and subsequently studied using a variety of field-based methods. Nearby secondary <span class="hlt">craters</span> were also formed at the time and were also imaged by AVIRIS. Adjacent to Sedan and also in alluvium is Scooter, about 90 m in diameter and formed by a high-explosive event. Schooner (240 m) and Danny Boy (80 m, Fig. 1) <span class="hlt">craters</span> were also important targets for AVIRIS as they were excavated in hard welded tuff and basaltic andesite, respectively [3, 4]. This variation in targets will allow the study of ejecta patterns, compositional modifications due to the explosions, and the role of <span class="hlt">craters</span> as subsurface probes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27957838','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27957838"><span>Theoretical Investigation of Regioselectivity and Stereoselectivity in AIBN/HSn<span class="hlt">Bu</span>3-Mediated Radical Cyclization of N-(<span class="hlt">2</span>-Iodo-4,6-dimethylphenyl)-N,<span class="hlt">2</span>-dimethyl-(<span class="hlt">2</span>E)-butenamide.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Li, Bai-Jian; Zhong, Hua; Yu, Hai-Tao</p> <p>2016-12-22</p> <p>In this study, we employed the density functional method to simulate AIBN/HSn<span class="hlt">Bu</span> 3 -mediated radical cyclizations with different axially chiral conformers of N-(<span class="hlt">2</span>-iodo-4,6-dimethylphenyl)-N,<span class="hlt">2</span>-dimethyl-(<span class="hlt">2</span>E)-butenamide as substrates. We constructed a reaction potential energy profile using the Gibbs free energies of the located stationary points. The thermodynamic and kinetic data of the profile were further used to evaluate the regioselectivity, stereoselectivity, and product distribution of the cyclizations. Additionally, we compared the present HSn<span class="hlt">Bu</span> 3 -mediated radical cyclization with the experimentally available Heck reaction and found that such a radical cyclization can convert (M,Z) and (P,Z) o-iodoanilide substrates to centrally chiral products with high chirality transfer. The goal of this study was to estimate the practicality of theoretically predicting the memory of chirality in such radical cyclizations. The present results can provide a strategy from a theoretical viewpoint for experimentally synthesizing highly stereoselective carbocyclic and heterocyclic compounds using radical cyclization methods.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://images.nasa.gov/#/details-PIA14954.html','SCIGOVIMAGE-NASA'); return false;" href="https://images.nasa.gov/#/details-PIA14954.html"><span>Fresh Dark Ray <span class="hlt">Crater</span></span></a></p> <p><a target="_blank" href="https://images.nasa.gov/">NASA Image and Video Library</a></p> <p></p> <p>2011-10-15</p> <p>The <span class="hlt">crater</span> on asteroid Vesta shown in this image from NASA Dawn spacecraft was emplaced onto the ejecta blanket of two large twin <span class="hlt">craters</span>. Commonly, rays from impact <span class="hlt">craters</span> are brighter than the surrounding surface.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=PIA03907&hterms=pluton&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dpluton','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=PIA03907&hterms=pluton&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dpluton"><span>Pandora Fretum <span class="hlt">Crater</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>2002-01-01</p> <p>[figure removed for brevity, see original site] (Released 26 July 2002) Another in a series of <span class="hlt">craters</span> with unusual interior deposits, this THEMIS image shows an unnamed <span class="hlt">crater</span> in the southern hemisphere Pandora Fretum region near the Hellas Basin. <span class="hlt">Craters</span> with eroded layered deposits are quite common on Mars but the crusty textured domes in the center of the image make this <span class="hlt">crater</span> more unusual. Looking vaguely like granitic intrusions, there erosional style is distinct from the rest of the interior deposit which shows a very obvious layered morphology. While it is unlikely that the domes are granite plutons, it is possible that they do represent some other shallowly emplaced magmatic intrusion. More likely still is that variations in induration of the layered deposit allow for variations in the erosional morphology. Note how the surface of the <span class="hlt">crater</span> floor in the northernmost portion of the image has a texture similar to that of the domes. This may represent an incipient form of the erosion that has produced the domes but has not progressed as far. An analysis of other <span class="hlt">craters</span> in the area may shed light on the origin of the domes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.H51A1344G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.H51A1344G"><span>The UNESCO-IHP Working Group on Land <span class="hlt">Subsidence</span>: Four Decades of International Contributions to Hydrogeological Related <span class="hlt">Subsidence</span> Research and Knowledge Exchange</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Galloway, D. L.; Carreon-Freyre, D.; Teatini, P.; Ye, S.</p> <p>2015-12-01</p> <p><span class="hlt">Subsidence</span> is globally prevalent and because much of it is related to hydrological processes affected by human development of local land and water resources, "Land <span class="hlt">Subsidence</span>" was included in the UNESCO programme of the International Hydrological Decade (IHD), 1965-1974 and an ad hoc working group on land <span class="hlt">subsidence</span> was formed. In 1975 <span class="hlt">subsidence</span> was retained under the framework of the UNESCO IHP (subproject 8.4: "Investigation of Land <span class="hlt">Subsidence</span> due to Groundwater Exploitation"), and UNESCO IHP formerly codified the Working Group on Land <span class="hlt">Subsidence</span> (WGLS). In 1984 the WGLS produced a comprehensive guidebook to serve scientists and engineers, confronting land <span class="hlt">subsidence</span> problems, particularly in developing countries (http://unesdoc.unesco.org/$other/unesdoc/pdf/065167eo.pdf). During the IHD, UNESCO IHP convened the 1st International Symposium on Land <span class="hlt">Subsidence</span> in 1969 in Tokyo, Japan. In collaboration with UNESCO IHP, IAHS, and other scientific organizations, the WGLS has convened eight more International Symposia on Land <span class="hlt">Subsidence</span> in different countries in Asia, Europe and North America. The 9 published symposia proceedings constitute an important source of global <span class="hlt">subsidence</span> research and case studies during the past 45 years, covering both anthropogenic and natural <span class="hlt">subsidence</span> processes. Currently, the WGLS comprising 20 <span class="hlt">subsidence</span> experts from 9 countries promotes and facilitates the international exchange of information regarding the design, implementation and evaluation of risk assessments and mitigation measures, the definition of water and land resource-management strategies that support sustainable development in areas vulnerable to <span class="hlt">subsidence</span> (http://landsubsidence-unesco.org), and the assessment of related geological risks such as earth fissuring and fault activation (www.igcp641.org). The WGLS has become an important global leader in promoting <span class="hlt">subsidence</span> awareness, scientific research and its application to <span class="hlt">subsidence</span> monitoring, analysis and management.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20150019437','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20150019437"><span>The Degradational History of Endeavour <span class="hlt">Crater</span>, Mars</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Grant, J. A.; Parker, T. J.; Crumpler, L. S.; Wilson, S. A.; Golombek, M. P.; Mittlefehldt, D. W.</p> <p>2015-01-01</p> <p>Endeavour <span class="hlt">crater</span> (<span class="hlt">2</span>.28 deg S, 354.77 deg E) is a Noachian-aged 22 km-diameter impact structure of complex morphology in Meridiani Planum. The degradation state of the <span class="hlt">crater</span> has been studied using Mars Reconnaissance Orbiter and Opportunity rover data. Exposed rim segments rise approximately 10 m to approximately 100 m above the level of the embaying Burns Formation and the <span class="hlt">crater</span> is 200-500 m deep with the southern interior wall exposing over approximately 300 m relief. Both pre-impact rocks (Matijevic Formation) and Endeavour impact ejecta (Shoemaker Formation) are present at Cape York, but only the Shoemaker crops out (up to approximately 140 m) along the rim segment from Murray Ridge to Cape Tribulation. Study of pristine complex <span class="hlt">craters</span> Bopolu and Tooting, and morphometry of other martian complex <span class="hlt">craters</span>, enables us to approximate Endeavour's pristine form. The original rim likely averaged 410 m (+/-)200 m in elevation and a 250-275 m section of ejecta ((+/-)50-60 m) would have composed a significant fraction of the rim height. The original <span class="hlt">crater</span> depth was likely between 1.5 km and <span class="hlt">2.2</span> km. Comparison between the predicted original and current form of Endeavour suggests approximately 100-200 m rim lowering that removed most ejecta in some locales (e.g., Cape York) while thick sections remain elsewhere (e.g., Cape Tribulation). Almost complete removal of ejecta at Cape York and minimal observable offset across fractures indicates current differences in rim relief are not solely due to original rim relief. Rim segments are embayed by approximately 100-200 m thickness of plains rocks outside the <span class="hlt">crater</span>, but thicker deposits lie inside the <span class="hlt">crater</span>. Ventifact textures confirm ongoing eolian erosion with the overall extent difficult to estimate. Analogy with degraded Noachian-aged <span class="hlt">craters</span> south of Endeavour, however, suggests fluvial erosion dominated rim degradation in the Noachian and was likely followed by approximately 10s of meters modification by alternate</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19920003687','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19920003687"><span>Degradation studies of Martian impact <span class="hlt">craters</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Barlow, N. G.</p> <p>1991-01-01</p> <p>The amount of obliteration suffered by Martian impact <span class="hlt">craters</span> is quantified by comparing measurable attributes of the current <span class="hlt">crater</span> shape to those values expected for a fresh <span class="hlt">crater</span> of identical size. <span class="hlt">Crater</span> diameters are measured from profiles obtained using photoclinometry across the structure. The relationship between the diameter of a fresh <span class="hlt">crater</span> and a <span class="hlt">crater</span> depth, floor width, rim height, central peak height, etc. was determined by empirical studies performed on fresh Martian impact <span class="hlt">craters</span>. We utilized the changes in <span class="hlt">crater</span> depth and rim height to judge the degree of obliteration suffered by Martian impact <span class="hlt">craters</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/AD1042379','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/AD1042379"><span>Inclement Weather <span class="hlt">Crater</span> Repair Tool Kit</span></a></p> <p><a target="_blank" href="http://www.dtic.mil/">DTIC Science & Technology</a></p> <p></p> <p>2017-11-30</p> <p>Force’s Rapid Airfield Damage Repair (RADR) Program developed technologies to return bomb -damaged runways and taxiways to full operational sortie...ERDC/GSL TR-17-26 3 <span class="hlt">2</span> Inclement Weather <span class="hlt">Crater</span> Repair Research This chapter gives an overview of the bomb -<span class="hlt">crater</span> repair process and presents</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://images.nasa.gov/#/details-PIA21410.html','SCIGOVIMAGE-NASA'); return false;" href="https://images.nasa.gov/#/details-PIA21410.html"><span>Yalode <span class="hlt">Crater</span> on Ceres</span></a></p> <p><a target="_blank" href="https://images.nasa.gov/">NASA Image and Video Library</a></p> <p></p> <p>2017-06-28</p> <p>Yalode <span class="hlt">crater</span> is so large -- at 162 miles, 260 kilometers in diameter -- that a variety of vantage points is necessary to understand its geological context. This view of the northern portion of Yalode is one of many images NASA's Dawn spacecraft has taken of this <span class="hlt">crater</span>. The large impact that formed the <span class="hlt">crater</span> likely involved a lot of heat, which explains the relatively smooth <span class="hlt">crater</span> floor punctuated by smaller <span class="hlt">craters</span>. A couple of larger <span class="hlt">craters</span> in Yalode have polygonal shapes. This type of <span class="hlt">crater</span> shape is frequently found on Ceres and may be indicative of extensive underground fractures. The larger <span class="hlt">crater</span> to the right of center in this image is called Lono (12 miles, 20 kilometers in diameter) and the one below it is called Besua (11 miles, 17 kilometers). Some of the small <span class="hlt">craters</span> are accompanied by ejecta blankets that are more reflective than their surroundings. The strange Nar Sulcus fractures can be seen in the bottom left corner of the picture. Linear features seen throughout the image may have formed when material collapsed above empty spaces underground. These linear features include linear chains of <span class="hlt">craters</span> called catenae. Dawn took this image on September 27, 2015, from 915 miles (1,470 kilometers) altitude. The center coordinates of this image are 32 degrees south latitude and 300 degrees east longitude. Yalode gets its name from a goddess worshipped by women at the harvest rites in the Dahomey culture of western Africa. Besua takes its name from the Egyptian grain god, and Lono from the Hawaiian god of agriculture. https://photojournal.jpl.nasa.gov/catalog/PIA21410</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1997DPS....29.1403W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1997DPS....29.1403W"><span>Ganymede Impact <span class="hlt">Crater</span> Morphology as Revealed by Galileo</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Weitz, C. M.; Head, J. W.; Pappalardo, R.; Chapman, C.; Greeley, R.; Helfenstein, P.; Neukum, G.; Galileo SSI Team</p> <p>1997-07-01</p> <p>We have used the Galileo G1, G<span class="hlt">2</span>, G7, and G8 images to study the morpholo- gy and degradation of impact <span class="hlt">craters</span> on Ganymede. Results from the G1 and G<span class="hlt">2</span> data showed three types of degradation states: pristine, partially degraded, and heavily degraded. With the more recent G7 and G8 images, there are now several other distinct <span class="hlt">crater</span> morphologies that we have identified. Enki Catena is about 120 km in length and consists of 13 attached impact <span class="hlt">craters</span>. The six <span class="hlt">craters</span> in the chain that impacted onto the bright terrain have visible bright ejecta while those that impacted onto the dark terrain have barely visible ejecta. Kittu <span class="hlt">crater</span> is about 15 km in diameter and it has a bright central peak surrounded by a bright floor and hummocky wall material. The <span class="hlt">crater</span> rim in the north is linear in appearance at the location that corresponds to the boundary between the groove terrain and the adjacent dark terrain, indicating structural control by the underlying topography. The dark rays that are easily seen in the Voyager images are barely visible in the Galileo image. Neith <span class="hlt">crater</span> has a central fractured dome surrounded by a jagged central ring, smoother outer ejecta facies, and less prominent outer rings. Achelous <span class="hlt">crater</span> and its neighbor, which were imaged at low sun angle to show topography, have smooth floors and subdued pedestal ejecta. Nicholson Regio has tectonically disrupted <span class="hlt">craters</span> on the groove and fractured terrains while the surrounding smoother dark terrain has numerous degrad- ed <span class="hlt">craters</span> that may indicate burial by resurfacing or by regolith development.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li class="active"><span>12</span></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_12 --> <div id="page_13" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li class="active"><span>13</span></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="241"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017Icar..295..140X','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017Icar..295..140X"><span>Ray <span class="hlt">craters</span> on Ganymede: Implications for <span class="hlt">cratering</span> apex-antapex asymmetry and surface modification processes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Xu, Luyuan; Hirata, Naoyuki; Miyamoto, Hideaki</p> <p>2017-10-01</p> <p>As the youngest features on Ganymede, ray <span class="hlt">craters</span> are useful in revealing the sources of recent impactors and surface modification processes on the satellite. We examine <span class="hlt">craters</span> with D > 10 km on Ganymede from images obtained by the Voyager and Galileo spacecraft to identify ray <span class="hlt">craters</span> and study their spatial distributions. Furthermore, we carefully select images of appropriate solar and emission angles to obtain unbiased ray <span class="hlt">crater</span> densities. As a result, we find that the density of large ray <span class="hlt">craters</span> (D > 25 km) on the bright terrain exhibits an apex-antapex asymmetry, and its degree of asymmetry is much lower than the theoretical estimation for ecliptic comets. For large <span class="hlt">craters</span> (D > 25 km), ecliptic comets ought to be less important than previously assumed, and a possible explanation is that nearly isotropic comets may play a more important role on Ganymede than previously thought. We also find that small ray <span class="hlt">craters</span> (10 km < D < 25 km) on the bright terrain and ray <span class="hlt">craters</span> (D > 10 km) on the dark terrain show no apex-antapex asymmetry. We interpret that the distribution difference between the terrain types comes from preferential thermal sublimation on the dark terrain, while the distribution difference between large and small ray <span class="hlt">craters</span> suggests that rays of small <span class="hlt">craters</span> are more readily erased by some surface modification processes, such as micrometeorite gardening.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://images.nasa.gov/#/details-PIA00088.html','SCIGOVIMAGE-NASA'); return false;" href="https://images.nasa.gov/#/details-PIA00088.html"><span>Venus - Stein Triplet <span class="hlt">Crater</span></span></a></p> <p><a target="_blank" href="https://images.nasa.gov/">NASA Image and Video Library</a></p> <p></p> <p>1996-01-29</p> <p>NASA Magellan synthetic aperture radar SAR imaged this unique triplet <span class="hlt">crater</span>, or <span class="hlt">crater</span> field during orbits 418-421 on Sept. 21, 1990. The three <span class="hlt">craters</span> appear to have relatively steep walls. http://photojournal.jpl.nasa.gov/catalog/PIA00088</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://images.nasa.gov/#/details-PIA22462.html','SCIGOVIMAGE-NASA'); return false;" href="https://images.nasa.gov/#/details-PIA22462.html"><span>A New Impact <span class="hlt">Crater</span></span></a></p> <p><a target="_blank" href="https://images.nasa.gov/">NASA Image and Video Library</a></p> <p></p> <p>2018-05-29</p> <p>NASA's Mars Reconnaissance Orbiter (MRO) keeps finding new impact sites on Mars. This one occurred within the dense secondary <span class="hlt">crater</span> field of Corinto <span class="hlt">Crater</span>, to the north-northeast. The new <span class="hlt">crater</span> and its ejecta have distinctive color patterns. Once the colors have faded in a few decades, this new <span class="hlt">crater</span> will still be distinctive compared to the secondaries by having a deeper cavity compared to its diameter. https://photojournal.jpl.nasa.gov/catalog/PIA22462</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70193297','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70193297"><span><span class="hlt">Subsidence</span> Induced by Underground Extraction</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Galloway, Devin L.</p> <p>2016-01-01</p> <p><span class="hlt">Subsidence</span> induced by underground extraction is a class of human-induced (anthropogenic) land <span class="hlt">subsidence</span> that principally is caused by the withdrawal of subsurface fluids (groundwater, oil, and gas) or by the underground mining of coal and other minerals.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19940011795','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19940011795"><span>A first-order model for impact <span class="hlt">crater</span> degradation on Venus</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Izenberg, Noam R.; Arvidson, Raymond E.; Phillips, Roger J.</p> <p>1993-01-01</p> <p>A first-order impact <span class="hlt">crater</span> aging model is presented based on observations of the global <span class="hlt">crater</span> population of Venus. The total population consists of 879 <span class="hlt">craters</span> found over the approximately 98 percent of the planet that has been mapped by the Magellan spacecraft during the first three cycles of its mission. The model is based upon three primary aspects of venusian impact <span class="hlt">craters</span>: (1) extended ejecta deposits (EED's); (<span class="hlt">2</span>) <span class="hlt">crater</span> rims and continuous ejecta deposits; and (3) <span class="hlt">crater</span> interiors and floors.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19780033374&hterms=Two+planets+moon&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3DTwo%2Bplanets%2Bmoon.','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19780033374&hterms=Two+planets+moon&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3DTwo%2Bplanets%2Bmoon."><span>Moon-Mercury - Relative preservation states of secondary <span class="hlt">craters</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Scott, D. H.</p> <p>1977-01-01</p> <p>Geologic studies including mapping of the Kuiper quadrangle of Mercury suggest that secondary <span class="hlt">craters</span> are much better preserved than those on the moon. Factors which may account for the apparent differences between lunar and Mercurian secondary <span class="hlt">crater</span> morphology include: (1) the rapid isostatic adjustment of the parent <span class="hlt">crater</span>, (<span class="hlt">2</span>) different impact fluxes of the two planets, (3) the greater concentration of Mercurian secondaries around impact areas, and (4) differences in <span class="hlt">crater</span> ejection velocities. It has been shown that the ejection velocities on Mercury are about 50% greater than those on the moon at equivalent ranges. This may account for morphologically enhanced secondary <span class="hlt">craters</span>, and may explain their better preservation with time.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011P%26SS...59..111S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011P%26SS...59..111S"><span>MA130301GT catalogue of Martian impact <span class="hlt">craters</span> and advanced evaluation of <span class="hlt">crater</span> detection algorithms using diverse topography and image datasets</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Salamunićcar, Goran; Lončarić, Sven; Pina, Pedro; Bandeira, Lourenço; Saraiva, José</p> <p>2011-01-01</p> <p>Recently, all the <span class="hlt">craters</span> from the major currently available manually assembled catalogues have been merged into the catalogue with 57 633 known Martian impact <span class="hlt">craters</span> (MA57633GT). In addition, the work on <span class="hlt">crater</span> detection algorithm (CDA), developed to search for still uncatalogued impact <span class="hlt">craters</span> using 1/128° MOLA data, resulted in MA115225GT. In parallel with this work another CDA has been developed which resulted in the Stepinski catalogue containing 75 919 <span class="hlt">craters</span> (MA75919T). The new MA130301GT catalogue presented in this paper is the result of: (1) overall merger of MA115225GT and MA75919T; (<span class="hlt">2</span>) 2042 additional <span class="hlt">craters</span> found using Shen-Castan based CDA from the previous work and 1/128° MOLA data; and (3) 3129 additional <span class="hlt">craters</span> found using CDA for optical images from the previous work and selected regions of 1/256° MDIM, 1/256° THEMIS-DIR, and 1/256° MOC datasets. All <span class="hlt">craters</span> from MA130301GT are manually aligned with all used datasets. For all the <span class="hlt">craters</span> that originate from the used catalogues (Barlow, Rodionova, Boyce, Kuzmin, Stepinski) we integrated all the attributes available in these catalogues. With such an approach MA130301GT provides everything that was included in these catalogues, plus: (1) the correlation between various morphological descriptors from used catalogues; (<span class="hlt">2</span>) the correlation between manually assigned attributes and automated depth/diameter measurements from MA75919T and our CDA; (3) surface dating which has been improved in resolution globally; (4) average errors and their standard deviations for manually and automatically assigned attributes such as position coordinates, diameter, depth/diameter ratio, etc.; and (5) positional accuracy of features in the used datasets according to the defined coordinate system referred to as MDIM <span class="hlt">2</span>.1, which incorporates 1232 globally distributed ground control points, while our catalogue contains 130 301 cross-references between each of the used datasets. Global completeness of MA130301GT is up to</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19930005181','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19930005181"><span>Impact <span class="hlt">craters</span> on Venus: An overview from Magellan observations</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Schaber, G. G.; Strom, R. G.; Moore, H. J.; Soderblom, L. A.; Kirk, R. L.; Chadwick, D. J.; Dawson, D. D.; Gaddis, L. R.; Boyce, J. M.; Russell, J.</p> <p>1992-01-01</p> <p>Magellan has revealed an ensemble of impact <span class="hlt">craters</span> on Venus that is unique in many important ways. We have compiled a database describing 842 <span class="hlt">craters</span> on 89 percent of the planet's surface mapped through orbit 2578 (the <span class="hlt">craters</span> range in diameter from 1.5 to 280 km). We have studied the distribution, size-frequency, morphology, and geology of these <span class="hlt">craters</span> both in aggregate and, for some <span class="hlt">craters</span>, in more detail. We have found the following: (1) the spatial distribution of <span class="hlt">craters</span> is highly uniform; (<span class="hlt">2</span>) the size-density distribution of <span class="hlt">craters</span> with diameters greater than or equal to 35 km is consistent with a 'production' population having a surprisingly young age of about 0.5 Ga (based on the estimated population of Venus-crossing asteroids); (3) the spectrum of <span class="hlt">crater</span> modification differs greatly from that on other planets--62 percent of all <span class="hlt">craters</span> are pristine, only 4 percent volcanically embayed, and the remainder affected by tectonism, but none are severely and progressively depleted based on size-density distribution extrapolated from larger <span class="hlt">craters</span>; (4) large <span class="hlt">craters</span> have a progression of morphologies generally similar to those on other planets, but small <span class="hlt">craters</span> are typically irregular or multiple rather than bowl shaped; (5) diffuse radar-bright or -dark features surround some <span class="hlt">craters</span>, and about 370 similar diffuse 'splotches' with no central <span class="hlt">crater</span> are observed whose size-density distribution is similar to that of small <span class="hlt">craters</span>; and (6) other features unique to Venus include radar-bright or -dark parabolic arcs opening westward and extensive outflows originating in <span class="hlt">crater</span> ejecta.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ca.water.usgs.gov/mojave/mojave-subsidence-2004-2009.html','USGSPUBS'); return false;" href="https://ca.water.usgs.gov/mojave/mojave-subsidence-2004-2009.html"><span><span class="hlt">Subsidence</span> (2004-2009) in and near lakebeds of the Mojave River and Morongo groundwater basins, southwest Mojave Desert, California</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Solt, Mike; Sneed, Michelle</p> <p>2014-01-01</p> <p><span class="hlt">Subsidence</span>, in the vicinity of dry lakebeds, within the Mojave River and Morongo groundwater basins of the southwest Mojave Desert has been measured by Interferometric Synthetic Aperture Radar (InSAR). The investigation has focused on determining the location, extent, and magnitude of changes in land-surface elevation. In addition, the relation of changes in land-surface elevation to changes in groundwater levels and lithology was explored. This report is the third in a series of reports investigating land-surface elevation changes in the Mojave and Morongo Groundwater Basins, California. The first report, <span class="hlt">U</span>.S. Geological Survey (USGS) Water-Resources Investigations Report 03-4015 by Sneed and others (2003), describes historical <span class="hlt">subsidence</span> and groundwater-level changes in the southwest Mojave Desert from 1969 to 1999. The second report, <span class="hlt">U</span>.S. Geological Survey Water-Resources Investigations Report 07-5097, an online interactive report and map, by Sneed and Brandt (2007), describes <span class="hlt">subsidence</span> and groundwater-level changes in the southwest Mojave Desert from 1999 to 2004. The purpose of this report is to document an updated assessment of <span class="hlt">subsidence</span> in these lakebeds and selected neighboring areas from 2004 to 2009 as measured by InSAR methods. In addition, continuous Global Positioning System (GPS)(2005-10), groundwater level (1951-2010), and lithologic data, if available, were used to characterize compaction mechanisms in these areas. The USGS California Water Science Center’s interactive website for the Mojave River and Morongo groundwater basins was created to centralize information pertaining to land <span class="hlt">subsidence</span> and water levels and to allow readers to access available data and related reports online. An interactive map of land <span class="hlt">subsidence</span> and water levels in the Mojave River and Morongo groundwater basins displays InSAR interferograms, <span class="hlt">subsidence</span> areas, <span class="hlt">subsidence</span> contours, hydrographs, well information, and water-level contours. Background information, including</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=PIA04436&hterms=block+chain&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dblock%2Bchain','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=PIA04436&hterms=block+chain&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dblock%2Bchain"><span><span class="hlt">Crater</span> Chains</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>2003-01-01</p> <p><p/> [figure removed for brevity, see original site] <p/>The large <span class="hlt">crater</span> at the top of this THEMIS visible image has several other <span class="hlt">craters</span> inside of it. Most noticeable are the <span class="hlt">craters</span> that form a 'chain' on the southern wall of the large <span class="hlt">crater</span>. These <span class="hlt">craters</span> are a wonderful example of secondary impacts. They were formed when large blocks of ejecta from an impact crashed back down onto the surface of Mars. Secondaries often form radial patterns around the impact <span class="hlt">crater</span> that generated them, allowing researchers to trace them back to their origin.<p/>Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.<p/>NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.<p/>Image information: VIS instrument. Latitude 19.3, Longitude 347.5 East (12.5 West). 19 meter/pixel resolution.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=PIA08783&hterms=duck&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dduck','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=PIA08783&hterms=duck&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dduck"><span>'Victoria <span class="hlt">Crater</span>' from 'Duck Bay'</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>2006-01-01</p> <p><p/> NASA's Mars rover Opportunity edged 3.7 meters (12 feet) closer to the top of the 'Duck Bay' alcove along the rim of 'Victoria <span class="hlt">Crater</span>' during the rover's 952nd Martian day, or sol (overnight Sept. 27 to Sept. 28), and gained this vista of the <span class="hlt">crater</span>. The rover's navigation camera took the seven exposures combined into this mosaic view of the <span class="hlt">crater</span>'s interior. This <span class="hlt">crater</span> has been the mission's long-term destination for the past 21 Earth months. <p/> The far side of the <span class="hlt">crater</span> is about 800 meters (one-half mile) away. The rim of the <span class="hlt">crater</span> is composed of alternating promontories, rocky points towering approximately 70 meters (230 feet) above the <span class="hlt">crater</span> floor, and recessed alcoves, such as Duck Bay. The bottom of the <span class="hlt">crater</span> is covered by sand that has been shaped into ripples by the Martian wind. The rocky cliffs in the foreground have been informally named 'Cape Verde,' on the left, and 'Cabo Frio,' on the right. <p/> Victoria <span class="hlt">Crater</span> is about five times wider than 'Endurance <span class="hlt">Crater</span>,' which Opportunity spent six months examining in 2004, and about 40 times wider than 'Eagle <span class="hlt">Crater</span>,' where Opportunity first landed. The great lure of Victoria is an expectation that the thick stack of geological layers exposed in the <span class="hlt">crater</span> walls could reveal the record of past environmental conditions over a much greater span of time than Opportunity has read from rocks examined earlier in the mission. <p/> This view is presented as a cylindrical projection with geometric seam correction.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70001640','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70001640"><span>Relationship between <span class="hlt">subsidence</span> and volcanic load, Hawaii</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Moore, J.G.</p> <p>1970-01-01</p> <p>A computer analysis of tide-gage records in the northeast Pacific indicates that the active volcanic islands of eastern Hawaii are <span class="hlt">subsiding</span> at a rate considerably faster than the eustatic rise of sea level. The rate of absolute <span class="hlt">subsidence</span> increases progressively toward the center of current activity on the Island of Hawaii. Honolulu, Oahu, appears to be stable; Kahului, Maui, is <span class="hlt">subsiding</span> at 1.7 mm per year; and Hilo, Hawaii, is <span class="hlt">subsiding</span> at 4.8 mm per year. This <span class="hlt">subsidence</span> is apparently related to downbowing of the crust throughout a zone 400 km in diameter by the weight of volcanic material added to the crust by active volcanoes, principally Mauna Loa and Kilauea on the Island of Hawaii. The Hawaiian Arch encircles the <span class="hlt">subsiding</span> zone and may be uplifted by material moving down and outward from the zone of <span class="hlt">subsidence</span>. The annual volume of <span class="hlt">subsidence</span> is about 270??106 m3, whereas the average annual volume of erupted basalt on the Island of Hawaii (based on historic records back to about 1820) is about 50??106 m3. The great excess of <span class="hlt">subsidence</span> over volcanic addition cannot be reconciled by isostatic models, and is apparently the result of other processes operating in the volcano and its basement thet are poorly understood. Probably the more important of these processes are intrusions and submarine volcanism, both of which are providing additional unseen load on the volcanoes. Furthermore, the rate of eruption may be uplifted by material moving down and outward from the zone of <span class="hlt">subsidence</span> may be overestimated due to localized downslope movement of the margins of the islands. ?? 1970 Stabilimento Tipografico Francesco Giannini & Figli.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70019214','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70019214"><span>The phanerozoic impact <span class="hlt">cratering</span> rate: Evidence from the farside of the Moon</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>McEwen, A.S.; Moore, Johnnie N.; Shoemaker, E.M.</p> <p>1997-01-01</p> <p>The relatively recent (< 1 b.y.) flux of asteroids and comets forming large <span class="hlt">craters</span> on the Earth and Moon may be accurately recorded by <span class="hlt">craters</span> with bright rays on the Moon's farside. Many previously unknown farside rayed <span class="hlt">craters</span> are clearly distinguished in the low-phase-angle images returned by the Clementine spacecraft. Some large rayed <span class="hlt">craters</span> on the lunar nearside are probably significantly older than 1 Ga; rays remain visible over the maria due to compositional contrasts long after soils have reached optical maturity. Most of the farside crust has a more homogeneous composition and only immature rays are visible. The size-frequency distribution of farside rayed <span class="hlt">craters</span> is similar to that measured for Eratosthenian <span class="hlt">craters</span> (up to 3.<span class="hlt">2</span> b.y.) at diameters larger than 15 km. The areal density of farside rayed <span class="hlt">craters</span> matches that of a corrected tabulation of nearside Copernican <span class="hlt">craters</span>. Hence the presence of bright rays due to immature soils around large <span class="hlt">craters</span> provides a consistent time-stratigraphic basis for defining the base of the Copernican System. The density of large <span class="hlt">craters</span> less than ???3.<span class="hlt">2</span> b.y. old is ???3.<span class="hlt">2</span> times higher than that of large farside rayed <span class="hlt">craters</span> alone. This observation can be interpreted in two ways: (1) the average <span class="hlt">cratering</span> rate has been constant over the past 3.<span class="hlt">2</span> b.y. and the base of the Copernican is ???1 Ga, or (<span class="hlt">2</span>) the <span class="hlt">cratering</span> rate has increased in recent geologic time and the base of the Copernican is less than 1 Ga. We favor the latter interpretation because the rays of Copernicus (800-850 m.y. old) appear to be very close to optical maturity, suggesting that the average Copernican <span class="hlt">cratering</span> rate was ???35% higher than the average Eratosthenian rate. Other lines of evidence for an increase in the Phanerozoic (545 Ga) <span class="hlt">cratering</span> rate are (1) the densities of small <span class="hlt">craters</span> superimposed on Copernicus and Apollo landing sites, (<span class="hlt">2</span>) the rates estimated from well-dated terrestrial <span class="hlt">craters</span> (??? 120 m.y.) and from present-day astronomical</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19890008969','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19890008969"><span>Absolute ages from <span class="hlt">crater</span> statistics: Using radiometric ages of Martian samples for determining the Martian <span class="hlt">cratering</span> chronology</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Neukum, G.</p> <p>1988-01-01</p> <p>In the absence of dates derived from rock samples, impact <span class="hlt">crater</span> frequencies are commonly used to date Martian surface units. All models for absolute dating rely on the lunar <span class="hlt">cratering</span> chronology and on the validity of its extrapolation to Martian conditions. Starting from somewhat different lunar chronologies, rather different Martian <span class="hlt">cratering</span> chronologies are found in the literature. Currently favored models are compared. The differences at old ages are significant, the differences at younger ages are considerable and give absolute ages for the same <span class="hlt">crater</span> frequencies as different as a factor of 3. The total uncertainty could be much higher, though, since the ratio of lunar to Martian <span class="hlt">cratering</span> rate which is of basic importance in the models is believed to be known no better than within a factor of <span class="hlt">2</span>. Thus, it is of crucial importance for understanding the the evolution of Mars and determining the sequence of events to establish an unambiguous Martian <span class="hlt">cratering</span> chronology from <span class="hlt">crater</span> statistics in combination with clean radiometric ages of returned Martian samples. For the dating goal, rocks should be as pristine as possible from a geologically simple area with a one-stage emplacement history of the local formation. A minimum of at least one highland site for old ages, two intermediate-aged sites, and one very young site is needed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20090041760','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20090041760"><span>Processing Images of <span class="hlt">Craters</span> for Spacecraft Navigation</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Cheng, Yang; Johnson, Andrew E.; Matthies, Larry H.</p> <p>2009-01-01</p> <p>A <span class="hlt">crater</span>-detection algorithm has been conceived to enable automation of what, heretofore, have been manual processes for utilizing images of <span class="hlt">craters</span> on a celestial body as landmarks for navigating a spacecraft flying near or landing on that body. The images are acquired by an electronic camera aboard the spacecraft, then digitized, then processed by the algorithm, which consists mainly of the following steps: 1. Edges in an image detected and placed in a database. <span class="hlt">2</span>. <span class="hlt">Crater</span> rim edges are selected from the edge database. 3. Edges that belong to the same <span class="hlt">crater</span> are grouped together. 4. An ellipse is fitted to each group of <span class="hlt">crater</span> edges. 5. Ellipses are refined directly in the image domain to reduce errors introduced in the detection of edges and fitting of ellipses. 6. The quality of each detected <span class="hlt">crater</span> is evaluated. It is planned to utilize this algorithm as the basis of a computer program for automated, real-time, onboard processing of <span class="hlt">crater</span>-image data. Experimental studies have led to the conclusion that this algorithm is capable of a detection rate >93 percent, a false-alarm rate <5 percent, a geometric error <0.5 pixel, and a position error <0.3 pixel.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://images.nasa.gov/#/details-PIA21915.html','SCIGOVIMAGE-NASA'); return false;" href="https://images.nasa.gov/#/details-PIA21915.html"><span>Kokopelli <span class="hlt">Crater</span> on Ceres</span></a></p> <p><a target="_blank" href="https://images.nasa.gov/">NASA Image and Video Library</a></p> <p></p> <p>2017-12-14</p> <p>This image obtained by NASA's Dawn spacecraft shows a field of small <span class="hlt">craters</span> next to Kokopelli <span class="hlt">Crater</span>, seen at bottom right in this image, on dwarf planet Ceres. The small <span class="hlt">craters</span> overlay a smooth, wavy material that represents ejecta from nearby Dantu <span class="hlt">Crater</span>. The small <span class="hlt">craters</span> were formed by blocks ejected in the Dantu impact event, and likely from the Kokopelli impact as well. Kokopelli is named after the fertility deity who presides over agriculture in the tradition of the Pueblo people from the southwestern United States. The <span class="hlt">crater</span> measures 21 miles (34 kilometers) in diameter. Dawn took this image during its first extended mission on August 11, 2016, from its low-altitude mapping orbit, at about 240 miles (385 kilometers) above the surface. The center coordinates of this image are 20 degrees north latitude, 123 degrees east longitude. https://photojournal.jpl.nasa.gov/catalog/PIA21915</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19940016252&hterms=origin+military&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dorigin%2Bmilitary','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19940016252&hterms=origin+military&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dorigin%2Bmilitary"><span>Named Venusian <span class="hlt">craters</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Russell, Joel F.; Schaber, Gerald G.</p> <p>1993-01-01</p> <p>Schaber et al. compiled a database of 841 <span class="hlt">craters</span> on Venus, based on Magellan coverage of 89 percent of the planet's surface. That database, derived from coverage of approximately 98 percent of Venus' surface, has been expanded to 912 <span class="hlt">craters</span>, ranging in diameter from 1.5 to 280 km. About 150 of the larger <span class="hlt">craters</span> were previously identified by Pioneer Venus and Soviet Venera projects and subsequently formally named by the International Astronomical Union (IAU). Altogether, the <span class="hlt">crater</span> names submitted to the IAU for approval to date number about 550, a little more than half of the number of <span class="hlt">craters</span> identified on Magellan images. The IAU will consider more names as they are submitted for approval. Anyone--planetary scientist or layman--may submit names; however, candidate names must conform to IAU rules. The person to be honored must be deceased for at least three years, must not be a religious figure or a military or political figure of the 19th or 20th century, and, for Venus, must be a woman. All formally and provisionally approved names for Venusian impact <span class="hlt">craters</span>, along with their latitude, longitude, size, and origin of their name, will be presented at LPSC and will be available as handouts.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017Icar..287..187R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017Icar..287..187R"><span><span class="hlt">Craters</span> of the Pluto-Charon system</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Robbins, Stuart J.; Singer, Kelsi N.; Bray, Veronica J.; Schenk, Paul; Lauer, Tod R.; Weaver, Harold A.; Runyon, Kirby; McKinnon, William B.; Beyer, Ross A.; Porter, Simon; White, Oliver L.; Hofgartner, Jason D.; Zangari, Amanda M.; Moore, Jeffrey M.; Young, Leslie A.; Spencer, John R.; Binzel, Richard P.; Buie, Marc W.; Buratti, Bonnie J.; Cheng, Andrew F.; Grundy, William M.; Linscott, Ivan R.; Reitsema, Harold J.; Reuter, Dennis C.; Showalter, Mark R.; Tyler, G. Len; Olkin, Catherine B.; Ennico, Kimberly S.; Stern, S. Alan; New Horizons Lorri, Mvic Instrument Teams</p> <p>2017-05-01</p> <p>NASA's New Horizons flyby mission of the Pluto-Charon binary system and its four moons provided humanity with its first spacecraft-based look at a large Kuiper Belt Object beyond Triton. Excluding this system, multiple Kuiper Belt Objects (KBOs) have been observed for only 20 years from Earth, and the KBO size distribution is unconstrained except among the largest objects. Because small KBOs will remain beyond the capabilities of ground-based observatories for the foreseeable future, one of the best ways to constrain the small KBO population is to examine the <span class="hlt">craters</span> they have made on the Pluto-Charon system. The first step to understanding the <span class="hlt">crater</span> population is to map it. In this work, we describe the steps undertaken to produce a robust <span class="hlt">crater</span> database of impact features on Pluto, Charon, and their two largest moons, Nix and Hydra. These include an examination of different types of images and image processing, and we present an analysis of variability among the <span class="hlt">crater</span> mapping team, where <span class="hlt">crater</span> diameters were found to average ± 10% uncertainty across all sizes measured (∼0.5-300 km). We also present a few basic analyses of the <span class="hlt">crater</span> databases, finding that Pluto's <span class="hlt">craters</span>' differential size-frequency distribution across the encounter hemisphere has a power-law slope of approximately -3.1 ± 0.1 over diameters D ≈ 15-200 km, and Charon's has a slope of -3.0 ± 0.<span class="hlt">2</span> over diameters D ≈ 10-120 km; it is significantly shallower on both bodies at smaller diameters. We also better quantify evidence of resurfacing evidenced by Pluto's <span class="hlt">craters</span> in contrast with Charon's. With this work, we are also releasing our database of potential and probable impact <span class="hlt">craters</span>: 5287 on Pluto, 2287 on Charon, 35 on Nix, and 6 on Hydra.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20170007522&hterms=ross&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAuthor-Name%26N%3D0%26No%3D10%26Ntt%3DWill%2Bross','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20170007522&hterms=ross&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAuthor-Name%26N%3D0%26No%3D10%26Ntt%3DWill%2Bross"><span><span class="hlt">Craters</span> of the Pluto-Charon System</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Robbins, Stuart J.; Singer, Kelsi N.; Bray, Veronica J.; Schenk, Paul; Lauer, Todd R.; Weaver, Harold A.; Runyon, Kirby; Mckinnon, William B.; Beyer, Ross A.; Porter, Simon; <a style="text-decoration: none; " href="javascript:void(0); " onClick="displayelement('author_20170007522'); toggleEditAbsImage('author_20170007522_show'); toggleEditAbsImage('author_20170007522_hide'); "> <img style="display:inline; width:12px; height:12px; " src="images/arrow-up.gif" width="12" height="12" border="0" alt="hide" id="author_20170007522_show"> <img style="width:12px; height:12px; display:none; " src="images/arrow-down.gif" width="12" height="12" border="0" alt="hide" id="author_20170007522_hide"></p> <p>2016-01-01</p> <p>NASA's New Horizons flyby mission of the Pluto-Charon binary system and its four moons provided humanity with its first spacecraft-based look at a large Kuiper Belt Object beyond Triton. Excluding this system, multiple Kuiper Belt Objects (KBOs) have been observed for only 20 years from Earth, and the KBO size distribution is unconstrained except among the largest objects. Because small KBOs will remain beyond the capabilities of ground-based observatories for the foreseeable future, one of the best ways to constrain the small KBO population is to examine the <span class="hlt">craters</span> they have made on the Pluto-Charon system. The first step to understanding the <span class="hlt">crater</span> population is to map it. In this work, we describe the steps undertaken to produce a robust <span class="hlt">crater</span> database of impact features on Pluto, Charon, and their two largest moons, Nix and Hydra. These include an examination of different types of images and image processing, and we present an analysis of variability among the <span class="hlt">crater</span> mapping team, where <span class="hlt">crater</span> diameters were found to average +/-10% uncertainty across all sizes measured (approx.0.5-300 km). We also present a few basic analyses of the <span class="hlt">crater</span> databases, finding that Pluto's <span class="hlt">craters</span>' differential size-frequency distribution across the encounter hemisphere has a power-law slope of approximately -3.1 +/- 0.1 over diameters D approx. = 15-200 km, and Charon's has a slope of -3.0 +/- 0.<span class="hlt">2</span> over diameters D approx. = 10-120 km; it is significantly shallower on both bodies at smaller diameters. We also better quantify evidence of resurfacing evidenced by Pluto's <span class="hlt">craters</span> in contrast with Charon's. With this work, we are also releasing our database of potential and probable impact <span class="hlt">craters</span>: 5287 on Pluto, 2287 on Charon, 35 on Nix, and 6 on Hydra.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006DPS....38.3015B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006DPS....38.3015B"><span>Interior and Ejecta Morphologies of Impact <span class="hlt">Craters</span> on Ganymede</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Barlow, Nadine G.; Klaybor, K.; Katz-Wigmore, J.</p> <p>2006-09-01</p> <p>We are utilizing Galileo SSI imagery of Ganymede to classify impact <span class="hlt">crater</span> interior and ejecta morphologies. Although we are in the early stages of compiling our Catalog of Impact <span class="hlt">Craters</span> on Ganymede, some interesting trends are beginning to emerge. Few <span class="hlt">craters</span> display obvious ejecta morphologies, but 68 <span class="hlt">craters</span> are classified as single layer ejecta and 3 as double layer ejecta. We see no obvious correlation of layered ejecta morphologies with terrain or latitude. All layered ejecta <span class="hlt">craters</span> have diameters between 10 and 40 km. Sinuosity ("lobateness") and ejecta extent ("ejecta mobility ratio") of Ganymede layered ejecta <span class="hlt">craters</span> are lower than for martian layered ejecta <span class="hlt">craters</span>. This suggests less mobility of ejecta materials on Ganymede, perhaps due to the colder temperatures. Interior structures being investigated include central domes, peaks, and pits. 57 dome <span class="hlt">craters</span>, 212 central peak <span class="hlt">craters</span>, and 313 central pit <span class="hlt">craters</span> have been identified. Central domes occur in 50-100 km diameter <span class="hlt">craters</span> while peaks are found in <span class="hlt">craters</span> between 20 and 50 km and central pit <span class="hlt">craters</span> range between 29 and 74 km in diameter. The Galileo Regio region displays higher concentrations of central dome and central pit <span class="hlt">craters</span> than other regions we have investigated. 67% of central pit <span class="hlt">craters</span> studied to date are small pits, where the ratio of pit diameter to <span class="hlt">crater</span> diameter is <0.<span class="hlt">2</span>. <span class="hlt">Craters</span> containing the three interior structures preferentially occur on darker terrain units, suggesting that an ice-silicate composition is more conducive to interior feature formation than pure ice alone. Results of this study have important implications not only for the formation of specific interior and ejecta morphologies on Ganymede but also for analogous features associated with Martian impact <span class="hlt">craters</span>. This research is funded through NASA Outer Planets Research Program Award #NNG05G116G to N. G. Barlow.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li class="active"><span>13</span></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_13 --> <div id="page_14" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li class="active"><span>14</span></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="261"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016Icar..266...44S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016Icar..266...44S"><span>Geomorphology of Lowell <span class="hlt">crater</span> region on the Moon</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Srivastava, N.; Varatharajan, I.</p> <p>2016-03-01</p> <p>Surface topography, surface morphology and <span class="hlt">crater</span> chronology studies have been carried out for the Lowell <span class="hlt">crater</span> region (occupying ∼198 × 198 km<span class="hlt">2</span> in the northwestern quadrant of the Orientale basin) using Kaguya TC-DTM, LRO-WAC data, and Chandrayaan-1 M3-750 nm image, to characterize and date Lowell impact event and to identify and assess the geological importance of the Lowell <span class="hlt">crater</span> and effect of pre-existing geological conditions on the present day appearance of Lowell <span class="hlt">crater</span>. The Lowell <span class="hlt">crater</span> has been found to be polygonal in shape with an average diameter of 69.03 km. Its average rim height and depth from pre-existing surface are 1.02 km and <span class="hlt">2</span>.82 km respectively. A prominent central peak with average height of 1.77 km above the <span class="hlt">crater</span> floor is present, which could have exposed undifferentiated mantle rocks. The peak exhibits a pronounced ;V; shaped slumped zone on the eastern side and a distinct ;V; shaped depression in the adjacent region on the <span class="hlt">crater</span> floor. Several other peculiarities noticed and mapped here include W-E asymmetry in the degree of slumping of the walls and height of the topographic rim, N-S asymmetry in the proximal ejecta distribution with most of the material lying in the northern direction, concentration of exterior melt pools in the northeastern direction only, presence of several cross cutting pre-existing lineaments on the <span class="hlt">crater</span> walls, presence of a superposed rayed <span class="hlt">crater</span> on the eastern wall, and a geologically interesting resurfaced unit, which could be an outcome of recent volcanic activity in the region. It has been inferred that the Lowell <span class="hlt">crater</span> formed due to impact of a ∼5.7 km diameter bolide in the Montes Rook region. The impact occurred at an angle of ∼30-45° from the S-SW direction. The age of the Lowell <span class="hlt">crater</span> has been estimated as 374 ± 28 Ma, therefore it is a Younger Copernican <span class="hlt">crater</span> consistent with the possibility expressed by McEwen et al. (McEwen, A.S., et al. [1993]. J. Geophys. Res. 98(E9), 17207</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20150002922','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20150002922"><span>Investigating CO<span class="hlt">2</span> Reservoirs at Gale <span class="hlt">Crater</span> and Evidence for a Dense Early Atmosphere</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Niles, P. B.; Archer, P. D.; Heil, E.; Eigenbrode, J.; McAdam, A.; Sutter, B.; Franz, H.; Navarro-Gonzalez, R.; Ming, D.; Mahaffy, P. R.; <a style="text-decoration: none; " href="javascript:void(0); " onClick="displayelement('author_20150002922'); toggleEditAbsImage('author_20150002922_show'); toggleEditAbsImage('author_20150002922_hide'); "> <img style="display:inline; width:12px; height:12px; " src="images/arrow-up.gif" width="12" height="12" border="0" alt="hide" id="author_20150002922_show"> <img style="width:12px; height:12px; display:none; " src="images/arrow-down.gif" width="12" height="12" border="0" alt="hide" id="author_20150002922_hide"></p> <p>2015-01-01</p> <p>One of the most compelling features of the Gale landing site is its age. Based on <span class="hlt">crater</span> counts, the formation of Gale <span class="hlt">crater</span> is dated to be near the beginning of the Hesperian near the pivotal Hesperian/Noachian transition. This is a time period on Mars that is linked to increased fluvial activity through valley network formation and also marks a transition from higher erosion rates/clay mineral formation to lower erosion rates with mineralogies dominated by sulfate minerals. Results from the Curiosity mission have shown extensive evidence for fluvial activity within the <span class="hlt">crater</span> suggesting that sediments on the floor of the <span class="hlt">crater</span> and even sediments making up Mt. Sharp itself were the result of longstanding activity of liquid water. Warm/wet conditions on early Mars are likely due to a thicker atmosphere and increased abundance of greenhouse gases including the main component of the atmosphere, CO<span class="hlt">2</span>. Carbon dioxide is minor component of the Earth's atmosphere yet plays a major role in surface water chemistry, weathering, and formation of secondary minerals. An ancient martian atmosphere was likely dominated by CO<span class="hlt">2</span> and any waters in equilibrium with this atmosphere would have different chemical characteristics. Studies have noted that high partial pressures of CO<span class="hlt">2</span> would result in increased carbonic acid formation and lowering of the pH so that carbonate minerals are not stable. However, if there were a dense CO<span class="hlt">2</span> atmosphere present at the Hesperian/Noachian transition, it would have to be stored in a carbon reservoir on the surface or lost to space. The Mt. Sharp sediments are potentially one of the best places on Mars to investigate these CO<span class="hlt">2</span> reservoirs as they are proposed to have formed in the early Hesperian, from an alkaline lake, and record the transition to an aeolian dominated regime near the top of the sequence. The total amount of CO<span class="hlt">2</span> in the Gale <span class="hlt">crater</span> soils and sediments is significant but lower than expected if a thick atmosphere was present at the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1992Metic..27R.276P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1992Metic..27R.276P"><span>Meteorite Sterlitamak -- A New <span class="hlt">Crater</span> Forming Fall</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Petaev, M. I.</p> <p>1992-07-01</p> <p>The Sterlitamak meteorite fell on May 17, 1990 at 23h20m local time (17h20m GMT) and formed a <span class="hlt">crater</span> in a field 20 km westward of the town of Sterlitamak (Petaev et al., 1991). Many witnesses in South Bashkiria saw a very bright fireball (up to -5 magnitude) moving from south to north at a ~45 degree angle to the horizon. Witnesses located ~<span class="hlt">2</span> km from the <span class="hlt">crater</span> observed the fireball glowing right up to the time of impact, after which several explosions were heard. The <span class="hlt">crater</span> was found on May 19. From witnesses' reports, the fresh <span class="hlt">crater</span> was 4.5-5 m in depth and had sheer walls ~3 m in height below which was a conical talus surface with a hole in the center. The <span class="hlt">crater</span> itself was surrounded by a continuous rim 60-70 cm in thickness and by radial ejecta. Our field team arrived at the <span class="hlt">crater</span> on May 23, six days after its formation. We found the <span class="hlt">crater</span> in rather good condition except for partial collapse of the rim, material from which had filled in the <span class="hlt">crater</span> up to ~3 m from the surface. The western wall of the <span class="hlt">crater</span> was composed of well-preserved brown loam with shale- like parting dipping 25-30 degrees away from the <span class="hlt">crater</span> center. A large slip block of autogenic breccia was observed along the eastern <span class="hlt">crater</span> wall. An allogenic breccia composed of a mixture of brown loam and black soil was traced to the depth of ~5 m from the surface. Outside the rim, the <span class="hlt">crater</span> ejecta formed an asymmetric continuous blanket and distinct radial rays. The southern rays were shorter and thicker than the northern and eastern rays. About <span class="hlt">2</span> dozen meteorite fragments, from several grams to several hundred grams in weight, were recovered in the <span class="hlt">crater</span> vicinity. A search for other meteorite fragments or individuals at distances up to 1 km southward from the <span class="hlt">crater</span> was unsuccessful. Two partly encrusted fragments (3 and 6 kg) with clear Widmanstatten pattern on a broken surface were found at a depth of ~8 m during <span class="hlt">crater</span> excavation. In May of 1991 a 315-kg partly fragmented individual was</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009AGUFM.H21B0838Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009AGUFM.H21B0838Z"><span>Data Acquisition for Land <span class="hlt">Subsidence</span> Control</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zhu, Y.; Balke, K.</p> <p>2009-12-01</p> <p>For controlling land <span class="hlt">subsidence</span> caused by groundwater over-exploitation, loading of engineered structures, mining and other anthropogenic activities in this fast changing world, a large variety of different data of various scales of concerning areas are needed for scientific study and administrative operational purposes. The economical, social and environmental impacts of anthropogenic land <span class="hlt">subsidence</span> have long been recognized by many scientific institutions and management authorities based on results of monitoring and analysis at an interdisciplinary level. The land <span class="hlt">subsidence</span> information systems composed of the surface and subsurface monitoring nets (monitoring and development wells, GPS stations and other facilities) and local data processing centers as a system management tool in Shanghai City was started with the use of GPS technology to monitor land <span class="hlt">subsidence</span> in 1998. After years of experiences with a set of initiatives by adopting adequate countermeasures, the particular attention given to new improved methodologies to monitor and model the process of land <span class="hlt">subsidence</span> in a simple and timely way, this is going to be promoted in the whole Yangtze River Delta region in China, where land <span class="hlt">subsidence</span> expands in the entire region of urban cluster. The Delta land <span class="hlt">subsidence</span> monitoring network construction aims to establish an efficient and coordinated water resource management system. The land <span class="hlt">subsidence</span> monitoring network records "living history" of land <span class="hlt">subsidence</span>, produces detailed scheduled reports and environmental impact statements. For the different areas with local factors and site characteristics, parallel packages need to be designed for predicting changes, land sensitivity and uncertainty analysis, especially for the risk analysis in the rapid growth of megacities and urban areas. In such cases, the new models with new types of local data and the new ways of data acquisition provide the best information for the decision makers for their mitigating</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016A%26A...594A..52W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016A%26A...594A..52W"><span>Analytical formulation of lunar <span class="hlt">cratering</span> asymmetries</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wang, Nan; Zhou, Ji-Lin</p> <p>2016-10-01</p> <p>Context. The <span class="hlt">cratering</span> asymmetry of a bombarded satellite is related to both its orbit and impactors. The inner solar system impactor populations, that is, the main-belt asteroids (MBAs) and the near-Earth objects (NEOs), have dominated during the late heavy bombardment (LHB) and ever since, respectively. Aims: We formulate the lunar <span class="hlt">cratering</span> distribution and verify the <span class="hlt">cratering</span> asymmetries generated by the MBAs as well as the NEOs. Methods: Based on a planar model that excludes the terrestrial and lunar gravitations on the impactors and assuming the impactor encounter speed with Earth venc is higher than the lunar orbital speed vM, we rigorously integrated the lunar <span class="hlt">cratering</span> distribution, and derived its approximation to the first order of vM/venc. Numerical simulations of lunar bombardment by the MBAs during the LHB were performed with an Earth-Moon distance aM = 20-60 Earth radii in five cases. Results: The analytical model directly proves the existence of a leading/trailing asymmetry and the absence of near/far asymmetry. The approximate form of the leading/trailing asymmetry is (1 + A1cosβ), which decreases as the apex distance β increases. The numerical simulations show evidence of a pole/equator asymmetry as well as the leading/trailing asymmetry, and the former is empirically described as (1 + A<span class="hlt">2</span>cos<span class="hlt">2</span>ϕ), which decreases as the latitude modulus | ϕ | increases. The amplitudes A1,<span class="hlt">2</span> are reliable measurements of asymmetries. Our analysis explicitly indicates the quantitative relations between <span class="hlt">cratering</span> distribution and bombardment conditions (impactor properties and the lunar orbital status) like A1 ∝ vM/venc, resulting in a method for reproducing the bombardment conditions through measuring the asymmetry. Mutual confirmation between analytical model and numerical simulations is found in terms of the <span class="hlt">cratering</span> distribution and its variation with aM. Estimates of A1 for <span class="hlt">crater</span> density distributions generated by the MBAs and the NEOs are 0.101-0.159 and 0</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=PIA00472&hterms=created+halo&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dcreated%2Bhalo','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=PIA00472&hterms=created+halo&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dcreated%2Bhalo"><span>Venus - Impact <span class="hlt">Crater</span> 'Jeanne</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>1991-01-01</p> <p>This Magellan full-resolution image shows Jeanne <span class="hlt">crater</span>, a 19.5 kilometer (12 mile) diameter impact <span class="hlt">crater</span>. Jeanne <span class="hlt">crater</span> is located at 40.0 degrees north latitude and 331.4 degrees longitude. The distinctive triangular shape of the ejecta indicates that the impacting body probably hit obliquely, traveling from southwest to northeast. The <span class="hlt">crater</span> is surrounded by dark material of two types. The dark area on the southwest side of the <span class="hlt">crater</span> is covered by smooth (radar-dark) lava flows which have a strongly digitate contact with surrounding brighter flows. The very dark area on the northeast side of the <span class="hlt">crater</span> is probably covered by smooth material such as fine-grained sediment. This dark halo is asymmetric, mimicking the asymmetric shape of the ejecta blanket. The dark halo may have been caused by an atmospheric shock or pressure wave produced by the incoming body. Jeanne <span class="hlt">crater</span> also displays several outflow lobes on the northwest side. These flow-like features may have formed by fine-grained ejecta transported by a hot, turbulent flow created by the arrival of the impacting object. Alternatively, they may have formed by flow of impact melt.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=PIA01090&hterms=Top+secrets&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DTop%2Bsecrets','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=PIA01090&hterms=Top+secrets&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DTop%2Bsecrets"><span>Khensu <span class="hlt">Crater</span> on Ganymede</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>1997-01-01</p> <p>The dark-floored <span class="hlt">crater</span>, Khensu, is the target of this image of Ganymede. The solid state imaging camera on NASA's Galileo spacecraft imaged this region as it passed Ganymede during its second orbit through the Jovian system. Khensu is located at <span class="hlt">2</span> degrees latitude and 153 degrees longitude in a region of bright terrain known as Uruk Sulcus, and is about 13 kilometers (8 miles) in diameter. Like some other <span class="hlt">craters</span> on Ganymede, it possesses an unusually dark floor and a bright ejecta blanket. The dark component may be residual material from the impactor that formed the <span class="hlt">crater</span>. Another possibility is that the impactor may have punched through the bright surface to reveal a dark layer beneath.<p/>Another large <span class="hlt">crater</span> named El is partly visible in the top-right corner of the image. This <span class="hlt">crater</span> is 54 kilometers (34 miles) in diameter and has a small 'pit' in its center. <span class="hlt">Craters</span> with such a 'central pit' are common across Ganymede and are especially intriguing since they may reveal secrets about the structure of the satellite's shallow subsurface.<p/>North is to the top-left of the picture and the sun illuminates the surface from nearly overhead. The image covers an area about 100 kilometers (62 miles) by 86 kilometers (54 miles) across at a resolution of 111 meters (370 feet) per picture element. The image was taken on September 6, 1996 by the solid state imaging (CCD) system on NASA's Galileo spacecraft.<p/>The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC. JPL is an operating division of California Institute of Technology (Caltech).<p/>This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://galileo.jpl.nasa.gov.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70010364','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70010364"><span>Relative age of Camelot <span class="hlt">crater</span> and <span class="hlt">crater</span> clusters near the Apollo 17 landing site</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Lucchitta, B.K.</p> <p>1979-01-01</p> <p>Topographic profiles and depth-diameter ratios from the <span class="hlt">crater</span> Camelot and <span class="hlt">craters</span> of the central cluster in the Apollo 17 landing area suggest that these <span class="hlt">craters</span> are of the same age. Therefore, layers that can be recognized in the deep-drill core and that can be identified as ejecta deposits from Camelot or from the cluster <span class="hlt">craters</span> should yield similar emplacement ages. ?? 1979.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2005AGUFM.P23A0184B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2005AGUFM.P23A0184B"><span>Machine Identification of Martian <span class="hlt">Craters</span> Using Digital Elevation Data</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bue, B.; Stepinski, T. F.</p> <p>2005-12-01</p> <p>Impact <span class="hlt">craters</span> are among the most studied features on Martian surface. Their importance stems from the worth of information that a detailed analysis of their number and morphology can bring forth. Because building manually a comprehensive dataset of <span class="hlt">craters</span> is a laborious process, there have been many previous attempts to develop an automatic, image-based <span class="hlt">crater</span> identifier. The resulting identifiers suffer from low efficiency and remain in an experimental stage. We have developed a DEM-based, fully autonomous <span class="hlt">crater</span> identifier that takes an arbitrarily large Martian site as an input and produces a catalog of <span class="hlt">craters</span> as an output. Using the topography data we calculate a topographic profile curvature that is thresholded to produce a binary image, pixels having maximum negative curvature are labeled black, the remaining pixels are labeled white. The black pixels outline <span class="hlt">craters</span> because <span class="hlt">crater</span> rims are the most convex feature in the Martian landscape. The Hough Transform (HT) is used for an actual recognition of <span class="hlt">craters</span> in the binary image. The image is first segmented (without cutting the <span class="hlt">craters</span>) into a large number of smaller images using the ``flood" algorithm that identifies basins. This segmentation makes possible the application of highly inefficient HT to large sites. The identifier is applied to a 106 km<span class="hlt">2</span> site located around the Herschel <span class="hlt">crater</span>. According to the Barlow catalog, this site contains 485 <span class="hlt">craters</span> >5 km. Our identifier finds 1099 segments, 628 of them are classified as <span class="hlt">craters</span> >5 km. Overall, there is an excellent agreement between the two catalogs, although the specific statistics are still pending due to the difficulties in recalculating the MDIM 1 coordinate system used in the Barlow catalog to the MDIM <span class="hlt">2</span>.1 coordinate system used by our identifier.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19920009568','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19920009568"><span>Planetary <span class="hlt">cratering</span> mechanics</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Okeefe, John D.; Ahrens, Thomas J.</p> <p>1992-01-01</p> <p>To obtain a quantitative understanding of the <span class="hlt">cratering</span> process over a broad range of conditions, we have numerically computed the evolution of impact induced flow fields and calculated the time histories of the major measures of <span class="hlt">crater</span> geometry (e.g., depth diameter, lip height ...) for variations in planetary gravity (0 to 10 exp 9 cm/sq seconds), material strength (0 to 140 kbar), thermodynamic properties, and impactor radius (0.05 to 5000 km). These results were fit into the framework of the scaling relations of Holsapple and Schmidt (1987). We describe the impact process in terms of four regimes: (1) penetration; (<span class="hlt">2</span>) inertial; (3) terminal; and (4) relaxation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19930020183','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19930020183"><span>Interplanetary meteoroid debris in LDEF metal <span class="hlt">craters</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Brownlee, D. E.; Joswiak, D.; Bradley, J.; Hoerz, Friedrich</p> <p>1993-01-01</p> <p>We have examined <span class="hlt">craters</span> in Al and Au LDEF surfaces to determine the nature of meteoroid residue in the rare cases where projectile material is abundantly preserved in the <span class="hlt">crater</span> floor. Typical <span class="hlt">craters</span> contain only small amounts of residue and we find that less than 10 percent of the <span class="hlt">craters</span> in Al have retained abundant residue consistent with survival of a significant fraction (greater than 20 percent) of the projectile mass. The residue-rich <span class="hlt">craters</span> can usually be distinguished optically because their interiors are darker than ones with little or no apparent projectile debris. The character of the meteoroid debris in these <span class="hlt">craters</span> ranges from thin glass liners, to thick vesicular glass containing unmelted mineral fragments, to debris dominated by unmelted mineral fragments. In the best cases of meteoroid survival, unmelted mineral fragments preserve both information on projectile mineralogy as well as other properties such as nuclear tracks caused by solar flare irradiation. The wide range of the observed abundance and alteration state of projectile residue is most probably due to differences in impact velocity. The <span class="hlt">crater</span> liners are being studied to determine the composition of meteoroids reaching the Earth. The compositional types most commonly seen in the <span class="hlt">craters</span> are: (1) chondritic (Mg, Si, S, Fe in approximately solar proportions), (<span class="hlt">2</span>) Mg silicate. amd (3) iron sulfide. These are also the most common compositional types of extraterrestrial particle types collected in the stratosphere. The correlation between these compositions indicates that vapor fractionation was not a major process influencing residue composition in these <span class="hlt">craters</span>. Although the biases involved with finding analyzable meteoroid debris in metal <span class="hlt">craters</span> differ from those for extraterrestrial particles collected in and below the atmosphere, there is a common bias favoring particles with low entry velocity. For <span class="hlt">craters</span> this is very strong and probably all of the metal <span class="hlt">craters</span> with abundant</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20090014052&hterms=mass+wasting&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dmass%2Bwasting','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20090014052&hterms=mass+wasting&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dmass%2Bwasting"><span>Degradation of Victoria <span class="hlt">Crater</span>, Mars</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Wilson, Sharon A.; Grant, John A.; Cohen, Barbara A.; Golombek, Mathew P.; Geissler, Paul E.; Sullivan, Robert J.; Kirk, Randolph L.; Parker, Timothy J.</p> <p>2008-01-01</p> <p>The $\\sim$750 m diameter and $\\sim$75 m deep Victoria <span class="hlt">crater</span> in Meridiani Planum, Mars, presents evidence for significant degradation including a low, serrated, raised rim characterized by alternating alcoves and promontories, a surrounding low relief annulus, and a floor partially covered by dunes. The amount and processes of degradation responsible for the modified appearance of Victoria <span class="hlt">crater</span> were evaluated using images obtained in situ by the Mars Exploration Rover Opportunity in concert with a digital elevation model created using orbital HiRISE images. Opportunity traversed along the north and northwest rim and annulus, but sufficiently characterized features visible in the DEM to enable detailed measurements of rim relief, ejecta thickness, and wall slopes around the entire degraded, primary impact structure. Victoria retains a 5 m raised rim consisting of 1-<span class="hlt">2</span> m of uplifted rocks overlain by 3 m of ejecta at the rim crest. The rim is $\\sim$120 to 220 m wide and is surrounded by a dark annulus reaching an average of 590 m beyond the raised rim. Comparison between observed morphology and that expected for pristine <span class="hlt">craters</span> 500 to 750 m across indicate the original, pristine <span class="hlt">crater</span> was close to 600 m in diameter. Hence, the <span class="hlt">crater</span> has been erosionally widened by approximately 150 m and infilled by about 50 m of sediments. Eolian processes are responsible for modification at Victoria, but lesser contributions from mass wasting or other processes cannot be ruled out. Erosion by prevailing winds is most significant along the exposed rim and upper walls and accounts for $\\sim$50 m widening across a WNW-ESE diameter. The volume of material eroded from the <span class="hlt">crater</span> walls and rim is $\\sim$20% less than the volume of sediments partially filling the <span class="hlt">crater</span>, indicating eolian infilling from sources outside the <span class="hlt">crater</span> over time. The annulus formed when $\\sim$1 m deflation of the ejecta created a lag of more resistant hematite spherules that trapped darker, regional</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/3489286','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/3489286"><span>Participation of interleukins in synergistic effect of <span class="hlt">Bu</span>-WSA on concanavalin A-induced DNA synthesis in mouse splenic lymphocytes.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Nitta, T; Konno-Ejiri, H; Nemoto, K; Okumura, S; Ozawa, A; Nakano, M</p> <p>1986-09-01</p> <p>Butanol-extracted water-soluble adjuvant (<span class="hlt">Bu</span>-WSA) obtained from Bacterionema matruchotii was mitogenic to murine splenic B lymphocytes, but not T lymphocytes. When murine splenic cells were cultured in the presence of <span class="hlt">Bu</span>-WSA and concanavalin A (Con A) together, [3H]thymidine uptake of the culture cells synergically increased. The mechanism of the synergy of Con A and <span class="hlt">Bu</span>-WSA and the participation of interleukin (IL) 1 and <span class="hlt">2</span> in the synergy were studied. The proliferation cells in the synergy were Lyt-1+23- lymphocytes. Ia-positive accessory cells were required for the response. When separated cell populations and Marbrook-type culture vessels were used, a mixed cell population of T lymphocytes and B lymphocytes or macrophages (M phi) produced some active factor(s) after co-stimulation by Con A and <span class="hlt">Bu</span>-WSA, and the factors enhanced DNA synthesis of another Con A-activated T lymphocyte population. Supernatants obtained from the spleen cell cultures or the mixed cell cultures with T lymphocytes and M phi in the presence of Con A and <span class="hlt">Bu</span>-WSA contained greater amounts of IL-1 and IL-<span class="hlt">2</span> than those from cultures containing Con A or <span class="hlt">Bu</span>-WSA alone. An addition of exogenous IL-1 or IL-<span class="hlt">2</span> to spleen cell cultures with Con A resulted in a proliferative response like that obtained through co-stimulation by Con A and <span class="hlt">Bu</span>-WSA. These results suggest that the synergistic effect of Con A and <span class="hlt">Bu</span>-WSA on the proliferative response in murine splenic cells is sustained by the enhancement of production of these T-lymphocyte growth factors.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EGUGA..17.9218H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EGUGA..17.9218H"><span>How Old is Cone <span class="hlt">Crater</span> at the Apollo 14 Landing Site?</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hiesinger, Harald; Simon, Ina; van der Bogert, Carolyn H.; Robinson, Mark S.; Plescia, Jeff B.</p> <p>2015-04-01</p> <p> and 23 Ma older than the exposure ages [e.g., 10]. We find that CSFD measurements performed on the ejecta blanket of Cone <span class="hlt">crater</span> yield AMAs that agree well with the exposure ages, considering the relatively small count areas and the hummocky nature of the ejecta blanket. However, the AMAs are generally older than the exposure ages, which may be due to the small count area sizes [16], a possibly higher recent impact rate [17], some unidentified secondary <span class="hlt">craters</span> [13], poor calibration of the production function, or inaccurate exposure ages. [1] Hiesinger et al. (2012) J. Geophys. Res. 117. [<span class="hlt">2</span>] Stöffler and Ryder (2001) Chronology and Evolution of Mars. [3] Neukum (1983) Habil. thesis, <span class="hlt">U</span>. of Munich. [4] Neukum et al. (2001) Space Sci. Rev. 96. [5] Swann et al. (1971) Apollo 14 Prelim. Sci. Rep. [6] Carlson (1978) NASA STI/Recon Technical Report. [7] Swann (1977) Washington US Govt. Print. Off. [8] Bhandari et al. (1972) Proc. Lunar Planet. Sci. Conf. 3. [9] Crozaz et al. (1972) Proc. Lunar Planet. Sci. Conf. 3. [10] Arvidson et al. (1975) Moon 13. [11] Stadermann et al. (1991) Geochim. Cosmochim. Acta 55. [12] Moore et al. (1980) Moon and Planets 23. [13] Plescia and Robinson (2011) LPSC 42. [14] Williams et al. (2014) Icarus 235. [15] Robbins (2014) Earth Planet. Sci. Lett. 403. [16] van der Bogert et al. (2015) LPSC 46. [17] McEwen et al. (2015) LPSC 46.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26200434','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26200434"><span>A Linear trans-Bis(imido) Neptunium(V) Actinyl Analog: Np(V)(NDipp)<span class="hlt">2</span>((t)<span class="hlt">Bu</span><span class="hlt">2</span>bipy)<span class="hlt">2</span>Cl (Dipp = <span class="hlt">2</span>,6-(i)Pr<span class="hlt">2</span>C6H3).</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Brown, Jessie L; Batista, Enrique R; Boncella, James M; Gaunt, Andrew J; Reilly, Sean D; Scott, Brian L; Tomson, Neil C</p> <p>2015-08-05</p> <p>The discovery that imido analogs of actinyl dioxo cations can be extended beyond uranium into the transuranic elements is presented. Synthesis of the Np(V) complex, Np(NDipp)<span class="hlt">2</span>((t)<span class="hlt">Bu</span><span class="hlt">2</span>bipy)<span class="hlt">2</span>Cl (1), is achieved through treatment of a Np(IV) precursor with a bipyridine coligand and lithium-amide reagent. Complex 1 has been structurally characterized, analyzed by (1)H NMR and UV-vis-NIR spectroscopies, and the electronic structure evaluated by DFT calculations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1239532-linear-trans-bis-imido-neptunium-actinyl-analog-npv-ndipp-tbu2-bipy-dipp-pr2c6h3','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1239532-linear-trans-bis-imido-neptunium-actinyl-analog-npv-ndipp-tbu2-bipy-dipp-pr2c6h3"><span>A Linear trans -Bis(imido) Neptunium(V) Actinyl Analog: Np V (NDipp) <span class="hlt">2</span> ( t<span class="hlt">Bu</span> <span class="hlt">2</span> bipy) <span class="hlt">2</span>Cl (Dipp = <span class="hlt">2</span>,6- i Pr <span class="hlt">2</span>C 6H 3)</span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Brown, Jessie L.; Batista, Enrique R.; Boncella, James M.; ...</p> <p>2015-07-22</p> <p>We present the discovery that imido analogs of actinyl dioxo cations can be extended beyond uranium into the transuranic elements. Synthesis of the Np(V) complex, Np(NDipp) <span class="hlt">2</span>( t<span class="hlt">Bu</span> <span class="hlt">2</span>bipy) <span class="hlt">2</span>Cl (1), is achieved through treatment of a Np(IV) precursor with a bipyridine co-ligand and lithium-amide reagent. Complex 1 has been structurally characterized, analyzed by 1H NMR and UV/vis/NIR spectroscopies, and the electronic structure evaluated by DFT calculations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFM.G41B..08T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFM.G41B..08T"><span>Megathrust earthquakes in Japan and Chile triggered multiple volcanoes to <span class="hlt">subside</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Takada, Y.; Pritchard, M. E.; Fukushima, Y.; Jay, J.; Aron, F. A.; Henderson, S.; Lara, L. E.</p> <p>2012-12-01</p> <p>With spaceborne interferometric synthetic aperture radar (InSAR) analysis, we found that two recent megathrust earthquakes, the 2011 Mw 9.0 Tohoku earthquake in Japan (March 11, 2011) and the 2010 Mw 8.8 Maule earthquake in Chile (February 27, 2010), have triggered unprecedented <span class="hlt">subsidence</span> of multiple volcanoes. There are strong similarities in the characteristics of the surface deformation in Chile and Japan; (1) the maximum amount of <span class="hlt">subsidence</span> is about 15 cm, (<span class="hlt">2</span>) the shape of <span class="hlt">subsidence</span> areas exhibit elliptic shape elongated in the North-South direction -- perpendicular to the principal axis of the extensional stress change, and (3) most of the <span class="hlt">subsidence</span> was aseismic. These similarities imply that volcanic <span class="hlt">subsidence</span> from megathrust earthquakes is a ubiquitous phenomenon. In both areas, we found that hydro-thermal reservoirs (including water, gas, and possibly magma) would play key roles in the <span class="hlt">subsidence</span>. Further continuous monitoring is necessary to determine if the surface <span class="hlt">subsidence</span> leads to additional volcanic unrest. For the 2011 Tohoku Earthquake, we used SAR data acquired before and after the mainshock by ALOS (PALSAR). By removing long wave-length phase trend from InSAR images, we obtained the localized <span class="hlt">subsidence</span> signals at five active volcanoes: Mt. Akitakoma, Mt. Kurikoma region, Mt. Zao, Mt. Azuma, and Mt. Nasu. All of them belong to the volcanic front of Northeast Japan and so they are among the closest volcanoes to the earthquake. The maximum amount of <span class="hlt">subsidence</span> reaches 15 cm at Mt. Azuma. GPS data from two volcanoes also indicate surface <span class="hlt">subsidence</span> consistent with the satellite radar observations. Furthermore, the GPS data show that the <span class="hlt">subsidence</span> occurred immediately after the earthquake. According to numerical modelling, the observed <span class="hlt">subsidence</span> can be explained by the co-seismic response of fluid-filled ellipsoid with horizontal dimensions of 10-40 × 5-15 km beneath each volcano. For the 2010 Maule Earthquake, we extracted the localized</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013JGRB..118.1778H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013JGRB..118.1778H"><span>Origins of oblique-slip faulting during caldera <span class="hlt">subsidence</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Holohan, Eoghan P.; Walter, Thomas R.; Schöpfer, Martin P. J.; Walsh, John J.; van Wyk de Vries, Benjamin; Troll, Valentin R.</p> <p>2013-04-01</p> <p>Although conventionally described as purely dip-slip, faults at caldera volcanoes may have a strike-slip displacement component. Examples occur in the calderas of Olympus Mons (Mars), Miyakejima (Japan), and Dolomieu (La Reunion). To investigate this phenomenon, we use numerical and analog simulations of caldera <span class="hlt">subsidence</span> caused by magma reservoir deflation. The numerical models constrain mechanical causes of oblique-slip faulting from the three-dimensional stress field in the initial elastic phase of <span class="hlt">subsidence</span>. The analog experiments directly characterize the development of oblique-slip faulting, especially in the later, non-elastic phases of <span class="hlt">subsidence</span>. The combined results of both approaches can account for the orientation, mode, and location of oblique-slip faulting at natural calderas. Kinematically, oblique-slip faulting originates to resolve the following: (1) horizontal components of displacement that are directed radially toward the caldera center and (<span class="hlt">2</span>) horizontal translation arising from off-centered or "asymmetric" <span class="hlt">subsidence</span>. We informally call these two origins the "camera iris" and "sliding trapdoor" effects, respectively. Our findings emphasize the fundamentally three-dimensional nature of deformation during caldera <span class="hlt">subsidence</span>. They hence provide an improved basis for analyzing structural, geodetic, and geophysical data from calderas, as well as analogous systems, such as mines and producing hydrocarbon reservoirs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=PIA07046&hterms=left&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dleft','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=PIA07046&hterms=left&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dleft"><span>Along Endurance <span class="hlt">Crater</span>'s Inner Wall (Left Eye)</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>2004-01-01</p> <p><p/> This view from the base of 'Burns Cliff' in the inner wall of 'Endurance <span class="hlt">Crater</span>' combines several frames taken by Opportunity's navigation camera during the NASA rover's 280th martian day (Nov. 6, 2004). It is the left-eye member of a stereo pair, presented in a cylindrical-perspective projection with geometric seam correction. The cliff dominates the left and right portions of the image, while the central portion looks down into the <span class="hlt">crater</span>. The '<span class="hlt">U</span>' shape of this mosaic results from the rover's tilt of about 30 degrees on the sloped ground below the cliff. Rover wheel tracks in the left half of the image show some of the slippage the rover experienced in making its way to this point. The site from which this image was taken has been designated as Opportunity's Site 37.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.water.usgs.gov/ofr97-047/','USGSPUBS'); return false;" href="http://pubs.water.usgs.gov/ofr97-047/"><span><span class="hlt">U</span>.S. Geological Survey <span class="hlt">Subsidence</span> Interest Group Conference; proceedings of the Technical Meeting, Las Vegas, Nevada, February 14-16, 1995</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Prince, Keith R.; Leake, Stanley A.</p> <p>1997-01-01</p> <p>Introducation to Papers: This report is a compilation of short papers that are based on oral presentations summarizing the results of recent research that were given at the third meeting of the <span class="hlt">Subsidence</span> Interest Group held in Las Vegas, Nevada, February 14?16, 1995. The report includes case studies of land <span class="hlt">subsidence</span> and aquifer-system deformation resulting from fluid withdrawal, geothermal development, and mine collapse. Methods for monitoring land <span class="hlt">subsidence</span> using Global Positioning System technology for the rapid and accurate measurement of changes in land-surface altitude also are described. The current status of numerical simulation of land <span class="hlt">subsidence</span> in the USGS is summarized, and several of the short papers deal with the development and application of new numerical techniques for simulation and quantification of aquifersystem deformation. Not all oral presentations made at the meeting are documented in this report. Several of the presentations were of ongoing research and as such, the findings were provisional in nature and were offered at the meeting to stimulate scientific discussion and debate among colleagues. The information presented in this report, although only a subset of the proceedings of the meeting in Las Vegas, should help expand the scientific basis for management decisions to mitigate or control the effects of land <span class="hlt">subsidence</span>. The short papers describing the results of these studies provide a cross section of ongoing research in aquifer mechanics and land <span class="hlt">subsidence</span> and also form an assessment of the current technology and 'state of the science.' The analytical and interpretive methods described in this report will be useful to scientists involved in studies of ground-water hydraulics and aquifer-system deformation.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li class="active"><span>14</span></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_14 --> <div id="page_15" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li class="active"><span>15</span></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="281"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFM.C21C1132G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFM.C21C1132G"><span><span class="hlt">Subsidence</span> from an artificial permafrost warming experiment.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gelvin, A.; Wagner, A. M.; Lindsey, N.; Dou, S.; Martin, E. R.; Ekblaw, I.; Ulrich, C.; James, S. R.; Freifeld, B. M.; Daley, T. M.; Saari, S.; Ajo Franklin, J. B.</p> <p>2017-12-01</p> <p>Using fiber optic sensing technologies (seismic, strain, and temperature) we installed a geophysical detection system to predict thaw <span class="hlt">subsidence</span> in Fairbanks, Alaska, United States. Approximately 5 km of fiber optic was buried in shallow trenches (20 cm depth), in an area with discontinuous permafrost, where the top of the permafrost is approximately 4 - 4.5m below the surface. The thaw <span class="hlt">subsidence</span> was enforced by 122 60-Watt vertical heaters installed over a 140 m<span class="hlt">2</span> area where seismic, strain, and temperature were continuously monitored throughout the length of the fiber. Several vertical thermistor strings were also recording ground temperatures to a depth of 10 m in parallel to the fiber optic to verify the measurements collected from the fiber optic cable. GPS, Electronic Distance Measurement (EDM) Traditional and LiDAR (Light and Detection and Ranging) scanning were used to investigate the surface <span class="hlt">subsidence</span>. The heaters were operating for approximately a three month period starting in August, 2016. During the heating process the soil temperatures at the heater element increased from 3.5 to 45 °C at a depth of 3 - 4 m. It took approximately 7 months for the temperature at the heater elements to recover to their initial temperature. The depth to the permafrost table was deepened by about 1 m during the heating process. By the end of the active heating, the surface had <span class="hlt">subsided</span> approximately 8 cm in the heating section where permafrost was closest to the surface. This was conclusively confirmed with GPS, EDM, and LiDAR. An additional LiDAR survey was performed about seven months after the heaters were turned off (in May 2017). A total <span class="hlt">subsidence</span> of approximately 20 cm was measured by the end of the passive heating process. This project successfully demonstrates that this is a viable approach for simulating both deep permafrost thaw and the resulting surface <span class="hlt">subsidence</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFM.P53A2172B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFM.P53A2172B"><span>Mapping Ejecta Thickness Around Small Lunar <span class="hlt">Craters</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Brunner, A.; Robinson, M. S.</p> <p>2016-12-01</p> <p>Detailed knowledge of the distribution of ejecta around small ( 1 km) <span class="hlt">craters</span> is still a key missing piece in our understanding of <span class="hlt">crater</span> formation. McGetchin et al. [1] compiled data from lunar, terrestrial, and synthetic <span class="hlt">craters</span> to generate a semi-empirical model of radial ejecta distribution. Despite the abundance of models, experiments, and previous field and remote sensing studies of this problem, images from the 0.5 m/pixel Lunar Reconnaissance Orbiter Camera (LROC) Narrow Angle Camera (NAC) [<span class="hlt">2</span>] provides the first chance to quantify the extent and thickness of ejecta around kilometer scale lunar <span class="hlt">craters</span>. Impacts excavate fresh (brighter) material from below the more weathered (darker) surface, forming a relatively bright ejecta blanket. Over time space weathering tends to lower the reflectance of the ejected fresh material [3] resulting in the fading of albedo signatures around <span class="hlt">craters</span>. Relatively small impacts that excavate through the high reflectance immature ejecta of larger fresh <span class="hlt">craters</span> provide the means of estimating ejecta thickness. These subsequent impacts may excavate material from within the high reflectance ejecta layer or from beneath that layer to the lower-reflectance mature pre-impact surface. The reflectance of the ejecta around a subsequent impact allows us to categorize it as either an upper or lower limit on the ejecta thickness at that location. The excavation depth of each <span class="hlt">crater</span> found in the ejecta blanket is approximated by assuming a depth-to-diameter relationship relevant for lunar simple <span class="hlt">craters</span> [4, e.g.]. Preliminary results [Figure] show that this technique is valuable for finding the radially averaged profile of the ejecta thickness and that the data are roughly consistent with the McGetchin equation. However, data from <span class="hlt">craters</span> with asymmetric ejecta blankets are harder to interpret. [1] McGetchin et al. (1973) Earth Planet. Sci. Lett., 20, 226-236. [<span class="hlt">2</span>] Robinson et al. (2010) Space Sci. Rev., 150, 1-4, 81-124. [3] Denevi et al</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018Geomo.306..128X','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018Geomo.306..128X"><span>Hailar <span class="hlt">crater</span> - A possible impact structure in Inner Mongolia, China</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Xiao, Zhiyong; Chen, Zhaoxu; Pu, Jiang; Xiao, Xiao; Wang, Yichen; Huang, Jun</p> <p>2018-04-01</p> <p>Hailar <span class="hlt">crater</span>, a probable impact structure, is a circular depression about 300 m diameter in Inner Mongolia, northeast China. With broad elevated rims, the present rim-to-floor depth is 8-20 m. Regional geological background and geomorphological comparison suggest that this feature is likely not formed by surface processes such as salt diapir, karst, aeolian, glacial, or volcanic activity. Its unique occurrence in this region and well-preserved morphology are most consistent with it being a Cenozoic impact <span class="hlt">crater</span>. Two field expeditions in 2016 and 2017 investigated the origin of this structure, recognizing that (1) no additional <span class="hlt">craters</span> were identified around Hailar <span class="hlt">crater</span> in the centimeter-scale digital topography models that were constructed using a drone imaging system and stereo photogrammetry; (<span class="hlt">2</span>) no bedrock exposures are visible within or adjacent to the <span class="hlt">crater</span> because of thick regolith coverage, and only small pieces of angular unconsolidated rocks are present on the <span class="hlt">crater</span> wall and the gently-sloped <span class="hlt">crater</span> rim, suggesting recent energetic formation of the <span class="hlt">crater</span>; (3) most samples collected from the <span class="hlt">crater</span> have identical lithology and petrographic characteristics with the background terrain, but some <span class="hlt">crater</span> samples contain more abundant clasts and silicate hydrothermal veins, indicating that rocks from depths have been exposed by the <span class="hlt">crater</span>; (4) no shock metamorphic features were found in the samples after thin section examinations; and (5) a systematic sample survey and iron detector scan within and outside of the <span class="hlt">crater</span> found no iron-rich meteorites larger than <span class="hlt">2</span> cm in size in a depth of 30 cm. Although no conclusive evidence for an impact origin is found yet, Hailar <span class="hlt">crater</span> was most likely formed by an impact based on its unique occurrence and comparative geomorphologic study. We suggest that drilling in the <span class="hlt">crater</span> center is required to verify the impact origin, where hypothesized melt-bearing impactites may be encountered.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EGUGA..19.9612S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..19.9612S"><span>The <span class="hlt">Crater</span> Ejecta Distribution on Ceres</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Schmedemann, Nico; Neesemann, Adrian; Schulzeck, Franziska; Krohn, Katrin; Gathen, Isabel; Otto, Katharina; Jaumann, Ralf; Michael, Gregory; Raymond, Carol; Russell, Christopher</p> <p>2017-04-01</p> <p>Since March 6 2015 the Dawn spacecraft [1] has been in orbit around the dwarf planet Ceres. At small <span class="hlt">crater</span> diameters Ceres appears to be peppered with secondary <span class="hlt">craters</span> that often align in chains or form clusters. Some of such possible <span class="hlt">crater</span> chains follow curved geometries and are not in a radial orientation with respect to possible source <span class="hlt">craters</span> [<span class="hlt">2</span>]. Ceres is a fast rotating body ( 9 h per revolution) with comparatively low surface gravity ( 0.27 m/s<span class="hlt">2</span>). A substantial fraction of impact ejecta may be launched with velocities similar to Ceres' escape velocity (510 m/s), which implies that many ejected particles follow high and long trajectories. Thus, due to Ceres' fast rotation the distribution pattern of the reimpacting ejected material is heavily affected by Coriolis forces that results in a highly asymmetrical and curved pattern of secondary <span class="hlt">crater</span> chains. In order to simulate flight trajectories and distribution of impact ejected material for individual <span class="hlt">craters</span> on Ceres we used the scaling laws by [3] adjusted to the Cerean impact conditions [4] and the impact ejecta model by [5]. These models provide the starting conditions for tracer particles in the simulation. The trajectories of the particles are computed as n-body simulation. The simulation calculates the positions and impact velocities of each impacting tracer particle with respect to the rotating surface of Ceres, which is approximated by a two-axis ellipsoid. Initial results show a number of interesting features in the simulated deposition geometries of specific <span class="hlt">crater</span> ejecta. These features are roughly in agreement with features that can be observed in Dawn imaging data of the Cerean surface. For example: ray systems of fresh impact <span class="hlt">craters</span>, non-radial <span class="hlt">crater</span> chains and global scale border lines of higher and lower color ratio areas. Acknowledgment: This work has been supported by the German Space Agency (DLR) on behalf of the Federal Ministry for Economic Affairs and Energy, Germany, grants 50 OW</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018PhDT.........9D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018PhDT.........9D"><span><span class="hlt">Cratering</span> Characteristics of the Europa Kinetic Ice Penetrator</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Danner, Mariah L.</p> <p></p> <p>This thesis further develops the Europa Kinetic Ice Penetrator (EKIP) landing technique for airless bodies, as well as characterizes the effect EKIP would have on Europa's surface. Damage to the extremophile Planococcus Halocryophilus OR1 (PHOR1) during a laboratory hypervelocity impact test was studied the effect of rapid application of pressure to microbes frozen in ice. Significant die-off occurred, however PHOR1 microbes survived a <span class="hlt">2.2</span>km/s impact. Field testing the second-stage deployment, as well as to characterize <span class="hlt">crater</span> morphology of the EKIP system was conducted. With low impact velocities, penetrators consistently had deeper, narrower <span class="hlt">craters</span> than natural impactors (rocks), and showed less radial and sub-impactor compression. This, and future <span class="hlt">crater</span> data into harder substrates, will create a <span class="hlt">cratering</span> hardness curve for this design impactor into airless bodies. This curve, used with the eventual in situ <span class="hlt">craters</span>, can be used to constrain the hardness and other physical properties of the surface of icy-bodies.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://images.nasa.gov/#/details-PIA00472.html','SCIGOVIMAGE-NASA'); return false;" href="https://images.nasa.gov/#/details-PIA00472.html"><span>Venus - Impact <span class="hlt">Crater</span> Jeanne</span></a></p> <p><a target="_blank" href="https://images.nasa.gov/">NASA Image and Video Library</a></p> <p></p> <p>1996-11-20</p> <p>This full-resolution image from NASA Magellan spacecraft shows Jeanne <span class="hlt">crater</span>, a 19.5 kilometer (12 mile) diameter impact <span class="hlt">crater</span>. Jeanne <span class="hlt">crater</span> is located at 40.0 degrees north latitude and 331.4 degrees longitude. The distinctive triangular shape of the ejecta indicates that the impacting body probably hit obliquely, traveling from southwest to northeast. The <span class="hlt">crater</span> is surrounded by dark material of two types. The dark area on the southwest side of the <span class="hlt">crater</span> is covered by smooth (radar-dark) lava flows which have a strongly digitate contact with surrounding brighter flows. The very dark area on the northeast side of the <span class="hlt">crater</span> is probably covered by smooth material such as fine-grained sediment. This dark halo is asymmetric, mimicking the asymmetric shape of the ejecta blanket. The dark halo may have been caused by an atmospheric shock or pressure wave produced by the incoming body. Jeanne <span class="hlt">crater</span> also displays several outflow lobes on the northwest side. These flow-like features may have formed by fine-grained ejecta transported by a hot, turbulent flow created by the arrival of the impacting object. Alternatively, they may have formed by flow of impact melt. http://photojournal.jpl.nasa.gov/catalog/PIA00472</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://images.nasa.gov/#/details-PIA12328.html','SCIGOVIMAGE-NASA'); return false;" href="https://images.nasa.gov/#/details-PIA12328.html"><span><span class="hlt">Crater</span> with Exposed Layers</span></a></p> <p><a target="_blank" href="https://images.nasa.gov/">NASA Image and Video Library</a></p> <p></p> <p>2017-01-17</p> <p>On Earth, geologists can dig holes and pull up core samples to find out what lies beneath the surface. On Mars, geologists cannot dig holes very easily themselves, but a process has been occurring for billions of years that has been digging holes for them: impact <span class="hlt">cratering</span>. Impact <span class="hlt">craters</span> form when an asteroid, meteoroid, or comet crashes into a planet's surface, causing an explosion. The energy of the explosion, and the resulting size of the impact <span class="hlt">crater</span>, depends on the size and density of the impactor, as well as the properties of the surface it hits. In general, the larger and denser the impactor, the larger the <span class="hlt">crater</span> it will form. The impact <span class="hlt">crater</span> in this image is a little less than 3 kilometers in diameter. The impact revealed layers when it excavated the Martian surface. Layers can form in a variety of different ways. Multiple lava flows in one area can form stacked sequences, as can deposits from rivers or lakes. Understanding the geology around impact <span class="hlt">craters</span> and searching for mineralogical data within their layers can help scientists on Earth better understand what the walls of impact <span class="hlt">craters</span> on Mars expose. http://photojournal.jpl.nasa.gov/catalog/PIA12328</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014acm..conf..357M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014acm..conf..357M"><span>Asteroid families from <span class="hlt">cratering</span>: Detection and models</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Milani, A.; Cellino, A.; Knežević, Z.; Novaković, B.; Spoto, F.; Paolicchi, P.</p> <p>2014-07-01</p> <p>A new asteroid families classification, more efficient in the inclusion of smaller family members, shows how relevant the <span class="hlt">cratering</span> impacts are on large asteroids. These do not disrupt the target, but just form families with the ejecta from large <span class="hlt">craters</span>. Of the 12 largest asteroids, 8 have <span class="hlt">cratering</span> families: number (<span class="hlt">2</span>), (4), (5), (10), (87), (15), (3), and (31). At least another 7 <span class="hlt">cratering</span> families can be identified. Of the <span class="hlt">cratering</span> families identified so far, 7 have >1000 members. This imposes a remarkable change from the focus on fragmentation families of previous classifications. Such a large dataset of asteroids believed to be <span class="hlt">crater</span> ejecta opens a new challenge: to model the <span class="hlt">crater</span> and family forming event(s) generating them. The first problem is to identify which <span class="hlt">cratering</span> families, found by the similarity of proper elements, can be formed at once, with a single collision. We have identified as a likely outcome of multiple collisions the families of (4), (10), (15), and (20). Of the ejecta generated by <span class="hlt">cratering</span>, only a fraction reaches the escape velocity from the surviving parent body. The distribution of velocities at infinity, giving to the resulting family an initial position and shape in the proper elements space, is highly asymmetric with respect to the parent body. This shape is deformed by the Yarkovsky effect and by the interaction with resonances. All the largest asteroids have been subjected to large <span class="hlt">cratering</span> events, thus the lack of a family needs to be interpreted. The most interesting case is (1) Ceres, which is not the parent body of the nearby family of (93). Two possible interpretations of the low family forming efficiency are based on either the composition of Ceres with a significant fraction of ice, protected by a thin crust, or with the larger escape velocity of ~500 m/s.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20050167173','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20050167173"><span>The Explorer's Guide to Impact <span class="hlt">Craters</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Chuang, F.; Pierazzo, E.; Osinski, G.</p> <p>2005-01-01</p> <p>Impact <span class="hlt">cratering</span> is a fundamental geologic process of our solar system. It competes with other processes, such as plate tectonics, volcanism, fluvial, glacial and eolian activity, in shaping the surfaces of planetary bodies. In some cases, like the Moon and Mercury, impact <span class="hlt">craters</span> are the dominant landform. On other planetary bodies impact <span class="hlt">craters</span> are being continuously erased by the action of other geological processes, like volcanism on Io, erosion and plate tectonics on the Earth, tectonic and volcanic resurfacing on Venus, or ancient erosion periods on Mars. The study of <span class="hlt">crater</span> populations is one of the principal tools for understanding the geologic history of a planetary surface. Among the general public, impact <span class="hlt">cratering</span> has drawn wide attention through its portrayal in several Hollywood movies. Questions that are raised after watching these movies include: How do scientists learn about impact <span class="hlt">cratering</span>? , and What information do impact <span class="hlt">craters</span> provide in understanding the evolution of a planetary surface? Fundamental approaches used by scientists to learn about impact <span class="hlt">cratering</span> include field work at known terrestrial <span class="hlt">craters</span>, remote sensing studies of <span class="hlt">craters</span> on various solid surfaces of solar system bodies, and theoretical and laboratory studies using the known physics of impact <span class="hlt">cratering</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EGUGA..1917637D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..1917637D"><span><span class="hlt">2</span>D and 3D high resolution seismic imaging of shallow Solfatara <span class="hlt">crater</span> in Campi Flegrei (Italy): new insights on deep hydrothermal fluid circulation processes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>De Landro, Grazia; Gammaldi, Sergio; Serlenga, Vincenzo; Amoroso, Ortensia; Russo, Guido; Festa, Gaetano; D'Auria, Luca; Bruno, Pier Paolo; Gresse, Marceau; Vandemeulebrouck, Jean; Zollo, Aldo</p> <p>2017-04-01</p> <p>Seismic tomography can be used to image the spatial variation of rock properties within complex geological media such as volcanoes. Solfatara is a volcano located within the Campi Flegrei still active caldera, characterized by periodic episodes of extended, low-rate ground <span class="hlt">subsidence</span> and uplift called bradyseism accompanied by intense seismic and geochemical activities. In particular, Solfatara is characterized by an impressive magnitude diffuse degassing, which underlines the relevance of fluid and heat transport at the <span class="hlt">crater</span> and prompted further research to improve the understanding of the hydrothermal system feeding the surface phenomenon. In this line, an active seismic experiment, Repeated Induced Earthquake and Noise (RICEN) (EU Project MEDSUV), was carried out between September 2013 and November 2014 to provide time-varying high-resolution images of the structure of Solfatara. In this study we used the datasets provided by two different acquisition geometries: a) A <span class="hlt">2</span>D array cover an area of 90 x 115 m ^ <span class="hlt">2</span> sampled by a regular grid of 240 vertical sensors deployed at the <span class="hlt">crater</span> surface; b) two 1D orthogonal seismic arrays deployed along NE-SW and NW-SE directions crossing the 400 m <span class="hlt">crater</span> surface. The arrays are sampled with a regular line of 240 receiver and 116 shots. We present <span class="hlt">2</span>D and 3D tomographic high-resolution P-wave velocity images obtained using two different tomographic methods adopting a multiscale strategy. The 3D image of the shallow (30-35 m) central part of Solfatara <span class="hlt">crater</span> is performed through the iterative, linearized, tomographic inversion of the P-wave first arrival times. <span class="hlt">2</span>D P-wave velocity sections (60-70 m) are obtained using a non-linear travel-time tomography method based on the evaluation of a posteriori probability density with a Bayesian approach. The 3D retrieved images integrated with resistivity section and temperature and CO<span class="hlt">2</span> flux measurements , define the following characteristics: 1. A depth dependent P-wave velocity layer</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=PIA06669&hterms=Nga&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3DNga','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=PIA06669&hterms=Nga&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3DNga"><span><span class="hlt">Crater</span> Highlands, Tanzania</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>2006-01-01</p> <p><p/> The Shuttle Radar Topography Mission (SRTM), flown aboard Space Shuttle Endeavour in February 2000, acquired elevation measurements for nearly all of Earth's landmass between 60oN and 56oS latitudes. For many areas of the world SRTM data provide the first detailed three-dimensional observation of landforms at regional scales. SRTM data were used to generate this view of the <span class="hlt">Crater</span> Highlands along the East African Rift in Tanzania. Landforms are depicted with colored height and shaded relief, using a vertical exaggeration of <span class="hlt">2</span>X and a southwestwardly look direction. <p/> Lake Eyasi is depicted in blue at the top of the image, and a smaller lake occurs in Ngorongoro <span class="hlt">Crater</span>. Near the image center, elevations peak at 3648 meters (11,968 feet) at Mount Loolmalasin, which is south of Ela Naibori <span class="hlt">Crater</span>. Kitumbeine (left) and Gelai (right) are the two broad mountains rising from the rift lowlands. Mount Longido is seen in the lower left, and the Meto Hills are in the right foreground. <p/> Tectonics, volcanism, landslides, erosion and deposition -- and their interactions -- are all very evident in this view. The East African Rift is a zone of spreading between the African (on the west) and Somali (on the east) crustal plates. Two branches of the rift intersect here in Tanzania, resulting in distinctive and prominent landforms. One branch trends nearly parallel the view and includes Lake Eyasi and the very wide Ngorongoro <span class="hlt">Crater</span>. The other branch is well defined by the lowlands that trend left-right across the image (below center, in green). Volcanoes are often associated with spreading zones where magma, rising to fill the gaps, reaches the surface and builds cones. <span class="hlt">Craters</span> form if a volcano explodes or collapses. Later spreading can fracture the volcanoes, which is especially evident on Kitumbeine and Gelai Mountains (left and right, respectively, lower center). <p/> The <span class="hlt">Crater</span> Highlands rise far above the adjacent savannas, capture moisture from passing air masses</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018Icar..303...22M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018Icar..303...22M"><span>Population characteristics of submicrometer-sized <span class="hlt">craters</span> on regolith particles from asteroid Itokawa</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Matsumoto, Toru; Hasegawa, S.; Nakao, S.; Sakai, M.; Yurimoto, H.</p> <p>2018-03-01</p> <p>We investigated impact <span class="hlt">crater</span> structures on regolith particles from asteroid Itokawa using scanning electron microscopy. We observed the surfaces of 51 Itokawa particles, ranging from 15 μm to 240 μm in size. <span class="hlt">Craters</span> with average diameters ranging from 10 nm to <span class="hlt">2</span>.8 μm were identified on 13 Itokawa particles larger than 80 μm. We examined the abundance, spatial distribution, and morphology of approximately 900 <span class="hlt">craters</span> on six Itokawa particles. <span class="hlt">Craters</span> with sizes in excess of 200 nm are widely dispersed, with spatial densities from <span class="hlt">2</span>.6 μm<span class="hlt">2</span> to 4.5 μm<span class="hlt">2</span>; a fraction of the <span class="hlt">craters</span> was locally concentrated with a density of 0.1 μm<span class="hlt">2</span>. The fractal dimension of the cumulative <span class="hlt">crater</span> diameters ranges from 1.3 to <span class="hlt">2</span>.3. <span class="hlt">Craters</span> of several tens of nanometers in diameter exhibit pit and surrounding rim structures. <span class="hlt">Craters</span> of more than 100 nm in diameter commonly have melted residue at their bottom. These morphologies are similar to those of submicrometer-sized <span class="hlt">craters</span> on lunar regolith. We estimated the impactor flux on Itokawa regolith-forming <span class="hlt">craters</span>, assuming that the <span class="hlt">craters</span> were accumulated during direct exposure to the space environment for 102 to 104 yr. The range of impactor flux onto Itokawa particles is estimated to be at least one order of magnitude higher than the interplanetary dust flux and comparable to the secondary impact flux on the Moon. This indicates that secondary ejecta impacts are probably the dominant <span class="hlt">cratering</span> process in the submicrometer range on Itokawa regolith particles, as well as on the lunar surface. We demonstrate that secondary submicrometer <span class="hlt">craters</span> can be produced anywhere in centimeter- to meter-sized depressions on Itokawa's surface through primary interplanetary dust impacts. If the surface unevenness on centimeter to meter scales is a significant factor determining the abundance of submicrometer secondary <span class="hlt">cratering</span>, the secondary impact flux could be independent of the overall shapes or sizes of celestial bodies, and the secondary</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70031393','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70031393"><span>Geology of five small Australian impact <span class="hlt">craters</span></span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Shoemaker, E.M.; Macdonald, F.A.; Shoemaker, C.S.</p> <p>2005-01-01</p> <p>Here we present detailed geological maps and cross-sections of Liverpool, Wolfe Creek, Boxhole, Veevers and Dalgaranga <span class="hlt">craters</span>. Liverpool <span class="hlt">crater</span> and Wolfe Creek Meteorite <span class="hlt">Crater</span> are classic bowlshaped, Barringer-type <span class="hlt">craters</span>, Liverpool was likely formed during the Neoproterozoic and was filled and covered with sediments soon thereafter. In the Cenozoic, this cover was exhumed exposing the <span class="hlt">crater</span>'s brecciated wall rocks. Wolfe Creek Meteorite <span class="hlt">Crater</span> displays many striking features, including well-bedded ejecta units, <span class="hlt">crater</span>-floor faults and sinkholes, a ringed aeromagnetic anomaly, rim-skirting dunes, and numerous iron-rich shale balls. Boxhole Meteorite <span class="hlt">Crater</span>, Veevers Meteorite <span class="hlt">Crater</span> and Dalgaranga <span class="hlt">crater</span> are smaller, Odessa-type <span class="hlt">craters</span> without fully developed, steep, overturned rims. Boxhole and Dalgaranga <span class="hlt">craters</span> are developed in highly follated Precambrian basement rocks with a veneer of Holocene colluvium. The pre-existing structure at these two sites complicates structural analyses of the <span class="hlt">craters</span>, and may have influenced target deformation during impact. Veevers Meteorite <span class="hlt">Crater</span> is formed in Cenozoic laterites, and is one of the best-preserved impact <span class="hlt">craters</span> on Earth. The <span class="hlt">craters</span> discussed herein were formed in different target materials, ranging from crystalline rocks to loosely consolidated sediments, containing evidence that the impactors struck at an array of angles and velocities. This facilitates a comparative study of the influence of these factors on the structural and topographic form of small impact <span class="hlt">craters</span>. ?? Geological Society of Australia.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://images.nasa.gov/#/details-PIA16630.html','SCIGOVIMAGE-NASA'); return false;" href="https://images.nasa.gov/#/details-PIA16630.html"><span>Dark <span class="hlt">Crater</span> Rims</span></a></p> <p><a target="_blank" href="https://images.nasa.gov/">NASA Image and Video Library</a></p> <p></p> <p>2013-01-03</p> <p>These mosaic images from NASA Dawn mission show how dark, carbon-rich materials tend to speckle the rims of smaller <span class="hlt">craters</span> or their immediate surroundings on the giant asteroid Vesta; Numisia <span class="hlt">Crater</span> is shown at left.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/1353344-crystal-structure-theoretical-analysis-green-gold-au-bu-nanomolecules-relation-au-bu','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/1353344-crystal-structure-theoretical-analysis-green-gold-au-bu-nanomolecules-relation-au-bu"><span>Crystal Structure and Theoretical Analysis of Green Gold Au 30 (S- t <span class="hlt">Bu</span>) 18 Nanomolecules and Their Relation to Au 30 S(S- t <span class="hlt">Bu</span>) 18</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Dass, Amala; Jones, Tanya; Rambukwella, Milan</p> <p></p> <p>We report the complete X-ray crystallographic structure as determined through single crystal X-ray diffraction and a thorough theoretical analysis of the green gold Au30(S-t<span class="hlt">Bu</span>)18. While the structure of Au30S(S-t<span class="hlt">Bu</span>)18 with 19 sulfur atoms has been reported, the crystal structure of Au30(S-t<span class="hlt">Bu</span>)18 without the μ3-sulfur has remained elusive until now, though matrix-assisted laser desorption ionization mass spectrometry (MALDI-MS) and electrospray ionization mass spectrometry (ESI-MS) data unequivocally shows its presence in abundance. The Au30(S-t<span class="hlt">Bu</span>)18 nanomolecule is not only distinct in its crystal structure but has unique temperature dependent optical properties. Structure determination allows a rigorous comparison and an excellent agreement with theoreticalmore » predictions of structure, stability, and optical response.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24067871','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24067871"><span>Natural versus anthropogenic <span class="hlt">subsidence</span> of Venice.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Tosi, Luigi; Teatini, Pietro; Strozzi, Tazio</p> <p>2013-09-26</p> <p>We detected land displacements of Venice by Persistent Scatterer Interferometry using ERS and ENVISAT C-band and TerraSAR-X and COSMO-SkyMed X-band acquisitions over the periods 1992-2010 and 2008-2011, respectively. By reason of the larger observation period, the C-band sensors was used to quantify the long-term movements, i.e. the <span class="hlt">subsidence</span> component primarily ascribed to natural processes. The high resolution X-band satellites reveal a high effectiveness to monitor short-time movements as those induced by human activities. Interpolation of the two datasets and removal of the C-band from the X-band map allows discriminating between the natural and anthropogenic components of the <span class="hlt">subsidence</span>. A certain variability characterizes the natural <span class="hlt">subsidence</span> (0.9 ± 0.7 mm/yr), mainly because of the heterogeneous nature and age of the lagoon subsoil. The 2008 displacements show that man interventions are responsible for movements ranging from -10 to <span class="hlt">2</span> mm/yr. These displacements are generally local and distributed along the margins of the city islands.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3783893','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3783893"><span>Natural versus anthropogenic <span class="hlt">subsidence</span> of Venice</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Tosi, Luigi; Teatini, Pietro; Strozzi, Tazio</p> <p>2013-01-01</p> <p>We detected land displacements of Venice by Persistent Scatterer Interferometry using ERS and ENVISAT C-band and TerraSAR-X and COSMO-SkyMed X-band acquisitions over the periods 1992–2010 and 2008–2011, respectively. By reason of the larger observation period, the C-band sensors was used to quantify the long-term movements, i.e. the <span class="hlt">subsidence</span> component primarily ascribed to natural processes. The high resolution X-band satellites reveal a high effectiveness to monitor short-time movements as those induced by human activities. Interpolation of the two datasets and removal of the C-band from the X-band map allows discriminating between the natural and anthropogenic components of the <span class="hlt">subsidence</span>. A certain variability characterizes the natural <span class="hlt">subsidence</span> (0.9 ± 0.7 mm/yr), mainly because of the heterogeneous nature and age of the lagoon subsoil. The 2008 displacements show that man interventions are responsible for movements ranging from −10 to <span class="hlt">2</span> mm/yr. These displacements are generally local and distributed along the margins of the city islands. PMID:24067871</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://images.nasa.gov/#/details-PIA22378.html','SCIGOVIMAGE-NASA'); return false;" href="https://images.nasa.gov/#/details-PIA22378.html"><span>Bamberg <span class="hlt">Crater</span></span></a></p> <p><a target="_blank" href="https://images.nasa.gov/">NASA Image and Video Library</a></p> <p></p> <p>2018-04-26</p> <p>Today's VIS image shows the western rim of Bamberg <span class="hlt">Crater</span>. The complex nature of the rim is one indication of the relative youth of this <span class="hlt">crater</span> in relation to it's surrounding. Many gullies dissect this rim. Orbit Number: 71254 Latitude: 39.6224 Longitude: 356.451 Instrument: VIS Captured: 2018-01-06 05:00 https://photojournal.jpl.nasa.gov/catalog/PIA22378</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19850047917&hterms=dg&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3Ddg','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19850047917&hterms=dg&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3Ddg"><span>The scaling of complex <span class="hlt">craters</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Croft, S. K.</p> <p>1985-01-01</p> <p>The empirical relation between the transient <span class="hlt">crater</span> diameter (Dg) and final <span class="hlt">crater</span> diameter (Dr) of complex <span class="hlt">craters</span> and basins is estimated using cumulative terrace widths, central uplift diameters, continuous ejecta radii, and transient <span class="hlt">crater</span> reconstructions determined from lunar and terrestrial impact structures. The ratio Dg/Dr is a power law function of Dr, decreasing uniformly from unity at the diameter of the simple-complex <span class="hlt">crater</span> morphology transition to about 0.5 for large multiring basins like Imbrium on the moon. The empirical constants in the Dg/Dr relation are interpreted physically to mean that the position of the final rim relative to the transient <span class="hlt">crater</span>, and hence the extent of collapse, is controlled or greatly influenced by the properties of the zone of dissociated material produced by the impact shock. The continuity of the Dg/Dr relation over the entire spectrum of morphologic types from complex <span class="hlt">craters</span> to multiring basins implies that the rims of all these structures form in the same tectonic environment despite morphologic differences.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFM.H42D..05F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFM.H42D..05F"><span>Monitoring <span class="hlt">Subsidence</span> in California with InSAR</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Farr, T. G.; Jones, C. E.; Liu, Z.; Neff, K. L.; Gurrola, E. M.; Manipon, G.</p> <p>2016-12-01</p> <p><span class="hlt">Subsidence</span> caused by groundwater pumping in the rich agricultural area of California's Central Valley has been a problem for decades. Over the last few years, interferometric synthetic aperture radar (InSAR) observations from satellite and aircraft platforms have been used to produce maps of <span class="hlt">subsidence</span> with cm accuracy. We are continuing work reported previously, using ESA's Sentinel-1 to extend our maps of <span class="hlt">subsidence</span> in time and space, in order to eventually cover all of California. The amount of data to be processed has expanded exponentially in the course of our work and we are now transitioning to the use of the ARIA project at JPL to produce the time series. ARIA processing employs large Amazon cloud instances to process single or multiple frames each, scaling from one to many (20+) instances working in parallel to meet the demand (700 GB InSAR products within 3 hours). The data are stored in Amazon long-term storage and an http view of the products are available for users of the ARIA system to download the products. Higher resolution InSAR data were also acquired along the California Aqueduct by the NASA UAVSAR from 2013 - 2016. Using multiple scenes acquired by these systems, we are able to produce time series of <span class="hlt">subsidence</span> at selected locations and transects showing how <span class="hlt">subsidence</span> varies both spatially and temporally. The maps show that <span class="hlt">subsidence</span> is continuing in areas with a history of <span class="hlt">subsidence</span> and that the rates and areas affected have increased due to increased groundwater extraction during the extended western US drought. Our maps also identify and quantify new, localized areas of accelerated <span class="hlt">subsidence</span>. The California Department of Water Resources (DWR) funded this work to provide the background and an update on <span class="hlt">subsidence</span> in the Central Valley to support future policy. Geographic Information System (GIS) files are being furnished to DWR for further analysis of the 4 dimensional <span class="hlt">subsidence</span> time-series maps. Part of this work was carried out at the</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li class="active"><span>15</span></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_15 --> <div id="page_16" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li class="active"><span>16</span></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="301"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017Icar..296..275B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017Icar..296..275B"><span>Viscous relaxation of Ganymede's impact <span class="hlt">craters</span>: Constraints on heat flux</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bland, Michael T.; Singer, Kelsi N.; McKinnon, William B.; Schenk, Paul M.</p> <p>2017-11-01</p> <p>Measurement of <span class="hlt">crater</span> depths in Ganymede's dark terrain have revealed substantial numbers of unusually shallow <span class="hlt">craters</span> indicative of viscous relaxation [see companion paper: Singer, K.N., Schenk, P. M., Bland, M.T., McKinnon, W.B., (2017). Relaxed impact <span class="hlt">craters</span> on Ganymede: Regional variations and high heat flow. Icarus, submitted]. These viscously relaxed <span class="hlt">craters</span> provide insight into the thermal history of the dark terrain: the rate of relaxation depends on the size of the <span class="hlt">crater</span> and the thermal structure of the lithosphere. Here we use finite element simulations of <span class="hlt">crater</span> relaxation to constrain the heat flux within the dark terrain when relaxation occurred. We show that the degree of viscous relaxation observed cannot be achieved through radiogenic heating alone, even if all of the relaxed <span class="hlt">craters</span> are ancient and experienced the high radiogenic fluxes present early in the satellite's history. For <span class="hlt">craters</span> with diameter ≥ 10 km, heat fluxes of 40-50 mW m-<span class="hlt">2</span> can reproduce the observed <span class="hlt">crater</span> depths, but only if the fluxes are sustained for ∼1 Gyr. These <span class="hlt">craters</span> can also be explained by shorter-lived "heat pulses" with magnitudes of ∼100 mW m-<span class="hlt">2</span> and timescales of 10-100 Myr. At small <span class="hlt">crater</span> diameters (4 km) the observed shallow depths are difficult to achieve even when heat fluxes as high as 150 mW m-<span class="hlt">2</span> are sustained for 1 Gyr. The extreme thermal conditions required to viscously relax small <span class="hlt">craters</span> may indicate that mechanisms other than viscous relaxation, such as topographic degradation, are also in play at small <span class="hlt">crater</span> diameters. The timing of the relaxation event(s) is poorly constrained due to the sparsity of adequate topographic information, though it likely occurred in Ganymede's middle history (neither recently, nor shortly after satellite formation). The consistency between the timing and magnitude of the heat fluxes derived here and those inferred from other tectonic features suggests that a single event caused both Ganymede's tectonic deformation and</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016MmSAI..87...19V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016MmSAI..87...19V"><span>Morphometric analysis of a fresh simple <span class="hlt">crater</span> on the Moon.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Vivaldi, V.; Ninfo, A.; Massironi, M.; Martellato, E.; Cremonese, G.</p> <p></p> <p>In this research we are proposing an innovative method to determine and quantify the morphology of a simple fresh impact <span class="hlt">crater</span>. Linné is a well preserved impact <span class="hlt">crater</span> of <span class="hlt">2.2</span> km in diameter, located at 27.7oN 11.8oE, near the western edge of Mare Serenitatis on the Moon. The <span class="hlt">crater</span> was photographed by the Lunar Orbiter and the Apollo space missions. Its particular morphology may place Linné as the most striking example of small fresh simple <span class="hlt">crater</span>. Morphometric analysis, conducted on recent high resolution DTM from LROC (NASA), quantitatively confirmed the pristine morphology of the <span class="hlt">crater</span>, revealing a clear inner layering which highlight a sequence of lava emplacement events.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20020051084','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20020051084"><span>Impact <span class="hlt">Cratering</span> Calculations</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Ahrens, Thomas J.</p> <p>2002-01-01</p> <p>Many Martian <span class="hlt">craters</span> are surrounded by ejecta blankets which appear to have been fluidized forming lobate and layered deposits terminated by one or more continuous distal scarps, or ramparts. One of the first hypotheses for the formation of so-called rampart ejecta features was shock-melting of subsurface ice, entrainment of liquid water into the ejecta blanket, and subsequent fluidized flow. Our work quantifies this concept. Rampart ejecta found on all but the youngest volcanic and polar regions, and the different rampart ejecta morphologies are correlated with <span class="hlt">crater</span> size and terrain. In addition, the minimum diameter of <span class="hlt">craters</span> with rampart features decreases with increasing latitude indicating that ice laden crust resides closer to the surface as one goes poleward on Mars. Our second goal in was to determine what strength model(s) reproduce the faults and complex features found in large scale gravity driven <span class="hlt">craters</span>. Collapse features found in large scale <span class="hlt">craters</span> require that the rock strength weaken as a result of the shock processing of rock and the later <span class="hlt">cratering</span> shear flows. In addition to the presence of molten silicate in the intensely shocked region, the presence of water, either ambient, or the result of shock melting of ice weakens rock. There are several other mechanisms for the reduction of strength in geologic materials including dynamic tensile and shear induced fracturing. Fracturing is a mechanism for large reductions in strength. We found that by incorporating damage into the models that we could in a single integrated impact calculation, starting in the atmosphere produce final <span class="hlt">crater</span> profiles having the major features found in the field measurements (central uplifts, inner ring, terracing and faulting). This was accomplished with undamaged surface strengths (0.1 GPa) and in depth strengths (1.0 GPa).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EPSC...10..284O','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EPSC...10..284O"><span>Polygonal <span class="hlt">Craters</span> on Dwarf-Planet Ceres</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Otto, K. A.; Jaumann, R.; Krohn, K.; Buczkowski, D. L.; von der Gathen, I.; Kersten, E.; Mest, S. C.; Preusker, F.; Roatsch, T.; Schenk, P. M.; Schröder, S.; Schulzeck, F.; Scully, J. E. C.; Stepahn, K.; Wagner, R.; Williams, D. A.; Raymond, C. A.; Russell, C. T.</p> <p>2015-10-01</p> <p>With approximately 950 km diameter and a mass of #1/3 of the total mass of the asteroid belt, (1) Ceres is the largest and most massive object in the Main Asteroid Belt. As an intact proto-planet, Ceres is key to understanding the origin and evolution of the terrestrialplanets [1]. In particular, the role of water during planet formation is of interest, because the differentiated dwarf-planet is thought to possess a water rich mantle overlying a rocky core [<span class="hlt">2</span>]. The Dawn space craft arrived at Ceres in March this year after completing its mission at (4) Vesta. At Ceres, the on-board Framing Camera (FC) collected image data which revealed a large variety of impact <span class="hlt">crater</span> morphologies including polygonal <span class="hlt">craters</span> (Figure 1). Polygonal <span class="hlt">craters</span> show straight rim sections aligned to form an angular shape. They are commonly associated with fractures in the target material. Simple polygonal <span class="hlt">craters</span> develop during the excavation stage when the excavation flow propagates faster along preexisting fractures [3, 5]. Complex polygonal <span class="hlt">craters</span> adopt their shape during the modification stage when slumping along fractures is favoured [3]. Polygonal <span class="hlt">craters</span> are known from a variety of planetary bodies including Earth [e.g. 4], the Moon [e.g. 5], Mars [e.g. 6], Mercury [e.g. 7], Venus [e.g. 8] and outer Solar System icy satellites [e.g. 9].</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://images.nasa.gov/#/details-PIA04017.html','SCIGOVIMAGE-NASA'); return false;" href="https://images.nasa.gov/#/details-PIA04017.html"><span>Trouvelot <span class="hlt">Crater</span> Deposit</span></a></p> <p><a target="_blank" href="https://images.nasa.gov/">NASA Image and Video Library</a></p> <p></p> <p>2002-12-04</p> <p>Like many of the <span class="hlt">craters</span> in the Oxia Palus region of Mars, Trouvelot <span class="hlt">Crater</span>, shown in this NASA Mars Odyssey image, hosts an eroded, light-toned, sedimentary deposit on its floor. Compared with the much larger example in Becquerel <span class="hlt">Crater</span> to the NE, the Trouvelot deposit has been so eroded by the scouring action of dark, wind-blown sand that very little of it remains. Tiny outliers of bright material separated from the main mass attest to the once, more really extensive coverage by the deposit. A similar observation can be made for White Rock, the best known example of a bright, <span class="hlt">crater</span> interior deposit. The origin of the sediments in these deposits remains enigmatic but they are likely the result of fallout from ash or dust carried by the thin martian atmosphere. http://photojournal.jpl.nasa.gov/catalog/PIA04017</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://images.nasa.gov/#/details-PIA22264.html','SCIGOVIMAGE-NASA'); return false;" href="https://images.nasa.gov/#/details-PIA22264.html"><span>Investigating Mars: Kaiser <span class="hlt">Crater</span> Dunes</span></a></p> <p><a target="_blank" href="https://images.nasa.gov/">NASA Image and Video Library</a></p> <p></p> <p>2018-02-01</p> <p>This VIS image of the floor of Kaiser <span class="hlt">Crater</span> contains several sand dune shapes and sizes. The "whiter" material is the hard <span class="hlt">crater</span> floor surface. Kaiser <span class="hlt">Crater</span> is located in the southern hemisphere in the Noachis region west of Hellas Planitia. Kaiser <span class="hlt">Crater</span> is just one of several large <span class="hlt">craters</span> with extensive dune fields on the <span class="hlt">crater</span> floor. Other nearby dune filled <span class="hlt">craters</span> are Proctor, Russell, and Rabe. Kaiser <span class="hlt">Crater</span> is 207 km (129 miles) in diameter. The dunes are located in the southern part of the <span class="hlt">crater</span> floor. The Odyssey spacecraft has spent over 15 years in orbit around Mars, circling the planet more than 71,000 times. It holds the record for longest working spacecraft at Mars. THEMIS, the IR/VIS camera system, has collected data for the entire mission and provides images covering all seasons and lighting conditions. Over the years many features of interest have received repeated imaging, building up a suite of images covering the entire feature. From the deepest chasma to the tallest volcano, individual dunes inside <span class="hlt">craters</span> and dune fields that encircle the north pole, channels carved by water and lava, and a variety of other feature, THEMIS has imaged them all. For the next several months the image of the day will focus on the Tharsis volcanoes, the various chasmata of Valles Marineris, and the major dunes fields. We hope you enjoy these images! Orbit Number: 39910 Latitude: -46.9063 Longitude: 19.8112 Instrument: VIS Captured: 2010-12-13 11:17 https://photojournal.jpl.nasa.gov/catalog/PIA22264</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://images.nasa.gov/#/details-PIA22263.html','SCIGOVIMAGE-NASA'); return false;" href="https://images.nasa.gov/#/details-PIA22263.html"><span>Investigating Mars: Kaiser <span class="hlt">Crater</span> Dunes</span></a></p> <p><a target="_blank" href="https://images.nasa.gov/">NASA Image and Video Library</a></p> <p></p> <p>2018-01-31</p> <p>This VIS image of the floor of Kaiser <span class="hlt">Crater</span> contains a large variety of sand dune shapes and sizes. The "whiter" material is the hard <span class="hlt">crater</span> floor surface. Kaiser <span class="hlt">Crater</span> is located in the southern hemisphere in the Noachis region west of Hellas Planitia. Kaiser <span class="hlt">Crater</span> is just one of several large <span class="hlt">craters</span> with extensive dune fields on the <span class="hlt">crater</span> floor. Other nearby dune filled <span class="hlt">craters</span> are Proctor, Russell, and Rabe. Kaiser <span class="hlt">Crater</span> is 207 km (129 miles) in diameter. The dunes are located in the southern part of the <span class="hlt">crater</span> floor. The Odyssey spacecraft has spent over 15 years in orbit around Mars, circling the planet more than 71,000 times. It holds the record for longest working spacecraft at Mars. THEMIS, the IR/VIS camera system, has collected data for the entire mission and provides images covering all seasons and lighting conditions. Over the years many features of interest have received repeated imaging, building up a suite of images covering the entire feature. From the deepest chasma to the tallest volcano, individual dunes inside <span class="hlt">craters</span> and dune fields that encircle the north pole, channels carved by water and lava, and a variety of other feature, THEMIS has imaged them all. For the next several months the image of the day will focus on the Tharsis volcanoes, the various chasmata of Valles Marineris, and the major dunes fields. We hope you enjoy these images! Orbit Number: 35430 Latitude: -46.8699 Longitude: 19.4731 Instrument: VIS Captured: 2009-12-09 14:09 https://photojournal.jpl.nasa.gov/catalog/PIA22263</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=PIA04448&hterms=Butterfly&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3DButterfly','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=PIA04448&hterms=Butterfly&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3DButterfly"><span>Cydonia <span class="hlt">Craters</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>2003-01-01</p> <p><p/> [figure removed for brevity, see original site] <p/>Eroded mesas and secondary <span class="hlt">craters</span> dot the landscape in this area of the Cydonia Mensae region. The single oval-shaped <span class="hlt">crater</span> displays a 'butterfly' ejecta pattern, indicating that the <span class="hlt">crater</span> formed from a low-angle impact.<p/>Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.<p/>NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.<p/>Image information: VIS instrument. Latitude 32.9, Longitude 343.8 East (16.<span class="hlt">2</span> West). 19 meter/pixel resolution.<p/></p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70023921','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70023921"><span>Steady <span class="hlt">subsidence</span> of Medicine Lake volcano, northern California, revealed by repeated leveling surveys</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Dzurisin, D.; Poland, Michael P.; Burgmann, R.</p> <p>2002-01-01</p> <p>Leveling surveys of a 193-km circuit across Medicine Lake volcano (MLV) in 1954 and 1989 show that the summit area <span class="hlt">subsided</span> by as much as 302 ?? 30 mm (-8.6 ?? 0.9 mm/yr) with respect to a datum point near Bartle, California, 40 km to the southwest. This result corrects an error in the earlier analysis of the same data by Dzurisin et al. [1991], who reported the <span class="hlt">subsidence</span> rate as -11.1 ?? 1.<span class="hlt">2</span> mm/yr. The <span class="hlt">subsidence</span> pattern extends across the entire volcano, with a surface area of nearly 2000 km<span class="hlt">2</span>. Two areas of localized <span class="hlt">subsidence</span> by as much as 20 cm can be attributed to shallow normal faulting near the volcano's periphery. Surveys of an east-west traverse across Lava Beds National Monument on the north flank of the volcano in 1990 and of a 23-km traverse across the summit area in 1999 show that <span class="hlt">subsidence</span> continued at essentially the same rate during 1989-1999 as 1954-1989. Volcano-wide <span class="hlt">subsidence</span> can be explained by either a point source of volume loss (Mogi) or a contracting horizontal rectangular dislocation (sill) at a depth of 10-11 km. Volume loss rate estimates range from 0.0013 to 0.0032 km3/yr, depending mostly on the source depth estimate and source type. Based on first-order quantitative considerations, we can rule out that the observed <span class="hlt">subsidence</span> is due to volume loss from magma withdrawal, thermal contraction, or crystallizing magma at depth. Instead, we attribute the <span class="hlt">subsidence</span> and faulting to: (1 gravitational loading of thermally weakened crust by the mass of the volcano and associated intrusive rocks, and (<span class="hlt">2</span>) thinning of locally weakened crust by Basin and Range deformation. The measured <span class="hlt">subsidence</span> rate exceeds long-term estimates from drill hole data, suggesting that over long timescales, steady <span class="hlt">subsidence</span> and episodic uplift caused by magmatic intrusions counteract each other to produce the lower net <span class="hlt">subsidence</span> rate.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://images.nasa.gov/#/details-PIA14611.html','SCIGOVIMAGE-NASA'); return false;" href="https://images.nasa.gov/#/details-PIA14611.html"><span>Line of <span class="hlt">Craters</span></span></a></p> <p><a target="_blank" href="https://images.nasa.gov/">NASA Image and Video Library</a></p> <p></p> <p>2012-06-04</p> <p>NASA Cassini spacecraft takes a close look at a row of <span class="hlt">craters</span> on Saturn moon Tethys during the spacecraft April 14, 2012, flyby of the moon. Three large <span class="hlt">craters</span> are visible along the terminator between day and night on Tethys.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://images.nasa.gov/#/details-PIA12935.html','SCIGOVIMAGE-NASA'); return false;" href="https://images.nasa.gov/#/details-PIA12935.html"><span>Fresh Copernican <span class="hlt">Crater</span></span></a></p> <p><a target="_blank" href="https://images.nasa.gov/">NASA Image and Video Library</a></p> <p></p> <p>2009-12-21</p> <p>A subset of NAC Image M112162602L showing landslides bottom covering impact melt on the floor top of a fresh Copernican-age <span class="hlt">crater</span> at the edge of Oceanus Procellarum and west of Balboa <span class="hlt">crater</span> taken by NASA Lunar Reconnaissance Orbiter.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=PIA07287&hterms=landslide&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dlandslide','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=PIA07287&hterms=landslide&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dlandslide"><span>Isidis <span class="hlt">Crater</span> Landslide</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>2005-01-01</p> <p><p/> [figure removed for brevity, see original site] <p/> The landslide in this VIS image is located inside an impact <span class="hlt">crater</span> located south of the Isidis Planitia region of Mars. As with the previous unnamed <span class="hlt">crater</span> landslide, this one formed due to slope failure of the inner <span class="hlt">crater</span> rim. <p/> Image information: VIS instrument. Latitude -<span class="hlt">2</span>.9, Longitude 90.8 East (269.<span class="hlt">2</span> West). 19 meter/pixel resolution. <p/> Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time. <p/> NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2002EGSGA..27.3588S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2002EGSGA..27.3588S"><span>Buried <span class="hlt">Craters</span> In Isidis Planitia, Mars</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Seabrook, A. M.; Rothery, D. A.; Wallis, D.; Bridges, J. C.; Wright, I. P.</p> <p></p> <p>We have produced a topographic map of Isidis Planitia, which includes the Beagle <span class="hlt">2</span> landing site, using interpolated Mars Orbiter Laser Altimeter (MOLA) data from the Mars Global Surveyor (MGS) spacecraft currently orbiting Mars. MOLA data have a vertical precision of 37.5 cm, a footprint size of 130 m, an along-track shot spacing of 330 m, and an across-track spacing that is variable and may be several kilometres. This has revealed subtle topographic detail within the relatively smooth basin of Isidis Planitia. Analysis of this map shows apparent wrinkle ridges that could be the volcanic basement to the basin and also several circular depressions with diameters of several to tens of kilometres which we interpreted as buried impact <span class="hlt">craters</span>, comparable to the so-called stealth <span class="hlt">craters</span> recognised elsewhere in the northern lowlands of Mars[1]. Stealth <span class="hlt">craters</span> are considered to be impact <span class="hlt">craters</span> subjected to erosion and/or burial. Some of these features in Isidis have depressions that are on the order of tens metres lower than their rims and are very smooth, and so are often not visible in MGS Mars Orbiter Camera (MOC) or Viking images of the basin. The Isidis stealth <span class="hlt">craters</span> are not restricted to the Hesperian Vastitas Borealis formations like those detected elsewhere in the northern lowlands by Kreslavsky and Head [1], but are also found in a younger Amazonian smooth plains unit. It is generally believed that Isidis Planitia has undergone one or more episodes of sedi- ment deposition, and so these buried <span class="hlt">craters</span> most likely lie on an earlier surface, which could be the postulated volcanic basement to the basin. Analysis of the buried <span class="hlt">craters</span> may give some understanding of the thickness, frequencies and ages of sedimentation episodes within the basin. This information will be important in developing a context in which information from the Beagle <span class="hlt">2</span> lander can be analysed when it arrives on Mars in December 2003. [1] Kreslavsky M. A. and Head J. W. (2001) LPS XXXII</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/12467633','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/12467633"><span>Structure-activity relationship of linear peptide <span class="hlt">Bu</span>-His-DPhe-Arg-Trp-Gly-NH(<span class="hlt">2</span>) at the human melanocortin-1 and -4 receptors: histidine substitution.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Cheung, Adrian Wai-Hing; Danho, Waleed; Swistok, Joseph; Qi, Lida; Kurylko, Grazyna; Rowan, Karen; Yeon, Mitch; Franco, Lucia; Chu, Xin-Jie; Chen, Li; Yagaloff, Keith</p> <p>2003-01-06</p> <p>Systematic substitution of His(6) residue using non-selective hMC4R pentapeptide agonist (<span class="hlt">Bu</span>-His(6)-DPhe(7)-Arg(8)-Trp(9)-Gly(10)-NH(<span class="hlt">2</span>)) as the template led to the identification of <span class="hlt">Bu</span>-Atc(6)(<span class="hlt">2</span>-aminotetraline-<span class="hlt">2</span>-carboxylic acid)-DPhe(7)-Arg(8)-Trp(9)-Gly(10)-NH(<span class="hlt">2</span>) which showed moderate selectivity towards hMC4R over hMC1R. Further SAR studies resulted in the discovery of Penta-5-BrAtc(6)-DPhe(7)-Arg(8)-Trp(9)-Gly(10)-NH(<span class="hlt">2</span>) and Penta-5-Me(<span class="hlt">2</span>)NAtc(6)-DPhe(7)-Arg(8)-Trp(9)-Gly(10)-NH(<span class="hlt">2</span>) which are potent hMC4R agonists and are inactive in hMC1R, hMC3R and hMC5R agonist assays.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=PIA03832&hterms=knife&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dknife','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=PIA03832&hterms=knife&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dknife"><span>Galle <span class="hlt">Crater</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>2002-01-01</p> <p>(Released 19 June 2002) The Science This image is of part of Galle <span class="hlt">Crater</span>, located at 51.9S, 29.5W. This image was taken far enough south and late enough into the southern hemisphere fall to catch observe water ice clouds partially obscuring the surface. The most striking aspect of the surface is the dissected layered unit to the left in the image. Other areas also appear to have layering, but they are either more obscured by clouds or are less well defined on the surface. The layers appear to be mostly flat lying and layer boundaries appear as topographic lines would on a map, but there are a few areas where it appears that these layers have been deformed to some level. Other areas of the image contain rugged, mountainous terrain as well as a separate pitted terrain where the surface appears to be a separate unit from the mountains and the layered terrain. The Story Galle <span class="hlt">Crater</span> is officially named after a German astronomer who, in 1846, was the first to observe the planet Neptune. It is better known, however, as the 'Happy Face <span class="hlt">Crater</span>.' The image above focuses on too small an area of the <span class="hlt">crater</span> to see its beguiling grin, but you can catch the rocky line of a 'half-smile' in the context image to the right (to the left of the red box). While water ice clouds make some of the surface harder to see, nothing detracts from the fabulous layering at the center left-hand edge of the image. If you click on the above image, the scalloped layers almost look as if a giant knife has swirled through a landscape of cake frosting. These layers, the rugged, mountains near them, and pits on the surface (upper to middle section of the image on the right-hand side) all create varying textures on the <span class="hlt">crater</span> floor. With such different features in the same place, geologists have a lot to study to figure out what has happened in the <span class="hlt">crater</span> since it formed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://images.nasa.gov/#/details-PIA22147.html','SCIGOVIMAGE-NASA'); return false;" href="https://images.nasa.gov/#/details-PIA22147.html"><span>Investigating Mars: Rabe <span class="hlt">Crater</span></span></a></p> <p><a target="_blank" href="https://images.nasa.gov/">NASA Image and Video Library</a></p> <p></p> <p>2017-12-21</p> <p>This is a false color image of Rabe <span class="hlt">Crater</span>. In this combination of filters "blue" typically means basaltic sand. This VIS image crosses the entire <span class="hlt">crater</span> and demonstrates how extensive the dunes are on the floor of Rabe <span class="hlt">Crater</span>. Rabe <span class="hlt">Crater</span> is 108 km (67 miles) across. <span class="hlt">Craters</span> of similar size often have flat floors. Rabe <span class="hlt">Crater</span> has some areas of flat floor, but also has a large complex pit occupying a substantial part of the floor. The interior fill of the <span class="hlt">crater</span> is thought to be layered sediments created by wind and or water action. The pit is eroded into this material. The eroded materials appear to have stayed within the <span class="hlt">crater</span> forming a large sand sheet with surface dune forms as well as individual dunes where the <span class="hlt">crater</span> floor is visible. The dunes also appear to be moving from the upper floor level into the pit. The THEMIS VIS camera contains 5 filters. The data from different filters can be combined in multiple ways to create a false color image. These false color images may reveal subtle variations of the surface not easily identified in a single band image. The Odyssey spacecraft has spent over 15 years in orbit around Mars, circling the planet more than 69000 times. It holds the record for longest working spacecraft at Mars. THEMIS, the IR/VIS camera system, has collected data for the entire mission and provides images covering all seasons and lighting conditions. Over the years many features of interest have received repeated imaging, building up a suite of images covering the entire feature. From the deepest chasma to the tallest volcano, individual dunes inside <span class="hlt">craters</span> and dune fields that encircle the north pole, channels carved by water and lava, and a variety of other feature, THEMIS has imaged them all. For the next several months the image of the day will focus on the Tharsis volcanoes, the various chasmata of Valles Marineris, and the major dunes fields. We hope you enjoy these images! Orbit Number: 67013 Latitude: -43.2572 Longitude: 34</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=PIA07169&hterms=night+shift&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dnight%2Bshift','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=PIA07169&hterms=night+shift&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dnight%2Bshift"><span><span class="hlt">Crater</span> At Night</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>2004-01-01</p> <p><p/> [figure removed for brevity, see original site] <p/> This nighttime IR image is dominated by a large <span class="hlt">crater</span>. The <span class="hlt">crater</span> no longer has any visible ejecta, and retains only it's rim - seen here as a varigated black/gray semi-circle surrounding a brighter floor. The smaller <span class="hlt">craters</span> in the image have bright rings representing their rocky rims. This <span class="hlt">crater</span> is located just south of Syrtis Major. <p/> Image information: IR instrument. Latitude <span class="hlt">2</span>.8, Longitude 76.4 East (283.6 West). 100 meter/pixel resolution. <p/> Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time. <p/> NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008epsc.conf..237K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008epsc.conf..237K"><span>Young populations of small <span class="hlt">craters</span> on Mars: A case study.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kreslavsky, M.</p> <p>2008-09-01</p> <p>Introduction The HiRISE camera imaged the Mars surface at scales that had never been studied before. Beside a host of other fascinating features, these images revealed small (diameter D down to 1 m) impact <span class="hlt">craters</span>. In planetary geology, impact <span class="hlt">craters</span> and properties of their populations have been used as valuable sources of information about surface history and geological processes. Small <span class="hlt">craters</span> on Mars can potentially give essential information about young terrains on this planet, resurfacing rates at small scales and the most recent events in the geological history, first of all, the most recent climate changes. Very young <span class="hlt">crater</span> populations are thought to be unaffected by distal secondary <span class="hlt">craters</span>, because they are formed after the most recent secondary-forming event. However, extracting this information is not simple or straightforward. Here I illustrate these difficulties and ways of overcoming them using a population of small <span class="hlt">craters</span> on ejecta of <span class="hlt">crater</span> Zunil as an example. Population of small <span class="hlt">craters</span> on Zunil ejecta Terrain I used HiRISE images PSP_001764_1880 and PSP_002397_1880. In these images I outlined an area (totally 52.8 km<span class="hlt">2</span>) to NE, NW and SW of the <span class="hlt">crater</span> limited by the toes of the outer walls of Zunil and the image boundaries. Terrain texture within the area is diverse; however, the area is entirely within the proximal ejecta lobes. The ejecta material was obviously emplaced as a result of the Zunil-forming impact and has a uniform age. The morphology of the surface indicates later resurfacing of steep slopes (over a small total area) and minor eolian modification of the terrain; some sub-areas might be modified by the post-impact hydrothermal activity. <span class="hlt">Crater</span> population I registered diameters and positions of all impact <span class="hlt">craters</span> in the area, a total of 1025 <span class="hlt">craters</span> with D > 1.5 m. The largest of them has D = 20 m. <span class="hlt">Craters</span> usually have no visible ejecta, which indicates some minor (perhaps, eolian) modification of the surface. Almost all <span class="hlt">craters</span></p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=PIA00804&hterms=magazine&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Dmagazine','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=PIA00804&hterms=magazine&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Dmagazine"><span>Crommelin <span class="hlt">Crater</span> #1</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>1998-01-01</p> <p>Dunes in etch pits and troughs in Crommelin <span class="hlt">Crater</span> in the Oxia Palus area. This 3.<span class="hlt">2</span> x 3.5 km image (frame 3001) is centered near 4.1 degrees north, 5.3 degrees west.<p/>Figure caption from Science Magazine</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009M%26PS...44..985K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009M%26PS...44..985K"><span>The Carancas meteorite impact <span class="hlt">crater</span>, Peru: Geologic surveying and modeling of <span class="hlt">crater</span> formation and atmospheric passage</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kenkmann, T.; Artemieva, N. A.; Wünnemann, K.; Poelchau, M. H.; Elbeshausen, D.; Núñez Del Prado, H.</p> <p>2009-08-01</p> <p>The recent Carancas meteorite impact event caused a worldwide sensation. An H4-5 chondrite struck the Earth south of Lake Titicaca in Peru on September 15, 2007, and formed a <span class="hlt">crater</span> 14.<span class="hlt">2</span> m across. It is the smallest, youngest, and one of two eye-witnessed impact <span class="hlt">crater</span> events on Earth. The impact violated the hitherto existing view that stony meteorites below a size of 100 m undergo major disruption and deceleration during their passage through the atmosphere and are not capable of producing <span class="hlt">craters</span>. Fragmentation occurs if the strength of the meteoroid is less than the aerodynamic stresses that occur in flight. The small fragments that result from a breakup rain down at terminal velocity and are not capable of producing impact <span class="hlt">craters</span>. The Carancas <span class="hlt">cratering</span> event, however, demonstrates that meter-sized stony meteoroids indeed can survive the atmospheric passage under specific circumstances. We present results of a detailed geologic survey of the <span class="hlt">crater</span> and its ejecta. To constrain the possible range of impact parameters we carried out numerical models of <span class="hlt">crater</span> formation with the iSALE hydrocode in two and three dimensions. Depending on the strength properties of the target, the impact energies range between approximately 100-1000 MJ (0.024- 0.24 t TNT). By modeling the atmospheric traverse we demonstrate that low cosmic velocities (12- 14 kms-1) and shallow entry angles (<20°) are prerequisites to keep aerodynamic stresses low (<10 MPa) and thus to prevent fragmentation of stony meteoroids with standard strength properties. This scenario results in a strong meteoroid deceleration, a deflection of the trajectory to a steeper impact angle (40-60°), and an impact velocity of 350-600 ms-1, which is insufficient to produce a shock wave and significant shock effects in target minerals. Aerodynamic and <span class="hlt">crater</span> modeling are consistent with field data and our microscopic inspection. However, these data are in conflict with trajectories inferred from the analysis of</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li class="active"><span>16</span></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_16 --> <div id="page_17" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li class="active"><span>17</span></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="321"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19870043241&hterms=Mexico+sonora&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3DMexico%2Bsonora','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19870043241&hterms=Mexico+sonora&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3DMexico%2Bsonora"><span>Radar characteristics of small <span class="hlt">craters</span> - Implications for Venus</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Greeley, Ronald; Christensen, Philip R.; Mchone, John F.</p> <p>1987-01-01</p> <p>Shuttle radar images (SIR-A) of volcanic and impact <span class="hlt">craters</span> were examined to assess their appearance on radar images. Radar characteristics were determined for (1) nine maarlikie <span class="hlt">craters</span> in the Pinacate volcanic field, Sonora, Mexico; (<span class="hlt">2</span>) the caldera of Cerro Volcan Quemado, in the Bolivian Andes; (3) Talemzane impact <span class="hlt">crater</span>, Algeria; and (4) Al Umchaimin, a possible impact structure in Iraq. SIR-A images were compared with conventional photographs and with results from field studies. Consideration was then given to radar images available for Venus, or anticipated from the Magellan mission. Of the criteria ordinarily used to identify impact <span class="hlt">craters</span>, some can be assessed with radar images and others cannot be used; planimetric form, expressed as circularity, and ejecta-block distribution can be assessed on radar images, but rim and floor elevations relative to the surrounding plain and disposition of rim strata are difficult or impossible to determine. It is concluded that it will be difficult to separate small impact <span class="hlt">craters</span> from small volcanic <span class="hlt">craters</span> on Venus using radar images and is suggested that it will be necessary to understand the geological setting of the areas containing the <span class="hlt">craters</span> in order to determine their origin.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=PIA05281&hterms=swiss+cheese&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dswiss%2Bcheese','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=PIA05281&hterms=swiss+cheese&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dswiss%2Bcheese"><span>Exhuming South Polar <span class="hlt">Crater</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>2004-01-01</p> <p>7 February 2004 The large, circular feature in this image is an old meteor impact <span class="hlt">crater</span>. The <span class="hlt">crater</span> is larger than the 3 kilometers-wide (1.9 miles-wide) Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image, thus only part of the <span class="hlt">crater</span> is seen. The bright mesas full of pits and holes--in some areas resembling swiss cheese--are composed of frozen carbon dioxide. In this summertime view, the mesa slopes and pit walls are darkened as sunlight causes some of the ice to sublime away. At one time in the past, the <span class="hlt">crater</span> shown here may have been completely covered with carbon dioxide ice, but, over time, it has been exhumed as the ice sublimes a little bit more each summer. The <span class="hlt">crater</span> is located near 86.8oS, 111.6oW. Sunlight illuminates this scene from the upper left.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://boletinsgm.igeolcu.unam.mx/bsgm/index.php/component/content/article/149-sitio/articulos/cuarta-epoca/6501/775-6501-10-galloway','USGSPUBS'); return false;" href="http://boletinsgm.igeolcu.unam.mx/bsgm/index.php/component/content/article/149-sitio/articulos/cuarta-epoca/6501/775-6501-10-galloway"><span>Analysis and simulation of regional <span class="hlt">subsidence</span> accompanying groundwater abstraction and compaction of susceptible aquifer systems in the USA</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Galloway, Devin L.; Sneed, Michelle</p> <p>2013-01-01</p> <p>Regional aquifer-system compaction and land <span class="hlt">subsidence</span> accompanying groundwater abstraction in susceptible aquifer systems in the USA is a challenge for managing groundwater resources and mitigating associated hazards. Developments in the assessment of regional <span class="hlt">subsidence</span> provide more information to constrain analyses and simulation of aquifer-system compaction. Current popular approaches to simulating vertical aquifer-system deformation (compaction), such as those embodied in the aquitard drainage model and the MODFLOW <span class="hlt">subsidence</span> packages, have proven useful from the perspective of regional groundwater resources assessment. However, these approaches inadequately address related local-scale hazards—ground ruptures and damages to engineered structures on the land surface arising from tensional stresses and strains accompanying groundwater abstraction. This paper presents a brief overview of the general approaches taken by the <span class="hlt">U</span>.S. Geological Survey toward understanding aquifer-system compaction and <span class="hlt">subsidence</span> with regard to a) identifying the affected aquifer systems; b) making regional assessments; c) analyzing the governing processes; and d) simulating historical and future groundwater flow and <span class="hlt">subsidence</span> conditions. Limitations and shortcomings of these approaches, as well as future challenges also are discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://images.nasa.gov/#/details-PIA20252.html','SCIGOVIMAGE-NASA'); return false;" href="https://images.nasa.gov/#/details-PIA20252.html"><span><span class="hlt">Craters</span> - False Color</span></a></p> <p><a target="_blank" href="https://images.nasa.gov/">NASA Image and Video Library</a></p> <p></p> <p>2016-02-04</p> <p>The THEMIS camera contains 5 filters. The data from different filters can be combined in multiple ways to create a false color image. This image captured by NASA 2001 Mars Odyssey spacecraft shows a group of unnamed <span class="hlt">craters</span> north of Fournier <span class="hlt">Crater</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.usgs.gov/of/2009/1158/','USGSPUBS'); return false;" href="https://pubs.usgs.gov/of/2009/1158/"><span>Recent <span class="hlt">Subsidence</span> and Erosion at Diverse Wetland Sites in the Southeastern Mississippi Delta Plain</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Morton, Robert A.; Bernier, Julie C.; Kelso, Kyle W.</p> <p>2009-01-01</p> <p>A prior study (<span class="hlt">U</span>.S. Geological Survey Open-File Report 2005-1216) examined historical land- and water-area changes and estimated magnitudes of land <span class="hlt">subsidence</span> and erosion at five wetland sites in the Terrebonne hydrologic basin of the Mississippi delta plain. The present study extends that work by analyzing interior wetland loss and relative magnitudes of <span class="hlt">subsidence</span> and erosion at five additional wetland sites in the adjacent Barataria hydrologic basin. The Barataria basin sites were selected for their diverse physical settings and their recent (post-1978) conversion from marsh to open water. Historical aerial photography, datum-corrected marsh elevations and water depths, sediment cores, and radiocarbon dates were integrated to evaluate land-water changes in the Mississippi delta plain on both historical and geological time scales. The thickness of the organic-rich sediments (peat) and the elevation of the stratigraphic contact between peat and underlying mud were compared at marsh and open-water sites across areas of formerly continuous marsh to estimate magnitudes of recent delta-plain elevation loss caused by vertical erosion and <span class="hlt">subsidence</span> of the wetlands. Results of these analyses indicate that erosion exceeded <span class="hlt">subsidence</span> at most of the study areas, although both processes have contributed to historical wetland loss. Comparison of these results with prior studies indicates that <span class="hlt">subsidence</span> largely caused rapid interior wetland loss in the Terrebonne basin before 1978, whereas erosional processes primarily caused more gradual interior wetland loss in the Barataria basin after 1978. Decadal variations in rates of relative sea-level rise at a National Ocean Service tide gage, elevation changes between repeat benchmark-leveling surveys, and GPS height monitoring at three National Geodetic Survey Continuously Operating Reference Stations indicate that <span class="hlt">subsidence</span> rates since the early 1990s are substantially lower than those previously reported and are similar in</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012SolED...4..363G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012SolED...4..363G"><span>In plain sight: the Chesapeake Bay <span class="hlt">crater</span> ejecta blanket</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Griscom, D. L.</p> <p>2012-02-01</p> <p>The discovery nearly two decades ago of a 90 km-diameter impact <span class="hlt">crater</span> below the lower Chesapeake Bay has gone unnoted by the general public because to date all published literature on the subject has described it as "buried". To the contrary, evidence is presented here that the so-called "upland deposits" that blanket ∼5000 km<span class="hlt">2</span> of the <span class="hlt">U</span>.S. Middle-Atlantic Coastal Plain (M-ACP) display morphologic, lithologic, and stratigraphic features consistent with their being ejecta from the 35.4 Ma Chesapeake Bay Impact Structure (CBIS) and absolutely inconsistent with the prevailing belief that they are of fluvial origin. Specifically supporting impact origin are the facts that (i) a 95 %-pure iron ore endemic to the upland deposits of southern Maryland, eastern Virginia, and the District of Columbia has previously been proven to be impactoclastic in origin, (ii) this iron ore welds together a small percentage of well-rounded quartzite pebbles and cobbles of the upland deposits into brittle sheets interpretable as "spall plates" created in the interference-zone of the CBIS impact, (iii) the predominantly non-welded upland gravels have long ago been shown to be size sorted with an extreme <span class="hlt">crater</span>-centric gradient far too large to have been the work of rivers, but well explained as atmospheric size-sorted interference-zone ejecta, (iv) new evidence is provided here that ~60 % of the non-welded quartzite pebbles and cobbles of the (lower lying) gravel member of the upland deposits display planar fractures attributable to interference-zone tensile waves, (v) the (overlying) loam member of the upland deposits is attributable to base-surge-type deposition, (vi) several exotic clasts found in a debris flow topographically below the upland deposits can only be explained as jetting-phase <span class="hlt">crater</span> ejecta, and (vii) an allogenic granite boulder found among the upland deposits is deduced to have been launched into space and sculpted by hypervelocity air friction during reentry. An</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018HydJ..tmp....9Q','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018HydJ..tmp....9Q"><span>Groundwater-pumping optimization for land-<span class="hlt">subsidence</span> control in Beijing plain, China</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Qin, Huanhuan; Andrews, Charles B.; Tian, Fang; Cao, Guoliang; Luo, Yong; Liu, Jiurong; Zheng, Chunmiao</p> <p>2018-01-01</p> <p>Beijing, in the North China plain, is one of the few megacities that uses groundwater as its main source of water supply. Groundwater accounts for about two-thirds of the city's water supply, and during the past 50 years the storage depletion from the unconsolidated aquifers underlying the city has been >10.4 billion m3. By 2010, groundwater pumping in the city had resulted in a cumulative <span class="hlt">subsidence</span> of greater than 100 mm in an area of about 3,900 km<span class="hlt">2</span>, with a maximum cumulative <span class="hlt">subsidence</span> of >1,200 mm. This <span class="hlt">subsidence</span> has caused significant social and economic losses in Beijing, including significant damage to underground utilities. This study was undertaken to evaluate various future pumping scenarios to assist in selecting an optimal pumping scenario to minimize overall <span class="hlt">subsidence</span>, meet the requirements of the Beijing Land <span class="hlt">Subsidence</span> Prevention Plan (BLSPP 2013-2020), and be consistent with continued sustainable economic development. A numerical groundwater and land-<span class="hlt">subsidence</span> model was developed for the aquifer system of the Beijing plain to evaluate land <span class="hlt">subsidence</span> rates under the possible future pumping scenarios. The optimal pumping scenario consistent with the evaluation constraints is a reduction in groundwater pumping from three major pumping centers by 100, 50 and 20%, respectively, while maintaining an annual pumping rate of 1.9 billion m3. This scenario's land-<span class="hlt">subsidence</span> rates satisfy the BLSPP 2013-2020 and the pumping scenario is consistent with continued economic development. It is recommended that this pumping scenario be adopted for future land-<span class="hlt">subsidence</span> management in Beijing.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018HydJ...26.1061Q','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018HydJ...26.1061Q"><span>Groundwater-pumping optimization for land-<span class="hlt">subsidence</span> control in Beijing plain, China</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Qin, Huanhuan; Andrews, Charles B.; Tian, Fang; Cao, Guoliang; Luo, Yong; Liu, Jiurong; Zheng, Chunmiao</p> <p>2018-06-01</p> <p>Beijing, in the North China plain, is one of the few megacities that uses groundwater as its main source of water supply. Groundwater accounts for about two-thirds of the city's water supply, and during the past 50 years the storage depletion from the unconsolidated aquifers underlying the city has been >10.4 billion m3. By 2010, groundwater pumping in the city had resulted in a cumulative <span class="hlt">subsidence</span> of greater than 100 mm in an area of about 3,900 km<span class="hlt">2</span>, with a maximum cumulative <span class="hlt">subsidence</span> of >1,200 mm. This <span class="hlt">subsidence</span> has caused significant social and economic losses in Beijing, including significant damage to underground utilities. This study was undertaken to evaluate various future pumping scenarios to assist in selecting an optimal pumping scenario to minimize overall <span class="hlt">subsidence</span>, meet the requirements of the Beijing Land <span class="hlt">Subsidence</span> Prevention Plan (BLSPP 2013-2020), and be consistent with continued sustainable economic development. A numerical groundwater and land-<span class="hlt">subsidence</span> model was developed for the aquifer system of the Beijing plain to evaluate land <span class="hlt">subsidence</span> rates under the possible future pumping scenarios. The optimal pumping scenario consistent with the evaluation constraints is a reduction in groundwater pumping from three major pumping centers by 100, 50 and 20%, respectively, while maintaining an annual pumping rate of 1.9 billion m3. This scenario's land-<span class="hlt">subsidence</span> rates satisfy the BLSPP 2013-2020 and the pumping scenario is consistent with continued economic development. It is recommended that this pumping scenario be adopted for future land-<span class="hlt">subsidence</span> management in Beijing.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/6982390','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/6982390"><span>Mitogenic activity of a water-soluble adjuvant (<span class="hlt">Bu</span>-WSA) obtained from Bacterionema matruchotii. IV. Synergistic effects of <span class="hlt">Bu</span>-WSA on Concanavalin A-induced proliferative response of human peripheral blood lymphocytes.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Nitta, T; Okumura, S; Tsushi, M; Nakano, M</p> <p>1982-01-01</p> <p>Butanol-extracted water-soluble adjuvant (<span class="hlt">Bu</span>-WSA) obtained from Bacterionema matruchotii was cultured with peripheral blood mononuclear cells (PBM) in the presence of sub- and/or supra-optimal mitogenic concentrations of concanavalin A (Con A). The addition of <span class="hlt">Bu</span>-WSA resulted in increased tritiated thymidine incorporation above that produced by Con A alone. <span class="hlt">Bu</span>-WSA by itself is not mitogenic for PBM and in fact produced a decrease in thymidine uptake compared to the control. We investigated the response of subpopulation(s) of PBM to <span class="hlt">Bu</span>-WSA, Con A and a mixture of <span class="hlt">Bu</span>-WSA and Con A. Separation of PBM into purified T cells, B cells and macrophages showed that cell-cell cooperation of T cells with B cells or macrophages is necessary for the observed synergistic effect of <span class="hlt">Bu</span>-WSA with Con A. A marked increase in thymidine incorporation by the mixture of T and B cell populations occurred, while only a small amount of thymidine was incorporated when the B cell population was absent. Mitomycin treatment revealed that the response could be ascribed to the T-cell response with a B-cell helper effect. Moreover, Con A and <span class="hlt">Bu</span>-WSA appeared to act on the same T cell population. This model may provide unique information about the activation of human peripheral blood T cells compared with the activation of these cells by other mitogens.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://images.nasa.gov/#/details-PIA22144.html','SCIGOVIMAGE-NASA'); return false;" href="https://images.nasa.gov/#/details-PIA22144.html"><span>Investigating Mars: Rabe <span class="hlt">Crater</span></span></a></p> <p><a target="_blank" href="https://images.nasa.gov/">NASA Image and Video Library</a></p> <p></p> <p>2017-12-18</p> <p>The majority of the dune field in Rabe <span class="hlt">Crater</span> consists of a sand sheet with dune forms on the surface. The sand sheet is where a thick layer of sand has been concentrated. As continued winds blow across the sand surface it creates dune forms. The depth of the sand sheet prevents excavation to the <span class="hlt">crater</span> floor and the dune forms all appear connected. Rabe <span class="hlt">Crater</span> is 108 km (67 miles) across. <span class="hlt">Craters</span> of similar size often have flat floors. Rabe <span class="hlt">Crater</span> has some areas of flat floor, but also has a large complex pit occupying a substantial part of the floor. The interior fill of the <span class="hlt">crater</span> is thought to be layered sediments created by wind and or water action. The pit is eroded into this material. The eroded materials appear to have stayed within the <span class="hlt">crater</span> forming a large sand sheet with surface dune forms as well as individual dunes where the <span class="hlt">crater</span> floor is visible. The dunes also appear to be moving from the upper floor level into the pit. The Odyssey spacecraft has spent over 15 years in orbit around Mars, circling the planet more than 69000 times. It holds the record for longest working spacecraft at Mars. THEMIS, the IR/VIS camera system, has collected data for the entire mission and provides images covering all seasons and lighting conditions. Over the years many features of interest have received repeated imaging, building up a suite of images covering the entire feature. From the deepest chasma to the tallest volcano, individual dunes inside <span class="hlt">craters</span> and dune fields that encircle the north pole, channels carved by water and lava, and a variety of other feature, THEMIS has imaged them all. For the next several months the image of the day will focus on the Tharsis volcanoes, the various chasmata of Valles Marineris, and the major dunes fields. We hope you enjoy these images! Orbit Number: 58024 Latitude: -43.6954 Longitude: 34.8236 Instrument: VIS Captured: 2015-01-12 09:48 https://photojournal.jpl.nasa.gov/catalog/PIA22144</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28842543','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28842543"><span>Lactolisterin <span class="hlt">BU</span>, a Novel Class II Broad-Spectrum Bacteriocin from Lactococcus lactis subsp. lactis bv. diacetylactis BGBU1-4.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Lozo, Jelena; Mirkovic, Nemanja; O'Connor, Paula M; Malesevic, Milka; Miljkovic, Marija; Polovic, Natalija; Jovcic, Branko; Cotter, Paul D; Kojic, Milan</p> <p>2017-11-01</p> <p>Lactococcus lactis subsp. lactis bv. diacetylactis BGBU1-4 produces a novel bacteriocin, lactolisterin <span class="hlt">BU</span>, with strong antimicrobial activity against many species of Gram-positive bacteria, including important food spoilage and foodborne pathogens, such as Listeria monocytogenes , Staphylococcus aureus , Bacillus spp., and streptococci. Lactolisterin <span class="hlt">BU</span> was extracted from the cell surface of BGBU1-4 by <span class="hlt">2</span>-propanol and purified to homogeneity by C 18 solid-phase extraction and reversed-phase high-performance liquid chromatography. The molecular mass of the purified lactolisterin <span class="hlt">BU</span> was 5,160.94 Da, and an internal fragment, AVSWAWQH, as determined by N-terminal sequencing, showed low-level similarity to existing antimicrobial peptides. Curing and transformation experiments revealed the presence of a corresponding bacteriocin operon on the smallest plasmid, p<span class="hlt">BU</span>6 (6.<span class="hlt">2</span> kb), of strain BGBU1-4. Analysis of the bacteriocin operon revealed a leaderless bacteriocin of 43 amino acids that exhibited similarity to bacteriocin BHT-B (63%) from Streptococcus ratti , a bacteriocin with analogy to aureocin A. IMPORTANCE Lactolisterin <span class="hlt">BU</span>, a broad-spectrum leaderless bacteriocin produced by L. lactis subsp. lactis bv. diacetylactis BGBU1-4, expresses strong antimicrobial activity against food spoilage and foodborne pathogens, such as Listeria monocytogenes , Staphylococcus aureus , Bacillus spp., and streptococci. Lactolisterin <span class="hlt">BU</span> showed the highest similarity to aureocin-like bacteriocins produced by different bacteria. The operon for synthesis is located on the smallest plasmid, p<span class="hlt">BU</span>6 (6.<span class="hlt">2</span> kb), of strain BGBU1-4, indicating possible horizontal transfer among producers. Copyright © 2017 American Society for Microbiology.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5648901','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5648901"><span>Lactolisterin <span class="hlt">BU</span>, a Novel Class II Broad-Spectrum Bacteriocin from Lactococcus lactis subsp. lactis bv. diacetylactis BGBU1-4</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Lozo, Jelena; Mirkovic, Nemanja; O'Connor, Paula M.; Malesevic, Milka; Miljkovic, Marija; Polovic, Natalija; Cotter, Paul D.</p> <p>2017-01-01</p> <p>ABSTRACT Lactococcus lactis subsp. lactis bv. diacetylactis BGBU1-4 produces a novel bacteriocin, lactolisterin <span class="hlt">BU</span>, with strong antimicrobial activity against many species of Gram-positive bacteria, including important food spoilage and foodborne pathogens, such as Listeria monocytogenes, Staphylococcus aureus, Bacillus spp., and streptococci. Lactolisterin <span class="hlt">BU</span> was extracted from the cell surface of BGBU1-4 by <span class="hlt">2</span>-propanol and purified to homogeneity by C18 solid-phase extraction and reversed-phase high-performance liquid chromatography. The molecular mass of the purified lactolisterin <span class="hlt">BU</span> was 5,160.94 Da, and an internal fragment, AVSWAWQH, as determined by N-terminal sequencing, showed low-level similarity to existing antimicrobial peptides. Curing and transformation experiments revealed the presence of a corresponding bacteriocin operon on the smallest plasmid, p<span class="hlt">BU</span>6 (6.<span class="hlt">2</span> kb), of strain BGBU1-4. Analysis of the bacteriocin operon revealed a leaderless bacteriocin of 43 amino acids that exhibited similarity to bacteriocin BHT-B (63%) from Streptococcus ratti, a bacteriocin with analogy to aureocin A. IMPORTANCE Lactolisterin <span class="hlt">BU</span>, a broad-spectrum leaderless bacteriocin produced by L. lactis subsp. lactis bv. diacetylactis BGBU1-4, expresses strong antimicrobial activity against food spoilage and foodborne pathogens, such as Listeria monocytogenes, Staphylococcus aureus, Bacillus spp., and streptococci. Lactolisterin <span class="hlt">BU</span> showed the highest similarity to aureocin-like bacteriocins produced by different bacteria. The operon for synthesis is located on the smallest plasmid, p<span class="hlt">BU</span>6 (6.<span class="hlt">2</span> kb), of strain BGBU1-4, indicating possible horizontal transfer among producers. PMID:28842543</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.usgs.gov/sir/2013/5142/pdf/sir2013-5142.pdf','USGSPUBS'); return false;" href="https://pubs.usgs.gov/sir/2013/5142/pdf/sir2013-5142.pdf"><span>Land <span class="hlt">subsidence</span> along the Delta-Mendota Canal in the northern part of the San Joaquin Valley, California, 2003-10</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Sneed, Michelle; Brandt, Justin; Solt, Mike</p> <p>2013-01-01</p> <p>Extensive groundwater withdrawal from the unconsolidated deposits in the San Joaquin Valley caused widespread aquifer-system compaction and resultant land <span class="hlt">subsidence</span> from 1926 to 1970—locally exceeding 8.5 meters. The importation of surface water beginning in the early 1950s through the Delta-Mendota Canal and in the early 1970s through the California Aqueduct resulted in decreased pumping, initiation of water-level recovery, and a reduced rate of compaction in some areas of the San Joaquin Valley. However, drought conditions during 1976–77 and 1987–92, and drought conditions and regulatory reductions in surface-water deliveries during 2007–10, decreased surface-water availability, causing pumping to increase, water levels to decline, and renewed compaction. Land <span class="hlt">subsidence</span> from this compaction has reduced freeboard and flow capacity of the Delta-Mendota Canal, the California Aqueduct, and other canals that deliver irrigation water and transport floodwater. The <span class="hlt">U</span>.S. Geological Survey, in cooperation with the <span class="hlt">U</span>.S. Bureau of Reclamation and the San Luis and Delta-Mendota Water Authority, assessed land <span class="hlt">subsidence</span> in the vicinity of the Delta-Mendota Canal as part of an effort to minimize future <span class="hlt">subsidence</span>-related damages to the canal. The location, magnitude, and stress regime of land-surface deformation during 2003–10 were determined by using extensometer, Global Positioning System (GPS), Interferometric Synthetic Aperture Radar (InSAR), spirit leveling, and groundwater-level data. Comparison of continuous GPS, shallow extensometer, and groundwater-level data, combined with results from a one-dimensional model, indicated the vast majority of the compaction took place beneath the Corcoran Clay, the primary regional confining unit. Land-surface deformation measurements indicated that much of the northern portion of the Delta-Mendota Canal (Clifton Court Forebay to Check 14) was fairly stable or minimally <span class="hlt">subsiding</span> on an annual basis; some areas showed</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EGUGA..17.6648G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EGUGA..17.6648G"><span>The flight of Arcadia: spatial CO<span class="hlt">2</span>/SO<span class="hlt">2</span> variations in a cross section above the Nord East <span class="hlt">crater</span> of Etna volcano</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Giuffrida, Giovanni; Calabrese, Sergio; Bobrowski, Nicole; Finkenzeller, Henning; Pecoraino, Giovannella; Scaglione, Sarah</p> <p>2015-04-01</p> <p>The CO<span class="hlt">2</span>/SO<span class="hlt">2</span> ratio in volcanic plumes of open conduit volcanoes can provide useful information about the magma depth inside a conduit and the possible occurrence of an eruptive event. Moreover, the same CO<span class="hlt">2</span> measurement when combined with a SO<span class="hlt">2</span> flux measurement, commonly carried out at many volcanoes nowadays, is used to contribute to an improved estimate of global volcanic CO<span class="hlt">2</span> budget. Today worldwide at 13 volcanoes automated in-situ instruments (known as Multi-GAS stations) are applied to continuously determine CO<span class="hlt">2</span>/SO<span class="hlt">2</span> ratios and to use this signal as additional parameter for volcanic monitoring. Usually these instruments carry out measurements of half an hour 4 - 6 times/day and thus provide continuous CO<span class="hlt">2</span>/SO<span class="hlt">2</span> values and their variability. The stations are located at <span class="hlt">crater</span> rims in a position that according to the prevailing winds is invested by the plume. Obviously, although the stations are carefully positioned, it is inevitable that other sources than the plume itself, e.g. soil degassing and surrounding fumaroles, contribute and will be measured as well, covering the 'real' values. Between July and September 2014 experiments were carried out on the North East <span class="hlt">crater</span> (NEC) of Mount Etna, installing a self-made cable car that crossed the <span class="hlt">crater</span> from one side to the other. The basket, called "Arcadia", was equipped with an automated standard Multi-GAS station and a GPS, which acquired at high frequency (0.5 Hz) the following parameters : CO<span class="hlt">2</span>, SO<span class="hlt">2</span>, H<span class="hlt">2</span>S, Rh, T, P and geo-coordinates. The choice of NEC of the volcano Etna was based on its accessibility, the relative small diameter (about 230 m) and the presence of a relatively constant and rather concentrated plume. Actually, NEC belongs also to the monitoring network EtnaPlume (managed by the INGV of Palermo). The aim of these experiments was to observe variations of each parameter, in particular the fluctuation of the CO<span class="hlt">2</span>/SO<span class="hlt">2</span> ratio within the plume, moving from the edge to the center of the <span class="hlt">crater</span>. The gained</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19930005204','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19930005204"><span>Low-emissivity impact <span class="hlt">craters</span> on Venus</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Weitz, C. M.; Elachi, C.; Moore, H. J.; Basilevsky, A. T.; Ivanov, B. A.; Schaber, G. G.</p> <p>1992-01-01</p> <p>An analysis of 144 impact <span class="hlt">craters</span> on Venus has shown that 11 of these have floors with average emissivities lower than 0.8. The remaining <span class="hlt">craters</span> have emissivities between 0.8 and 0.9, independent of the specific backscatter cross section of the <span class="hlt">crater</span> floors. These 144 impact <span class="hlt">craters</span> were chosen from a possible 164 <span class="hlt">craters</span> with diameters greater than 30 km as identified by researchers for 89 percent of the surface of Venus. We have only looked at <span class="hlt">craters</span> below 6053.5 km altitude because a mineralogical change causes high reflectivity/low emissivity above the altitude. We have also excluded all <span class="hlt">craters</span> with diameters smaller than 30 km because the emissivity footprint at periapsis is 16 x 24 km and becomes larger at the poles.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2004AGUFMED51A0004P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2004AGUFMED51A0004P"><span>The Explorer's Guide to Impact <span class="hlt">Craters</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pierazzo, E.; Osinski, G.; Chuang, F.</p> <p>2004-12-01</p> <p>Impact <span class="hlt">cratering</span> is a fundamental geologic process of our solar system. It competes with other processes, such as plate tectonics, volcanism, or fluvial, glacial and eolian activity, in shaping the surfaces of planetary bodies. In some cases, like the Moon and Mercury, impact <span class="hlt">craters</span> are the dominant landform. On other planetary bodies impact <span class="hlt">craters</span> are being continuously erased by the action of other geological processes, like volcanism on Io, erosion and plate tectonics on the Earth, tectonic and volcanic resurfacing on Venus, or ancient erosion periods on Mars. The study of <span class="hlt">crater</span> populations is one of the principal tools for understanding the geologic history of a planetary surface. Among the general public, impact <span class="hlt">cratering</span> has drawn wide attention through its portrayal in several Hollywood movies. Questions that are raised after watching these movies include: ``How do scientists learn about impact <span class="hlt">cratering</span>?'', and ``What information do impact <span class="hlt">craters</span> provide in understanding the evolution of a planetary surface?'' Fundamental approaches used by scientists to learn about impact <span class="hlt">cratering</span> include field work at known terrestrial <span class="hlt">craters</span>, remote sensing studies of <span class="hlt">craters</span> on various solid surfaces of solar system bodies, and theoretical and laboratory studies using the known physics of impact <span class="hlt">cratering</span>. We will provide students, science teachers, and the general public an opportunity to experience the scientific endeavor of understanding and exploring impact <span class="hlt">craters</span> through a multi-level approach including images, videos, and rock samples. This type of interactive learning can also be made available to the general public in the form of a website, which can be addressed worldwide at any time.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015PIAHS.372..115A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015PIAHS.372..115A"><span>Study on the risk and impacts of land <span class="hlt">subsidence</span> in Jakarta</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Abidin, H. Z.; Andreas, H.; Gumilar, I.; Brinkman, J. J.</p> <p>2015-11-01</p> <p>Jakarta is the capital city of Indonesia located in the west-northern coast of Java island, within a deltaic plain and passes by 13 natural and artificial rivers. This megapolitan has a population of about 10.<span class="hlt">2</span> million people inhabiting an area of about 660 km<span class="hlt">2</span>, with relatively rapid urban development. It has been reported for many years that several places in Jakarta are <span class="hlt">subsiding</span> at different rates. The main causative factors of land <span class="hlt">subsidence</span> in Jakarta are most probably excessive groundwater extraction, load of constructions (i.e., settlement of high compressibility soil), and natural consolidation of alluvial soil. Land <span class="hlt">subsidence</span> in Jakarta has been studied using leveling surveys, GPS surveys, InSAR and Geometric-Historic techniques. The results obtained from leveling surveys, GPS surveys and InSAR technique over the period between 1974 and 2010 show that land <span class="hlt">subsidence</span> in Jakarta has spatial and temporal variations with typical rates of about 3-10 cm year-1. Rapid urban development, relatively young alluvium soil, and relatively weak mitigation and adapatation initiatives, are risk increasing factors of land <span class="hlt">subsidence</span> in Jakarta. The <span class="hlt">subsidence</span> impacts can be seen already in the field in forms of cracking and damage of housing, buildings and infrastructure; wider expansion of (riverine and coastal) flooding areas, malfunction of drainage system, changes in river canal and drain flow systems and increased inland sea water intrusion. These impacts can be categorized into infrastructural, environmental, economic and social impacts. The risk and impacts of land <span class="hlt">subsidence</span> in Jakarta and their related aspects are discussed in this paper.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1986JApMe..25.1088C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1986JApMe..25.1088C"><span><span class="hlt">Subsidence</span> in the Nocturnal Boundary Layer.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Carlson, Merrilee A.; Stull, Roland B.</p> <p>1986-08-01</p> <p>Nights with clear skies and strong radiative cooling that favor the formation of statically stable nocturnal boundary layers (NBL) are also those nights most likely to have <span class="hlt">subsidence</span>, because of the presence of synoptic high-pressure regions. The divergence associated with <span class="hlt">subsidence</span> laterally removes some of the chilled nocturnal boundary layer air causing the NBL to not grow as rapidly as would otherwise be expected. An equivalent interpretation is that <span class="hlt">subsidence</span>-induced heating partially counteracts the radiative and turbulent cooling.A new form of nocturnal integral depth scale, HT, is introduced that incorporates the heating and cooling contributions at night. This scale can be used with a variety of idealized temperature profile shapes, including slab, linear, and exponential. It is shown that observed values of <span class="hlt">subsidence</span> for two case studies can reduce the NBL growth rate, as measured by HT/t, by 5 to 50% and can cause corresponding errors in the estimation of accumulated cooling unless there is a proper accounting of <span class="hlt">subsidence.Subsidence</span> plays a very minor role close to the ground, but for the case studies presented here its heating rate increases with height and becomes of comparable magnitude to the cooling rates of turbulence and radiation within the top third of the NBL. Although no adequate measurements of horizontal advective effects were available for the case studies used here, it appears from an energy balance that advection must not be neglected because its magnitude can be as large as turbulence and radiation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70031822','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70031822"><span>Six years of land <span class="hlt">subsidence</span> in shanghai revealed by JERS-1 SAR data</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Damoah-Afari, P.; Ding, X.-L.; Li, Z.; Lu, Z.; Omura, M.</p> <p>2008-01-01</p> <p>Differential interferometric synthetic aperture radar (SAR) (DInSAR) has proven to be very useful in mapping and monitoring land <span class="hlt">subsidence</span> in many regions of the world. Shanghai, China's largest city, is one of such areas suffering from land <span class="hlt">subsidence</span> as a result of severe withdrawal of groundwater for different usages. DInSAR application in Shanghai with the C-band European Remote Sensing 1 & <span class="hlt">2</span> (ERS-1/<span class="hlt">2</span>) SAR data has been difficult mainly due to the problem of decorrelation of InSAR pairs with temporal baselines larger than 10 months. To overcome the coherence loss of C-band InSAR data, we used eight L-band Japanese Earth Resource Satellite (JERS-1) SAR data acquired during <span class="hlt">2</span> October 1992 to 15 July 1998 to study land <span class="hlt">subsidence</span> phenomenon in Shanghai. Three of the images were used to produce two separate digital elevation models (DEMs) of the study area to remove topographic fringes from the interferograms used for <span class="hlt">subsidence</span> mapping. Six interferograms were used to generate <span class="hlt">2</span> different time series of deformation maps over Shanghai. The cumulative <span class="hlt">subsidence</span> map generated from each of the time series is in agreement with the land <span class="hlt">subsidence</span> measurements of Shanghai city from 1990-1998, produced from other survey methods. ?? 2007 IEEE.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/12005486','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/12005486"><span>Cyclometalated products of [(COE)(<span class="hlt">2</span>)RhCl](<span class="hlt">2</span>) and 1,3-(RSCH(<span class="hlt">2))(2</span>)C(6)H(4) (R = (t)<span class="hlt">Bu</span>, (i)Pr) Are Dimeric. Synthesis, molecular structures, and solution dynamics of [mu-ClRh(H)(RSCH(<span class="hlt">2))(2</span>)C(6)H(3)-<span class="hlt">2,6](2</span>).</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Evans, Daniel R; Huang, Mingsheng; Seganish, W Michael; Chege, Esther W; Lam, Yiu-Fai; Fettinger, James C; Williams, Tracie L</p> <p>2002-05-20</p> <p>Two tridentate thioether pincer ligands, 1,3-(RSCH(<span class="hlt">2))(2</span>)C(6)H(4) (R = (t)()<span class="hlt">Bu</span>, 1a; R = (i)()Pr, 1b) underwent cyclometalation using [(COE)(<span class="hlt">2</span>)RhCl](<span class="hlt">2</span>) in air/moisture-free benzene at room temperature. The resultant complexes, [mu-ClRh(H)(RSCH(<span class="hlt">2))(2</span>)C(6)H(3)-<span class="hlt">2,6](2</span>) (R = (t)<span class="hlt">Bu</span>, <span class="hlt">2</span>a; R = (i)Pr, <span class="hlt">2</span>b) are dimeric both in the solid state and in solution. A battery of variable-temperature one- and two-dimensional (1)H NMR experiments showed conclusively that both complexes undergo dynamic exchange in solution. Exchange between two dimeric diastereomers of <span class="hlt">2</span>a in solution occurred via rotation about the Rh-C(ipso) bond. The dynamic exchange of <span class="hlt">2</span>b was significantly more complex as an additional exchange mechanism, sulfur inversion, occurred, which resulted in the exchange between several diastereomers in solution.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li class="active"><span>17</span></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_17 --> <div id="page_18" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li class="active"><span>18</span></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="341"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://images.nasa.gov/#/details-PIA21152.html','SCIGOVIMAGE-NASA'); return false;" href="https://images.nasa.gov/#/details-PIA21152.html"><span>Palikir <span class="hlt">Crater</span></span></a></p> <p><a target="_blank" href="https://images.nasa.gov/">NASA Image and Video Library</a></p> <p></p> <p>2016-10-27</p> <p>Today's VIS image is of Palikir <span class="hlt">Crater</span> in Terra Sirenum. The inner rim of the <span class="hlt">crater</span> is dissected with numerous gullies. In higher resolution images from other imagers these gullies are the location of changing linea, which appear to grow and retreat as seasons change. Orbit Number: 65311 Latitude: -41.6177 Longitude: 202.206 Instrument: VIS Captured: 2016-09-03 13:12 http://photojournal.jpl.nasa.gov/catalog/PIA21152</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://images.nasa.gov/#/details-PIA20092.html','SCIGOVIMAGE-NASA'); return false;" href="https://images.nasa.gov/#/details-PIA20092.html"><span>Central Pit <span class="hlt">Crater</span></span></a></p> <p><a target="_blank" href="https://images.nasa.gov/">NASA Image and Video Library</a></p> <p></p> <p>2015-11-13</p> <p><span class="hlt">Crater</span> floors can have a range of features, from flat to a central peak or a central pit. This image from NASA 2001 Mars Odyssey spacecraft shows an unnamed <span class="hlt">crater</span> in Terra Sabaea has a central pit. This unnamed <span class="hlt">crater</span> in Terra Sabaea has a central pit. The different floor features develop do due several factors, including the size of the impactor, the geology of the surface material and the geology of the materials at depth. Orbit Number: 60737 Latitude: 22.3358 Longitude: 61.2019 Instrument: VIS Captured: 2015-08-23 20:13 http://photojournal.jpl.nasa.gov/catalog/PIA20092</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19930062613&hterms=neither+deep+shallow&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dneither%2Bdeep%2Bshallow','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19930062613&hterms=neither+deep+shallow&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dneither%2Bdeep%2Bshallow"><span>Shallow and deep fresh impact <span class="hlt">craters</span> in Hesperia Planum, Mars</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Mouginis-Mark, Peter J.; Hayashi, Joan N.</p> <p>1993-01-01</p> <p>The depths of 109 impact <span class="hlt">craters</span> about <span class="hlt">2</span>-16 km in diameter, located on the ridged plains materials of Hesperia Planum, Mars, have been measured from their shadow lengths using digital Viking Orbiter images (orbit numbers 417S-419S) and the PICS computer software. On the basis of their pristine morphology (very fresh lobate ejecta blankets, well preserved rim crests, and lack of superposed impact <span class="hlt">craters</span>), 57 of these <span class="hlt">craters</span> have been selected for detailed analysis of their spatial distribution and geometry. We find that south of 30 deg S, <span class="hlt">craters</span> less than 6.0 km in diameter are markedly shallower than similar-sized <span class="hlt">craters</span> equatorward of this latitude. No comparable relationship is observed for morphologically fresh <span class="hlt">craters</span> greater than 6.0 km diameter. We also find that two populations exist for older <span class="hlt">craters</span> less than 6.0 km diameter. When <span class="hlt">craters</span> that lack ejecta blankets are grouped on the basis of depth/diameter ratio, the deeper <span class="hlt">craters</span> also typically lie equatorward of 30 S. We interpret the spatial variation in <span class="hlt">crater</span> depth/diameter ratios as most likely due to a poleward increase in volatiles within the top 400 m of the surface at the times these <span class="hlt">craters</span> were formed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5769684','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5769684"><span>Do hospitals cross-<span class="hlt">subsidize</span>?</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>David, Guy; Lindrooth, Richard C.; Helmchen, Lorens A.; Burns, Lawton R.</p> <p>2017-01-01</p> <p>Despite its salience as a regulatory tool to ensure the delivery of unprofitable medical services, cross-<span class="hlt">subsidization</span> of services within hospital systems has been notoriously difficult to detect and quantify. We use repeated shocks to a profitable service in the market for hospital-based medical care to test for cross-<span class="hlt">subsidization</span> of unprofitable services. Using patient-level data from general short-term hospitals in Arizona and Colorado before and after entry by cardiac specialty hospitals, we study how incumbent hospitals adjusted their provision of three uncontested services that are widely considered to be unprofitable. We estimate that the hospitals most exposed to entry reduced their provision of psychiatric, substance-abuse, and trauma care services at a rate of about one uncontested-service admission for every four cardiac admissions they stood to lose. Although entry by single-specialty hospitals may adversely affect the provision of unprofitable uncontested services, these findings warrant further evaluation of service-line cross-<span class="hlt">subsidization</span> as a means to finance them. PMID:25062300</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20000031463&hterms=cold+chain&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dcold%2Bchain','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20000031463&hterms=cold+chain&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dcold%2Bchain"><span><span class="hlt">Cratering</span> on Titan: A Pre-Cassini Perspective</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Lorenz, R. D.</p> <p>1997-01-01</p> <p>The NASA-ESA Cassini mission, comprising a formidably instrumented orbiter and parachute-borne probe to be launched this October, promises to reveal a <span class="hlt">crater</span> population on Titan that has been heretofore hidden by atmospheric haze. This population on the largest remaining unexplored surface in the solar system will be invaluable in comparative planetological studies, since it introduces evidence of the atmospheric effects of <span class="hlt">cratering</span> on an icy satellite. Here, I highlight some impact features we may hope to find and could devote some modeling effort toward. Titan in a Nutshell: Radius= 2575 km. Density= 1880 kg/cubic m consistent with rock-ice composition. Surface pressure = 1.5 bar. Surface gravity = 1.35 m/square s Atmosphere -94% N<span class="hlt">2</span> 6% CH, Surface temperature = 94K Tropopause temperature = 70K at 40 km alt. Probable liquid hydrocarbon deposits exist on or near the surface.Titan in a Nutshell: Radius= 2575 km. Density= 1880 kg/cubic m consistent with rock-ice composition. Surface pressure = 1.5 bar. Surface gravity = 1.35 m/square s; Atmosphere about 94% N<span class="hlt">2</span> 6% CH, Surface temperature = 94K Tropopause temperature = 70K at 40 km alt. Probable liquid hydrocarbon deposits exist on or near the surface. Titan is comparable to Callisto and Ganymede for strength/gravity, Mars/Earth/Venus for atmospheric interaction, and Hyperion, Rhea, and Iapetus for impactor distribution. The leading/trailing asymmetry of <span class="hlt">crater</span> density from heliocentric impactors is expected to be about 5-6, in the absence of resurfacing. Any Saturnocentric impactor population is likely to alter this. In particular the impact disruption of Hyperion is noted; because of the 3:4 orbital resonance with Titan, fragments from the proto-Hyperion breakup would have rapidly accreted onto Titan. Titan's resurfacing history is of course unknown. The disruption of impactors into fragments that individually create small <span class="hlt">craters</span> is expected to occur. A crude estimate suggests a maximum separation of about <span class="hlt">2</span> km</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1997LPICo.922...31L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1997LPICo.922...31L"><span><span class="hlt">Cratering</span> on Titan: A Pre-Cassini Perspective</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lorenz, R. D.</p> <p>1997-01-01</p> <p>The NASA-ESA Cassini mission, comprising a formidably instrumented orbiter and parachute-borne probe to be launched this October, promises to reveal a <span class="hlt">crater</span> population on Titan that has been heretofore hidden by atmospheric haze. This population on the largest remaining unexplored surface in the solar system will be invaluable in comparative planetological studies, since it introduces evidence of the atmospheric effects of <span class="hlt">cratering</span> on an icy satellite. Here, I highlight some impact features we may hope to find and could devote some modeling effort toward. Titan in a Nutshell: Radius= 2575 km. Density= 1880 kg/cubic m consistent with rock-ice composition. Surface pressure = 1.5 bar. Surface gravity = 1.35 m/square s Atmosphere -94% N<span class="hlt">2</span> 6% CH, Surface temperature = 94K Tropopause temperature = 70K at 40 km alt. Probable liquid hydrocarbon deposits exist on or near the surface.Titan in a Nutshell: Radius= 2575 km. Density= 1880 kg/cubic m consistent with rock-ice composition. Surface pressure = 1.5 bar. Surface gravity = 1.35 m/square s; Atmosphere about 94% N<span class="hlt">2</span> 6% CH, Surface temperature = 94K Tropopause temperature = 70K at 40 km alt. Probable liquid hydrocarbon deposits exist on or near the surface. Titan is comparable to Callisto and Ganymede for strength/gravity, Mars/Earth/Venus for atmospheric interaction, and Hyperion, Rhea, and Iapetus for impactor distribution. The leading/trailing asymmetry of <span class="hlt">crater</span> density from heliocentric impactors is expected to be about 5-6, in the absence of resurfacing. Any Saturnocentric impactor population is likely to alter this. In particular the impact disruption of Hyperion is noted; because of the 3:4 orbital resonance with Titan, fragments from the proto-Hyperion breakup would have rapidly accreted onto Titan. Titan's resurfacing history is of course unknown. The disruption of impactors into fragments that individually create small <span class="hlt">craters</span> is expected to occur. A crude estimate suggests a maximum separation of about <span class="hlt">2</span> km</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014EGUGA..1610635H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014EGUGA..1610635H"><span>An in-depth study of Marcia <span class="hlt">Crater</span>, Vesta</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hiesinger, Harald; Ruesch, Ottaviano; Williams, David A.; Nathues, Andreas; Prettyman, Thomas H.; Tosi, Frederico; De Sanctis, M. Christina; Scully, Jennifer E. C.; Schenk, Paul M.; Aileen Yingst, R.; Denevi, Bret W.; Jaumann, Ralf; Raymond, Carol A.; Russell, Chris T.</p> <p>2014-05-01</p> <p>After visiting the second most massive asteroid Vesta from July 2011 to September 2012, the Dawn spacecraft is now on its way to asteroid Ceres. Dawn observed Vesta with three instruments: the German Framing Camera (FC), the Italian Visible and InfraRed mapping spectrometer (VIR), and the American Gamma Ray and Neutron Detector (GRaND) [1]. Marcia <span class="hlt">crater</span> (190°E, 10°N; 68 x 58 km) is the largest of three adjacent impact structures: Marcia (youngest), Calpurnia, and Minucia (oldest). It is the largest well-preserved post-Rheasilvia impact <span class="hlt">crater</span>, shows a complex geology [<span class="hlt">2</span>], is young [<span class="hlt">2</span>], exhibits evidence for gully-like mass wasting [3], contains the largest location of pitted terrain [4], has smooth impact melt ponds [5], shows enhanced spectral pyroxene signatures on its inner walls [<span class="hlt">2</span>], and has low abundances of OH and H in comparison to the surrounding low-albedo terrain [6, 7]. Geophysically, the broad region of Marcia and Calpurnia <span class="hlt">craters</span> is characterized by a higher Bouguer gravity, indicating denser material [9]. Williams et al. [<span class="hlt">2</span>] have produced a detailed geologic map of Marcia <span class="hlt">crater</span> and the surrounding terrain. They identified several units within Marcia <span class="hlt">crater</span>, including bright <span class="hlt">crater</span> material, pitted terrain, and smooth material. Units outside Marcia, include undivided <span class="hlt">crater</span> ejecta material, bright lobate material, dark lobate material, and dark <span class="hlt">crater</span> ray material [<span class="hlt">2</span>]. Because of its extensive ejecta and fresh appearance, the Marcia impact defines a major stratigraphic event, postdating the Rheasilvia impact [<span class="hlt">2</span>]. However, the exact age of Marcia <span class="hlt">crater</span> is still under debate. Compositionally, Marcia <span class="hlt">crater</span> is characterized by higher iron abundances, which were interpreted as more basaltic-eucrite-rich materials suggesting that this region has not been blanketed by diogenitic materials from large impact events [10, 11]. Using FC data, [13] identified "gray material" associated with the ejecta blanket of Marcia <span class="hlt">crater</span>. This material is characterized</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70034646','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70034646"><span>Review: Regional land <span class="hlt">subsidence</span> accompanying groundwater extraction</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Galloway, Devin L.; Burbey, Thomas J.</p> <p>2011-01-01</p> <p>The extraction of groundwater can generate land <span class="hlt">subsidence</span> by causing the compaction of susceptible aquifer systems, typically unconsolidated alluvial or basin-fill aquifer systems comprising aquifers and aquitards. Various ground-based and remotely sensed methods are used to measure and map <span class="hlt">subsidence</span>. Many areas of <span class="hlt">subsidence</span> caused by groundwater pumping have been identified and monitored, and corrective measures to slow or halt <span class="hlt">subsidence</span> have been devised. Two principal means are used to mitigate <span class="hlt">subsidence</span> caused by groundwater withdrawal—reduction of groundwater withdrawal, and artificial recharge. Analysis and simulation of aquifer-system compaction follow from the basic relations between head, stress, compressibility, and groundwater flow and are addressed primarily using two approaches—one based on conventional groundwater flow theory and one based on linear poroelasticity theory. Research and development to improve the assessment and analysis of aquifer-system compaction, the accompanying <span class="hlt">subsidence</span> and potential ground ruptures are needed in the topic areas of the hydromechanical behavior of aquitards, the role of horizontal deformation, the application of differential synthetic aperture radar interferometry, and the regional-scale simulation of coupled groundwater flow and aquifer-system deformation to support resource management and hazard mitigation measures.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://eric.ed.gov/?q=working+AND+home&pg=2&id=EJ782854','ERIC'); return false;" href="https://eric.ed.gov/?q=working+AND+home&pg=2&id=EJ782854"><span>Family Home Childcare Providers: A Comparison of <span class="hlt">Subsidized</span> and Non-<span class="hlt">Subsidized</span> Working Environments and Employee Issues</span></a></p> <p><a target="_blank" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p>Shriner, Michael; Schlee, Bethanne M.; Mullis, Ronald L.; Cornille, Thomas A.; Mullis, Ann K.</p> <p>2008-01-01</p> <p>Federal and State Governments provide childcare subsidies for low-income working families. This study compares the encountered issues and working environments of family home providers of <span class="hlt">subsidized</span> and non-<span class="hlt">subsidized</span> childcare. Questionnaires were distributed throughout a southeastern state in the United States to 548 family home childcare…</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=PIA04868&hterms=cutting&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dcutting','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=PIA04868&hterms=cutting&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dcutting"><span>Cutting <span class="hlt">Craters</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>2003-01-01</p> <p><p/> [figure removed for brevity, see original site] <p/>Released 12 November 2003<p/>The rims of two old and degraded impact <span class="hlt">craters</span> are intersected by a graben in this THEMIS image taken near Mangala Fossa. Yardangs and low-albedo wind streaks are observed at the top of the image as well as interesting small grooves on the <span class="hlt">crater</span> floor. The origin of these enigmatic grooves may be the result of mud or lava and volatile interactions. Variable surface textures observed in the bottom <span class="hlt">crater</span> floor are the result of different aged lava flows.<p/>Image information: VIS instrument. Latitude -15.<span class="hlt">2</span>, Longitude 219.<span class="hlt">2</span> East (140.8 West). 19 meter/pixel resolution.<p/>Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time. <p/>NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://images.nasa.gov/#/details-PIA21911.html','SCIGOVIMAGE-NASA'); return false;" href="https://images.nasa.gov/#/details-PIA21911.html"><span>Emesh <span class="hlt">Crater</span> on Ceres</span></a></p> <p><a target="_blank" href="https://images.nasa.gov/">NASA Image and Video Library</a></p> <p></p> <p>2017-11-02</p> <p>This image taken by NASA's Dawn spacecraft shows Emesh, a <span class="hlt">crater</span> on Ceres. Emesh, named after the Sumerian god of vegetation and agriculture, is 12 miles (20 kilometers) wide. Located at the edge of the Vendimia Planitia, the floor of this <span class="hlt">crater</span> is asymmetrical with terraces distributed along the eastern rim. Additionally, this image shows many subtle linear features that are likely the surface expressions of faults. These faults play a big role in shaping Ceres' <span class="hlt">craters</span>, leading to non-circular <span class="hlt">craters</span> such as Emesh. To the left of Emesh in this view, a much older <span class="hlt">crater</span> of similar size has mostly been erased by impacts and their ejecta. Dawn took this image on May 11, 2016, from its low-altitude mapping orbit, at a distance of about 240 miles (385 kilometers) above the surface. The center coordinates of this image are 11 degrees north latitude, 158 degrees east longitude. https://photojournal.jpl.nasa.gov/catalog/PIA21911</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28367902','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28367902"><span>Antibacterial and synergistic effects of the n-<span class="hlt">Bu</span>OH fraction of Sophora flavescens root against oral bacteria.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Lee, Kyung-Yeol; Cha, Su-Mi; Choi, Sung-Mi; Cha, Jeong-Dan</p> <p>2017-01-01</p> <p>The antibacterial activity of an extract and several fractions of Sophora flavescens (S. flavescens) root alone and in combination with antibiotics against oral bacteria was investigated by checkerboard assay and time-kill assay. The minimum inhibitory concentration/minimum bactericidal concentration (MIC/MBC) values for all examined bacteria were 0.313-<span class="hlt">2.5/0.625-2</span>.5 μg/mL for the n-<span class="hlt">Bu</span>OH fraction, 0.625-5/1.25-10 μg/mL for the EtOAc fraction, 0.25-8/0.25-16 μg/mL for ampicillin, 0.5-256/1-512 μg/mL for gentamicin, 0.008-32/0.016-64 μg/mL for erythromycin, and 0.25-64/0.5-128 μg/mL for vancomycin. The n-butanol (n-<span class="hlt">Bu</span>OH) and ethyl acetate (EtOAc) fractions exhibited stronger antibacterial activity against oral bacteria than other fractions and extracts. The MICs and MBCs were reduced to between one half and one quarter when the n-<span class="hlt">Bu</span>OH and EtOAc fractions were combined with antibiotics. After 24 h of incubation, combination of 1/<span class="hlt">2</span> MIC of the n-<span class="hlt">Bu</span>OH fraction with antibiotics increased the degree of bactericidal activity. The present results suggest that n-<span class="hlt">Bu</span>OH and EtOAc extracts of S. flavescens root might be applicable as new natural antimicrobial agents against oral pathogens.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://images.nasa.gov/#/details-PIA22265.html','SCIGOVIMAGE-NASA'); return false;" href="https://images.nasa.gov/#/details-PIA22265.html"><span>Investigating Mars: Kaiser <span class="hlt">Crater</span> Dunes</span></a></p> <p><a target="_blank" href="https://images.nasa.gov/">NASA Image and Video Library</a></p> <p></p> <p>2018-02-02</p> <p>This is a false color image of Kaiser <span class="hlt">Crater</span>. In this combination of filters "blue" typically means basaltic sand. This VIS image crosses 3/4 of the <span class="hlt">crater</span> and demonstrates how extensive the dunes are on the floor of Kaiser <span class="hlt">Crater</span>. Kaiser <span class="hlt">Crater</span> is located in the southern hemisphere in the Noachis region west of Hellas Planitia. Kaiser <span class="hlt">Crater</span> is just one of several large <span class="hlt">craters</span> with extensive dune fields on the <span class="hlt">crater</span> floor. Other nearby dune filled <span class="hlt">craters</span> are Proctor, Russell, and Rabe. Kaiser <span class="hlt">Crater</span> is 207 km (129 miles) in diameter. The dunes are located in the southern part of the <span class="hlt">crater</span> floor. The THEMIS VIS camera contains 5 filters. The data from different filters can be combined in multiple ways to create a false color image. These false color images may reveal subtle variations of the surface not easily identified in a single band image. The Odyssey spacecraft has spent over 15 years in orbit around Mars, circling the planet more than 71,000 times. It holds the record for longest working spacecraft at Mars. THEMIS, the IR/VIS camera system, has collected data for the entire mission and provides images covering all seasons and lighting conditions. Over the years many features of interest have received repeated imaging, building up a suite of images covering the entire feature. From the deepest chasma to the tallest volcano, individual dunes inside <span class="hlt">craters</span> and dune fields that encircle the north pole, channels carved by water and lava, and a variety of other feature, THEMIS has imaged them all. For the next several months the image of the day will focus on the Tharsis volcanoes, the various chasmata of Valles Marineris, and the major dunes fields. We hope you enjoy these images! Orbit Number: 66602 Latitude: -47.0551 Longitude: 19.446 Instrument: VIS Captured: 2016-12-18 21:42 https://photojournal.jpl.nasa.gov/catalog/PIA22265</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012EGUGA..1410868H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012EGUGA..1410868H"><span>Thermally-driven <span class="hlt">subsidence</span> of large platformal basins: linking growth of the lithosphere <span class="hlt">subsidence</span> patterns on the surface</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Holt, P.; Allen, M. B.; Van Hunen, J.</p> <p>2012-04-01</p> <p>A large number of areas which have experienced platformal <span class="hlt">subsidence</span> during the Phanerozoic are located upon regions of juvenile accretionary crust. These include the Palaeozoic basins of North Africa, the Paraná and Parnaíba basins in South America, the Cape-Karoo basin in South Africa, the Mesozoic Scythian and Turan platforms in Central Asia and the Eastern Australian basins. We hypothesise that the juvenile accretionary crust is initially underlain by a thin mantle lithosphere. This is most likely inherited from the island arcs, accretionary prisms and microcontinents that collided to form this juvenile crust, although it could also be due to lithospheric delamination as a result of the collision. Once the crust has stabilised the lithosphere begins to cool and thicken, which drives the observed <span class="hlt">subsidence</span>. To test this we constructed a simple 1D forward finite difference model which calculates heat conduction through a column of crust, mantle lithosphere and upper mantle as it cools. The model then isostatically calculates the water loaded <span class="hlt">subsidence</span> produced by this process. This allows us to use <span class="hlt">subsidence</span> curves calculated from the sedimentary record preserved within the basin to test whether the basins could be forming in response to growth of the lithosphere. The results from the model showed that the <span class="hlt">subsidence</span> produced was most sensitive to variations in crustal thickness and plate thickness (final lithospheric thickness). The modelled <span class="hlt">subsidence</span> curves were then compared to <span class="hlt">subsidence</span> curves acquired by backstripping the sediments within the basins mentioned above. The parameters were varied iteratively to find the best fit between the modelled and the observed <span class="hlt">subsidence</span>. This produced good fits and also provided another method to validate the model results. The crustal thickness and final lithospheric thickness from the models were then compared to measurements of these parameters from other sources such as deep seismic lines and tomographic</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://images.nasa.gov/#/details-PIA22261.html','SCIGOVIMAGE-NASA'); return false;" href="https://images.nasa.gov/#/details-PIA22261.html"><span>Investigating Mars: Kaiser <span class="hlt">Crater</span> Dunes</span></a></p> <p><a target="_blank" href="https://images.nasa.gov/">NASA Image and Video Library</a></p> <p></p> <p>2018-01-29</p> <p>This VIS image of Kaiser <span class="hlt">Crater</span> shows a region of the dunes with varied appearances. The different dune forms developed due to different amounts of available sand, different wind directions, and the texture of the <span class="hlt">crater</span> floor. The dune forms change from the bottom to the top of the image - large long connected dunes, to large individual dunes, to the very small individual dunes at the top of the image. Kaiser <span class="hlt">Crater</span> is located in the southern hemisphere in the Noachis region west of Hellas Planitia. Kaiser <span class="hlt">Crater</span> is just one of several large <span class="hlt">craters</span> with extensive dune fields on the <span class="hlt">crater</span> floor. Other nearby dune filled <span class="hlt">craters</span> are Proctor, Russell, and Rabe. Kaiser <span class="hlt">Crater</span> is 207 km (129 miles) in diameter. The dunes are located in the southern part of the <span class="hlt">crater</span> floor. The Odyssey spacecraft has spent over 15 years in orbit around Mars, circling the planet more than 71,000 times. It holds the record for longest working spacecraft at Mars. THEMIS, the IR/VIS camera system, has collected data for the entire mission and provides images covering all seasons and lighting conditions. Over the years many features of interest have received repeated imaging, building up a suite of images covering the entire feature. From the deepest chasma to the tallest volcano, individual dunes inside <span class="hlt">craters</span> and dune fields that encircle the north pole, channels carved by water and lava, and a variety of other feature, THEMIS has imaged them all. For the next several months the image of the day will focus on the Tharsis volcanoes, the various chasmata of Valles Marineris, and the major dunes fields. We hope you enjoy these images! Orbit Number: 17686 Latitude: -46.6956 Longitude: 19.8394 Instrument: VIS Captured: 2005-12-09 13:25 https://photojournal.jpl.nasa.gov/catalog/PIA22261</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://images.nasa.gov/#/details-PIA22173.html','SCIGOVIMAGE-NASA'); return false;" href="https://images.nasa.gov/#/details-PIA22173.html"><span>Investigating Mars: Kaiser <span class="hlt">Crater</span> Dunes</span></a></p> <p><a target="_blank" href="https://images.nasa.gov/">NASA Image and Video Library</a></p> <p></p> <p>2018-01-24</p> <p>This VIS image of Kaiser <span class="hlt">Crater</span> shows individual dunes and where the dunes have coalesced into longer dune forms. The addition of sand makes the dunes larger and the intra-dune areas go from sand-free to complete coverage of the hard surface of the <span class="hlt">crater</span> floor. With a continued influx of sand the region will transition from individual dunes to a sand sheet with surface dune forms. Kaiser <span class="hlt">Crater</span> is located in the southern hemisphere in the Noachis region west of Hellas Planitia. Kaiser <span class="hlt">Crater</span> is just one of several large <span class="hlt">craters</span> with extensive dune fields on the <span class="hlt">crater</span> floor. Other nearby dune filled <span class="hlt">craters</span> are Proctor, Russell, and Rabe. Kaiser <span class="hlt">Crater</span> is 207 km (129 miles) in diameter. The dunes are located in the southern part of the <span class="hlt">crater</span> floor. The Odyssey spacecraft has spent over 15 years in orbit around Mars, circling the planet more than 69000 times. It holds the record for longest working spacecraft at Mars. THEMIS, the IR/VIS camera system, has collected data for the entire mission and provides images covering all seasons and lighting conditions. Over the years many features of interest have received repeated imaging, building up a suite of images covering the entire feature. From the deepest chasma to the tallest volcano, individual dunes inside <span class="hlt">craters</span> and dune fields that encircle the north pole, channels carved by water and lava, and a variety of other feature, THEMIS has imaged them all. For the next several months the image of the day will focus on the Tharsis volcanoes, the various chasmata of Valles Marineris, and the major dunes fields. We hope you enjoy these images! Orbit Number: 1423 Latitude: -46.9573 Longitude: 18.6192 Instrument: VIS Captured: 2002-04-10 16:44 https://photojournal.jpl.nasa.gov/catalog/PIA22173</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/29363268','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/29363268"><span>Synthesis of Two-Electron Bimetallic Cu-Ag and Cu-Au Clusters by using [Cu13 (S<span class="hlt">2</span> CNn <span class="hlt">Bu</span><span class="hlt">2</span> )6 (C≡CPh)4 ]+ as a Template.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Silalahi, Rhone P Brocha; Chakrahari, Kiran Kumarvarma; Liao, Jian-Hong; Kahlal, Samia; Liu, Yu-Chiao; Chiang, Ming-Hsi; Saillard, Jean-Yves; Liu, C W</p> <p>2018-03-02</p> <p>Atomically precise Cu-rich bimetallic superatom clusters have been synthesized by adopting a galvanic exchange strategy. [Cu@Cu 12 (S <span class="hlt">2</span> CN n <span class="hlt">Bu</span> <span class="hlt">2</span> ) 6 (C≡CPh) 4 ][CuCl <span class="hlt">2</span> ] (1) was used as a template to generate compositionally uniform clusters [M@Cu 12 (S <span class="hlt">2</span> CN n <span class="hlt">Bu</span> <span class="hlt">2</span> ) 6 (C≡CPh) 4 ][CuCl <span class="hlt">2</span> ], where M=Ag (<span class="hlt">2</span>), Au (3). Structures of 1, <span class="hlt">2</span> and 3 were determined by single crystal X-ray diffraction and the results were supported by ESI-MS. The anatomies of clusters 1-3 are very similar, with a centred cuboctahedral cationic core that is surrounded by six di-butyldithiocarbamate (dtc) and four phenylacetylide ligands. The doped Ag and Au atoms were found to preferentially occupy the centre of the 13-atom cuboctahedral core. Experimental and theoretical analyses of the synthesized clusters revealed that both Ag and Au doping result in significant changes in cluster stability, optical characteristics and enhancement in luminescence properties. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19970023492','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19970023492"><span>Impact <span class="hlt">Cratering</span> Calculations</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Ahrens, Thomas J.</p> <p>1997-01-01</p> <p>Understanding the physical processes of impact <span class="hlt">cratering</span> on planetary surfaces and atmospheres as well as collisions of finite-size self-gravitating objects is vitally important to planetary science. The observation has often been made that <span class="hlt">craters</span> are the most ubiquitous landform on the solid planets and the satellites. The density of <span class="hlt">craters</span> is used to date surfaces on planets and satellites. For large ringed basin <span class="hlt">craters</span> (e.g. Chicxulub), the issue of identification of exactly what 'diameter' transient <span class="hlt">crater</span> is associated with this structure is exemplified by the arguments of Sharpton et al. (1993) versus those of Hildebrand et al. (1995). The size of a transient <span class="hlt">crater</span>, such as the K/T extinction <span class="hlt">crater</span> at Yucatan, Mexico, which is thought to be the source of SO,-induced sulfuric acid aerosol that globally acidified surface waters as the result of massive vaporization of CASO, in the target rock, is addressed by our present project. The impact process excavates samples of planetary interiors. The degree to which this occurs (e.g. how deeply does excavation occur for a given <span class="hlt">crater</span> diameter) has been of interest, both with regard to exposing mantle rocks in <span class="hlt">crater</span> floors, as well as launching samples into space which become part of the terrestrial meteorite collection (e.g. lunar meteorites, SNC's from Mars). Only in the case of the Earth can we test calculations in the laboratory and field. Previous calculations predict, independent of diameter, that the depth of excavation, normalized by <span class="hlt">crater</span> diameter, is d(sub ex)/D = 0.085 (O'Keefe and Ahrens, 1993). For Comet Shoemaker-Levy 9 (SL9) fragments impacting Jupiter, predicted excavation depths of different gas-rich layers in the atmosphere, were much larger. The trajectory and fate of highly shocked material from a large impact on the Earth, such as the K/T bolide is of interest. Melosh et al. (1990) proposed that the condensed material from the impact upon reentering the Earth's atmosphere induced. radiative</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1984EOSTr..65R1180.','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1984EOSTr..65R1180."><span>Land <span class="hlt">Subsidence</span> International Symposium held in Venice</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p></p> <p></p> <p>The Third International Symposium on Land <span class="hlt">Subsidence</span> was held March 18-25, 1984, in Venice, Italy. Sponsors were the Ground-Water Commission of the International Association of Hydrological Sciences (IAHS), the United Nations Educational, Scientific, and Cultural Organization (UNESCO), the Italian National Research Council (CNR), the Italian Regions of Veneto and Emilia-Romagna, the Italian Municipalities of Venice, Ravenna, and Modena, the Venice Province, and the European Research Office. Cosponsors included the International Association of Hydrogeologists (IAH), the International Society for Soil Mechanics and Foundation Engineering (ISSMFE), and the Association of Geoscientists for International Development (AGID).Organized within the framework of UNESCO's International Hydrological Program, the symposium brought together over 200 international interdisciplinary specialists in the problems of land <span class="hlt">subsidence</span> due to fluid and mineral withdrawal. Because man's continuing heavy development of groundwater, gas, oil, and minerals is changing the natural regime and thus causing more and more <span class="hlt">subsiding</span> areas in the world, there had been sufficient new land <span class="hlt">subsidence</span> occurrence, problems, research, and remedial measures since the 1976 Second International Symposium held in Anaheim, California, to develop a most interesting program of nearly 100 papers from about 30 countries. The program consisted of papers covering case histories of fluid and mineral withdrawal, engineering theory and analysis, karst “sink-hole”-type <span class="hlt">subsidence</span>, <span class="hlt">subsidence</span> due to dewatering of organic deposits or due to application of water (hydrocompaction), instrumentation, legal, socioeconomic, and environmental effects of land <span class="hlt">subsidence</span>, and remedial works.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19890012013','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19890012013"><span>Non-random <span class="hlt">cratering</span> flux in recent time</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Schultz, P. H.</p> <p>1988-01-01</p> <p>Proposed periodic cycles of mass mortality have been linked to periodic changes in the impact flux on Earth. Such changes in the impact flux, however, also should be recorded on the Moon. Previous studies have concluded that the impact flux on the Moon over the last 1 to <span class="hlt">2</span> billion years has been reasonably constant, but sudden changes in the impact flux over time intervals as short as 30 my could not be detected in these studies unless the added <span class="hlt">crater</span> population greatly exceeded the cumulative <span class="hlt">cratering</span> record. Consequently this study focuses only on bright-rayed <span class="hlt">craters</span> larger than 1 km thereby not only limiting the study to recent <span class="hlt">craters</span> but also largely eliminating contamination by secondary <span class="hlt">craters</span>. Preservation of ray patterns and other fine-scale surface textures in the ejecta provides first-order culling of <span class="hlt">craters</span> younger than Tycho, i.e., about 100 my. Although a periodic change in the impact flux in the Earth-Moon system cannot yet be confirmed from the data, a non-random component appears to exist with an increased flux around 7 and 15 my. The concentrations in different quadrants of the lunar hemisphere would be consistent with a shower of debris generally smaller than 0.5 km.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li class="active"><span>18</span></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_18 --> <div id="page_19" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li class="active"><span>19</span></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="361"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://images.nasa.gov/#/details-PIA21753.html','SCIGOVIMAGE-NASA'); return false;" href="https://images.nasa.gov/#/details-PIA21753.html"><span>Juling and Kupalo <span class="hlt">Craters</span></span></a></p> <p><a target="_blank" href="https://images.nasa.gov/">NASA Image and Video Library</a></p> <p></p> <p>2017-08-17</p> <p>This region on Ceres, located in the vicinity of Toharu <span class="hlt">Crater</span>, presents two small <span class="hlt">craters</span>: Juling at top (12 miles, 20 kilometers in diameter) and Kupalo at bottom (16 miles, 26 kilometers in diameter). Both <span class="hlt">craters</span> are relatively young, as indicated by their sharp rims. These features are located at about the same latitude (about 38 degrees south) as Tawals <span class="hlt">Crater</span> and show similar <span class="hlt">crater</span> shapes and rugged terrain. These features may reflect the presence of ice below the surface. Subtle bright features can be distinguished in places. These likely were excavated by small impacts and landslides along the slopes of the <span class="hlt">crater</span> rims. This suggests that a different type of material, likely rich in salts, is present in the shallow subsurface. Juling is named after the Sakai/Orang Asli spirit of the crops from Malaysia, and Kupalo gets its name from the Russian god of vegetation and of the harvest. NASA's Dawn spacecraft acquired this picture on August 24, 2016. The image was taken during Dawn's extended mission, from its low altitude mapping orbit at about 240 miles (385 kilometers) above the surface. The center coordinates of this image are 38 degrees south latitude, 165 degrees east longitude. https://photojournal.jpl.nasa.gov/catalog/PIA21753</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EGUGA..1710921R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EGUGA..1710921R"><span>Diffuse Carbon Dioxide (CO<span class="hlt">2</span>) degassing from the summit <span class="hlt">crater</span> of Pico do Fogo during the 2014-15 eruption, Cape Verde</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Rodríguez, Fatima; Dionis, Samara; Padrón, Eleazar; Fernandes, Paulo; Melián, Gladys V.; Pérez, Nemesio M.; Hernández, Pedro A.; Silva, Sónia; Pereira, José Manuel; Cardoso, Nadir; Asensio-Ramos, María; Barrancos, José; Padilla, Germán; Calvo, David; Semedo, Helio</p> <p>2015-04-01</p> <p>On January 3, 2015, a new diffuse CO<span class="hlt">2</span> degassing survey at the summit <span class="hlt">crater</span> of Pico do Fogo volcano (<span class="hlt">2</span>,829 m above sea level) was carried out by ITER/INVOLCAN/UNICV/OVCV research team to investigate the effect of the 2014-15 Fogo eruption on the diffuse degassing through the summit <span class="hlt">crater</span>. Before the eruption onset on November 23, 2014, these type of surveys were periodically performed by ITER/INVOLCAN/UNICV/OVCV research team since May 2007. The first published data on diffuse CO<span class="hlt">2</span> degassing rate from the summit <span class="hlt">crater</span> of Pico do Fogo volcano (219 ± 36 t d-1) is related to a survey performed on February 2010 (Dionis et al., 2015). Each survey implies about 65 CO<span class="hlt">2</span> efflux measurements to obtain a good spatial distribution and cover homogeneously the summit <span class="hlt">crater</span> area (0.14 km<span class="hlt">2</span>). Because of the sudden falls of rocks of different sizes inside the summit <span class="hlt">crater</span> during the January 3 survey, the research team aborted continues working in the summit <span class="hlt">crater</span> without completing the survey only 32 of the 65 CO<span class="hlt">2</span> efflux measurements were performed covering a smaller area (0.065 km<span class="hlt">2</span>). Observed CO<span class="hlt">2</span> efflux values ranged from non detectable (< 1.5 g m-<span class="hlt">2</span> d-1) up to 12188 g m-<span class="hlt">2</span> d-1 and showed a mean value of 1090.<span class="hlt">2</span> g m-<span class="hlt">2</span> d-1. The observed CO<span class="hlt">2</span> efflux median values from the same sampling sites in previous surveys (83.1 g m-<span class="hlt">2</span> d-1 for March 2014; 15.5 g m-<span class="hlt">2</span> d-1 for October 2013; <span class="hlt">2</span>.3 g m-<span class="hlt">2</span> d-1 for April 2013; 14.6 g m-<span class="hlt">2</span> d-1 for February 2012; 64.7 g m-<span class="hlt">2</span> d-1 for March 2011; 64.5 for Febraury 2010 ) were lower than the median of the January 2015 survey (249.4 g m-<span class="hlt">2</span> d-1) suggesting a higher degassing rate for this new survey. The diffuse CO<span class="hlt">2</span> emission from the study area of 0.065 km<span class="hlt">2</span>, within the summit <span class="hlt">crater</span>, was 74 t d-1 on January 3, 2015, which is a similar degassing rate to those estimated for the same study area on the July 2014 (90 t d-1) and August 2014 (66 t d-1) surveys, and relatively higher than the estimated for October 2012 survey (27 t d-1). Since the diffuse CO<span class="hlt">2</span> emission rate</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017Geomo.296...11M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017Geomo.296...11M"><span>Snow-avalanche impact <span class="hlt">craters</span> in southern Norway: Their morphology and dynamics compared with small terrestrial meteorite <span class="hlt">craters</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Matthews, John A.; Owen, Geraint; McEwen, Lindsey J.; Shakesby, Richard A.; Hill, Jennifer L.; Vater, Amber E.; Ratcliffe, Anna C.</p> <p>2017-11-01</p> <p>This regional inventory and study of a globally uncommon landform type reveals similarities in form and process between <span class="hlt">craters</span> produced by snow-avalanche and meteorite impacts. Fifty-two snow-avalanche impact <span class="hlt">craters</span> (mean diameter 85 m, range 10-185 m) were investigated through field research, aerial photographic interpretation and analysis of topographic maps. The <span class="hlt">craters</span> are sited on valley bottoms or lake margins at the foot of steep avalanche paths (α = 28-59°), generally with an easterly aspect, where the slope of the final 200 m of the avalanche path (β) typically exceeds 15°. <span class="hlt">Crater</span> diameter correlates with the area of the avalanche start zone, which points to snow-avalanche volume as the main control on <span class="hlt">crater</span> size. Proximal erosional scars ('blast zones') up to 40 m high indicate up-range ejection of material from the <span class="hlt">crater</span>, assisted by air-launch of the avalanches and impulse waves generated by their impact into water-filled <span class="hlt">craters</span>. Formation of distal mounds up to 12 m high of variable shape is favoured by more dispersed down-range deposition of ejecta. Key to the development of snow-avalanche impact <span class="hlt">craters</span> is the repeated occurrence of topographically-focused snow avalanches that impact with a steep angle on unconsolidated sediment. Secondary <span class="hlt">craters</span> or pits, a few metres in diameter, are attributed to the impact of individual boulders or smaller bodies of snow ejected from the main avalanche. The process of <span class="hlt">crater</span> formation by low-density, low-velocity, large-volume snow flows occurring as multiple events is broadly comparable with <span class="hlt">cratering</span> by single-event, high-density, high-velocity, small-volume projectiles such as small meteorites. Simple comparative modelling of snow-avalanche events associated with a <span class="hlt">crater</span> of average size (diameter 85 m) indicates that the kinetic energy of a single snow-avalanche impact event is two orders of magnitude less than that of a single meteorite-impact event capable of producing a <span class="hlt">crater</span> of similar size</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19930005117','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19930005117"><span>Bright <span class="hlt">crater</span> outflows: Possible emplacement mechanisms</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Chadwick, D. John; Schaber, Gerald G.; Strom, Robert G.; Duval, Darla M.</p> <p>1992-01-01</p> <p>Lobate features with a strong backscatter are associated with 43 percent of the impact <span class="hlt">craters</span> cataloged in Magellan's cycle 1. Their apparent thinness and great lengths are consistent with a low-viscosity material. The longest outflow yet identified is about 600 km in length and flows from the 90-km-diameter <span class="hlt">crater</span> Addams. There is strong evidence that the outflows are largely composed of impact melt, although the mechanisms of their emplacement are not clearly understood. High temperatures and pressures of target rocks on Venus allow for more melt to be produced than on other terrestrial planets because lower shock pressures are required for melting. The percentage of impact <span class="hlt">craters</span> with outflows increases with increasing <span class="hlt">crater</span> diameter. The mean diameter of <span class="hlt">craters</span> without outflows is 14.4 km, compared with 27.8 km for <span class="hlt">craters</span> with outflows. No <span class="hlt">craters</span> smaller than 3 km, 43 percent of <span class="hlt">craters</span> in the 10- to 30-km-diameter range, and 90 percent in the 80- to 100-km-diameter range have associated bright outflows. More melt is produced in the more energetic impact events that produce larger <span class="hlt">craters</span>. However, three of the four largest <span class="hlt">craters</span> have no outflows. We present four possible mechanisms for the emplacement of bright outflows. We believe this 'shotgun' approach is justified because all four mechanisms may indeed have operated to some degree.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28941250','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28941250"><span>Mitogenic Activity of a Water-Soluble Adjuvant (<span class="hlt">Bu</span>-WSA) Obtained from Bacterionema matruchotii: IV. Synergistic Effects of <span class="hlt">Bu</span>-WSA on Concanavalin A-Induced Proliferative Response of Human Peripheral Blood Lymphocytes.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Nitta, Toshimasa; Okumura, Seiichi; Tsushi, Masao; Nakano, Masayasu</p> <p>1982-07-01</p> <p>Butanol-extracted water-soluble adjuvant (<span class="hlt">Bu</span>-WSA) obtained from Bacterionema matruchotii was cultured with peripheral blood mononuclear cells (PBM) in the presence of sub- and/or supra-optimal mitogenic concentrations of concanavalin A (Con A). The addition of <span class="hlt">Bu</span>-WSA resulted in increased tritiated thymidine incorporation above that produced by Con A alone. <span class="hlt">Bu</span>-WSA by itself is not mitogenic for PBM and in fact produced a decrease in thymidine uptake compared to the control. We investigated the response of subpopulation(s) of PBM to <span class="hlt">Bu</span>-WSA, Con A and a mixture of <span class="hlt">Bu</span>-WSA and Con A. Separation of PBM into purified T cells, B cells and macrophages showed that cell-cell cooperation of T cells with B cells or macrophages is necessary for the observed synergistic effect of <span class="hlt">Bu</span>-WSA with Con A. A marked increase in thymidine incorporation by the mixture of T and B cell populations occurred, while only a small amount of thymidine was incorporated when the B cell population was absent. Mitomycin treatment revealed that the response could be ascribed to the T-cell response with a B-cell helper effect. Moreover, Con A and <span class="hlt">Bu</span>-WSA appeared to act on the same T cell population. This model may provide unique information about the activation of human peripheral blood T cells compared with the activation of these cells by other mitogens. © owned by Center for Academic Publications Japan (Publisher).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://images.nasa.gov/#/details-PIA15121.html','SCIGOVIMAGE-NASA'); return false;" href="https://images.nasa.gov/#/details-PIA15121.html"><span>Vesta <span class="hlt">Cratered</span> Landscape: Double <span class="hlt">Crater</span> and <span class="hlt">Craters</span> with Bright Ejecta</span></a></p> <p><a target="_blank" href="https://images.nasa.gov/">NASA Image and Video Library</a></p> <p></p> <p>2011-11-23</p> <p>This image from NASA Dawn spacecraft is dominated by a double <span class="hlt">crater</span> which may have been formed by the simultaneous impact of a binary asteroid. Binary asteroids are asteroids that orbit their mutual center of mass.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://images.nasa.gov/#/details-PIA20696.html','SCIGOVIMAGE-NASA'); return false;" href="https://images.nasa.gov/#/details-PIA20696.html"><span>Shadowed <span class="hlt">Craters</span> on Ceres</span></a></p> <p><a target="_blank" href="https://images.nasa.gov/">NASA Image and Video Library</a></p> <p></p> <p>2016-07-08</p> <p>At the poles of Ceres, scientists have found <span class="hlt">craters</span> that are permanently in shadow (indicated by blue markings). Such <span class="hlt">craters</span> are called "cold traps" if they remain below about minus 240 degrees Fahrenheit (minus 151 degrees Celsius). These shadowed <span class="hlt">craters</span> may have been collecting ice for billions of years because they are so cold. This image was created using data from NASA's Dawn spacecraft. http://photojournal.jpl.nasa.gov/catalog/PIA20696</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19930043867&hterms=barlow&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dbarlow','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19930043867&hterms=barlow&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dbarlow"><span>The Martian impact <span class="hlt">cratering</span> record</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Strom, Robert G.; Croft, Steven K.; Barlow, Nadine G.</p> <p>1992-01-01</p> <p>A detailed analysis of the Martian impact <span class="hlt">cratering</span> record is presented. The major differences in impact <span class="hlt">crater</span> morphology and morphometry between Mars and the moon and Mercury are argued to be largely the result of subsurface volatiles on Mars. In general, the depth to these volatiles may decrease with increasing latitude in the southern hemisphere, but the base of this layer may be at a more or less constant depth. The Martial crustal dichotomy could have been the result of a very large impact near the end of the accretion of Mars. Monte Carlo computer simulations suggest that such an impact was not only possible, but likely. The Martian highland <span class="hlt">cratering</span> record shows a marked paucity of <span class="hlt">craters</span> less than about 30 km in diameter relative to the lunar highlands. This paucity of <span class="hlt">craters</span> was probably the result of the obliteration of <span class="hlt">craters</span> by an early period of intense erosion and deposition by aeolian, fluvial, and glacial processes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018JGeo..117...60L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018JGeo..117...60L"><span>Quantitative analysis of the tectonic <span class="hlt">subsidence</span> in the Potiguar Basin (NE Brazil)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lopes, Juliana A. G.; de Castro, David L.; Bertotti, Giovanni</p> <p>2018-06-01</p> <p>The Potiguar Basin, located in the Brazilian Equatorial Margin, evolved from a complex rifting process implemented during the Atlantic Ocean opening in the Jurassic/Cretaceous. Different driving mechanisms were responsible for the onset of an aborted onshore rift and an offshore rift that initiated crustal rupture and the formation of a continental transform margin. Therefore, we applied the backstripping method to quantify the tectonic <span class="hlt">subsidence</span> during the rift and post-rift phases of Potiguar Basin formation and to analyze the spatial variation of <span class="hlt">subsidence</span> during the two successive and distinct tectonic events responsible for the basin evolution. The parameters required to apply this methodology were extracted from <span class="hlt">2</span>D seismic lines and exploratory well data. The tectonic <span class="hlt">subsidence</span> curves present periods with moderate <span class="hlt">subsidence</span> rates (up to 300 m/My), which correspond to the evolution of the onshore Potiguar Rift (∼141 to 128 Ma). From 128-118 Ma, the tectonic <span class="hlt">subsidence</span> curves show no <span class="hlt">subsidence</span> in the onshore Potiguar Basin, whereas <span class="hlt">subsidence</span> occurred at high rates (over 300 m/My) in the offshore rift. The post-rift phase began ca. 118 Ma (Aptian), when the tectonic <span class="hlt">subsidence</span> drastically slowed to less than 35 m/My, probably related to thermal relaxation. The tectonic <span class="hlt">subsidence</span> rates in the various sectors of the Potiguar Rift, during the different rift phases, indicate that more intense faulting occurred in the southern portion of the onshore rift, along the main border faults, and in the southeastern portion of the offshore rift. During the post-rift phase, the tectonic <span class="hlt">subsidence</span> rates increased from the onshore portion towards the offshore portion until the continental slope. The highest rates of post-rift <span class="hlt">subsidence</span> (up to 35 m/My) are concentrated in the central region of the offshore portion and may be related to lithospheric processes related to the continental crust rupture and oceanic seafloor spreading. The variation in <span class="hlt">subsidence</span> rates and</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70113377','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70113377"><span>Kilauea's 5-9 March 2011 Kamoamoa fissure eruption and its relation to 30+ years of activity from Pu'<span class="hlt">u</span> 'Ō'ō: Chapter 18</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Orr, Tim R.; Poland, Michael P.; Patrick, Matthew R.; Thelen, Weston A.; Sutton, A.J.; Elias, Tamar; Thornber, Carl R.; Parcheta, Carolyn; Wooten, Kelly M.; Carey, Rebecca; Cayol, Valérie; Poland, Michael P.; Weis, Dominique</p> <p>2015-01-01</p> <p>Lava output from Kīlauea's long-lived East Rift Zone eruption, ongoing since 1983, began waning in 2010 and was coupled with uplift, increased seismicity, and rising lava levels at the volcano's summit and Pu‘<span class="hlt">u</span> ‘Ō‘ō vent. These changes culminated in the four-day-long Kamoamoa fissure eruption on the East Rift Zone starting on 5 March 2011. About <span class="hlt">2</span>.7 × 106 m3 of lava erupted, accompanied by ˜15 cm of summit <span class="hlt">subsidence</span>, draining of Kīlauea's summit lava lake, a 113 m drop of Pu‘<span class="hlt">u</span> ‘Ō‘ō's <span class="hlt">crater</span> floor, ˜3 m of East Rift Zone widening, and eruptive SO<span class="hlt">2</span> emissions averaging 8500 tonnes/day. Lava effusion resumed at Pu‘<span class="hlt">u</span> ‘Ō‘ō shortly after the Kamoamoa eruption ended, marking the onset of a new period of East Rift Zone activity. Multiparameter monitoring before and during the Kamoamoa eruption suggests that it was driven by an imbalance between magma supplied to and erupted from Kīlauea's East Rift Zone and that eruptive output is affected by changes in the geometry of the rift zone plumbing system. These results imply that intrusions and eruptive changes during ongoing activity at Kīlauea may be anticipated from the geophysical, geological, and geochemical manifestations of magma supply and magma plumbing system geometry.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19780062837&hterms=geomorphology&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dgeomorphology','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19780062837&hterms=geomorphology&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dgeomorphology"><span>Geomorphology of <span class="hlt">crater</span> and basin deposits - Emplacement of the Fra Mauro formation</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Morrison, R. H.; Oberbeck, V. R.</p> <p>1975-01-01</p> <p>Characteristics of continuous deposits near lunar <span class="hlt">craters</span> larger than about 1 km wide are considered, and it is concluded that (1) concentric dunes, radial ridges, and braided lineations result from deposition of the collision products of ejecta from adjacent pairs of similarly oriented secondary-<span class="hlt">crater</span> chains and are, therefore, concentrations of secondary-<span class="hlt">crater</span> ejecta; (<span class="hlt">2</span>) intracrater ridges are produced within preexisting <span class="hlt">craters</span> surrounding a fresh primary <span class="hlt">crater</span> by ricocheting and focusing of secondary-<span class="hlt">crater</span> ejecta from the preexisting <span class="hlt">craters</span>' walls; and (3) secondary <span class="hlt">cratering</span> has produced many of the structures of the continuous deposits of relatively small lunar <span class="hlt">craters</span> and is the dominant process for emplacement of most of the radial facies of the continuous deposits of large lunar <span class="hlt">craters</span> and basins. The percentages of Imbrium ejecta in deposits and the nature of Imbrium sculpturing are investigated.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JVGR..335..128F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JVGR..335..128F"><span>Eruptive history of the Ubehebe <span class="hlt">Crater</span> cluster, Death Valley, California</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Fierstein, Judy; Hildreth, Wes</p> <p>2017-04-01</p> <p>A sequence of late Holocene eruptions from the Ubehebe <span class="hlt">Crater</span> cluster in Death Valley was short-lived, emplacing several phreatomagmatic and magmatic deposits. Seven <span class="hlt">craters</span> form the main group, which erupted along a north-south alignment 1.5 km long. At least five more make a 500-m east-west alignment west of the main <span class="hlt">crater</span> group. One more is an isolated shallow <span class="hlt">crater</span> 400 m south of that alignment. All erupted through Miocene fanglomerate and sandstone, which are now distributed as comminuted matrix and lithic clasts in all Ubehebe deposits. Stratigraphic evidence showing that all Ubehebe strata were emplaced within a short time interval includes: (1) deposits from the many Ubehebe vents make a multi-package sequence that conformably drapes paleo-basement topography with no erosive gullying between emplacement units; (<span class="hlt">2</span>) several <span class="hlt">crater</span> rims that formed early in the eruptive sequence are draped smoothly by subsequent deposits; and (3) tack-welded to agglutinated spatter and bombs that erupted at various times through the sequence remained hot enough to oxidize the overlying youngest emplacement package. In addition, all deposits sufficiently consolidated to be drilled yield reliable paleomagnetic directions, with site mean directions showing no evidence of geomagnetic secular variation. Chemical analyses of juvenile components representing every eruptive package yield a narrow range in major elements [SiO<span class="hlt">2</span> (48.65-50.11); MgO (4.98-6.23); K<span class="hlt">2</span>O (<span class="hlt">2.24-2</span>.39)] and trace elements [Rb (28-33); Sr (1513-1588); Zr (373-404)]. Despite lithologic similarities, individual fall units can be traced outward from vent by recording layer thicknesses, maximum scoria and lithic sizes, and juvenile clast textural variations. This permits reconstruction of the eruptive sequence, which produced a variety of eruptive styles. The largest and northernmost of the <span class="hlt">craters</span>, Ubehebe <span class="hlt">Crater</span>, is the youngest of the group. Its largely phreatomagmatic deposits drape all of the others, thicken in</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/22136537-large-crater-asteroid-steins-really-impact-crater','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22136537-large-crater-asteroid-steins-really-impact-crater"><span>IS THE LARGE <span class="hlt">CRATER</span> ON THE ASTEROID (2867) STEINS REALLY AN IMPACT <span class="hlt">CRATER</span>?</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Morris, A. J. W.; Price, M. C.; Burchell, M. J., E-mail: m.j.burchell@kent.ac.uk</p> <p></p> <p>The large <span class="hlt">crater</span> on the asteroid (2867) Steins attracted much attention when it was first observed by the Rosetta spacecraft in 2008. Initially, it was widely thought to be unusually large compared to the size of the asteroid. It was quickly realized that this was not the case and there are other examples of similar (or larger) <span class="hlt">craters</span> on small bodies in the same size range; however, it is still widely accepted that it is a <span class="hlt">crater</span> arising from an impact onto the body which occurred after its formation. The asteroid (2867) Steins also has an equatorial bulge, usually consideredmore » to have arisen from redistribution of mass due to spin-up of the body caused by the YORP effect. Conversely, it is shown here that, based on catastrophic disruption experiments in laboratory impact studies, a similarly shaped body to the asteroid Steins can arise from the break-up of a parent in a catastrophic disruption event; this includes the presence of a large <span class="hlt">crater</span>-like feature and equatorial bulge. This suggests that the large <span class="hlt">crater</span>-like feature on Steins may not be a <span class="hlt">crater</span> from a subsequent impact, but may have arisen directly from the fragmentation process of a larger, catastrophically disrupted parent.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19780057835&hterms=TNT&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3DTNT','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19780057835&hterms=TNT&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3DTNT"><span><span class="hlt">Cratering</span> motions and structural deformation in the rim of the Prairie Flat multiring explosion <span class="hlt">crater</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Roddy, D. J.; Ullrich, G. W.; Sauer, F. M.; Jones, G. H. S.</p> <p>1977-01-01</p> <p><span class="hlt">Cratering</span> motions and structural deformation are described for the rim of the Prairie Flat multiring <span class="hlt">crater</span>, 85.5 m across and 5.3 m deep, which was formed by the detonation of a 500-ton TNT surface-tangent sphere. The terminal displacement and motion data are derived from marker cans and velocity gages emplaced in drill holes in a three-dimensional matrix radial to the <span class="hlt">crater</span>. The integration of this data with a detailed geologic cross section, mapped from deep trench excavations through the rim, provides a composite view of the general sequence of motions that formed a transiently uplifted rim, overturned flap, inverted stratigraphy, downfolded rim, and deformed strata in the <span class="hlt">crater</span> walls. Preliminary comparisons with laboratory experimental <span class="hlt">cratering</span> and with numerical simulations indicate that explosion <span class="hlt">craters</span> of the Prairie Flat-type generated by surface and near-surface energy sources tend to follow predictable motion sequences and produce comparable structural deformation. More specifically, central uplift and multiring impact <span class="hlt">craters</span> with morphologies and structures comparable to Prairie Flat are inferred to have experienced similar deformational histories of the rim, such as uplift, overturning, terracing, and downfolding.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014CEJG....6..207P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014CEJG....6..207P"><span>Ensemble of ground <span class="hlt">subsidence</span> hazard maps using fuzzy logic</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Park, Inhye; Lee, Jiyeong; Saro, Lee</p> <p>2014-06-01</p> <p>Hazard maps of ground <span class="hlt">subsidence</span> around abandoned underground coal mines (AUCMs) in Samcheok, Korea, were constructed using fuzzy ensemble techniques and a geographical information system (GIS). To evaluate the factors related to ground <span class="hlt">subsidence</span>, a spatial database was constructed from topographic, geologic, mine tunnel, land use, groundwater, and ground <span class="hlt">subsidence</span> maps. Spatial data, topography, geology, and various ground-engineering data for the <span class="hlt">subsidence</span> area were collected and compiled in a database for mapping ground-<span class="hlt">subsidence</span> hazard (GSH). The <span class="hlt">subsidence</span> area was randomly split 70/30 for training and validation of the models. The relationships between the detected ground-<span class="hlt">subsidence</span> area and the factors were identified and quantified by frequency ratio (FR), logistic regression (LR) and artificial neural network (ANN) models. The relationships were used as factor ratings in the overlay analysis to create ground-<span class="hlt">subsidence</span> hazard indexes and maps. The three GSH maps were then used as new input factors and integrated using fuzzy-ensemble methods to make better hazard maps. All of the hazard maps were validated by comparison with known <span class="hlt">subsidence</span> areas that were not used directly in the analysis. As the result, the ensemble model was found to be more effective in terms of prediction accuracy than the individual model.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018ISPAr42.3.1589S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018ISPAr42.3.1589S"><span>Analysis of Land <span class="hlt">Subsidence</span> Monitoring in Mining Area with Time-Series Insar Technology</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sun, N.; Wang, Y. J.</p> <p>2018-04-01</p> <p>Time-series InSAR technology has become a popular land <span class="hlt">subsidence</span> monitoring method in recent years, because of its advantages such as high accuracy, wide area, low expenditure, intensive monitoring points and free from accessibility restrictions. In this paper, we applied two kinds of satellite data, ALOS PALSAR and RADARSAT-<span class="hlt">2</span>, to get the <span class="hlt">subsidence</span> monitoring results of the study area in two time periods by time-series InSAR technology. By analyzing the deformation range, rate and amount, the time-series analysis of land <span class="hlt">subsidence</span> in mining area was realized. The results show that InSAR technology could be used to monitor land <span class="hlt">subsidence</span> in large area and meet the demand of <span class="hlt">subsidence</span> monitoring in mining area.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://images.nasa.gov/#/details-PIA03859.html','SCIGOVIMAGE-NASA'); return false;" href="https://images.nasa.gov/#/details-PIA03859.html"><span>Iturralde <span class="hlt">Crater</span>, Bolivia</span></a></p> <p><a target="_blank" href="https://images.nasa.gov/">NASA Image and Video Library</a></p> <p></p> <p>2002-09-17</p> <p>NASA scientists will venture into an isolated part of the Bolivian Amazon to try and uncover the origin of a 5 mile (8 kilometer) diameter <span class="hlt">crater</span> there known as the Iturralde <span class="hlt">Crater</span>. Traveling to this inhospitable forest setting, the Iturralde <span class="hlt">Crater</span> Expedition 2002 will seek to determine if the unusual circular <span class="hlt">crater</span> was created by a meteor or comet. Organized by Dr. Peter Wasilewski of NASA's Goddard Space Flight Center, Greenbelt, Md., the Iturralde <span class="hlt">Crater</span> Expedition 2002 will be led by Dr. Tim Killeen of Conservation International, which is based in Bolivia. Killeen will be assisted by Dr. Compton Tucker of Goddard. The team intends to collect and analyze rocks and soil, look for glass particles that develop from meteor impacts and study magnetic properties in the area to determine if the Iturralde site was indeed created by a meteor. This image was acquired on June 29, 2001 by the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) on NASA's Terra satellite. With its 14 spectral bands from the visible to the thermal infrared wavelength region, and its high spatial resolution of 15 to 90 meters (about 50 to 300 feet), ASTER will image Earth for the next 6 years to map and monitor the changing surface of our planet. http://photojournal.jpl.nasa.gov/catalog/PIA03859</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://images.nasa.gov/#/details-PIA22142.html','SCIGOVIMAGE-NASA'); return false;" href="https://images.nasa.gov/#/details-PIA22142.html"><span>Investigating Mars: Rabe <span class="hlt">Crater</span></span></a></p> <p><a target="_blank" href="https://images.nasa.gov/">NASA Image and Video Library</a></p> <p></p> <p>2017-12-14</p> <p>This VIS image of Rabe <span class="hlt">Crater</span> is dominated by the extensive dunes that cover the <span class="hlt">crater</span> floor. To the top of the image part of the pit is visible, as well as a small peninsula that has been eroded into the upper level floor materials. On the upper elevation on the side left of the peninsula the dunes cascade onto the lower pit elevation. There is also a slight arc to the dunes on the pit floor due to how the peninsula changed the wind pattern. Rabe <span class="hlt">Crater</span> is 108 km (67 miles) across. <span class="hlt">Craters</span> of similar size often have flat floors. Rabe <span class="hlt">Crater</span> has some areas of flat floor, but also has a large complex pit occupying a substantial part of the floor. The interior fill of the <span class="hlt">crater</span> is thought to be layered sediments created by wind and or water action. The pit is eroded into this material. The eroded materials appear to have stayed within the <span class="hlt">crater</span> forming a large sand sheet with surface dune forms as well as individual dunes where the <span class="hlt">crater</span> floor is visible. The dunes also appear to be moving from the upper floor level into the pit. The Odyssey spacecraft has spent over 15 years in orbit around Mars, circling the planet more than 69000 times. It holds the record for longest working spacecraft at Mars. THEMIS, the IR/VIS camera system, has collected data for the entire mission and provides images covering all seasons and lighting conditions. Over the years many features of interest have received repeated imaging, building up a suite of images covering the entire feature. From the deepest chasma to the tallest volcano, individual dunes inside <span class="hlt">craters</span> and dune fields that encircle the north pole, channels carved by water and lava, and a variety of other feature, THEMIS has imaged them all. For the next several months the image of the day will focus on the Tharsis volcanoes, the various chasmata of Valles Marineris, and the major dunes fields. We hope you enjoy these images! Orbit Number: 52206 Latitude: -43.6573 Longitude: 34.9551 Instrument: VIS Captured: 2013</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://images.nasa.gov/#/details-PIA22141.html','SCIGOVIMAGE-NASA'); return false;" href="https://images.nasa.gov/#/details-PIA22141.html"><span>Investigating Mars: Rabe <span class="hlt">Crater</span></span></a></p> <p><a target="_blank" href="https://images.nasa.gov/">NASA Image and Video Library</a></p> <p></p> <p>2017-12-13</p> <p>Dunes cover the majority of this image of Rabe <span class="hlt">Crater</span>. As the dunes are created by wind action the forms of the dunes record the wind direction. Dunes will have a long low angle component and a short high angle side. The steep side is called the slip face. The wind blows up the long side of the dune. In this VIS image the slip faces are illuminated more than the longer side. In this part of the <span class="hlt">crater</span> the winds were generally moving from the lower right corner of the image towards the upper left. Rabe <span class="hlt">Crater</span> is 108 km (67 miles) across. <span class="hlt">Craters</span> of similar size often have flat floors. Rabe <span class="hlt">Crater</span> has some areas of flat floor, but also has a large complex pit occupying a substantial part of the floor. The interior fill of the <span class="hlt">crater</span> is thought to be layered sediments created by wind and or water action. The pit is eroded into this material. The eroded materials appear to have stayed within the <span class="hlt">crater</span> forming a large sand sheet with surface dune forms as well as individual dunes where the <span class="hlt">crater</span> floor is visible. The dunes also appear to be moving from the upper floor level into the pit. The Odyssey spacecraft has spent over 15 years in orbit around Mars, circling the planet more than 69000 times. It holds the record for longest working spacecraft at Mars. THEMIS, the IR/VIS camera system, has collected data for the entire mission and provides images covering all seasons and lighting conditions. Over the years many features of interest have received repeated imaging, building up a suite of images covering the entire feature. From the deepest chasma to the tallest volcano, individual dunes inside <span class="hlt">craters</span> and dune fields that encircle the north pole, channels carved by water and lava, and a variety of other feature, THEMIS has imaged them all. For the next several months the image of the day will focus on the Tharsis volcanoes, the various chasmata of Valles Marineris, and the major dunes fields. We hope you enjoy these images! Orbit Number: 35105 Latitude: -43</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFMGC23D1279B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFMGC23D1279B"><span>Understanding Mississippi Delta <span class="hlt">Subsidence</span> through Stratigraphic and Geotechnical Analysis of a Continuous Holocene Core at a <span class="hlt">Subsidence</span> Superstation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bridgeman, J.; Tornqvist, T. E.; Allison, M. A.; Jafari, N.</p> <p>2016-12-01</p> <p>Land-surface <span class="hlt">subsidence</span> is a major contributor to recent Mississippi Delta land loss. Despite significant research efforts, the primary mechanisms and rates of delta <span class="hlt">subsidence</span> remain the subject of debate. This has led to a broad range of <span class="hlt">subsidence</span> rate estimates across the delta, making differentiating between <span class="hlt">subsidence</span> mechanisms as well as coastal restoration efforts more challenging. New data from a continuous 39 m long, 12 cm diameter core taken during the installation of a <span class="hlt">subsidence</span> monitoring superstation near the Mississippi River, SW of New Orleans, provides insight into the grain size, bulk density, geochronology, and geotechnical parameters of the entire Holocene succession. The core consists of three major sections. The top 11 m contain a modern marsh peat, followed by a silty clay loam with interspersed humic clays (14C age 1250 BP), a peat bed (14C age 2200-2950 BP), and silt loams. The middle section from 11 to 35 m is dominated by clay and silty clay, with a relative bulk density of 1.5 g/cc, which gradually becomes denser with depth and the bottom section (35 to 39 m) is marked by a high energy, shell-rich sand facies and a basal peat (14C age 9850 BP), which terminates at the core base in a densely packed, blue-gray silty clay loam, characteristic of the Pleistocene. The radiocarbon ages of marsh peat beds, combined with sea-level markers derived from basal peat elsewhere in the delta, enable the reconstruction of the local <span class="hlt">subsidence</span> history at this site. Notably, the data shows a significant amount of vertical displacement from the dated organics in the top section of the core; 3.5 m in the humic clays and up to 5 m in the peat bed. The <span class="hlt">subsidence</span> rates measured by the superstation apparatus, and the geotechnical measurements of core sediments, will aid in determining the dominant <span class="hlt">subsidence</span> mechanisms (shallow vs. deep) in the region.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li class="active"><span>19</span></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_19 --> <div id="page_20" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li class="active"><span>20</span></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="381"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1995Metic..30..578S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1995Metic..30..578S"><span>Impact <span class="hlt">Crater</span> Identified on the Navajo Nation Near Chinle, Arizona</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Shoemaker, E. M.; Roddy, D. J.; Moore, C. B.; Pfeilsticker, R.; Curley, C. L.; Dunkelman, T.; Kuerzel, K.; Taylor, M.; Shoemaker, C.; Donnelly, P.</p> <p>1995-09-01</p> <p>A small impact <span class="hlt">crater</span> has been identified about 8 km north of Chinle, Arizona on the Navajo Nation. Preliminary studies show that the <span class="hlt">crater</span> is elongate in a N-S direction, measuring about 23 by 34 m in diameter, with a depth of about 1.3 m. The impact origin of the <span class="hlt">crater</span> is identified by its shape, subsurface deformation, and an iron-nickel oxide fragment. We estimate the age to be about 150 to 250 years. The impact site is on the east side of the Chinle Valley at an altitude of 1685 m and is about <span class="hlt">2</span> km east of Chinle Wash. The <span class="hlt">crater</span> formed on an alluvial surface that slopes gently west toward the Wash. About <span class="hlt">2</span> m of reddish brown alluvial sand and silt of the Jeddito Formation of late Pleistocene age rests on the Petrified Forest Member of the Chinle Formation of late Triassic age. A moderately developed late Pleistocene pedocal soil has developed on the Jeddito. Several thin discontinuous caliche horizons occur at a depth of about 1 m. The caliche horizons provided easily traced markers by which we could delimit the original walls of the <span class="hlt">crater</span> and recognize deformation along the <span class="hlt">crater</span> walls. Three trenches were excavated down to the top of the Chinle bedrock: 1) an east- west trench 31 m long across the center of the <span class="hlt">crater</span>, <span class="hlt">2</span>) a north-south trench 13 m long in the north <span class="hlt">crater</span> rim, and 3) a north-south trench 12 m long in the south <span class="hlt">crater</span> rim. Excavation width was about 1 m and provided excellent exposures of the subsurface stratigraphy and deformation. The trenches revealed that the original <span class="hlt">crater</span> was about 23 m wide and 27 m long. The original rim crests have entirely eroded away so that no perceptible raised rim remains. At the center of the <span class="hlt">crater</span>, the original depth was about 3 m; material washed from the rims now fills the <span class="hlt">crater</span> floor to a depth of 1.5 m. The <span class="hlt">crater</span> is symmetrical; however, the deepest part of the original <span class="hlt">crater</span> lies south of the center and was not reached in the south trench. The east-west trench showed that the initial floor of</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20060038747&hterms=Saunders&qs=N%3D0%26Ntk%3DAuthor-Name%26Ntx%3Dmode%2Bmatchall%26Ntt%3DSaunders%252C%2BM','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20060038747&hterms=Saunders&qs=N%3D0%26Ntk%3DAuthor-Name%26Ntx%3Dmode%2Bmatchall%26Ntt%3DSaunders%252C%2BM"><span>(abstract) Radiophysical Properties of Venusian Impact <span class="hlt">Craters</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Weitz, C. M.; Saunders, R. S.; Plaut, J. J.; Elachi, C.; Moore, H. J.</p> <p>1993-01-01</p> <p>An analysis of 222 large (greater than 20-km-diameter) impact <span class="hlt">craters</span> on Venus using both cycle 1 and cycle <span class="hlt">2</span> Magellan data is being conducted to determine the radiophysical properties (i.e., backscatter cross section, emissivity, reflectivity, rms slope) of the <span class="hlt">craters</span> and to search for correlations with target region properties and subsequent geological history.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=PIA01039&hterms=water+meter&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dwater%2Bmeter','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=PIA01039&hterms=water+meter&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dwater%2Bmeter"><span>Evidence for Recent Liquid Water on Mars: Channeled Aprons in a Small <span class="hlt">Crater</span> within Newton <span class="hlt">Crater</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>2000-01-01</p> <p>[figure removed for brevity, see original site] <p/>Newton <span class="hlt">Crater</span> is a large basin formed by an asteroid impact that probably occurred more than 3 billion years ago. It is approximately 287 kilometers (178 miles) across. The picture shown here (top) highlights the north wall of a specific, smaller <span class="hlt">crater</span> located in the southwestern quarter of Newton <span class="hlt">Crater</span> (above). The <span class="hlt">crater</span> of interest was also formed by an impact; it is about 7 km (4.4 mi) across, which is about 7 times bigger than the famous Meteor <span class="hlt">Crater</span> in northern Arizona in North America.<p/>The north wall of the small <span class="hlt">crater</span> has many narrow gullies eroded into it. These are hypothesized to have been formed by flowing water and debris flows. Debris transported with the water created lobed and finger-like deposits at the base of the <span class="hlt">crater</span> wall where it intersects the floor (bottom center top image). Many of the finger-like deposits have small channels indicating that a liquid--most likely water--flowed in these areas. Hundreds of individual water and debris flow events might have occurred to create the scene shown here. Each outburst of water from higher upon the <span class="hlt">crater</span> slopes would have constituted a competition between evaporation, freezing, and gravity.<p/>The individual deposits at the ends of channels in this MOC image mosaic were used to get a rough estimate of the minimum amount of water that might be involved in each flow event. This is done first by assuming that the deposits are like debris flows on Earth. In a debris flow, no less than about 10% (and no more than 30%) of their volume is water. Second, the volume of an apron deposit is estimated by measuring the area covered in the MOC image and multiplying it by a conservative estimate of thickness, <span class="hlt">2</span> meters (6.5 feet). For a flow containing only 10% water, these estimates conservatively suggest that about <span class="hlt">2</span>.5 million liters (660,000 gallons) of water are involved in each event; this is enough to fill about 7 community-sized swimming pools or</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://images.nasa.gov/#/details-PIA21920.html','SCIGOVIMAGE-NASA'); return false;" href="https://images.nasa.gov/#/details-PIA21920.html"><span>Juling <span class="hlt">Crater</span>'s Floor</span></a></p> <p><a target="_blank" href="https://images.nasa.gov/">NASA Image and Video Library</a></p> <p></p> <p>2018-03-14</p> <p>This view from NASA's Dawn mission shows the floor of Ceres' Juling <span class="hlt">Crater</span>. The <span class="hlt">crater</span> floor shows evidence of the flow of ice and rock, similar to rock glaciers in Earth's polar regions. Dawn acquired the picture with its framing camera on Aug. 30, 2016. https://photojournal.jpl.nasa.gov/catalog/PIA21920</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015Icar..256...78K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015Icar..256...78K"><span>Dione's resurfacing history as determined from a global impact <span class="hlt">crater</span> database</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kirchoff, Michelle R.; Schenk, Paul</p> <p>2015-08-01</p> <p>Saturn's moon Dione has an interesting and unique resurfacing history recorded by the impact <span class="hlt">craters</span> on its surface. In order to further resolve this history, we compile a <span class="hlt">crater</span> database that is nearly global for diameters (D) equal to and larger than 4 km using standard techniques and Cassini Imaging Science Subsystem images. From this database, spatial <span class="hlt">crater</span> density maps for different diameter ranges are generated. These maps, along with the observed surface morphology, have been used to define seven terrain units for Dione, including refinement of the smooth and "wispy" (or faulted) units from Voyager observations. Analysis of the terrains' <span class="hlt">crater</span> size-frequency distributions (SFDs) indicates that: (1) removal of D ≈ 4-50 km <span class="hlt">craters</span> in the "wispy" terrain was most likely by the formation of D ≳ 50 km <span class="hlt">craters</span>, not faulting, and likely occurred over a couple billion of years; (<span class="hlt">2</span>) resurfacing of the smooth plains was most likely by cryovolcanism at ∼<span class="hlt">2</span> Ga; (3) most of Dione's largest <span class="hlt">craters</span> (D ⩾ 100 km), including Evander (D = 350 km), may have formed quite recently (<<span class="hlt">2</span> Ga), but are still relaxed, indicating Dione has been thermally active for at least half its history; and (4) the variation in <span class="hlt">crater</span> SFDs at D ≈ 4-15 km is plausibly due to different levels of minor resurfacing (mostly subsequent large impacts) within each terrain.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017Icar..286...15W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017Icar..286...15W"><span>The role of strength defects in shaping impact <span class="hlt">crater</span> planforms</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Watters, W. A.; Geiger, L. M.; Fendrock, M.; Gibson, R.; Hundal, C. B.</p> <p>2017-04-01</p> <p>High-resolution imagery and digital elevation models (DEMs) were used to measure the planimetric shapes of well-preserved impact <span class="hlt">craters</span>. These measurements were used to characterize the size-dependent scaling of the departure from circular symmetry, which provides useful insights into the processes of <span class="hlt">crater</span> growth and modification. For example, we characterized the dependence of the standard deviation of radius (σR) on <span class="hlt">crater</span> diameter (D) as σR ∼ Dm. For complex <span class="hlt">craters</span> on the Moon and Mars, m ranges from 0.9 to 1.<span class="hlt">2</span> among strong and weak target materials. For the martian simple <span class="hlt">craters</span> in our data set, m varies from 0.5 to 0.8. The value of m tends toward larger values in weak materials and modified <span class="hlt">craters</span>, and toward smaller values in relatively unmodified <span class="hlt">craters</span> as well as <span class="hlt">craters</span> in high-strength targets, such as young lava plains. We hypothesize that m ≈ 1 for planforms shaped by modification processes (slumping and collapse), whereas m tends toward ∼ 1/<span class="hlt">2</span> for planforms shaped by an excavation flow that was influenced by strength anisotropies. Additional morphometric parameters were computed to characterize the following planform properties: the planform aspect ratio or ellipticity, the deviation from a fitted ellipse, and the deviation from a convex shape. We also measured the distribution of <span class="hlt">crater</span> shapes using Fourier decomposition of the planform, finding a similar distribution for simple and complex <span class="hlt">craters</span>. By comparing the strength of small and large circular harmonics, we confirmed that lunar and martian complex <span class="hlt">craters</span> are more polygonal at small sizes. Finally, we have used physical and geometrical principles to motivate scaling arguments and simple Monte Carlo models for generating synthetic planforms, which depend on a characteristic length scale of target strength defects. One of these models can be used to generate populations of synthetic planforms which are very similar to the measured population of well-preserved simple <span class="hlt">craters</span> on</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70188371','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70188371"><span>Subsurface volatile content of martian double-layer ejecta (DLE) <span class="hlt">craters</span></span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Viola, Donna; McEwen, Alfred S.; Dundas, Colin M.; Byrne, Shane</p> <p>2017-01-01</p> <p>Excess ice is widespread throughout the martian mid-latitudes, particularly in Arcadia Planitia, where double-layer ejecta (DLE) <span class="hlt">craters</span> also tend to be abundant. In this region, we observe the presence of thermokarstically-expanded secondary <span class="hlt">craters</span> that likely form from impacts that destabilize a subsurface layer of excess ice, which subsequently sublimates. The presence of these expanded <span class="hlt">craters</span> shows that excess ice is still preserved within the adjacent terrain. Here, we focus on a 15-km DLE <span class="hlt">crater</span> that contains abundant superposed expanded <span class="hlt">craters</span> in order to study the distribution of subsurface volatiles both at the time when the secondary <span class="hlt">craters</span> formed and, by extension, remaining today. To do this, we measure the size distribution of the superposed expanded <span class="hlt">craters</span> and use topographic data to calculate <span class="hlt">crater</span> volumes as a proxy for the volumes of ice lost to sublimation during the expansion process. The inner ejecta layer contains <span class="hlt">craters</span> that appear to have undergone more expansion, suggesting that excess ice was most abundant in that region. However, both of the ejecta layers had more expanded <span class="hlt">craters</span> than the surrounding terrain. We extrapolate that the total volume of ice remaining within the entire ejecta deposit is as much as 74 km3 or more. The variation in ice content between the ejecta layers could be the result of (1) volatile preservation from the formation of the DLE <span class="hlt">crater</span>, (<span class="hlt">2</span>) post-impact deposition in the form of ice lenses; or (3) preferential accumulation or preservation of subsequent snowfall. We have ruled out (<span class="hlt">2</span>) as the primary mode for ice deposition in this location based on inconsistencies with our observations, though it may operate in concert with other processes. Although none of the existing DLE formation hypotheses are completely consistent with our observations, which may merit a new or modified mechanism, we can conclude that DLE <span class="hlt">craters</span> contain a significant quantity of excess ice today.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://images.nasa.gov/#/details-PIA21908.html','SCIGOVIMAGE-NASA'); return false;" href="https://images.nasa.gov/#/details-PIA21908.html"><span>Axomama <span class="hlt">Crater</span> on Ceres</span></a></p> <p><a target="_blank" href="https://images.nasa.gov/">NASA Image and Video Library</a></p> <p></p> <p>2017-10-06</p> <p>This image from NASA's Dawn spacecraft highlights Axomama <span class="hlt">Crater</span>, the small <span class="hlt">crater</span> shown to the right of center. It is 3 miles (5 kilometers) in diameter and located just inside the western rim of Dantu <span class="hlt">Crater</span>. Axomama is one of the newly named <span class="hlt">craters</span> on Ceres. Its sharp edges indicate recent emplacement by a small impact. This picture also shows details on the floor of Dantu, which comprises most of the image. The many fractures and the central pit (see also PIA20303) are reminiscent of Occator <span class="hlt">Crater</span> and could point to a similar formation history, involving activity driven by the presence of liquid water in the subsurface. Axomama is named after the Incan goddess of potato, or "Potato-mother." NASA's Dawn spacecraft acquired this picture during its extended mission on July 24, 2016, from its low altitude mapping orbit at about 240 miles (385 kilometers) above the surface. The center coordinates of this image are 24 degrees north latitude, 131 degrees east longitude. https://photojournal.jpl.nasa.gov/catalog/PIA21908</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://images.nasa.gov/#/details-PIA00503.html','SCIGOVIMAGE-NASA'); return false;" href="https://images.nasa.gov/#/details-PIA00503.html"><span>Roter Kamm Impact <span class="hlt">Crater</span> in Namibia</span></a></p> <p><a target="_blank" href="https://images.nasa.gov/">NASA Image and Video Library</a></p> <p></p> <p>1996-11-13</p> <p>This space radar image shows the Roter Kamm impact <span class="hlt">crater</span> in southwest Namibia. The <span class="hlt">crater</span> rim is seen in the lower center of the image as a radar-bright, circular feature. Geologists believe the <span class="hlt">crater</span> was formed by a meteorite that collided with Earth approximately 5 million years ago. The data were acquired by the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) instrument onboard space shuttle Endeavour on April 14, 1994. The area is located at 27.8 degrees south latitude and 16.<span class="hlt">2</span> degrees east longitude in southern Africa. The colors in this image were obtained using the following radar channels: red represents the L-band (horizontally transmitted and received); green represents the L-band (horizontally transmitted and vertically received); and blue represents the C-band (horizontally transmitted and vertically received). The area shown is approximately 25.5 kilometers (15.8 miles) by 36.4 kilometers (22.5 miles), with north toward the lower right. The bright white irregular feature in the lower left corner is a small hill of exposed rock outcrop. Roter Kamm is a moderate sized impact <span class="hlt">crater</span>, <span class="hlt">2</span>.5 kilometers (1.5 miles) in diameter rim to rim, and is 130 meters (400 feet) deep. However, its original floor is covered by sand deposits at least 100 meters (300 feet) thick. In a conventional aerial photograph, the brightly colored surfaces immediately surrounding the <span class="hlt">crater</span> cannot be seen because they are covered by sand. The faint blue surfaces adjacent to the rim may indicate the presence of a layer of rocks ejected from the <span class="hlt">crater</span> during the impact. The darkest areas are thick windblown sand deposits which form dunes and sand sheets. The sand surface is smooth relative to the surrounding granite and limestone rock outcrops and appears dark in radar image. The green tones are related primarily to larger vegetation growing on sand soil, and the reddish tones are associated with thinly mantled limestone outcrops. Studies of impact <span class="hlt">craters</span> on</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2013-title36-vol1/pdf/CFR-2013-title36-vol1-sec7-2.pdf','CFR2013'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2013-title36-vol1/pdf/CFR-2013-title36-vol1-sec7-2.pdf"><span>36 CFR 7.<span class="hlt">2</span> - <span class="hlt">Crater</span> Lake National Park.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2013&page.go=Go">Code of Federal Regulations, 2013 CFR</a></p> <p></p> <p>2013-07-01</p> <p>... with snow poles and signs, only that portion of the North Entrance Road intended for wheeled vehicle... permitted in <span class="hlt">Crater</span> Lake National Park on the North Entrance Road from its intersection with the Rim Drive to the park boundary, and on intermittent routes detouring from the North Entrance Road as designated...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2012-title36-vol1/pdf/CFR-2012-title36-vol1-sec7-2.pdf','CFR2012'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2012-title36-vol1/pdf/CFR-2012-title36-vol1-sec7-2.pdf"><span>36 CFR 7.<span class="hlt">2</span> - <span class="hlt">Crater</span> Lake National Park.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2012&page.go=Go">Code of Federal Regulations, 2012 CFR</a></p> <p></p> <p>2012-07-01</p> <p>... with snow poles and signs, only that portion of the North Entrance Road intended for wheeled vehicle... permitted in <span class="hlt">Crater</span> Lake National Park on the North Entrance Road from its intersection with the Rim Drive to the park boundary, and on intermittent routes detouring from the North Entrance Road as designated...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2014-title36-vol1/pdf/CFR-2014-title36-vol1-sec7-2.pdf','CFR2014'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2014-title36-vol1/pdf/CFR-2014-title36-vol1-sec7-2.pdf"><span>36 CFR 7.<span class="hlt">2</span> - <span class="hlt">Crater</span> Lake National Park.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2014&page.go=Go">Code of Federal Regulations, 2014 CFR</a></p> <p></p> <p>2014-07-01</p> <p>... with snow poles and signs, only that portion of the North Entrance Road intended for wheeled vehicle... permitted in <span class="hlt">Crater</span> Lake National Park on the North Entrance Road from its intersection with the Rim Drive to the park boundary, and on intermittent routes detouring from the North Entrance Road as designated...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2011-title36-vol1/pdf/CFR-2011-title36-vol1-sec7-2.pdf','CFR2011'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2011-title36-vol1/pdf/CFR-2011-title36-vol1-sec7-2.pdf"><span>36 CFR 7.<span class="hlt">2</span> - <span class="hlt">Crater</span> Lake National Park.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2011&page.go=Go">Code of Federal Regulations, 2011 CFR</a></p> <p></p> <p>2011-07-01</p> <p>... with snow poles and signs, only that portion of the North Entrance Road intended for wheeled vehicle... permitted in <span class="hlt">Crater</span> Lake National Park on the North Entrance Road from its intersection with the Rim Drive to the park boundary, and on intermittent routes detouring from the North Entrance Road as designated...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2010-title36-vol1/pdf/CFR-2010-title36-vol1-sec7-2.pdf','CFR'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2010-title36-vol1/pdf/CFR-2010-title36-vol1-sec7-2.pdf"><span>36 CFR 7.<span class="hlt">2</span> - <span class="hlt">Crater</span> Lake National Park.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2010&page.go=Go">Code of Federal Regulations, 2010 CFR</a></p> <p></p> <p>2010-07-01</p> <p>... with snow poles and signs, only that portion of the North Entrance Road intended for wheeled vehicle... permitted in <span class="hlt">Crater</span> Lake National Park on the North Entrance Road from its intersection with the Rim Drive to the park boundary, and on intermittent routes detouring from the North Entrance Road as designated...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012ttt..work...24S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012ttt..work...24S"><span>Titan's Impact <span class="hlt">Cratering</span> Record: Erosion of Ganymedean (and other) <span class="hlt">Craters</span> on a Wet Icy Landscape</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Schenk, P.; Moore, J.; Howard, A.</p> <p>2012-04-01</p> <p>We examine the <span class="hlt">cratering</span> record of Titan from the perspective of icy satellites undergoing persistent landscape erosion. First we evaluate whether Ganymede (and Callisto) or the smaller low-gravity neighboring icy satellites of Saturn are the proper reference standard for evaluating Titan’s impact <span class="hlt">crater</span> morphologies, using topographic and morphometric measurements (Schenk, 2002; Schenk et al. (2004) and unpublished data). The special case of Titan’s largest <span class="hlt">crater</span>, Minrva, is addressed through analysis of large impact basins such as Gilgamesh, Lofn, Odysseus and Turgis. Second, we employ a sophisticated landscape evolution and modification model developed for study of martian and other planetary landforms (e.g., Howard, 2007). This technique applies mass redistribution principles due to erosion by impact, fluvial and hydrological processes to a planetary landscape. The primary advantage of our technique is the possession of a limited but crucial body of areal digital elevation models (DEMs) of Ganymede (and Callisto) impact <span class="hlt">craters</span> as well as global DEM mapping of Saturn’s midsize icy satellites, in combination with the ability to simulate rainfall and redeposition of granular material to determine whether Ganymede <span class="hlt">craters</span> can be eroded to resemble Titan <span class="hlt">craters</span> and the degree of erosion required. References: Howard, A. D., “Simulating the development of martian highland landscapes through the interaction of impact <span class="hlt">cratering</span>, fluvial erosion, and variable hydrologic forcing”, Geomorphology, 91, 332-363, 2007. Schenk, P. "Thickness constraints on the icy shells of the galilean satellites from impact <span class="hlt">crater</span> shapes". Nature, 417, 419-421, 2002. Schenk, P.M., et al. "Ages and interiors: the <span class="hlt">cratering</span> record of the Galilean satellites". In: Jupiter: The Planet, Satellites, and Magnetosphere, Cambridge University Press, Cambridge, UK, pp. 427-456, 2004.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20030067009&hterms=TURTLES&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3DTURTLES','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20030067009&hterms=TURTLES&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3DTURTLES"><span>Numerical Simulations of Silverpit <span class="hlt">Crater</span> Collapse</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Collins, G. S.; Ivanov, B. A.; Turtle, E. P.; Melosh, H. J.</p> <p>2003-01-01</p> <p>The Silverpit <span class="hlt">crater</span> is a recently discovered, 60-65 Myr old complex <span class="hlt">crater</span>, which lies buried beneath the North Sea, about 150 km east of Britain. High-resolution images of Silverpit's subsurface structure, provided by three-dimensional seismic reflection data, reveal an inner-<span class="hlt">crater</span> morphology similar to that expected for a 5-8 km diameter terrestrial <span class="hlt">crater</span>. The <span class="hlt">crater</span> walls show evidence of terrace-style slumping and there is a distinct central uplift, which may have produced a central peak in the pristine <span class="hlt">crater</span> morphology. However, Silverpit is not a typical 5-km diameter terrestrial <span class="hlt">crater</span>, because it exhibits multiple, concentric rings outside the main cavity. External concentric rings are normally associated with much larger impact structures, for example Chicxulub on Earth, or Orientale on the Moon. Furthermore, external rings associated with large impacts on the terrestrial planets and moons are widely-spaced, predominantly inwardly-facing, asymmetric scarps. However, the seismic data show that the external rings at Silverpit represent closely-spaced, concentric faultbound graben, with both inwardly and outwardly facing fault-scarps. This type of multi-ring structure directly analogous to the Valhalla-type multi-ring basins found on the icy satellites. Thus, the presence and style of the multiple rings at Silverpit is surprising given both the size of the <span class="hlt">crater</span> and its planetary setting. A further curiosity of the Silverpit structure is that the external concentric rings appear to be extensional features on the West side of the <span class="hlt">crater</span> and compressional features on the East side. The <span class="hlt">crater</span> also lies in a local depression, thought to be created by postimpact movement of a salt layer buried beneath the <span class="hlt">crater</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=PIA07041&hterms=tale&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dtale','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=PIA07041&hterms=tale&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dtale"><span>A Tale of 3 <span class="hlt">Craters</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>2004-01-01</p> <p><p/> 11 November 2004 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image captures some of the complexity of the martian upper crust. Mars does not simply have an impact-<span class="hlt">cratered</span> surface, it's upper crust is a <span class="hlt">cratered</span> volume. Over time, older <span class="hlt">craters</span> on Mars have been eroded, filled, buried, and in some cases exhumed and re-exposed at the martian surface. The crust of Mars is layered to depths of 10 or more kilometers, and mixed in with the layered bedrock are a variety of ancient <span class="hlt">craters</span> with diameters ranging from a few tens of meters (a few tens of yards) to several hundred kilometers (more than one or two hundred miles). <p/> The picture shown here captures some of the essence of the layered, <span class="hlt">cratered</span> volume of the upper crust of Mars in a very simple form. The image shows three distinct circular features. The smallest, in the lower right quarter of the image, is a meteor <span class="hlt">crater</span> surrounded by a mound of material. This small <span class="hlt">crater</span> formed within a layer of bedrock that once covered the entire scene, but today is found only in this small remnant adjacent to the <span class="hlt">crater</span>. The intermediate-sized <span class="hlt">crater</span>, west (left) of the small one, formed either in the next layer down--that is, below the layer in which the small <span class="hlt">crater</span> formed--or it formed in some layers that are now removed, but was big enough to penetrate deeply into the rock that is near the surface today. The largest circular feature in the image, in the upper right quarter of the image, is still largely buried. It formed in layers of rock that are below the present surface. Erosion has brought traces of its rim back to the surface of Mars. This picture is located near 50.0oS, 77.8oW, and covers an area approximately 3 km (1.9 mi) across. Sunlight illuminates this October 2004 image from the upper left.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.H52E..01F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.H52E..01F"><span><span class="hlt">Subsidence</span> in the Central Valley, California 2007 - present measured by InSAR</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Farr, T. G.; Liu, Z.; Jones, C. E.</p> <p>2015-12-01</p> <p><span class="hlt">Subsidence</span> caused by groundwater pumping in the rich agricultural area of California's Central Valley has been a problem for decades. Over the last few years, interferometric synthetic aperture radar (InSAR) observations from satellite and aircraft platforms have been used to produce maps of <span class="hlt">subsidence</span> with ~cm accuracy. For this study, we have obtained and analyzed Japanese PALSAR data for 2006 - 2011, Canadian Radarsat-1 data for 2011 - 2013, Radarsat-<span class="hlt">2</span> data for 2012 - 2015, and ESA's Sentinel-1A for 2015 and produced maps of <span class="hlt">subsidence</span> for those periods. High resolution InSAR data were also acquired along the California Aqueduct by the NASA UAVSAR from 2013 - 2015. Using multiple scenes acquired by these systems, we were able to produce the time histories of <span class="hlt">subsidence</span> at selected locations and transects showing how <span class="hlt">subsidence</span> varies both spatially and temporally. The maps show that <span class="hlt">subsidence</span> is continuing in areas with a history of <span class="hlt">subsidence</span> and that the rates and areas affected have increased due to increased groundwater extraction during the extended western US drought. The high resolution maps from UAVSAR were used to identify and quantify new, highly localized areas of accelerated <span class="hlt">subsidence</span> along the California Aqueduct that occurred in 2014. The California Department of Water Resources (DWR) funded this work to provide the background and an update on <span class="hlt">subsidence</span> in the Central Valley to support future policy. Geographic Information System (GIS) files are being furnished to DWR for further analysis of the 4 dimensional <span class="hlt">subsidence</span> time-series maps. Part of this work was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under contract with NASA.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFM.T21A2513L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFM.T21A2513L"><span>Regional <span class="hlt">subsidence</span> history and 3D visualization with MATLAB of the Vienna Basin, central Europe</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lee, E.; Novotny, J.; Wagreich, M.</p> <p>2013-12-01</p> <p>This study reconstructed the <span class="hlt">subsidence</span> history by the backstripping and 3D visualization techniques, to understand tectonic evolution of the Neogene Vienna Basin. The backstripping removes the compaction effect of sediment loading and quantifies the tectonic <span class="hlt">subsidence</span>. The amount of decompaction was calculated by porosity-depth relationships evaluated from seismic velocity data acquired from two boreholes. About 100 wells have been investigated to quantify the <span class="hlt">subsidence</span> history of the Vienna Basin. The wells have been sorted into 10 groups; N1-4 in the northern part, C1-4 in the central part and L1-<span class="hlt">2</span> in the northernmost and easternmost parts, based on their position within the same block bordered by major faults. To visualize 3D <span class="hlt">subsidence</span> maps, the wells were arranged to a set of 3D points based on their map location (x, y) and depths (z1, z<span class="hlt">2</span>, z3 ...). The division of the stratigraphic column and age range was arranged based on the Central Paratethys regional Stages. In this study, MATLAB, a numerical computing environment, was used to calculate the TPS interpolation function. The Thin-Plate Spline (TPS) can be employed to reconstruct a smooth surface from a set of 3D points. The basic physical model of the TPS is based on the bending behavior of a thin metal sheet that is constrained only by a sparse set of fixed points. In the Lower Miocene, 3D <span class="hlt">subsidence</span> maps show strong evidence that the pre-Neogene basement of the Vienna Basin was <span class="hlt">subsiding</span> along borders of the Alpine-Carpathian nappes. This <span class="hlt">subsidence</span> event is represented by a piggy-back basin developed on top of the NW-ward moving thrust sheets. In the late Lower Miocene, Group C and N display a typical <span class="hlt">subsidence</span> pattern for the pull-apart basin with a very high <span class="hlt">subsidence</span> event (0.<span class="hlt">2</span> - 1.0 km/Ma). After the event, Group N shows remarkably decreasing <span class="hlt">subsidence</span>, following the thin-skinned extension which was regarded as the extension model of the Vienna Basin in the literature. But the <span class="hlt">subsidence</span> in</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006AGUFM.P34B..02S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006AGUFM.P34B..02S"><span>Robust System for Automated Identification of Martian Impact <span class="hlt">Craters</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Stepinski, T. F.; Mendenhall, M. P.</p> <p>2006-12-01</p> <p>Detailed analysis of the number and morphology of impact <span class="hlt">craters</span> on Mars provides the worth of information about the geologic history of its surface. Global catalogs of Martian <span class="hlt">craters</span> have been compiled (for example, the Barlow catalog) but they are not comprehensive, especially for small <span class="hlt">craters</span>. Existing methods for machine detection of <span class="hlt">craters</span> from images suffer from low efficiency and are not practical for global surveys. We have developed a robust two-stage system for an automated cataloging of <span class="hlt">craters</span> from digital topography data (DEM). In the first stage an innovative <span class="hlt">crater</span>-finding transform is performed on a DEM to identify centers of potential <span class="hlt">craters</span>, their extents, and their basic characteristics. This stage produces a preliminary catalog. In the second stage a machine learning methods are employed to eliminate false positives. Using the MOLA derived DEMs with resolution of 1/128 degrees/pixel, we have applied our system to six ~ 106 km<span class="hlt">2</span> sites. The system has identified 3217 <span class="hlt">craters</span>, 43% more than are present in the Barlow catalog. The extra finds are predominantly small <span class="hlt">craters</span> that are most difficult to account for in manual surveys. Because our automated survey is DEM-based, the resulting catalog lists <span class="hlt">craters</span>' depths in addition to their positions, sizes, and measures of shape. This feature significantly increases the scientific utility of any catalog generated using our system. Our initial calculations yield a training set that will be used to identify <span class="hlt">craters</span> over the entire Martian surface with estimated accuracy of 95%. Moreover, because our method is pixel-based and scale- independent, the present training set may be used to identify <span class="hlt">craters</span> in higher resolution DEMs derived from Mars Express HRSC images. It also can be applied to future topography data from Mars and other planets. For example, it may be utilized to catalog <span class="hlt">craters</span> on Mercury and the Moon using altimetry data to be gathered by Messenger and Lunar Reconnaissance Orbiter</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li class="active"><span>20</span></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_20 --> <div id="page_21" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li class="active"><span>21</span></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="401"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19770054896&hterms=conversion+rate&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dconversion%2Brate%2527','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19770054896&hterms=conversion+rate&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dconversion%2Brate%2527"><span>Relative <span class="hlt">crater</span> production rates on planets</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Hartmann, W. K.</p> <p>1977-01-01</p> <p>The relative numbers of impacts on different planets, estimated from the dynamical histories of planetesimals in specified orbits (Wetherill, 1975), are converted by a described procedure to <span class="hlt">crater</span> production rates. Conversions are dependent on impact velocity and surface gravity. <span class="hlt">Crater</span> retention ages can then be derived from the ratio of the <span class="hlt">crater</span> density to the <span class="hlt">crater</span> production rate. The data indicate that the terrestrial planets have <span class="hlt">crater</span> production rates within a factor ten of each other. As an example, for the case of Mars, least-squares fits to <span class="hlt">crater</span>-count data suggest an average age of 0.3 to 3 billion years for two types of channels. The age of Olympus Mons is discussed, and the effect of Tharsis volcanism on channel formation is considered.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/403046-subsidence-well-failure-south-belridge-diatomite-field','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/403046-subsidence-well-failure-south-belridge-diatomite-field"><span><span class="hlt">Subsidence</span> and well failure in the South Belridge Diatomite field</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Rouffignac, E.P. de; Bondor, P.L.; Karanikas, J.M. Hara, S.K.</p> <p>1995-12-31</p> <p>Withdrawal of fluids from shallow, thick and low strength rock can cause substantial reservoir compaction leading to surface <span class="hlt">subsidence</span> and well failure. This is the case for the Diatomite reservoir, where over 10 ft of <span class="hlt">subsidence</span> have occurred in some areas. Well failure rates have averaged over 3% per year, resulting in several million dollars per year in well replacement and repair costs in the South Belridge Diatomite alone. A program has been underway to address this issue, including experimental, modeling and field monitoring work. An updated elastoplastic rock law based on laboratory data has been generated which includes notmore » only standard shear failure mechanisms but also irreversible pore collapse occurring at low effective stresses (<150 psi). This law was incorporated into a commercial finite element geomechanics simulator. Since the late 1980s, a network of level survey monuments has been used to monitor <span class="hlt">subsidence</span> at Belridge. Model predictions of <span class="hlt">subsidence</span> in Section 33 compare very well with field measured data, which show that water injection reduces <span class="hlt">subsidence</span> from 7--8 inches per year to 1--<span class="hlt">2</span> inches per year, but does not abate well failure.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011PhDT.........6R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011PhDT.........6R"><span>Planetary Surface Properties, <span class="hlt">Cratering</span> Physics, and the Volcanic History of Mars from a New Global Martian <span class="hlt">Crater</span> Database</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Robbins, Stuart James</p> <p></p> <p>Impact <span class="hlt">craters</span> are arguably the primary exogenic planetary process contributing to the surface evolution of solid bodies in the solar system. <span class="hlt">Craters</span> appear across the entire surface of Mars, and they are vital to understanding its crustal properties as well as surface ages and modification events. They allow inferences into the ancient climate and hydrologic history, and they add a key data point for the understanding of impact physics. Previously available databases of Mars impact <span class="hlt">craters</span> were created from now antiquated datasets, automated algorithms with biases and inaccuracies, were limited in scope, and/or complete only to multikilometer diameters. This work presents a new global database for Mars that contains 378,540 <span class="hlt">craters</span> statistically complete for diameters D ≳ 1 km. This detailed database includes location and size, ejecta morphology and morphometry, interior morphology and degradation state, and whether the <span class="hlt">crater</span> is a secondary impact. This database allowed exploration of global <span class="hlt">crater</span> type distributions, depth, and morphologies in unprecedented detail that were used to re-examine basic <span class="hlt">crater</span> scaling laws for the planet. The inclusion of hundreds of thousands of small, approximately kilometer-sized impacts facilitated a detailed study of the properties of nearby fields of secondary <span class="hlt">craters</span> in relation to their primary <span class="hlt">crater</span>. It also allowed the discovery of vast distant clusters of secondary <span class="hlt">craters</span> over 5000 km from their primary <span class="hlt">crater</span>, Lyot. Finally, significantly smaller <span class="hlt">craters</span> were used to age-date volcanic calderas on the planet to re-construct the timeline of the last primary eruption events from 20 of the major Martian volcanoes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://images.nasa.gov/#/details-PIA22146.html','SCIGOVIMAGE-NASA'); return false;" href="https://images.nasa.gov/#/details-PIA22146.html"><span>Investigating Mars: Rabe <span class="hlt">Crater</span></span></a></p> <p><a target="_blank" href="https://images.nasa.gov/">NASA Image and Video Library</a></p> <p></p> <p>2017-12-20</p> <p>This is a false color image of Rabe <span class="hlt">Crater</span>. In this combination of filters "blue" typically means basaltic sand. Rabe <span class="hlt">Crater</span> is 108 km (67 miles) across. <span class="hlt">Craters</span> of similar size often have flat floors. Rabe <span class="hlt">Crater</span> has some areas of flat floor, but also has a large complex pit occupying a substantial part of the floor. The interior fill of the <span class="hlt">crater</span> is thought to be layered sediments created by wind and or water action. The pit is eroded into this material. The eroded materials appear to have stayed within the <span class="hlt">crater</span> forming a large sand sheet with surface dune forms as well as individual dunes where the <span class="hlt">crater</span> floor is visible. The dunes also appear to be moving from the upper floor level into the pit. The THEMIS VIS camera contains 5 filters. The data from different filters can be combined in multiple ways to create a false color image. These false color images may reveal subtle variations of the surface not easily identified in a single band image. The Odyssey spacecraft has spent over 15 years in orbit around Mars, circling the planet more than 69000 times. It holds the record for longest working spacecraft at Mars. THEMIS, the IR/VIS camera system, has collected data for the entire mission and provides images covering all seasons and lighting conditions. Over the years many features of interest have received repeated imaging, building up a suite of images covering the entire feature. From the deepest chasma to the tallest volcano, individual dunes inside <span class="hlt">craters</span> and dune fields that encircle the north pole, channels carved by water and lava, and a variety of other feature, THEMIS has imaged them all. For the next several months the image of the day will focus on the Tharsis volcanoes, the various chasmata of Valles Marineris, and the major dunes fields. We hope you enjoy these images! Orbit Number: 52231 Latitude: -43.6665 Longitude: 34.2627 Instrument: VIS Captured: 2013-09-22 14:29 https://photojournal.jpl.nasa.gov/catalog/PIA22146</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://images.nasa.gov/#/details-PIA22148.html','SCIGOVIMAGE-NASA'); return false;" href="https://images.nasa.gov/#/details-PIA22148.html"><span>Investigating Mars: Rabe <span class="hlt">Crater</span></span></a></p> <p><a target="_blank" href="https://images.nasa.gov/">NASA Image and Video Library</a></p> <p></p> <p>2017-12-22</p> <p>This is a false color image of Rabe <span class="hlt">Crater</span>. In this combination of filters "blue" typically means basaltic sand. Rabe <span class="hlt">Crater</span> is 108 km (67 miles) across. <span class="hlt">Craters</span> of similar size often have flat floors. Rabe <span class="hlt">Crater</span> has some areas of flat floor, but also has a large complex pit occupying a substantial part of the floor. The interior fill of the <span class="hlt">crater</span> is thought to be layered sediments created by wind and or water action. The pit is eroded into this material. The eroded materials appear to have stayed within the <span class="hlt">crater</span> forming a large sand sheet with surface dune forms as well as individual dunes where the <span class="hlt">crater</span> floor is visible. The dunes also appear to be moving from the upper floor level into the pit. The THEMIS VIS camera contains 5 filters. The data from different filters can be combined in multiple ways to create a false color image. These false color images may reveal subtle variations of the surface not easily identified in a single band image. The Odyssey spacecraft has spent over 15 years in orbit around Mars, circling the planet more than 69000 times. It holds the record for longest working spacecraft at Mars. THEMIS, the IR/VIS camera system, has collected data for the entire mission and provides images covering all seasons and lighting conditions. Over the years many features of interest have received repeated imaging, building up a suite of images covering the entire feature. From the deepest chasma to the tallest volcano, individual dunes inside <span class="hlt">craters</span> and dune fields that encircle the north pole, channels carved by water and lava, and a variety of other feature, THEMIS has imaged them all. For the next several months the image of the day will focus on the Tharsis volcanoes, the various chasmata of Valles Marineris, and the major dunes fields. We hope you enjoy these images! Orbit Number: 67144 Latitude: -43.5512 Longitude: 34.5951 Instrument: VIS Captured: 2017-02-01 12:57 https://photojournal.jpl.nasa.gov/catalog/PIA22148</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://images.nasa.gov/#/details-PIA22145.html','SCIGOVIMAGE-NASA'); return false;" href="https://images.nasa.gov/#/details-PIA22145.html"><span>Investigating Mars: Rabe <span class="hlt">Crater</span></span></a></p> <p><a target="_blank" href="https://images.nasa.gov/">NASA Image and Video Library</a></p> <p></p> <p>2017-12-19</p> <p>This is a false color image of Rabe <span class="hlt">Crater</span>. In this combination of filters "blue" typically means basaltic sand. Rabe <span class="hlt">Crater</span> is 108 km (67 miles) across. <span class="hlt">Craters</span> of similar size often have flat floors. Rabe <span class="hlt">Crater</span> has some areas of flat floor, but also has a large complex pit occupying a substantial part of the floor. The interior fill of the <span class="hlt">crater</span> is thought to be layered sediments created by wind and or water action. The pit is eroded into this material. The eroded materials appear to have stayed within the <span class="hlt">crater</span> forming a large sand sheet with surface dune forms as well as individual dunes where the <span class="hlt">crater</span> floor is visible. The dunes also appear to be moving from the upper floor level into the pit. The THEMIS VIS camera contains 5 filters. The data from different filters can be combined in multiple ways to create a false color image. These false color images may reveal subtle variations of the surface not easily identified in a single band image. The Odyssey spacecraft has spent over 15 years in orbit around Mars, circling the planet more than 69000 times. It holds the record for longest working spacecraft at Mars. THEMIS, the IR/VIS camera system, has collected data for the entire mission and provides images covering all seasons and lighting conditions. Over the years many features of interest have received repeated imaging, building up a suite of images covering the entire feature. From the deepest chasma to the tallest volcano, individual dunes inside <span class="hlt">craters</span> and dune fields that encircle the north pole, channels carved by water and lava, and a variety of other feature, THEMIS has imaged them all. For the next several months the image of the day will focus on the Tharsis volcanoes, the various chasmata of Valles Marineris, and the major dunes fields. We hope you enjoy these images! Orbit Number: 51157 Latitude: -43.6787 Longitude: 34.3985 Instrument: VIS Captured: 2013-06-26 05:33 https://photojournal.jpl.nasa.gov/catalog/PIA22145</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://images.nasa.gov/#/details-PIA22140.html','SCIGOVIMAGE-NASA'); return false;" href="https://images.nasa.gov/#/details-PIA22140.html"><span>Investigating Mars: Rabe <span class="hlt">Crater</span></span></a></p> <p><a target="_blank" href="https://images.nasa.gov/">NASA Image and Video Library</a></p> <p></p> <p>2017-12-12</p> <p>In this VIS image of the floor of Rabe <span class="hlt">Crater</span> the step down into the pit is visible in the sinuous ridges on the left side of the image. The appearance of the exposed side of the cliffs does not look like a volcanic, difficult to erode material, but rather an easy to erode material such as layered sediments. Rabe <span class="hlt">Crater</span> is 108 km (67 miles) across. <span class="hlt">Craters</span> of similar size often have flat floors. Rabe <span class="hlt">Crater</span> has some areas of flat floor, but also has a large complex pit occupying a substantial part of the floor. The interior fill of the <span class="hlt">crater</span> is thought to be layered sediments created by wind and or water action. The pit is eroded into this material. The eroded materials appear to have stayed within the <span class="hlt">crater</span> forming a large sand sheet with surface dune forms as well as individual dunes where the <span class="hlt">crater</span> floor is visible. The dunes also appear to be moving from the upper floor level into the pit. The Odyssey spacecraft has spent over 15 years in orbit around Mars, circling the planet more than 69000 times. It holds the record for longest working spacecraft at Mars. THEMIS, the IR/VIS camera system, has collected data for the entire mission and provides images covering all seasons and lighting conditions. Over the years many features of interest have received repeated imaging, building up a suite of images covering the entire feature. From the deepest chasma to the tallest volcano, individual dunes inside <span class="hlt">craters</span> and dune fields that encircle the north pole, channels carved by water and lava, and a variety of other feature, THEMIS has imaged them all. For the next several months the image of the day will focus on the Tharsis volcanoes, the various chasmata of Valles Marineris, and the major dunes fields. We hope you enjoy these images! Orbit Number: 34456 Latitude: -43.7164 Longitude: 34.4056 Instrument: VIS Captured: 2009-09-20 09:38 https://photojournal.jpl.nasa.gov/catalog/PIA22140</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20160003300','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20160003300"><span>Amorphous and Crystalline H20 Ice at Rhea's Inktomi <span class="hlt">Crater</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Lewis, Emma M.; Dalle Ore, Cristina M.; Cruikshank, Dale P.; White, Oliver L.</p> <p>2014-01-01</p> <p>We present the analysis of Cassini spectral data from spectral mapping of Saturnian icy moons Dione and Rhea, to investigate possible effects of impact <span class="hlt">crater</span> formation on the relative abundances of crystalline and amorphous water ice in the moons' ice crusts. Both moons display morphologically young ray <span class="hlt">craters</span> as well as older <span class="hlt">craters</span>. Possible changes in ice properties due to <span class="hlt">crater</span> formation are conjectured to be more visible in younger <span class="hlt">craters</span>, and as such Rhea's well imaged ray <span class="hlt">crater</span> Inktomi is analysed, as are older <span class="hlt">craters</span> for comparison. We used data from Cassini's Visual and Infrared Mapping Spectrometer (VIMS). For each pixel in the VIMS maps, spectral data were extracted in the near-infrared range (1.75 micrometers less than lambda less than <span class="hlt">2</span>.45 micrometers). Analysis was begun by fitting a single Gaussian to the peak in absorption at <span class="hlt">2</span>.0 micrometers, which was then subtracted from the data, leaving residuals with a minimum on either side of the original <span class="hlt">2</span>.0-micrometers band. The spectra of the individual spatial pixels were then clustered by the differences between these minima, which are sensitive to changes in both ice grain size and crystallinity. This yielded preliminary maps which approximated the physical characteristics of the landscape and were used to identify candidates for further analysis. Spectra were then clustered by the properties of the 1.5-micrometers band, to divide the map into regions based on inferred grain size. For each region, the predicted differences in minima from the Gaussian residuals, over a range of crystallinities, were calculated based on the found grain sizes. This model was used to find the crystallinity of each pixel via grain size and characteristics of the residual function. Preliminary results show a greater degree of crystallization of young <span class="hlt">crater</span> interiors, particularly in Rhea's ray <span class="hlt">crater</span> Inktomi, where ice showed crystalline ice abundances between 33 percent and 61 percent. These patterns in ice</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19950017405','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19950017405"><span>Small <span class="hlt">craters</span> on the meteoroid and space debris impact experiment</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Humes, Donald H.</p> <p>1995-01-01</p> <p>Examination of 9.34 m(exp <span class="hlt">2</span>) of thick aluminum plates from the Long Duration Exposure Facility (LDEF) using a 25X microscope revealed 4341 <span class="hlt">craters</span> that were 0.1 mm in diameter or larger. The largest was 3 mm in diameter. Most were roughly hemispherical with lips that were raised above the original plate surface. The <span class="hlt">crater</span> diameter measured was the diameter at the top of the raised lips. There was a large variation in the number density of <span class="hlt">craters</span> around the three-axis gravity-gradient stabilized spacecraft. A model of the near-Earth meteoroid environment is presented which uses a meteoroid size distribution based on the <span class="hlt">crater</span> size distribution on the space end of the LDEF. An argument is made that nearly all the <span class="hlt">craters</span> on the space end must have been caused by meteoroids and that very few could have been caused by man-made orbital debris. However, no chemical analysis of impactor residue that will distinguish between meteoroids and man-made debris is yet available. A small area (0.0447 m(exp <span class="hlt">2</span>)) of one of the plates on the space end was scanned with a 200X microscope revealing 155 <span class="hlt">craters</span> between 10 micron and 100 micron in diameter and 3 <span class="hlt">craters</span> smaller than 10 micron. This data was used to extend the size distribution of meteoroids down to approximately 1 micron. New penetration equations developed by Alan Watts were used to relate <span class="hlt">crater</span> dimensions to meteoroid size. The equations suggest that meteoroids must have a density near <span class="hlt">2</span>.5 g/cm(exp 3) to produce <span class="hlt">craters</span> of the shape found on the LDEF. The near-Earth meteoroid model suggests that about 80 to 85 percent of the 100 micron to 1 mm diameter <span class="hlt">craters</span> on the twelve peripheral rows of the LDEF were caused by meteoroids, leaving 15 to 20 percent to be caused by man-made orbital debris.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://images.nasa.gov/#/details-PIA22172.html','SCIGOVIMAGE-NASA'); return false;" href="https://images.nasa.gov/#/details-PIA22172.html"><span>Investigating Mars: Kaiser <span class="hlt">Crater</span> Dunes</span></a></p> <p><a target="_blank" href="https://images.nasa.gov/">NASA Image and Video Library</a></p> <p></p> <p>2018-01-23</p> <p>Kaiser <span class="hlt">Crater</span> is located in the southern hemisphere in the Noachis region west of Hellas Planitia. Kaiser <span class="hlt">Crater</span> is just one of several large <span class="hlt">craters</span> with extensive dune fields on the <span class="hlt">crater</span> floor. Other nearby dune filled <span class="hlt">craters</span> are Proctor, Russell, and Rabe. Kaiser <span class="hlt">Crater</span> is 207 km (129 miles) in diameter. The dunes are located in the southeastern part of the <span class="hlt">crater</span> floor. Most of the individual dunes in Kaiser <span class="hlt">Crater</span> are barchan dunes. Barchan dunes are crescent shaped with the points of the crescent pointing downwind. The sand is blown up the low angle side of the dune and then tumbles down the steep slip face. This dune type forms on hard surfaces where there is limited amounts of sand. Barchan dunes can merge together over time with increased sand in the local area. The Odyssey spacecraft has spent over 15 years in orbit around Mars, circling the planet more than 69000 times. It holds the record for longest working spacecraft at Mars. THEMIS, the IR/VIS camera system, has collected data for the entire mission and provides images covering all seasons and lighting conditions. Over the years many features of interest have received repeated imaging, building up a suite of images covering the entire feature. From the deepest chasma to the tallest volcano, individual dunes inside <span class="hlt">craters</span> and dune fields that encircle the north pole, channels carved by water and lava, and a variety of other feature, THEMIS has imaged them all. For the next several months the image of the day will focus on the Tharsis volcanoes, the various chasmata of Valles Marineris, and the major dunes fields. We hope you enjoy these images! Orbit Number: 1036 Latitude: -46.7795 Longitude: 20.2075 Instrument: VIS Captured: 2002-03-09 20:07 https://photojournal.jpl.nasa.gov/catalog/PIA22172</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.usgs.gov/sim/3297/downloads/sim3297_pamphlet.pdf','USGSPUBS'); return false;" href="https://pubs.usgs.gov/sim/3297/downloads/sim3297_pamphlet.pdf"><span>Geologic map of Tooting <span class="hlt">crater</span>, Amazonis Planitia region of Mars</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Mouginis-Mark, Peter J.</p> <p>2015-01-01</p> <p>Tooting <span class="hlt">crater</span> has a diameter of 27.<span class="hlt">2</span> km, and formed on virtually flat lava flows within Amazonis Planitia ~1,300 km west of the summit of Olympus Mons volcano, where there appear to have been no other major topographic features prior to the impact. The <span class="hlt">crater</span> formed in an area ~185 x 135 km that is at an elevation between −3,870 m and −3,874 m relative to the Mars Orbiter Laser Altimeter (MOLA) Mars datum. This fortuitous situation (for example, a bland, horizontal target) allows the geometry of the <span class="hlt">crater</span> and the thickness of the ejecta blanket to be accurately determined by subtracting the appropriate elevation of the surrounding landscape (−3,872 m) from the individual MOLA measurements across the <span class="hlt">crater</span>. Thus, for the first time, it is possible to determine the radial decrease of ejecta thickness as a function of distance away from the rim crest. On the basis of the four discrete ejecta layers surrounding the <span class="hlt">crater</span> cavity, Tooting <span class="hlt">crater</span> is classified as a Multiple-Layered Ejecta (MLE) <span class="hlt">crater</span>. By virtue of the asymmetric distribution of secondary <span class="hlt">craters</span> and the greater thickness of ejecta to the northeast, Morris and others (2010) proposed that Tooting <span class="hlt">crater</span> formed by an oblique impact from the southwest. The maximum range of blocks that produced identifiable secondary <span class="hlt">craters</span> is ~500 km (~36.0 <span class="hlt">crater</span> radii) from the northeast rim crest. In contrast, secondary <span class="hlt">craters</span> are only identifiable ~215 km (15.8 radii) to the southeast and 225 km (16.5 radii) to the west.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19750027104&hterms=History+Genetics&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DHistory%2BGenetics','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19750027104&hterms=History+Genetics&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DHistory%2BGenetics"><span>Martian planetwide <span class="hlt">crater</span> distributions - Implications for geologic history and surface processes</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Soderblom, L. A.; Condit, C. D.; West, R. A.; Herman, B. M.; Kreidler, T. J.</p> <p>1974-01-01</p> <p>Three different diameter size ranges are considered in connection with the Martian <span class="hlt">crater</span> distribution, taking into account small <span class="hlt">craters</span> from 0.6 to 1.<span class="hlt">2</span> km, intermediate-sized <span class="hlt">craters</span> from 4 to 10 km, and large <span class="hlt">craters</span> with diameters exceeding 20 km. One of the objectives of the investigation reported is to establish the effects of eolian processes in the modification of <span class="hlt">craters</span> in the different size ranges. Another objective is concerned with a description of the genetic relationships among the three size ranges of <span class="hlt">craters</span>. Observables related to the relative age of geologic provinces are to be separated from observables related to geographic variations in eolian transport and deposition. Lunar and Martian <span class="hlt">cratering</span> histories are compared as a basis for establishing relative and absolute time scales for the geological evolution of Mars.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011AGUFM.A53D..04M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011AGUFM.A53D..04M"><span>Nocturnal Air Seiches in the Arizona Meteor <span class="hlt">Crater</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Muschinski, A.; Fritts, D. C.; Zhong, S.; Oncley, S. P.</p> <p>2011-12-01</p> <p>The Arizona Meteor <span class="hlt">Crater</span> near Winslow, AZ is 170 m deep, has a diameter of 1.<span class="hlt">2</span> km, and it has a nearly circular shape. The motivation of the Meteor <span class="hlt">Crater</span> Experiment (METCRAX), conducted in October 2006, was to use the Meteor <span class="hlt">Crater</span> as a natural laboratory to study atmospheric phenomena that are typical for small basins. Among other observations, high-resolution wind, temperature and pressure measurements were collected with sonics and microbarometers, respectively, during the entire month. The sensors were mounted between 0.5 m and 8.5 m AGL on seven portable towers, five of which were located within the <span class="hlt">crater</span> and two on the <span class="hlt">crater</span> rim. Here we report observations of nocturnal air seiches, that is, standing gravity waves associated with the time-harmonic sloshing of the cold-air pool that forms at the bottom of the <span class="hlt">crater</span> due to radiative cooling at night. We present time series, spectra, and spectrograms of temperature, wind and pressure fluctuations that characterize those air seiches. Typical seiche periods were 15 min. We compare the observations with the time-harmonic solutions of the shallow-water equation and with numerical simulations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.usgs.gov/of/1984/0114/report.pdf','USGSPUBS'); return false;" href="https://pubs.usgs.gov/of/1984/0114/report.pdf"><span>Stratigraphic and volcano-tectonic relations of <span class="hlt">Crater</span> Flat Tuff and some older volcanic units, Nye County, Nevada</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Carr, W.J.; Byers, F.M.; Orkild, Paul P.</p> <p>1984-01-01</p> <p>The <span class="hlt">Crater</span> Flat Tuff is herein revised to include a newly recognized lowest unit, the Tram Member, exposed at scattered localities in the southwest Nevada Test Site region, and in several drill holes in the Yucca Mountain area. The overlying Bullfrog and Prow Pass Members are well exposed at the type locality of the formation near the southeast edge of <span class="hlt">Crater</span> Flat, just north of <span class="hlt">U</span>.S. Highway 95. In previous work, the Tram Member was thought to be the Bullfrog Member, and therefore was shown as Bullfrog or as undifferentiated <span class="hlt">Crater</span> Flat Tuff on published maps. The revised <span class="hlt">Crater</span> Flat Tuff is stratigraphically below the Topopah Spring Member of the Paintbrush Tuff and above the Grouse Canyon Member of the Belted Range Tuff, and is approximately 13.6 m.y. old. Drill holes on Yucca Mountain and near Fortymile Wash penetrate all three members of the <span class="hlt">Crater</span> Flat as well as an underlying quartz-poor unit, which is herein defined as the Lithic Ridge Tuff from exposures on Lithic Ridge near the head of Topopah Wash. In outcrops between Calico Hills and Yucca Flat, the Lithic Ridge Tuff overlies a Bullfrog-like unit of reverse magnetic polarity that probably correlates with a widespread unit around and under Yucca Flat, referred to previously as <span class="hlt">Crater</span> Flat Tuff. This unit is here informally designated as the tuff of Yucca Flat. Although older, it may be genetically related to the <span class="hlt">Crater</span> Flat Tuff. Although the rocks are poorly exposed, geophysical and geologic evidence to date suggests that (1) the source of the <span class="hlt">Crater</span> Flat Tuff is a caldera complex in the <span class="hlt">Crater</span> Flat area between Yucca Mountain and Bare Mountain, and (<span class="hlt">2</span>) there are at least two cauldrons within this complex--one probably associated with eruption of the Tram, the other with the Bullfrog and Prow Pass Members. The complex is named the <span class="hlt">Crater</span> Flat-Prospector Pass caldera complex. The northern part of the Yucca Mountain area is suggested as the general location of the source of pre-<span class="hlt">Crater</span> Flat tuffs, but a</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFM.P51B2582K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFM.P51B2582K"><span>The Effects of Terrain Properties on Determining <span class="hlt">Crater</span> Model Ages of Lunar Surfaces</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kirchoff, M. R.; Marchi, S.</p> <p>2017-12-01</p> <p>Analyzing <span class="hlt">crater</span> size-frequency distributions (SFDs) and using them to determine model ages of surfaces is an important technique for understanding the Moon's geologic history and evolution. Small <span class="hlt">craters</span> with diameters (D) < 1 km are frequently used, especially given the very high resolution imaging now available from Lunar Reconnaissance Orbiter Narrow and Wide Angle Cameras (LROC-NAC/WAC) and the Selene Terrain Camera. However, for these diameters, final <span class="hlt">crater</span> sizes and shapes are affected by the properties of the terrains on which they are formed [1], which alters <span class="hlt">crater</span> SFD shapes [<span class="hlt">2</span>]. We use the Model Production Function (MPF; [<span class="hlt">2</span>]), which includes terrain properties in computing <span class="hlt">crater</span> production functions, to explore how incorporating terrain properties affects the estimation of <span class="hlt">crater</span> model ages. First, <span class="hlt">crater</span> SFDs are compiled utilizing LROC-WAC/NAC images to measure <span class="hlt">craters</span> with diameters from 10 m up to 20 km (size of largest <span class="hlt">crater</span> measured depends on the terrain). A nested technique is used to obtain this wide diameter range: D ≥ 0.5 km <span class="hlt">craters</span> are measured in the largest area, D = 0.09-0.5 km <span class="hlt">craters</span> are measured in a smaller area within the largest area, and D = 0.01-0.1 km <span class="hlt">craters</span> are measured in the smallest area located in both of the larger areas. Then, we quantitatively fit the <span class="hlt">crater</span> SFD with distinct MPFs that use broadly different terrain properties. Terrain properties are varied through coarsely altering the parameters in the <span class="hlt">crater</span> scaling law [1] that represent material type (consolidated, unconsolidated, porous), material tensile strength, and material density (for further details see [<span class="hlt">2</span>]). We also discuss the effect of changing terrain properties with depth (i.e., layering). Finally, fits are used to compute the D = 1 km <span class="hlt">crater</span> model ages for the terrains. We discuss the new constraints on how terrain properties affect <span class="hlt">crater</span> model ages from our analyses of a variety of lunar terrains from highlands to mare and impact melt to</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19910013683','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19910013683"><span>Martian <span class="hlt">crater</span> counts on Elysium Mons</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Mcbride, Kathleen; Barlow, Nadine G.</p> <p>1990-01-01</p> <p>Without returned samples from the Martian surface, relative age chronologies and stratigraphic relationships provide the best information for determining the ages of geomorphic features and surface regions. <span class="hlt">Crater</span>-size frequency distributions of six recently mapped geological units of Elysium Mons were measured to establish their relative ages. Most of the <span class="hlt">craters</span> on Elysium Mons and the adjacent plains units are between 500 and 1000 meters in diameter. However, only <span class="hlt">craters</span> 1 km in diameter or larger were used because of inadequate spatial resolution of some of the Viking images and to reduce probability of counting secondary <span class="hlt">craters</span>. The six geologic units include all of the Elysium Mons construct and a portion of the plains units west of the volcano. The surface area of the units studied is approximately 128,000 sq km. Four of the geologic units were used to create <span class="hlt">crater</span> distribution curves. There are no <span class="hlt">craters</span> larger than 1 km within the Elysium Mons caldera. <span class="hlt">Craters</span> that lacked raised rims, were irregularly shaped, or were arranged in a linear pattern were assumed to be endogenic in origin and not counted. A <span class="hlt">crater</span> frequency distribution analysis is presented.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=PIA01402&hterms=spiders&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dspiders','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=PIA01402&hterms=spiders&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dspiders"><span>Mannann'an <span class="hlt">Crater</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>1998-01-01</p> <p>This composite view taken by NASA's Galileo spacecraft shows the rim and interior of the impact <span class="hlt">crater</span>, Mannann'an, on Jupiter's moon, Europa. A high resolution image (20 meters per picture element) was combined with lower resolution (80 meters per picture element) color images taken through violet, green and near-infrared filters, to produce this synthetic color composite image. The color data can be used to distinguish between regions of purer (clean) and more contaminated (dirty) ice on the surface, and also offers information on the size of the ice grains. The reddish brown material is thought to be dirty ice, while the bluish areas inside the <span class="hlt">crater</span> are purer ice. The <span class="hlt">crater</span> rim is on the left at the boundary between the reddish brown material and the gray material.<p/>The high resolution data show small features inside the <span class="hlt">crater</span>, including concentric fractures and a spider-like set of fractures near the right (east) edge of the image. For a more regional perspective, the Mannann'an <span class="hlt">crater</span> can be seen as a large circular feature with bright rays in the lower left corner of a regional image from Galileo's first orbit of Jupiter in June 1996.<p/>North is to the top of the picture and the Sun illuminates the scene from the east (right). The image, centered at 3 degrees north latitude and 240 degrees west longitude, covers an area approximately 18 by 4 kilometers (11 by <span class="hlt">2</span>.5 miles). The finest details that can be discerned in this picture are about 40 meters (44 yards) across. The images were taken by the spacecraft's onboard solid state imaging camera when Galileo flew by Europa on March 29th, 1998 at a distance of 1,934 kilometers (1,200 miles).<p/>The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC. JPL is an operating division of California Institute of Technology (Caltech).<p/>This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20100017206','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20100017206"><span>Topography of the Martian Impact <span class="hlt">Crater</span> Tooting</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Mouginis-Mark, P. J.; Garbeil, H.; Boyce, J. M.</p> <p>2009-01-01</p> <p>Tooting <span class="hlt">crater</span> is approx.29 km in diameter, is located at 23.4degN, 207.5degE, and is classified as a multi-layered ejecta <span class="hlt">crater</span> [1]. Our mapping last year identified several challenges that can now be addressed with HiRISE and CTX images, but specifically the third dimension of units. To address the distribution of ponded sediments, lobate flows, and volatile-bearing units within the <span class="hlt">crater</span> cavity, we have focused this year on creating digital elevation models (DEMs) for the <span class="hlt">crater</span> and ejecta blanket from stereo CTX and HiRISE images. These DEMs have a spatial resolution of approx.50 m for CTX data, and <span class="hlt">2</span> m for HiRISE data. Each DEM is referenced to all of the available individual MOLA data points within an image, which number approx.5,000 and 800 respectively for the two data types</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20140010577','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20140010577"><span>Pu'<span class="hlt">u</span> Poli'ahu, Mauna Kea: A Possible Analog for the Hematite Bearing Layer Located in Gale <span class="hlt">Crater</span>, Mars.</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Adams, M. E.</p> <p>2014-01-01</p> <p>Hyperspectral data detected by the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) on board Mars Reconnaissance Orbiter (MRO) indicated the presence of a hematite bearing ridge on Mount Sharp situated in the Gale <span class="hlt">Crater</span>, Mars. [Fraeman]. The presence of this mineral in high concentrations is indicative of possible aqueous origins. [Fraeman] In 2012, Curiosity Rover landed in Gale <span class="hlt">Crater</span> on Mars. Curiosity's mission is to determine Mars' habitability and is equipped with an advanced suite of scientific instruments that are capable of conducting analyses on rocks and soil. The hematite bearing ridge on Mount Sharp is thought to be a good candidate of study for Curiosity. To better understand this type of terrain, the study of analog sites similar in geologic setting is of great importance. One site thought to be a comparable analog is a cinder cone called Pu'<span class="hlt">u</span> Poli'ahu located on the summit of Mauna Kea, Hawai?i. Poli'ahu is unique among the tephra cones of Mauna Kea because it is thought to have formed in subaqueous conditions approximately 170,000 to 175,000 years ago. [Porter] Consequently located on the inner flanks of Poli'ahu is a rock outcrop that contains hematite. Samples were collected from the outcrop and characterized using the following instruments: Digital Microscope, Panalytical X-ray diffraction (XRD), and scanning electron microscope (SEM). The initial preparation of the rocks involved documenting each sample by creating powdered samples, thick sections, and photo documentation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016HydJ...24..649C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016HydJ...24..649C"><span>Land <span class="hlt">subsidence</span> and earth fissures in south-central and southern Arizona, USA</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Conway, Brian D.</p> <p>2016-05-01</p> <p>Land <span class="hlt">subsidence</span> due to groundwater overdraft has been an ongoing problem in south-central and southern Arizona (USA) since the 1940s. The first earth fissure attributed to excessive groundwater withdrawal was discovered in the early 1950s near Picacho. In some areas of the state, groundwater-level declines of more than 150 m have resulted in extensive land <span class="hlt">subsidence</span> and earth fissuring. Land <span class="hlt">subsidence</span> in excess of 5.7 m has been documented in both western metropolitan Phoenix and Eloy. The Arizona Department of Water Resources (ADWR) has been monitoring land <span class="hlt">subsidence</span> since 2002 using interferometric synthetic aperture radar (InSAR) and since 1998 using a global navigation satellite system (GNSS). The ADWR InSAR program has identified more than 25 individual land <span class="hlt">subsidence</span> features that cover an area of more than 7,300 km<span class="hlt">2</span>. Using InSAR data in conjunction with groundwater-level datasets, ADWR is able to monitor land <span class="hlt">subsidence</span> areas as well as identify areas that may require additional monitoring. One area of particular concern is the Willcox groundwater basin in southeastern Arizona, which is the focus of this paper. The area is experiencing rapid groundwater declines, as much as 32.1 m during 2005-2014 (the largest land <span class="hlt">subsidence</span> rate in Arizona State—up to 12 cm/year), and a large number of earth fissures. The declining groundwater levels in Arizona are a challenge for both future groundwater availability and mitigating land <span class="hlt">subsidence</span> associated with these declines. ADWR's InSAR program will continue to be a critical tool for monitoring land <span class="hlt">subsidence</span> due to excessive groundwater withdrawal.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li class="active"><span>21</span></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_21 --> <div id="page_22" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li class="active"><span>22</span></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="421"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://connection.ebscohost.com/c/articles/9710051096/secrets-wabar-craters','USGSPUBS'); return false;" href="http://connection.ebscohost.com/c/articles/9710051096/secrets-wabar-craters"><span>Secrets of the Wabar <span class="hlt">craters</span></span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Wynn, Jeffrey C.; Shoemaker, Eugene M.</p> <p>1997-01-01</p> <p>Focuses on the existence of <span class="hlt">craters</span> in the Empty Quarter of Saudi Arabia created by the impact of meteors in early times. Mars Pathfinder and Mars Global Surveyor's encounter with impact <span class="hlt">craters</span>; Elimination of <span class="hlt">craters</span> in the Earth's surface by the action of natural elements; Impact sites' demand for careful scientific inspections; Location of the impact sites.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFM.P11A2500F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFM.P11A2500F"><span>The curious history of Tethys as evidenced by irregular <span class="hlt">craters</span> and variable tectonism</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ferguson, S. N.; Rhoden, A.; Nayak, M.; Asphaug, E. I.</p> <p>2017-12-01</p> <p>At first glance, the surface of Saturn's moon Tethys appears dominated by <span class="hlt">craters</span> and its large canyon system, Ithaca Chasma. However, high-resolution Cassini imagery reveals a surface rife with curious geologic features, perhaps indicative of non-heliocentric impact populations and, potentially, a history of tectonic activity. We mapped three regions on Tethys to survey the diversity of features present on the surface, determine <span class="hlt">crater</span> counts for each region, map and analyze fracture patterns, and identify constraints on the impactor populations. One study region is just south and west of the Odysseus impact basin (R1), and the other two regions sit slightly west of Ithaca Chasma (R<span class="hlt">2</span> and R3). The regions were imaged at average resolutions of 200m/pix, which is adequate to identify <span class="hlt">craters</span> down to D=1km. Of 1200 total <span class="hlt">craters</span> counted, we have identified 195 elliptical <span class="hlt">craters</span> and 28 polygonal <span class="hlt">craters</span>. Elliptical <span class="hlt">craters</span> likely form from slow, oblique impacts, whereas polygonal <span class="hlt">craters</span> are indicative of underlying tectonic structure. We identified 605 small <span class="hlt">craters</span>, D=1-<span class="hlt">2</span>km, across the three regions; we find that R1 has many more 1-10 km <span class="hlt">craters</span> than R<span class="hlt">2</span> and R3. We also mapped 367 linear features. The median and range of orientations of the linear features vary across the regions. Despite their proximity, the orientations of lineations in R<span class="hlt">2</span> and R3 are not consistent with the orientation of Ithaca Chasma. This could be suggestive of different epochs of tectonic activity on Tethys. When compared with R<span class="hlt">2</span> and R3, R1 has more small <span class="hlt">craters</span>, more lineations, and a preferred orientation of lineations that is distinct from the other two regions. Possible causes for a larger population of small <span class="hlt">craters</span> in R1 include secondary <span class="hlt">craters</span> from Odysseus and oblique impacts from debris ejected from Tethys' co-orbital moons, which should create many more 1km <span class="hlt">craters</span> in R1 than the other regions. Due to the oblique impact angles predicted for incoming co-orbital debris, these impacts</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19940023803','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19940023803"><span>Some implications of large impact <span class="hlt">craters</span> and basins on Venus for terrestrial ringed <span class="hlt">craters</span> and planetary evolution</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Mckinnon, W. B.; Alexopoulos, J. S.</p> <p>1994-01-01</p> <p>Approximately 950 impact <span class="hlt">craters</span> have been identified on the surface of Venus, mainly in Magellan radar images. From a combination of Earth-based Arecibo, Venera 15/1, and Magellan radar images, we have interpreted 72 as unequivocal peak-ring <span class="hlt">craters</span> and four as multiringed basins. The morphological and structural preservation of these <span class="hlt">craters</span> is high owing to the low level of geologic activity on the venusian surface (which is in some ways similar to the terrestrial benthic environment). Thus these <span class="hlt">craters</span> should prove crucial to understanding the mechanics of ringed <span class="hlt">crater</span> formation. They are also the most direct analogs for <span class="hlt">craters</span> formed on the Earth in Phanerozoic time, such as Chicxulub. We summarize our findings to date concerning these structures.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFM.P53A2166R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFM.P53A2166R"><span>On the usefulness of optical maturity for relative age classification of fresh <span class="hlt">craters</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ravi, S.; Meyer, H. M.; Mahanti, P.; Robinson, M. S.</p> <p>2016-12-01</p> <p>Copernican and Eratosthenian <span class="hlt">craters</span> represent the two most recent geologic periods in the lunar timescale, and their characterization is essential for understanding impact <span class="hlt">crater</span> flux over the last 3 Gy. <span class="hlt">Craters</span> from both periods exhibit crisp morphologies, but Copernican <span class="hlt">craters</span> are 'rayed <span class="hlt">craters</span>' per Wilhelms (1) classification scheme. Distinguishing compositional from maturity rays is possible using compositional estimates and the optical maturity parameter (OMAT; <span class="hlt">2</span>). From OMAT estimates, Grier et al. (3) classified 50 fresh <span class="hlt">craters</span> (diameter (D) > 20 km) into young (OMAT > 0.22), intermediate, and old (OMAT < 0.16) classes. In this work we analyze morphology and optical maturity for a population of 12,000 <span class="hlt">craters</span> (D> 10 km; 60 to investigate the applicability of OMAT for relative age classification among Copernican <span class="hlt">craters</span>. <span class="hlt">Craters</span> obtained from (4,5) were initially classified based on crispness of morphology (LROC WAC observations (6)) and then were then analyzed based on OMAT values averaged from rim out to one <span class="hlt">crater</span> radius (n=2000). We found that typically <span class="hlt">craters</span> larger than Copernicus (D = 95 km) were had lower OMAT values than Copernicus (OMAT = 0.17) except for Vavilov, Pythagorus, Fizeau and Moretus which had OMAT > 0.17. These large <span class="hlt">craters</span> are clearly affected by rays from small, nearby <span class="hlt">craters</span>. We estimate that at least 250 <span class="hlt">craters</span> (D > 10 km; OMAT > 0.22) on the Moon are Copernican (> <span class="hlt">2</span>% of all <span class="hlt">craters</span> analyzed) and of these at least 100 are as optically immature (or more so) than Tycho <span class="hlt">crater</span> (OMAT >= 0.24). A calibration curve (OMAT vs Absolute Model Age) obtained for <span class="hlt">craters</span> with known ages showed that OMAT <=0.15 displays little change with AMA and are thus unsuitable for estimating relative ages. Normalization by <span class="hlt">crater</span> size was found to reduce the uncertainty associated with the relation between AMA and OMAT. 1) Wilhelms (1987), The Geologic History of the Moon, USGS, pp. 1348. <span class="hlt">2</span>) Lucey et al (2000), JGR, 105, 20377-20386. 3) Grier et al</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFMNH32A..08S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFMNH32A..08S"><span>Differential <span class="hlt">subsidence</span> in Mexico City and implications to its Collective Transport System (Metro).</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Solano Rojas, D. E.; Wdowinski, S.; Cabral-Cano, E.; Osmanoglu, B.</p> <p>2017-12-01</p> <p>Mexico City is one of the fastest <span class="hlt">subsiding</span> metropolis in the world. At displacement rates ranging from 0 to -380 [mm/yr], the complex geological setting is subjected to differential <span class="hlt">subsidence</span>, which has led to damage, operation interruptions, and accidents to the Collective Transport System, or Metro. The Metro plays a critical role in Mexico City, carrying more than four million passengers per day. However, no previous study has focused on the deformation monitoring along the 93 km of the Metro surface railways, mainly because of the limitations of the traditional geodetic techniques. In this study, we use high-resolution Interferometric Synthetic Aperture Radar (InSAR) observations to monitor land <span class="hlt">subsidence</span> throughout the city and quantify differential <span class="hlt">subsidence</span> along surface Metro lines. Our analysis is based on 34 TerraSAR-X StripMap scenes acquired from May 2011 to June 2013 and 36 COSMO-SkyMed Stripmap scenes acquired from June 2011 to June 2012. The data were processed using the StaMPS InSAR time series technique, obtaining point densities of up to 4827 points/km<span class="hlt">2</span>. Our post-processing methodologies include the following two components: (1) Detection of differential <span class="hlt">subsidence</span> along the metro lines by calculating <span class="hlt">subsidence</span> gradients, and (<span class="hlt">2</span>) Detection of apparent uplift—areas <span class="hlt">subsiding</span> slower than their surroundings—by using spatial frequency filtering. The two analyses allow us to recognize four main consequences of differential <span class="hlt">subsidence</span> in the Metro system: 1. Deflection in elevated railways, <span class="hlt">2</span>. Deflection in street-level railways, 3. Columns with decreased loading capacity, and 4. Apparent uplift affecting surrounding infrastructure. Our results aim at shortening the large gap between scientific geodetic studies and applicable engineering parameters that can be used by local authorities in the city for maintenance and new lines development.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=PIA03469&hterms=falling+meteors&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dfalling%2Bmeteors','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=PIA03469&hterms=falling+meteors&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dfalling%2Bmeteors"><span>Fresh Impact <span class="hlt">Crater</span> and Rays in Tharsis</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>2002-01-01</p> <p>The Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) Extended Mission has included dozens of opportunities to point the spacecraft directly at features of interest so that pictures of things not seen during the earlier Mapping Mission can be obtained. The example shown here is a small meteorite impact <span class="hlt">crater</span> in northern Tharsis near 17.<span class="hlt">2</span>oN, 113.8oW. Viking Orbiter images from the late 1970's showed at this location what appeared to be a dark patch with dark rays emanating from a brighter center. The MOC team surmised that the dark rays may be indicating the location of afresh <span class="hlt">crater</span> formed by impact sometime in the past few centuries (since dark ray are quickly covered by dust falling out of the martian atmosphere). All through MOC's Mapping Mission in 1999 and 2000, attempts were made to image the <span class="hlt">crater</span> as predictions indicated that the spacecraft would pass over the site, but the <span class="hlt">crater</span> was never seen. Finally, in June 2001, Extended Mission operations allowed the MOC team to point the spacecraft (and hence the camera, which is fixed to the spacecraft)directly at the center of the dark rays, where we expected to find the <span class="hlt">crater</span>.<p/>The picture on the left (above, A) is a mosaic of three MOC high resolution images and one much lower-resolution Viking image. From left to right, the images used in the mosaic are: Viking 1 516A55, MOC E05-01904, MOCM21-00272, and MOC M08-03697. Image E05-01904 is the one taken in June 2001 by pointing the spacecraft. It captured the impact <span class="hlt">crater</span> responsible for the rays. A close-up of the <span class="hlt">crater</span>, which is only 130 meters (427 ft)across, is shown on the right (above, B). This <span class="hlt">crater</span> is only one-tenth the size of the famous Meteor <span class="hlt">Crater</span> in northern Arizona.<p/>The June 2001 MOC image reveals many surprises about this feature. For one, the <span class="hlt">crater</span> is not located at the center of the bright area from which the dark rays radiate. The rays point to the center of this bright area, not the <span class="hlt">crater</span>. Further, the dark material ejected</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.water.usgs.gov/ofr03-308/','USGSPUBS'); return false;" href="http://pubs.water.usgs.gov/ofr03-308/"><span><span class="hlt">U</span>.S. Geological Survey <span class="hlt">Subsidence</span> Interest Group Conference : proceedings of the Technical Meeting, Galveston, Texas, November 27-29, 2001</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Prince, Keith R.; Galloway, Devin L.</p> <p>2003-01-01</p> <p>InSAR is a powerful technique that uses radar data acquired at different times to measure land-surface deformation, or displacement, over large areas at a high level of spatial detail and a high degree of measurement resolution. InSAR displacement maps (interferograms), in conjunction with other hydrogeologic data, have been used to determine aquifer-system characteristics for areas where surface deformation is the result of stress induced changes in the granular skeleton of the aquifer system. Interferograms and measurements of aquifer-system compaction from borehole extensometers, and ground-water levels in wells in Santa Clara Valley, California, have shown that land-surface changes caused by aquifer-system deformation for September 23, 1992-August <span class="hlt">2</span>, 1997, are elastic (reversible): During the summer when water levels are declining, the land surface <span class="hlt">subsides</span>, and during the winter when water levels are recovering, the land surface uplifts, resulting in no net surface deformation. Interferograms used with fault maps of Santa Clara Valley and of Las Vegas Valley, Nevada, have shown that the extent of regional land-surface changes caused by aquifer-system deformation may be partially controlled by faults. Interferograms of Yucca Flat, Nevada, show <span class="hlt">subsidence</span> associated with the recovery of elevated hydraulic heads caused by underground weapons testing at depths of more than 600 meters. For these selected case studies, continuing or renewed deformation of the aquifer system is coupled with pore-fluid-pressure changes. When applied stresses (water-level changes) can be measured accurately for periods that the interferograms show displacement, stress-strain relations, and thus bulk storage properties, can be evaluated. For areas where additional ground-water-level, land-surface-elevation, aquifer-system-compaction, or other environmental data are needed, the interferograms can be used as a guide for designing appropriate monitoring networks. Aquifer-system properties</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20170001959','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20170001959"><span>Investigating Evolved Compositions Around Wolf <span class="hlt">Crater</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Greenhagen, B. T.; Cahill, J. T. S.; Jolliff, B. L.; Lawrence, S. J.; Glotch, T. D.</p> <p>2017-01-01</p> <p>Wolf <span class="hlt">crater</span> is an irregularly shaped, approximately 25 km <span class="hlt">crater</span> in the south-central portion of Mare Nubium on the lunar nearside. While not previously identified as a lunar "red spot", Wolf <span class="hlt">crater</span> was identified as a Th anomaly by Lawrence and coworkers. We have used data from the Lunar Reconnaissance Orbiter (LRO) to determine the area surrounding Wolf <span class="hlt">crater</span> has composition more similar to highly evolved, non-mare volcanic structures than typical lunar crustal lithology. In this presentation, we will investigate the geomorphology and composition of the Wolf <span class="hlt">crater</span> and discuss implications for the origin of the anomalous terrain.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://images.nasa.gov/#/details-PIA02937.html','SCIGOVIMAGE-NASA'); return false;" href="https://images.nasa.gov/#/details-PIA02937.html"><span>Heavily <span class="hlt">Cratered</span> Terrain at South Pole</span></a></p> <p><a target="_blank" href="https://images.nasa.gov/">NASA Image and Video Library</a></p> <p></p> <p>2000-08-05</p> <p>NASA Mariner 10 photo reveals a heavily <span class="hlt">cratered</span> terrain on Mercury with a prominent scrap extending several hundred kilometers across the upper left. A <span class="hlt">crater</span>, nested in a larger <span class="hlt">crater</span>, is at top center.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70016303','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70016303"><span>Recent crustal <span class="hlt">subsidence</span> at Yellowstone Caldera, Wyoming</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Dzurisin, D.; Savage, J.C.; Fournier, R.O.</p> <p>1990-01-01</p> <p>Following a period of net uplift at an average rate of 15??1 mm/year from 1923 to 1984, the east-central floor of Yellowstone Caldera stopped rising during 1984-1985 and then <span class="hlt">subsided</span> 25??7 mm during 1985-1986 and an additional 35??7 mm during 1986-1987. The average horizontal strain rates in the northeast part of the caldera for the period from 1984 to 1987 were: {Mathematical expression}1 = 0.10 ?? 0.09 ??strain/year oriented N33?? E??9?? and {Mathematical expression}<span class="hlt">2</span> = 0.20 ?? 0.09 ??strain/year oriented N57?? W??9?? (extension reckoned positive). A best-fit elastic model of the 1985-1987 vertical and horizontal displacements in the eastern part of the caldera suggests deflation of a horizontal tabular body located 10??5 km beneath Le Hardys Rapids, i.e., within a deep hydrothermal system or within an underlying body of partly molten rhyolite. Two end-member models each explain most aspects of historical unrest at Yellowstone, including the recent reversal from uplift to <span class="hlt">subsidence</span>. Both involve crystallization of an amount of rhyolitic magma that is compatible with the thermal energy requirements of Yellowstone's vigorous hydrothermal system. In the first model, injection of basalt near the base of the rhyolitic system is the primary cause of uplift. Higher in the magmatic system, rhyolite crystallizes and releases all of its magmatic volatiles into the shallow hydrothermal system. Uplift stops and <span class="hlt">subsidence</span> starts whenever the supply rate of basalt is less than the <span class="hlt">subsidence</span> rate produced by crystallization of rhyolite and associated fluid loss. In the second model, uplift is caused primarily by pressurization of the deep hydrothermal system by magmatic gas and brine that are released during crystallization of rhyolite and them trapped at lithostatic pressure beneath an impermeable self-sealed zone. <span class="hlt">Subsidence</span> occurs during episodic hydrofracturing and injection of pore fluid from the deep lithostatic-pressure zone into a shallow hydrostatic-pressure zone</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014DPS....4641310H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014DPS....4641310H"><span>Modeling the Provenance of <span class="hlt">Crater</span> Ejecta</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Huang, Ya-Huei; Minton, David A.</p> <p>2014-11-01</p> <p>The <span class="hlt">cratering</span> history of the Moon provides a way to study the violent early history of our early solar system. Nevertheless, we are still limited in our ability to interpret the lunar <span class="hlt">cratering</span> history because the complex process of generation and subsequent transportation and destruction of impact melt products is relatively poorly understood. Here we describe a preliminary model for the transport of datable impact melt products by <span class="hlt">craters</span> over Gy timescales on the lunar surface. We use a numerical model based on the Maxwell Z-model to model the exhumation and transport of ejecta material from within the excavation flow of a transient <span class="hlt">crater</span>. We describe our algorithm for rapidly estimating the provenance of ejecta material for use in a Monte Carlo <span class="hlt">cratering</span> code capable of simulating lunar <span class="hlt">cratering</span> over Gy timescales.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=PIA01541&hterms=copernicus&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dcopernicus','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=PIA01541&hterms=copernicus&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dcopernicus"><span><span class="hlt">Crater</span> Copernicus</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>1999-01-01</p> <p>HUBBLE SHOOTS THE MOON in a change of venue from peering at the distant universe, NASA's Hubble Space Telescope has taken a look at Earth's closest neighbor in space, the Moon. Hubble was aimed at one of the Moon's most dramatic and photogenic targets, the 58 mile-wide (93 km) impact <span class="hlt">crater</span> Copernicus. The image was taken while the Space Telescope Imaging Spectrograph(STIS) was aimed at a different part of the moon to measure the colors of sunlight reflected off the Moon. Hubble cannot look at the Sun directly and so must use reflected light to make measurements of the Sun's spectrum. Once calibrated by measuring the Sun's spectrum, the STIS can be used to study how the planets both absorb and reflect sunlight.(upper left)The Moon is so close to Earth that Hubble would need to take a mosaic of 130 pictures to cover the entire disk. This ground-based picture from Lick Observatory shows the area covered in Hubble's photomosaic with the WideField Planetary Camera <span class="hlt">2</span>..(center)Hubble's crisp bird's-eye view clearly shows the ray pattern of bright dust ejected out of the <span class="hlt">crater</span> over one billion years ago, when an asteroid larger than a mile across slammed into the Moon. Hubble can resolve features as small as 600 feet across in the terraced walls of the <span class="hlt">crater</span>, and the hummock-like blanket of material blasted out by the meteor impact.(lower right)A close-up view of Copernicus' terraced walls. Hubble can resolve features as small as 280 feet across.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=PIA01157&hterms=industrial+age&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dindustrial%2Bage','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=PIA01157&hterms=industrial+age&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dindustrial%2Bage"><span>Schiaparelli <span class="hlt">Crater</span> Rim and Interior Deposits</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>1998-01-01</p> <p>A portion of the rim and interior of the large impact <span class="hlt">crater</span> Schiaparelli is seen at different resolutions in images acquired October 18, 1997 by the Mars Global Surveyor Orbiter Camera (MOC) and by the Viking Orbiter 1 twenty years earlier. The left image is a MOC wide angle camera 'context' image showing much of the eastern portion of the <span class="hlt">crater</span> at roughly 1 km (0.6 mi) per picture element. The image is about 390 by 730 km (240 X 450 miles). Shown within the wide angle image is the outline of a portion of the best Viking image (center, 371S53), acquired at a resolution of about 240 m/pixel (790 feet). The area covered is 144 X 144 km (89 X 89 miles). The right image is the high resolution narrow angle camera view. The area covered is very small--3.9 X 10.<span class="hlt">2</span> km (<span class="hlt">2</span>.4 X 6.33 mi)--but is seen at 63 times higher resolution than the Viking image. The subdued relief and bright surface are attributed to blanketing by dust; many small <span class="hlt">craters</span> have been completely filled in, and only the most recent (and very small) <span class="hlt">craters</span> appear sharp and bowl-shaped. Some of the small <span class="hlt">craters</span> are only 10-12 m (30-35 feet) across. Occasional dark streaks on steeper slopes are small debris slides that have probably occurred in the past few decades. The two prominent, narrow ridges in the center of the image may be related to the adjustment of the <span class="hlt">crater</span> floor to age or the weight of the material filling the basin.<p/>Malin Space Science Systems (MSSS) and the California Institute of Technology built the MOC using spare hardware from the Mars Observer mission. MSSS operates the camera from its facilities in San Diego, CA. The Jet Propulsion Laboratory's Mars Surveyor Operations Project operates the Mars Global Surveyor spacecraft with its industrial partner, Lockheed Martin Astronautics, from facilities in Pasadena, CA and Denver, CO.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://images.nasa.gov/#/details-PIA04410.html','SCIGOVIMAGE-NASA'); return false;" href="https://images.nasa.gov/#/details-PIA04410.html"><span><span class="hlt">Crater</span> Wall and Floor</span></a></p> <p><a target="_blank" href="https://images.nasa.gov/">NASA Image and Video Library</a></p> <p></p> <p>2003-02-18</p> <p>The impact <span class="hlt">crater</span> observed in this NASA Mars Odyssey image taken in Terra Cimmeria suggests sediments have filled the <span class="hlt">crater</span> due to the flat and smooth nature of the floor compared to rougher surfaces at higher elevations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018Icar..306..214S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018Icar..306..214S"><span>Relaxed impact <span class="hlt">craters</span> on Ganymede: Regional variation and high heat flows</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Singer, Kelsi N.; Bland, Michael T.; Schenk, Paul M.; McKinnon, William B.</p> <p>2018-05-01</p> <p>Viscously relaxed <span class="hlt">craters</span> provide a window into the thermal history of Ganymede, a satellite with copious geologic signs of past high heat flows. Here we present measurements of relaxed <span class="hlt">craters</span> in four regions for which suitable imaging exists: near Anshar Sulcus, Tiamat Sulcus, northern Marius Regio, and Ganymede's south pole. We describe a technique to measure apparent depth, or depth of the <span class="hlt">crater</span> with respect to the surrounding terrain elevation. Measured relaxation states are compared with results from finite element modeling to constrain heat flow scenarios [see companion paper: Bland et al. (2017)]. The presence of numerous, substantially relaxed <span class="hlt">craters</span> indicates high heat flows-in excess of 30-40 mW m-<span class="hlt">2</span> over <span class="hlt">2</span> Gyr, with many small (<10 km in diameter) relaxed <span class="hlt">craters</span> indicating even higher heat flows. <span class="hlt">Crater</span> relaxation states are bimodal for some equatorial regions but not in the region studied near the south pole, which suggests regional variations in Ganymede's thermal history.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70196308','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70196308"><span>Relaxed impact <span class="hlt">craters</span> on Ganymede: Regional variation and high heat flows</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Singer, Kelsi N.; Bland, Michael T.; Schenk, Paul M.; McKinnon, William B.</p> <p>2018-01-01</p> <p>Viscously relaxed <span class="hlt">craters</span> provide a window into the thermal history of Ganymede, a satellite with copious geologic signs of past high heat flows. Here we present measurements of relaxed <span class="hlt">craters</span> in four regions for which suitable imaging exists: near Anshar Sulcus, Tiamat Sulcus, northern Marius Regio, and Ganymede's south pole. We describe a technique to measure apparent depth, or depth of the <span class="hlt">crater</span> with respect to the surrounding terrain elevation. Measured relaxation states are compared with results from finite element modeling to constrain heat flow scenarios [see companion paper: Bland et al. (2017)]. The presence of numerous, substantially relaxed <span class="hlt">craters</span> indicates high heat flows—in excess of 30–40 mW m−<span class="hlt">2</span> over <span class="hlt">2</span> Gyr, with many small (<10 km in diameter) relaxed <span class="hlt">craters</span> indicating even higher heat flows. <span class="hlt">Crater</span> relaxation states are bimodal for some equatorial regions but not in the region studied near the south pole, which suggests regional variations in Ganymede's thermal history.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/16738651','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/16738651"><span>Space geodesy: <span class="hlt">subsidence</span> and flooding in New Orleans.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Dixon, Timothy H; Amelung, Falk; Ferretti, Alessandro; Novali, Fabrizio; Rocca, Fabio; Dokka, Roy; Sella, Giovanni; Kim, Sang-Wan; Wdowinski, Shimon; Whitman, Dean</p> <p>2006-06-01</p> <p>It has long been recognized that New Orleans is <span class="hlt">subsiding</span> and is therefore susceptible to catastrophic flooding. Here we present a new <span class="hlt">subsidence</span> map for the city, generated from space-based synthetic-aperture radar measurements, which reveals that parts of New Orleans underwent rapid <span class="hlt">subsidence</span> in the three years before Hurricane Katrina struck in August 2005. One such area is next to the Mississippi River-Gulf Outlet (MRGO) canal, where levees failed during the peak storm surge: the map indicates that this weakness could be explained by <span class="hlt">subsidence</span> of a metre or more since their construction.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014M%26PS...49.2175F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014M%26PS...49.2175F"><span>Shock metamorphism and impact melting in small impact <span class="hlt">craters</span> on Earth: Evidence from Kamil <span class="hlt">crater</span>, Egypt</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Fazio, Agnese; Folco, Luigi; D'Orazio, Massimo; Frezzotti, Maria Luce; Cordier, Carole</p> <p>2014-12-01</p> <p>Kamil is a 45 m diameter impact <span class="hlt">crater</span> identified in 2008 in southern Egypt. It was generated by the hypervelocity impact of the Gebel Kamil iron meteorite on a sedimentary target, namely layered sandstones with subhorizontal bedding. We have carried out a petrographic study of samples from the <span class="hlt">crater</span> wall and ejecta deposits collected during our first geophysical campaign (February 2010) in order to investigate shock effects recorded in these rocks. Ejecta samples reveal a wide range of shock features common in quartz-rich target rocks. They have been divided into two categories, as a function of their abundance at thin section scale: (1) pervasive shock features (the most abundant), including fracturing, planar deformation features, and impact melt lapilli and bombs, and (<span class="hlt">2</span>) localized shock features (the least abundant) including high-pressure phases and localized impact melting in the form of intergranular melt, melt veins, and melt films in shatter cones. In particular, Kamil <span class="hlt">crater</span> is the smallest impact <span class="hlt">crater</span> where shatter cones, coesite, stishovite, diamond, and melt veins have been reported. Based on experimental calibrations reported in the literature, pervasive shock features suggest that the maximum shock pressure was between 30 and 60 GPa. Using the planar impact approximation, we calculate a vertical component of the impact velocity of at least 3.5 km s-1. The wide range of shock features and their freshness make Kamil a natural laboratory for studying impact <span class="hlt">cratering</span> and shock deformation processes in small impact structures.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=PIA04912&hterms=marte&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dmarte','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=PIA04912&hterms=marte&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dmarte"><span><span class="hlt">Crater</span> in Marte Vallis</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>2003-01-01</p> <p>MGS MOC Release No. MOC<span class="hlt">2</span>-566, 6 December 2003<p/>This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a streamlined tail-pointing toward the upper right (northeast)--in the lee of a meteor impact <span class="hlt">crater</span> in Marte Vallis, a large valley and channel complex southeast and east of the Elysium volcanic region. The fluid that went through Marte Vallis, whether water, mud, lava, or otherwise, created this form as it moved from the lower left (southwest) toward the upper right. The <span class="hlt">crater</span> is located near 19.0oN, 174.9oW. The image covers an area 3 km (1.9 mi) wide and is illuminated from the left.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://images.nasa.gov/#/details-PIA22139.html','SCIGOVIMAGE-NASA'); return false;" href="https://images.nasa.gov/#/details-PIA22139.html"><span>Investigating Mars: Rabe <span class="hlt">Crater</span></span></a></p> <p><a target="_blank" href="https://images.nasa.gov/">NASA Image and Video Library</a></p> <p></p> <p>2017-12-11</p> <p>Rabe <span class="hlt">Crater</span> is 108 km (67 miles) across. <span class="hlt">Craters</span> of similar size often have flat floors. Rabe <span class="hlt">Crater</span> has some areas of flat floor, but also has a large complex pit occupying a substantial part of the floor. The interior fill of the <span class="hlt">crater</span> is thought to be layered sediments created by wind and or water action. The pit is eroded into this material. The eroded materials appear to have stayed within the <span class="hlt">crater</span> forming a large sand sheet with surface dune forms as well as individual dunes where the <span class="hlt">crater</span> floor is visible. The dunes also appear to be moving from the upper floor level into the pit. In this VIS image the rim of the pit is visible near the top of the image. The Odyssey spacecraft has spent over 15 years in orbit around Mars, circling the planet more than 69000 times. It holds the record for longest working spacecraft at Mars. THEMIS, the IR/VIS camera system, has collected data for the entire mission and provides images covering all seasons and lighting conditions. Over the years many features of interest have received repeated imaging, building up a suite of images covering the entire feature. From the deepest chasma to the tallest volcano, individual dunes inside <span class="hlt">craters</span> and dune fields that encircle the north pole, channels carved by water and lava, and a variety of other feature, THEMIS has imaged them all. For the next several months the image of the day will focus on the Tharsis volcanoes, the various chasmata of Valles Marineris, and the major dunes fields. We hope you enjoy these images! Orbit Number: 17074 Latitude: -43.6954 Longitude: 34.66 Instrument: VIS Captured: 2005-10-20 04:05 https://photojournal.jpl.nasa.gov/catalog/PIA22139</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li class="active"><span>22</span></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_22 --> <div id="page_23" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li class="active"><span>23</span></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="441"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70001158','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70001158"><span><span class="hlt">Crater</span> dimensions from apollo data and supplemental sources</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Pike, R.J.</p> <p>1976-01-01</p> <p>A catalog of <span class="hlt">crater</span> dimensions that were compiled mostly from the new Apollo-based Lunar Topographic Orthophotomaps is presented in its entirety. Values of <span class="hlt">crater</span> diameter, depth, rim height, flank width, circularity, and floor diameter (where applicable) are tabulated for a sample of 484 <span class="hlt">craters</span> on the Moon and 22 <span class="hlt">craters</span> on Earth. Systematic techniques of mensuration are detailed. The lunar <span class="hlt">craters</span> range in size from 400 m to 300 km across and include primary impact <span class="hlt">craters</span> of the main sequence, secondary impact <span class="hlt">craters</span>, craterlets atop domes and cones, and dark-halo <span class="hlt">craters</span>. The terrestrial <span class="hlt">craters</span> are between 10 m and 22.5 km in diameter and were formed by meteorite impact. ?? 1976 D. Reidel Publishing Company.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008JVGR..177..578P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008JVGR..177..578P"><span>Geology of the Side <span class="hlt">Crater</span> of the Erebus volcano, Antarctica</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Panter, Kurt S.; Winter, Brian</p> <p>2008-11-01</p> <p>The summit cone of the Erebus volcano contains two <span class="hlt">craters</span>. The Main <span class="hlt">crater</span> is roughly circular (˜ 500 m diameter) and contains an active persistent phonolite lava lake ˜ 200 m below the summit rim. The Side <span class="hlt">Crater</span> is adjacent to the southwestern rim of the Main <span class="hlt">Crater</span>. It is a smaller spoon-shaped <span class="hlt">Crater</span> (250-350 m diameter, 50-100 m deep) and is inactive. The floor of the Side <span class="hlt">Crater</span> is covered by snow/ice, volcanic colluvium or weakly developed volcanic soil in geothermal areas (a.k.a. warm ground). But in several places the walls of the Side <span class="hlt">Crater</span> provide extensive vertical exposure of rock which offers an insight into the recent eruptive history of Erebus. The deposits consist of lava flows with subordinate volcanoclastic lithologies. Four lithostratigraphic units are described: SC 1 is a compound lava with complex internal flow fabrics; SC <span class="hlt">2</span> consists of interbedded vitric lavas, autoclastic and pyroclastic breccias; SC 3 is a thick sequence of thin lavas with minor autoclastic breccias; SC 4 is a pyroclastic fall deposit containing large scoriaceous lava bombs in a matrix composed primarily of juvenile lapilli-sized pyroclasts. Ash-sized pyroclasts from SC 4 consist of two morphologic types, spongy and blocky, indicating a mixed strombolian-phreatomagmatic origin. All of the deposits are phonolitic and contain anorthoclase feldspar. The stratigraphy and morphology of the Side <span class="hlt">Crater</span> provides a record of recent volcanic activity at the Erebus volcano and is divided into four stages. Stage I is the building of the main summit cone and eruption of lavas (SC 1 and SC 3) from Main <span class="hlt">Crater</span> vent(s). A secondary cone was built during Stage II by effusive and explosive activity (SC <span class="hlt">2</span>) from the Side <span class="hlt">Crater</span> vent. A mixed strombolian and phreatomagmatic eruption (SC 4) delimits Stage III. The final stage (IV) represents a period of erosion and enlargement of the Side <span class="hlt">Crater</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19830035018&hterms=clay+viscosity&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dclay%2Bviscosity','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19830035018&hterms=clay+viscosity&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dclay%2Bviscosity"><span>Experimental simulation of impact <span class="hlt">cratering</span> on icy satellites</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Greeley, R.; Fink, J. H.; Gault, D. E.; Guest, J. E.</p> <p>1982-01-01</p> <p><span class="hlt">Cratering</span> processes on icy satellites were simulated in a series of 102 laboratory impact experiments involving a wide range of target materials. For impacts into homogeneous clay slurries with impact energies ranging from five million to ten billion ergs, target yield strengths ranged from 100 to 38 Pa, and apparent viscosities ranged from 8 to 200 Pa s. Bowl-shaped <span class="hlt">craters</span>, flat-floored <span class="hlt">craters</span>, central peak <span class="hlt">craters</span> with high or little relief, and <span class="hlt">craters</span> with no relief were observed. <span class="hlt">Crater</span> diameters increased steadily as energies were raised. A similar sequence was seen for experiment in which impact energy was held constant but target viscosity and strength progressively decreases. The experiments suggest that the physical properties of the target media relative to the gravitationally induced stresses determined the final <span class="hlt">crater</span> morphology. <span class="hlt">Crater</span> palimpsests could form by prompt collapse of large central peak <span class="hlt">craters</span> formed in low target strength materials. Ages estimated from <span class="hlt">crater</span> size-frequency distributions that include these large <span class="hlt">craters</span> may give values that are too high.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.usgs.gov/sir/2014/5075/pdf/sir2014-5075.pdf','USGSPUBS'); return false;" href="https://pubs.usgs.gov/sir/2014/5075/pdf/sir2014-5075.pdf"><span>Land <span class="hlt">subsidence</span>, groundwater levels, and geology in the Coachella Valley, California, 1993-2010</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Sneed, Michelle; Brandt, Justin T.; Solt, Mike</p> <p>2014-01-01</p> <p>Land <span class="hlt">subsidence</span> associated with groundwater-level declines has been investigated by the <span class="hlt">U</span>.S. Geological Survey in the Coachella Valley, California, since 1996. Groundwater has been a major source of agricultural, municipal, and domestic supply in the valley since the early 1920s. Pumping of groundwater resulted in water-level declines as much as 15 meters (50 feet) through the late 1940s. In 1949, the importation of Colorado River water to the southern Coachella Valley began, resulting in a reduction in groundwater pumping and a recovery of water levels during the 1950s through the 1970s. Since the late 1970s, demand for water in the valley has exceeded deliveries of imported surface water, resulting in increased pumping and associated groundwater-level declines and, consequently, an increase in the potential for land <span class="hlt">subsidence</span> caused by aquifer-system compaction. Global Positioning System (GPS) surveying and Interferometric Synthetic Aperture Radar (InSAR) methods were used to determine the location, extent, and magnitude of the vertical land-surface changes in the southern Coachella Valley during 1993–2010. The GPS measurements taken at 11 geodetic monuments in 1996 and in 2010 in the southern Coachella Valley indicated that the elevation of the land surface changed –136 to –23 millimeters (mm) ±54 mm (–0.45 to –0.08 feet (ft) ±0.18 ft) during the 14-year period. Changes at 6 of the 11 monuments exceeded the maximum expected uncertainty of ±54 mm (±0.18 ft) at the 95-percent confidence level, indicating that <span class="hlt">subsidence</span> occurred at these monuments between June 1996 and August 2010. GPS measurements taken at 17 geodetic monuments in 2005 and 2010 indicated that the elevation of the land surface changed –256 to +16 mm ±28 mm (–0.84 to +0.05 ft ±0.09 ft) during the 5-year period. Changes at 5 of the 17 monuments exceeded the maximum expected uncertainty of ±28 mm (±0.09 ft) at the 95-percent confidence level, indicating that <span class="hlt">subsidence</span> occurred</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JVGR..339...41A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JVGR..339...41A"><span>Compound maar <span class="hlt">crater</span> and co-eruptive scoria cone in the Lunar <span class="hlt">Crater</span> Volcanic Field (Nevada, USA)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Amin, Jamal; Valentine, Greg A.</p> <p>2017-06-01</p> <p>Bea's <span class="hlt">Crater</span> (Lunar <span class="hlt">Crater</span> Volcanic Field, Nevada, USA) consists of two coalesced maar <span class="hlt">craters</span> with diameters of 440 m and 1050 m, combined with a co-eruptive scoria cone that straddles the northeast rim of the larger <span class="hlt">crater</span>. The two <span class="hlt">craters</span> and the cone form an alignment that parallels many local and regional structures such as normal faults, and is interpreted to represent the orientation of the feeder dyke near the surface. The maar formed among a dense cluster of scoria cones; the cone-cluster topography resulted in <span class="hlt">crater</span> rim that has a variable elevation. These older cones are composed of variably welded agglomerate and scoria with differing competence that subsequently affected the shape of Bea's <span class="hlt">Crater</span>. Tephra ring deposits associated with phreatomagmatic maar-forming eruptions are rich in basaltic lithics derived from < 250 m depth, with variable contents of deeper-seated ignimbrite lithic clasts, consistent with ejection from relatively shallow explosions although a diatreme might extend to deeper levels beneath the maar. Interbedding of deposits on the northeastern cone and in the tephra ring record variations in the magmatic volatile driven and phreatomagmatic eruption styles in both space and time along a feeder dike.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://images.nasa.gov/#/details-PIA19304.html','SCIGOVIMAGE-NASA'); return false;" href="https://images.nasa.gov/#/details-PIA19304.html"><span><span class="hlt">Craters</span> Near Nilokeras Scopulus</span></a></p> <p><a target="_blank" href="https://images.nasa.gov/">NASA Image and Video Library</a></p> <p></p> <p>2015-03-04</p> <p>This image from NASA Mars Reconnaissance Orbiter of <span class="hlt">craters</span> near Nilokeras Scopulus shows two pits partially filled with lumpy material, probably trapped dust that blew in from the atmosphere. This image shows two pits partially filled with lumpy material, probably trapped dust that blew in from the atmosphere. The pits themselves resemble impact <span class="hlt">craters</span>, but they are part of a chain of similar features aligned with nearby faults, so they could be collapse features instead. Note also the tracks left by rolling boulders at the bottom of the <span class="hlt">craters</span>. Nilokeras Scopulus is the name for the cliff, about 756 kilometers long, in the northern hemisphere of Mars where these <span class="hlt">craters</span> are located. It was named based on an albedo (brightness) feature mapped by astronomer E. M. Antoniadi in 1930. http://photojournal.jpl.nasa.gov/catalog/PIA19304</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19820038840&hterms=projectile+motion&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dprojectile%2Bmotion','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19820038840&hterms=projectile+motion&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dprojectile%2Bmotion"><span>Impact <span class="hlt">cratering</span> in viscous targets - Laboratory experiments</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Greeley, R.; Fink, J.; Snyder, D. B.; Gault, D. E.; Guest, J. E.; Schultz, P. H.</p> <p>1980-01-01</p> <p>To determine the effects of target yield strength and viscosity on the formation and morphology of Martian multilobed, slosh and rampart-type impact <span class="hlt">craters</span>, 75 experiments in which target properties and impact energies were varied were carried out for high-speed motion picture observation in keeping with the following sequence: (1) projectile initial impact; (<span class="hlt">2</span>) <span class="hlt">crater</span> excavation and rise of ejecta plume; (3) formation of a transient central mound which generates a surge of material upon collapse that can partly override the plume deposit; and (4) oscillation of the central mound with progressively smaller surges of material leaving the <span class="hlt">crater</span>. A dimensional analysis of the experimental results indicates that the dimensions of the central mound are proportional to (1) the energy of the impacting projectile and (<span class="hlt">2</span>) to the inverse of both the yield strength and viscosity of the target material, and it is determined that extrapolation of these results to large Martian <span class="hlt">craters</span> requires an effective surface layer viscosity of less than 10 to the 10th poise. These results may also be applicable to impacts on outer planet satellites composed of ice-silicate mixtures.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19830035017&hterms=geologic+time+scale&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dgeologic%2Btime%2Bscale','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19830035017&hterms=geologic+time+scale&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dgeologic%2Btime%2Bscale"><span><span class="hlt">Cratering</span> time scales for the Galilean satellites</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Shoemaker, E. M.; Wolfe, R. F.</p> <p>1982-01-01</p> <p>An attempt is made to estimate the present <span class="hlt">cratering</span> rate for each Galilean satellite within the correct order of magnitude and to extend the <span class="hlt">cratering</span> rates back into the geologic past on the basis of evidence from the earth-moon system. For collisions with long and short period comets, the magnitudes and size distributions of the comet nuclei, the distribution of their perihelion distances, and the completeness of discovery are addressed. The diameters and masses of cometary nuclei are assessed, as are <span class="hlt">crater</span> diameters and <span class="hlt">cratering</span> rates. The dynamical relations between long period and short period comets are discussed, and the population of Jupiter-crossing asteroids is assessed. Estimated present <span class="hlt">cratering</span> rates on the Galilean satellites are compared and variations of <span class="hlt">cratering</span> rate with time are considered. Finally, the consistency of derived <span class="hlt">cratering</span> time scales with the <span class="hlt">cratering</span> record of the icy Galilean satellites is discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFMEP53B1722M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFMEP53B1722M"><span>The sinking Mekong delta; modeling 25 years of groundwater extraction and <span class="hlt">subsidence</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Minderhoud, P. S. J.; Erkens, G.; Pham, H. V.; Bui, V. T.; Erban, L. E.; Kooi, H.; Stouthamer, E.</p> <p>2017-12-01</p> <p>The Vietnamese Mekong delta, the third's largest delta in the world, is experiencing annual <span class="hlt">subsidence</span> rates up to several centimeters. As a result, vulnerability to flooding and storm surges, salinization and, ultimately, permanent inundation increases. Extraction of groundwater from the soft deltaic subsurface can be a major driving mechanism of <span class="hlt">subsidence</span>, however a quantification of temporal and spatial impact to <span class="hlt">subsidence</span> in the Mekong delta was not done yet. We developed a delta-wide, 3D hydrogeological model coupled to a 1D geotechnical module to quantify the contribution of excessive groundwater exploitation to <span class="hlt">subsidence</span>. The modelling period of 25 years captures the period in which the hydrogeological state of the delta transforming from almost undisturbed to a situation with increasing aquifer depletion. Our model provides a quantitative spatially-explicit assessment of groundwater extraction-induced <span class="hlt">subsidence</span> for the entire Mekong delta since the start of widespread depletion of the groundwater reserves. Over the past decades <span class="hlt">subsidence</span> related to groundwater extraction has accelerated towards the highest sinking rates at present. During the past 25 years, the delta sank on average 18 cm, with areas over 30 cm. Currently the delta experiences an average <span class="hlt">subsidence</span> rate of 1.1 cm yr-1, some areas <span class="hlt">subside</span> over <span class="hlt">2</span>.5 cm yr-1, due to groundwater exploitation. These rates outpace global sea level rise almost by an order of magnitude. Given the increasing trends in groundwater demand in the delta, the current rates are likely to increase in the near future.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://images.nasa.gov/#/details-PIA13611.html','SCIGOVIMAGE-NASA'); return false;" href="https://images.nasa.gov/#/details-PIA13611.html"><span>Fresh <span class="hlt">Crater</span> with Gullies</span></a></p> <p><a target="_blank" href="https://images.nasa.gov/">NASA Image and Video Library</a></p> <p></p> <p>2010-11-12</p> <p>The <span class="hlt">crater</span> shown in this image from NASA Mars Reconnaissance Orbiter has very few <span class="hlt">craters</span> superposed on it, which attests to its youth. It also has very steep slopes and a sharp rim; more evidence of its young age.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008cosp...37.2720S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008cosp...37.2720S"><span>Extensions of the framework for evaluation of <span class="hlt">crater</span> detection algorithms: new ground truth catalogue with 57633 <span class="hlt">craters</span>, additional subsystems and evaluations</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Salamunićcar, Goran</p> <p></p> <p><span class="hlt">Crater</span> detection algorithms' (CDAs) applications range from approximating the age of a planetary surface and autonomous landing to planets and asteroids to advanced statistical analyses [ASR, 33, 2281-2287]. A large amount of work on CDAs has already been published. However, problems arise when evaluation results of some new CDA have to be compared with already published evaluation results. The Framework for Evaluation of <span class="hlt">Crater</span> Detection Algorithms (FECDA) was recently proposed as an initial step for solving the problem of objective evaluation of CDAs [ASR, in press, doi:10.1016/j.asr.2007.04.028]. The framework includes: (1) a definition of the measure for differences between <span class="hlt">craters</span>; (<span class="hlt">2</span>) test-field topography based on the 1/64° MOLA data; (3) the Ground Truth (GT) catalogue wherein each of 17582 impact <span class="hlt">craters</span> is aligned with MOLA data and confirmed with catalogues by N. G. Barlow et al. and J. F. Rodionova et al.; (4) selection of methodology for training and testing; and (5) a Free-response Receiver Operating Characteristics (F-ROC) curves as a way to measure CDA performance. Recently, the GT catalogue with 17582 <span class="hlt">craters</span> has been improved using cross-analysis. The result is a more complete GT catalogue with 18711 impact <span class="hlt">craters</span> [7thMars abstract 3067]. Once this is done, the integration with Barlow, Rodionova, Boyce, Kuzmin and the catalogue from our previous work has been completed by merging. The result is even more complete GT catalogue with 57633 impact <span class="hlt">craters</span> [39thLPS abstract 1372]. All <span class="hlt">craters</span> from the resulting GT catalogue have been additionally registered, using 1/128° MOLA data as bases, with 1/256° THEMIS-DIR, 1/256° MDIM and 1/256° MOC data-sets. Thanks to that, the GT catalogue can also be used with these additional subsystems, so the FECDA can be extended with them. Part of the FECDA is also the <span class="hlt">Craters</span> open-source C++ project. It already contains a number of implemented CDAs [38thLPS abstract 1351, 7thMars abstract 3066, 39thLPS abstracts</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2013-title30-vol3/pdf/CFR-2013-title30-vol3-sec817-121.pdf','CFR2013'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2013-title30-vol3/pdf/CFR-2013-title30-vol3-sec817-121.pdf"><span>30 CFR 817.121 - <span class="hlt">Subsidence</span> control.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2013&page.go=Go">Code of Federal Regulations, 2013 CFR</a></p> <p></p> <p>2013-07-01</p> <p>... 30 Mineral Resources 3 2013-07-01 2013-07-01 false <span class="hlt">Subsidence</span> control. 817.121 Section 817.121... ACTIVITIES § 817.121 <span class="hlt">Subsidence</span> control. (a) Measures to prevent or minimize damage. (1) The permittee must... control plan prepared pursuant to § 784.20 of this chapter. (c) Repair of damage—(1) Repair of damage to...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2011-title30-vol3/pdf/CFR-2011-title30-vol3-sec817-121.pdf','CFR2011'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2011-title30-vol3/pdf/CFR-2011-title30-vol3-sec817-121.pdf"><span>30 CFR 817.121 - <span class="hlt">Subsidence</span> control.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2011&page.go=Go">Code of Federal Regulations, 2011 CFR</a></p> <p></p> <p>2011-07-01</p> <p>... 30 Mineral Resources 3 2011-07-01 2011-07-01 false <span class="hlt">Subsidence</span> control. 817.121 Section 817.121... ACTIVITIES § 817.121 <span class="hlt">Subsidence</span> control. (a) Measures to prevent or minimize damage. (1) The permittee must... control plan prepared pursuant to § 784.20 of this chapter. (c) Repair of damage—(1) Repair of damage to...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2012-title30-vol3/pdf/CFR-2012-title30-vol3-sec817-121.pdf','CFR2012'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2012-title30-vol3/pdf/CFR-2012-title30-vol3-sec817-121.pdf"><span>30 CFR 817.121 - <span class="hlt">Subsidence</span> control.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2012&page.go=Go">Code of Federal Regulations, 2012 CFR</a></p> <p></p> <p>2012-07-01</p> <p>... 30 Mineral Resources 3 2012-07-01 2012-07-01 false <span class="hlt">Subsidence</span> control. 817.121 Section 817.121... ACTIVITIES § 817.121 <span class="hlt">Subsidence</span> control. (a) Measures to prevent or minimize damage. (1) The permittee must... control plan prepared pursuant to § 784.20 of this chapter. (c) Repair of damage—(1) Repair of damage to...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2014-title30-vol3/pdf/CFR-2014-title30-vol3-sec817-121.pdf','CFR2014'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2014-title30-vol3/pdf/CFR-2014-title30-vol3-sec817-121.pdf"><span>30 CFR 817.121 - <span class="hlt">Subsidence</span> control.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2014&page.go=Go">Code of Federal Regulations, 2014 CFR</a></p> <p></p> <p>2014-07-01</p> <p>... 30 Mineral Resources 3 2014-07-01 2014-07-01 false <span class="hlt">Subsidence</span> control. 817.121 Section 817.121... ACTIVITIES § 817.121 <span class="hlt">Subsidence</span> control. (a) Measures to prevent or minimize damage. (1) The permittee must... control plan prepared pursuant to § 784.20 of this chapter. (c) Repair of damage—(1) Repair of damage to...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2010-title30-vol3/pdf/CFR-2010-title30-vol3-sec817-121.pdf','CFR'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2010-title30-vol3/pdf/CFR-2010-title30-vol3-sec817-121.pdf"><span>30 CFR 817.121 - <span class="hlt">Subsidence</span> control.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2010&page.go=Go">Code of Federal Regulations, 2010 CFR</a></p> <p></p> <p>2010-07-01</p> <p>... 30 Mineral Resources 3 2010-07-01 2010-07-01 false <span class="hlt">Subsidence</span> control. 817.121 Section 817.121... ACTIVITIES § 817.121 <span class="hlt">Subsidence</span> control. (a) Measures to prevent or minimize damage. (1) The permittee must... control plan prepared pursuant to § 784.20 of this chapter. (c) Repair of damage—(1) Repair of damage to...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19790055292&hterms=gravity+anomaly&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dgravity%2Banomaly','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19790055292&hterms=gravity+anomaly&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dgravity%2Banomaly"><span>Lunar Bouguer gravity anomalies - Imbrian age <span class="hlt">craters</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Dvorak, J.; Phillips, R. J.</p> <p>1978-01-01</p> <p>The Bouguer gravity of mass anomalies associated with four Imbrian age <span class="hlt">craters</span>, analyzed in the present paper, are found to differ considerably from the values of the mass anomalies associated with some young lunar <span class="hlt">craters</span>. Of the Imbrian age <span class="hlt">craters</span>, only Piccolomini exhibits a negative gravity anomaly (i.e., a low density region) which is characteristic of the young <span class="hlt">craters</span> studied. The Bouguer gravity anomalies are zero for each of the remaining Imbrian age <span class="hlt">craters</span>. Since, Piccolomini is younger, or at least less modified, than the other Imbrian age <span class="hlt">craters</span>, it is suggested that the processes responsible for the post-impact modification of the Imbrian age <span class="hlt">craters</span> may also be responsible for removing the negative mass anomalies initially associated with these features.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=PIA08785&hterms=duck&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dduck','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=PIA08785&hterms=duck&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dduck"><span>'Victoria <span class="hlt">Crater</span>' from 'Duck Bay' (Polar Projection)</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>2006-01-01</p> <p><p/> NASA's Mars rover Opportunity edged 3.7 meters (12 feet) closer to the top of the 'Duck Bay' alcove along the rim of 'Victoria <span class="hlt">Crater</span>' during the rover's 952nd Martian day, or sol (overnight Sept. 27 to Sept. 28), and gained this vista of the <span class="hlt">crater</span>. The rover's navigation camera took the seven exposures combined into this mosaic view of the <span class="hlt">crater</span>'s interior. This <span class="hlt">crater</span> has been the mission's long-term destination for the past 21 Earth months. <p/> The far side of the <span class="hlt">crater</span> is about 800 meters (one-half mile) away. The rim of the <span class="hlt">crater</span> is composed of alternating promontories, rocky points towering approximately 70 meters (230 feet) above the <span class="hlt">crater</span> floor, and recessed alcoves, such as Duck Bay. The bottom of the <span class="hlt">crater</span> is covered by sand that has been shaped into ripples by the Martian wind. The rocky cliffs in the foreground have been informally named 'Cape Verde,' on the left, and 'Cabo Frio,' on the right. <p/> Victoria <span class="hlt">Crater</span> is about five times wider than 'Endurance <span class="hlt">Crater</span>,' which Opportunity spent six months examining in 2004, and about 40 times wider than 'Eagle <span class="hlt">Crater</span>,' where Opportunity first landed. The great lure of Victoria is an expectation that the thick stack of geological layers exposed in the <span class="hlt">crater</span> walls could reveal the record of past environmental conditions over a much greater span of time than Opportunity has read from rocks examined earlier in the mission. <p/> This view is presented as a polar projection with geometric seam correction.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=PIA08786&hterms=duck&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dduck','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=PIA08786&hterms=duck&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dduck"><span>'Victoria <span class="hlt">Crater</span>' from 'Duck Bay' (Vertical Projection)</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>2006-01-01</p> <p><p/> NASA's Mars rover Opportunity edged 3.7 meters (12 feet) closer to the top of the 'Duck Bay' alcove along the rim of 'Victoria <span class="hlt">Crater</span>' during the rover's 952nd Martian day, or sol (overnight Sept. 27 to Sept. 28), and gained this vista of the <span class="hlt">crater</span>. The rover's navigation camera took the seven exposures combined into this mosaic view of the <span class="hlt">crater</span>'s interior. This <span class="hlt">crater</span> has been the mission's long-term destination for the past 21 Earth months. <p/> The far side of the <span class="hlt">crater</span> is about 800 meters (one-half mile) away. The rim of the <span class="hlt">crater</span> is composed of alternating promontories, rocky points towering approximately 70 meters (230 feet) above the <span class="hlt">crater</span> floor, and recessed alcoves, such as Duck Bay. The bottom of the <span class="hlt">crater</span> is covered by sand that has been shaped into ripples by the Martian wind. The rocky cliffs in the foreground have been informally named 'Cape Verde,' on the left, and 'Cabo Frio,' on the right. <p/> Victoria <span class="hlt">Crater</span> is about five times wider than 'Endurance <span class="hlt">Crater</span>,' which Opportunity spent six months examining in 2004, and about 40 times wider than 'Eagle <span class="hlt">Crater</span>,' where Opportunity first landed. The great lure of Victoria is an expectation that the thick stack of geological layers exposed in the <span class="hlt">crater</span> walls could reveal the record of past environmental conditions over a much greater span of time than Opportunity has read from rocks examined earlier in the mission. <p/> This view is presented as a vertical projection with geometric seam correction.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://images.nasa.gov/#/details-PIA20340.html','SCIGOVIMAGE-NASA'); return false;" href="https://images.nasa.gov/#/details-PIA20340.html"><span>A Young, Fresh <span class="hlt">Crater</span> in Hellespontus</span></a></p> <p><a target="_blank" href="https://images.nasa.gov/">NASA Image and Video Library</a></p> <p></p> <p>2016-01-14</p> <p>This image from NASA Mars Reconnaissance Orbiter spacecraft is of a morphologically fresh and simple impact <span class="hlt">crater</span> in the Hellespontus region. At 1.3 kilometers in diameter, this unnamed <span class="hlt">crater</span> is only slightly larger than Arizona's Barringer (aka Meteor) <span class="hlt">Crater</span>, by about 200 meters. Note the simple bowl shape and the raised <span class="hlt">crater</span> rim. Rock and soil excavated out of the <span class="hlt">crater</span> by the impacting meteor -- called ejecta -- forms the ejecta deposit. It is continuous for about one <span class="hlt">crater</span> radius away from the rim and is likely composed of about 90 percent ejecta and 10 percent in-place material that was re-worked by both the impact and the subsequently sliding ejecta. The discontinuous ejecta deposit extends from about one <span class="hlt">crater</span> radius outward. Here, high velocity ejecta that was launched from close to the impact point -- and got the biggest kick -- flew a long way, landed, rolled, slid, and scoured the ground, forming long tendrils of ejecta and v-shaped ridges. http://photojournal.jpl.nasa.gov/catalog/PIA20340</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li class="active"><span>23</span></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_23 --> <div id="page_24" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li class="active"><span>24</span></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="461"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://images.nasa.gov/#/details-PIA22262.html','SCIGOVIMAGE-NASA'); return false;" href="https://images.nasa.gov/#/details-PIA22262.html"><span>Investigating Mars: Kaiser <span class="hlt">Crater</span> Dunes</span></a></p> <p><a target="_blank" href="https://images.nasa.gov/">NASA Image and Video Library</a></p> <p></p> <p>2018-01-30</p> <p>At the top of this VIS image crescent shaped dunes are visible. As the dunes approach a break in elevation the forms change to connect the crescents together forming long aligned dune forms. Kaiser <span class="hlt">Crater</span> is located in the southern hemisphere in the Noachis region west of Hellas Planitia. Kaiser <span class="hlt">Crater</span> is just one of several large <span class="hlt">craters</span> with extensive dune fields on the <span class="hlt">crater</span> floor. Other nearby dune filled <span class="hlt">craters</span> are Proctor, Russell, and Rabe. Kaiser <span class="hlt">Crater</span> is 207 km (129 miles) in diameter. The dunes are located in the southern part of the <span class="hlt">crater</span> floor. The Odyssey spacecraft has spent over 15 years in orbit around Mars, circling the planet more than 71,000 times. It holds the record for longest working spacecraft at Mars. THEMIS, the IR/VIS camera system, has collected data for the entire mission and provides images covering all seasons and lighting conditions. Over the years many features of interest have received repeated imaging, building up a suite of images covering the entire feature. From the deepest chasma to the tallest volcano, individual dunes inside <span class="hlt">craters</span> and dune fields that encircle the north pole, channels carved by water and lava, and a variety of other feature, THEMIS has imaged them all. For the next several months the image of the day will focus on the Tharsis volcanoes, the various chasmata of Valles Marineris, and the major dunes fields. We hope you enjoy these images! Orbit Number: 34157 Latitude: -46.9336 Longitude: 18.9272 Instrument: VIS Captured: 2009-08-26 18:49 https://photojournal.jpl.nasa.gov/catalog/PIA22262</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70013801','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70013801"><span><span class="hlt">Cratering</span> history of Miranda: Implications for geologic processes</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Plescia, J.B.</p> <p>1988-01-01</p> <p>Miranda's surface is divisible into <span class="hlt">cratered</span> terrain and coronae. The <span class="hlt">cratered</span> terrain is the most heavily <span class="hlt">cratered</span> of the terrains and presumably is the oldest. The frequency of <span class="hlt">craters</span> in the <span class="hlt">cratered</span> terrain is variable and related to position on the satellite. The coronae are also variably <span class="hlt">cratered</span>. Elsinore and Arden Coronae have similar <span class="hlt">crater</span> frequencies and may have formed simultaneously. They are of intermediate agompared to the <span class="hlt">cratered</span> terrain and to Inverness Corona, which is the youngest major terrain. Graben formation appears to have occured both before and after the formation of the coronae reflecting periods of global expansion. Miranda's surfaces are, in general, the least <span class="hlt">cratered</span> and therefore inferred to be the youngest within the Uranian system. ?? 1988.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010Icar..207..248S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010Icar..207..248S"><span>The formation of floor-fractured <span class="hlt">craters</span> in Xanthe Terra</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sato, Hiroyuki; Kurita, Kei; Baratoux, David</p> <p>2010-05-01</p> <p>Floor-fractured <span class="hlt">craters</span> (FFC) are a peculiar form of degradation of impact <span class="hlt">craters</span> defined by the presence of crevice networks and mesas affecting <span class="hlt">crater</span> floors. They are preferentially distributed near chaotic terrains and outflow channels. The scope of this paper is to present a detailed systematic analysis of FFC at Xanthe Terra. FFC morphologies in this region are classified into five types making a picture of different stages of the same degradation process. FFC are geographically intermixed with un-fractured normal <span class="hlt">craters</span> (non-FFC). Young <span class="hlt">craters</span> are less prone to show this type of degradation, as suggested by fresh ejecta layer with preserved <span class="hlt">crater</span> floor. Size distributions of FFC and non-FFC indicate that larger <span class="hlt">craters</span> are preferentially fractured. Careful examinations of the <span class="hlt">crater</span> floor elevations reveal that the crevices often extend deeper than the original <span class="hlt">crater</span> cavity. Furthermore, an onset depth for the formation of FFC is evidenced from the difference of spatial distributions between FFC and non-FFC. Roof-collapsed depressions observed in the same region have been also documented and their characteristics suggest the removal of subsurface material at depth from about 1200 to 4000 m. These observations taken together suggest a subsurface zone of volume deficit at depth from 1 to <span class="hlt">2</span> km down to several kilometers responsible for FFC formation. Then a scenario of FFC formations is presented in the context of groundwater discharge events at the late Hesperian. This scenario involves two key processes, Earth fissuring and piping erosion, known to occur with rapid groundwater migrations on Earth.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19980008049','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19980008049"><span>Scaling Impact-Melt and <span class="hlt">Crater</span> Dimensions: Implications for the Lunar <span class="hlt">Cratering</span> Record</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Cintala , Mark J.; Grieve, Richard A. F.</p> <p>1997-01-01</p> <p>The consequences of impact on the solid bodies of the solar system are manifest and legion. Although the visible effects on planetary surfaces, such as the Moon's, are the most obvious testimony to the spatial and temporal importance of impacts, less dramatic chemical and petrographic characteristics of materials affected by shock abound. Both the morphologic and petrologic aspects of impact <span class="hlt">cratering</span> are important in deciphering lunar history, and, ideally, each should complement the other. In practice, however, a gap has persisted in relating large-scale <span class="hlt">cratering</span> processes to petrologic and geochemical data obtained from lunar samples. While this is due in no small part to the fact that no Apollo mission unambiguously sampled deposits of a large <span class="hlt">crater</span>, it can also be attributed to the general state of our knowledge of <span class="hlt">cratering</span> phenomena, particularly those accompanying large events. The most common shock-metamorphosed lunar samples are breccias, but a substantial number are impact-melt rocks. Indeed, numerous workers have called attention to the importance of impact-melt rocks spanning a wide range of ages in the lunar sample collection. Photogeologic studies also have demonstrated the widespread occurrence of impact-melt lithologies in and around lunar <span class="hlt">craters</span>. Thus, it is clear that impact melting has been a fundamental process operating throughout lunar history, at scales ranging from pits formed on individual regolith grains to the largest impact basins. This contribution examines the potential relationship between impact melting on the Moon and the interior morphologies of large <span class="hlt">craters</span> and peaking basins. It then examines some of the implications of impact melting at such large scales for lunar-sample provenance and evolution of the lunar crust.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.usgs.gov/of/1979/0951/report.pdf','USGSPUBS'); return false;" href="https://pubs.usgs.gov/of/1979/0951/report.pdf"><span>Earth fissures and localized differential <span class="hlt">subsidence</span></span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Holzer, Thomas L.; Pampeyan, Earl Haig</p> <p>1979-01-01</p> <p>Long tension cracks caused by declines of ground-water level at four sites in Arizona, California, and Nevada occur at points of maximum, convex-upward curvature in <span class="hlt">subsidence</span> profiles based on relevelings of closely-spaced bench marks aligned perpendicular to the cracks. We conclude the cracks are caused by horizontal strains associated with the differential <span class="hlt">subsidence</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014Icar..243..337S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014Icar..243..337S"><span>Occurrence and mechanisms of impact melt emplacement at small lunar <span class="hlt">craters</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Stopar, Julie D.; Hawke, B. Ray; Robinson, Mark S.; Denevi, Brett W.; Giguere, Thomas A.; Koeber, Steven D.</p> <p>2014-11-01</p> <p>Using observations from the Lunar Reconnaissance Orbiter Camera (LROC), we assess the frequency and occurrence of impact melt at simple <span class="hlt">craters</span> less than 5 km in diameter. Nine-hundred-and-fifty fresh, randomly distributed impact <span class="hlt">craters</span> were identified for study based on their maturity, albedo, and preservation state. The occurrence, frequency, and distribution of impact melt deposits associated with these <span class="hlt">craters</span>, particularly ponded melt and lobate flows, are diagnostic of melt emplacement mechanisms. Like larger <span class="hlt">craters</span>, those smaller than a few kilometers in diameter often exhibit ponded melt on the <span class="hlt">crater</span> floor as well as lobate flows near the <span class="hlt">crater</span> rim crest. The morphologies of these deposits suggest gravity-driven flow while the melt was molten. Impact melt deposits emplaced as veneers and ;sprays;, thin layers of ejecta that drape other <span class="hlt">crater</span> materials, indicate deposition late in the <span class="hlt">cratering</span> process; the deposits of fine sprays are particularly sensitive to degradation. Exterior melt deposits found near the rims of a few dozen <span class="hlt">craters</span> are distributed asymmetrically around the <span class="hlt">crater</span> and are rare at <span class="hlt">craters</span> less than <span class="hlt">2</span> km in diameter. Pre-existing topography plays a role in the occurrence and distribution of these melt deposits, particularly for <span class="hlt">craters</span> smaller than 1 km in diameter, but does not account for all observed asymmetries in impact melt distribution. The observed relative abundance and frequency of ponded melt and flows in and around simple lunar <span class="hlt">craters</span> increases with <span class="hlt">crater</span> diameter, as was previously predicted from models. However, impact melt deposits are found more commonly at simple lunar <span class="hlt">craters</span> (i.e., those less than a few kilometers in diameter) than previously expected. Ponded melt deposits are observed in roughly 15% of fresh <span class="hlt">craters</span> smaller than 300 m in diameter and 80% of fresh <span class="hlt">craters</span> between 600 m and 5 km in diameter. Furthermore, melt deposits are observed at roughly twice as many non-mare <span class="hlt">craters</span> than at mare <span class="hlt">craters</span>. We</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/4008567-high-explosive-crater-studies-tuff','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/4008567-high-explosive-crater-studies-tuff"><span>HIGH EXPLOSIVE <span class="hlt">CRATER</span> STUDIES: TUFF</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Murphey, B.F.</p> <p>1961-04-01</p> <p>Spherical charges of TNT, each weighing 256 pounds, were exploded at various depths in tuff to determine apparent <span class="hlt">crater</span> dimensions in a soft rock. No <span class="hlt">craters</span> were obtained for depths of burst equal to or greater than 13.3 feet. It was deduced that rock fragments were sufficiently large that charges of greater magnitude should be employed for <span class="hlt">crater</span> experiments intended as models of nuclear explosions. (auth)</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1992JSSCh..96..199C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1992JSSCh..96..199C"><span>Synthesis and characterization of two layered aluminophosphates, ( T) <span class="hlt">2</span>HAl <span class="hlt">2</span>P 3O 12 ( T=<span class="hlt">2</span>-<span class="hlt">Bu</span>NH 3+) and ( T)H <span class="hlt">2</span>Al <span class="hlt">2</span>P 3O 12 ( T=pyH +)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Chippindale, Ann M.; Powell, Anthony V.; Bull, Lucy M.; Jones, Richard H.; Cheetham, Anthony K.; Thomas, John M.; Xu, Ruren</p> <p>1992-01-01</p> <p>Two new aluminophosphates, ( T) <span class="hlt">2</span>HAl <span class="hlt">2</span>P 3O 12 ( T=<span class="hlt">2</span>-<span class="hlt">Bu</span>NH 3+) ( I) and ( T)H <span class="hlt">2</span>Al <span class="hlt">2</span>P 3O 12 ( T=pyH +) ( II) with the same framework stoichiometry but different layer structures have been prepared under nonaqueous conditions and the structures determined by single-crystal X-ray diffraction. Compound ( I) crystallizes in the monoclinic space group P<span class="hlt">2</span> 1/ c ( Z=4), with lattice parameters a=9.261(1) b=8.365(6), c=27.119(4) Å, β=91.50(1)δ, and V=2100.1 Å 3 ( R=0.072 and R w=0.090). The structure consists of Al-and P-centered tetrahedra linked to form layers. Protonated <span class="hlt">2</span>-butylamine molecules are located in the interlayer spaces and hydrogen bonded to the layers through NH 3+ groups. Weak hydrophobic van der Waals' interactions between alkyl groups of the <span class="hlt">2</span>-<span class="hlt">Bu</span>NH 3+ cations hold the layers together. Compound ( II) crystallizes in the triclinic space group P-1 ( Z=<span class="hlt">2</span>), with a=8.574(<span class="hlt">2</span>), b=8.631(3), c=10.371(<span class="hlt">2</span>) Å, α=81.84(3), β=87.53(<span class="hlt">2</span>), γ=69.07(<span class="hlt">2</span>)δ, and V=709.49Å 3 ( R=0.039 and R w=0.052). The structure contains tetrahedrally coordinated P atoms and both tetrahedral and trigonal pyramidal Al atoms linked to form layers which are held together through hydrogen bonding, creating cavities in which pyH + cations reside.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://images.nasa.gov/#/details-PIA15093.html','SCIGOVIMAGE-NASA'); return false;" href="https://images.nasa.gov/#/details-PIA15093.html"><span>Topography of Gale <span class="hlt">Crater</span></span></a></p> <p><a target="_blank" href="https://images.nasa.gov/">NASA Image and Video Library</a></p> <p></p> <p>2011-11-21</p> <p>Color coding in this image of Gale <span class="hlt">Crater</span> on Mars represents differences in elevation. The vertical difference from a low point inside the landing ellipse for NASA Mars Science Laboratory yellow dot to a high point on the mountain inside the <span class="hlt">crater</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20050166963','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20050166963"><span>Martian Impact <span class="hlt">Craters</span> as Revealed by MGS and Odyssey</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Barlow, N. G.</p> <p>2005-01-01</p> <p>A variety of ejecta and interior morphologies were revealed for martian impact <span class="hlt">craters</span> by Viking imagery. Numerous studies have classified these ejecta and interior morphologies and looked at how these morphologies correlate with <span class="hlt">crater</span> diameter, latitude, terrain, and elevation [1, <span class="hlt">2</span>, 3, 4]. Many of these features, particularly the layered (fluidized) ejecta morphologies and central pits, have been proposed to result when the <span class="hlt">crater</span> formed in target material containing high concentrations of volatiles. The Catalog of Large Martian Impact <span class="hlt">Craters</span> was originally derived from the Viking 1:<span class="hlt">2</span>,000,000 photomosaics and contains information on 42,283 impact <span class="hlt">craters</span> 5-km diameter distributed across the entire martian surface. The information in this Catalog has been used to study the distributions of <span class="hlt">craters</span> displaying specific ejecta and interior morphologies in an attempt to understand the environmental conditions which give rise to these features and to estimate the areal and vertical extents of subsurface volatile reservoirs [4, 5]. The Catalog is currently undergoing revision utilizing Mars Global Surveyor (MGS) and Mars Odyssey data [6]. The higher resolution multispectral imagery is resulting in numerous revisions to the original classifications and the addition of new elemental, thermophysical, and topographic data is allowing new insights into the environmental conditions under which these features form. A few of the new results from analysis of data in the revised Catalog are discussed below.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018Icar..302..296G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018Icar..302..296G"><span>A global catalogue of Ceres impact <span class="hlt">craters</span> ≥ 1 km and preliminary analysis</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gou, Sheng; Yue, Zongyu; Di, Kaichang; Liu, Zhaoqin</p> <p>2018-03-01</p> <p>The orbital data products of Ceres, including global LAMO image mosaic and global HAMO DTM with a resolution of 35 m/pixel and 135 m/pixel respectively, are utilized in this research to create a global catalogue of impact <span class="hlt">craters</span> with diameter ≥ 1 km, and their morphometric parameters are calculated. Statistics shows: (1) There are 29,219 <span class="hlt">craters</span> in the catalogue, and the <span class="hlt">craters</span> have a various morphologies, e.g., polygonal <span class="hlt">crater</span>, floor fractured <span class="hlt">crater</span>, complex <span class="hlt">crater</span> with central peak, etc.; (<span class="hlt">2</span>) The identifiable smallest <span class="hlt">crater</span> size is extended to 1 km and the <span class="hlt">crater</span> numbers have been updated when compared with the <span class="hlt">crater</span> catalogue (D ≥ 20 km) released by the Dawn Science Team; (3) The d/D ratios for fresh simple <span class="hlt">craters</span>, obviously degraded simple <span class="hlt">crater</span> and polygonal simple <span class="hlt">crater</span> are 0.11 ± 0.04, 0.05 ± 0.04 and 0.14 ± 0.02 respectively. (4) The d/D ratios for non-polygonal complex <span class="hlt">crater</span> and polygonal complex <span class="hlt">crater</span> are 0.08 ± 0.04 and 0.09 ± 0.03. The global <span class="hlt">crater</span> catalogue created in this work can be further applied to many other scientific researches, such as comparing d/D with other bodies, inferring subsurface properties, determining surface age, and estimating average erosion rate.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://images.nasa.gov/#/details-PIA15519.html','SCIGOVIMAGE-NASA'); return false;" href="https://images.nasa.gov/#/details-PIA15519.html"><span>Large Subdued and Small Fresh <span class="hlt">Craters</span></span></a></p> <p><a target="_blank" href="https://images.nasa.gov/">NASA Image and Video Library</a></p> <p></p> <p>2012-03-27</p> <p>This image from NASA Dawn spacecraft shows many large subdued <span class="hlt">craters</span> that have smaller, younger <span class="hlt">craters</span> on top of them on asteroid Vesta. There are two large subdued <span class="hlt">craters</span> in the center of the image, which have very degraded and rounded rims.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016DPS....4822304M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016DPS....4822304M"><span>Quantifying Slope Effects and Variations in <span class="hlt">Crater</span> Density across a Single Geologic Unit</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Meyer, Heather; Mahanti, Prasun; Robinson, Mark; Povilaitis, Reinhold</p> <p>2016-10-01</p> <p>Steep underlying slopes (>~5°) significantly increase the rate of degradation of <span class="hlt">craters</span> [1-3]. As a result, the density of <span class="hlt">craters</span> is less on steeper slopes for terrains of the same age [<span class="hlt">2</span>, 4]. Thus, when age-dating a planetary surface, an area encompassing one geologic unit of constant low slope is chosen. However, many key geologic units, such as ejecta blankets, lack sufficient area of constant slope to derive robust age estimates. Therefore, accurate age-dating of such units requires an accurate understanding of the effects of slope on age estimates. This work seeks to determine if the observed trend of decreasing <span class="hlt">crater</span> density with increasing slopes [<span class="hlt">2</span>] holds for <span class="hlt">craters</span> >1 km and to quantify the effect of slope for <span class="hlt">craters</span> of this size, focusing on the effect of slopes over the kilometer scale. Our study focuses on the continuous ejecta of Orientale basin, where we measure <span class="hlt">craters</span> >1 km excluding secondaries that occur as chains or clusters. Age-dating via <span class="hlt">crater</span> density measurements relies on uniform <span class="hlt">cratering</span> across a single geologic unit. In the case of ejecta blankets and other impact related surfaces, this assumption may not hold due to the formation of auto- secondary <span class="hlt">craters</span>. As such, we use LRO WAC mosaics [5], <span class="hlt">crater</span> size-frequency distributions, absolute age estimates, a 3 km slope map derived from the WAC GLD100 [6], and density maps for various <span class="hlt">crater</span> size ranges to look for evidence of non-uniform <span class="hlt">cratering</span> across the continuous ejecta of Orientale and to determine the effect of slope on <span class="hlt">crater</span> density. Preliminary results suggest that <span class="hlt">crater</span> density does decrease with increasing slope for <span class="hlt">craters</span> >1 km in diameter though at a slower rate than for smaller <span class="hlt">craters</span>.References: [1] Trask N. J. and Rowan L. C. (1967) Science 158, 1529-1535. [<span class="hlt">2</span>] Basilevsky (1976) Proc. Lunar Sci. Conf. 7th, p. 1005-1020. [3] Pohn and Offield (1970) USGS Prof. Pap., 153-162. [4] Xiao et al. (2013) Earth and Planet. Sci. Lett., 376, pgs. 1-11. doi:10.1016/j.epsl.2013</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/6775068-land-subsidence-associated-hydrocarbon-production-texas-gulf-coast','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/6775068-land-subsidence-associated-hydrocarbon-production-texas-gulf-coast"><span>Land <span class="hlt">subsidence</span> associated with hydrocarbon production, Texas Gulf Coast</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Kreitler, C.W.; White, W.A.; Akhter, M.S.</p> <p>1988-01-01</p> <p>Although ground-water withdrawal has been the predominant cause of land <span class="hlt">subsidence</span> in the Texas Gulf Coast, localized <span class="hlt">subsidence</span> and faulting have also resulted from hydrocarbon production. <span class="hlt">Subsidence</span> was documented as early as the 1920s over the Goose Creek field. Since then, <span class="hlt">subsidence</span> and/or faulting have been identified over the Saxet, South Houston, Chocolate Bayou, Hastings, Alco-Mag, Clinton, Mykawa, Blue Ridge, Webster, and Caplen oil fields. Oil-production-related <span class="hlt">subsidence</span> over these fields generally creates few environmental or engineering problems. One exception is the <span class="hlt">subsidence</span> and faulting over the Caplen oil field on Bolivar Peninsula, where more than 1,000 ac of saltwater marshmore » has been replaced by subaqueous flats. <span class="hlt">Subsidence</span> may be occurring over other fields but has not been identified because of limited releveled benchmark data. An evaluation of drill-stem and bottom-hole pressure data for the Frio Formation in Texas indicates extensive depressurization presumably from hydrocarbon production. Nearly 12,000 measurements from a pressure data base of 17,000 measurements indicate some depressurization. Some of the Frio zones have pressure declines of more than 1,500 psi from original hydrostatic conditions. <span class="hlt">Subsidence</span> and faulting may be associated with these fields in the Frio as well as other Tertiary formations where extensive hydrocarbon production and subsequent depressurization have occurred.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28872072','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28872072"><span>A phase transition caught in mid-course: independent and concomitant analyses of the monoclinic and triclinic structures of (n<span class="hlt">Bu</span>4N)[Co(orotate)<span class="hlt">2</span>(bipy)]·3H<span class="hlt">2</span>O.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Castro, Miguel; Falvello, Larry R; Forcén-Vázquez, Elena; Guerra, Pablo; Al-Kenany, Nuha A; Martínez, Gema; Tomás, Milagros</p> <p>2017-09-01</p> <p>The preparation and characterization of the n <span class="hlt">Bu</span> 4 N + salts of two bis-orotate(<span class="hlt">2</span>-) complexes of cobalt, namely bis(tetra-n-butylammonium) diaquabis(<span class="hlt">2</span>,4-dioxo-1,<span class="hlt">2</span>,3,4-tetrahydropyrimidin-1-ide-6-carboxylato-κ <span class="hlt">2</span> N 1 ,O 6 )cobalt(II) 1.8-hydrate, (C 16 H 36 N) <span class="hlt">2</span> [Co(C 5 H <span class="hlt">2</span> N <span class="hlt">2</span> O 4 ) <span class="hlt">2</span> (H <span class="hlt">2</span> O) <span class="hlt">2</span> ]·1.8H <span class="hlt">2</span> O, (1), and tetra-n-butylammonium (<span class="hlt">2,2</span>'-bipyridine-κ <span class="hlt">2</span> N,N')bis(<span class="hlt">2</span>,4-dioxo-1,<span class="hlt">2</span>,3,4-tetrahydropyrimidin-1-ide-6-carboxylato-κ <span class="hlt">2</span> N 1 ,O 6 )cobalt(III) trihydrate, (C 16 H 36 N)[Co(C 5 H <span class="hlt">2</span> N <span class="hlt">2</span> O 4 ) <span class="hlt">2</span> (C 10 H 8 N <span class="hlt">2</span> )]·3H <span class="hlt">2</span> O, (<span class="hlt">2</span>), are reported. The Co III complex, (<span class="hlt">2</span>), which is monoclinic at room temperature, presents a conservative single-crystal-to-single-crystal phase transition below 200 K, producing a triclinic twin. The transition, which involves a conformational change in one of the n <span class="hlt">Bu</span> groups of the cation, is reversible and can be cycled. Both end phases have been characterized structurally and the system was also characterized structurally in a two-phase intermediate state, using single-crystal diffraction techniques, with both the monoclinic and triclinic phases present. Thermal analysis allows a rough estimate of the small energy content, viz. 0.25 kJ mol -1 , for both the monoclinic-to-triclinic transformation and the reverse transition, in agreement with the nature of the structural changes involving only the n <span class="hlt">Bu</span> 4 N + cation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/11878353','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/11878353"><span><span class="hlt">Cratering</span> rates on the Galilean satellites.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Zahnle, K; Dones, L; Levison, H F</p> <p>1998-12-01</p> <p>We exploit recent theoretical advances toward the origin and orbital evolution of comets and asteroids to obtain revised estimates for <span class="hlt">cratering</span> rates in the jovian system. We find that most, probably more than 90%, of the <span class="hlt">craters</span> on the Galilean satellites are caused by the impact of Jupiter-family comets (JFCs). These are comets with short periods, in generally low-inclination orbits, whose dynamics are dominated by Jupiter. Nearly isotropic comets (long period and Halley-type) contribute at the 1-10% level. Trojan asteroids might also be important at the 1-10% level; if they are important, they would be especially important for smaller <span class="hlt">craters</span>. Main belt asteroids are currently unimportant, as each 20-km <span class="hlt">crater</span> made on Ganymede implies the disruption of a 200-km diameter parental asteroid, a destruction rate far beyond the resources of today's asteroid belt. Twenty-kilometer diameter <span class="hlt">craters</span> are made by kilometer-size impactors; such events occur on a Galilean satellite about once in a million years. The paucity of 20-km <span class="hlt">craters</span> on Europa indicates that its surface is of order 10 Ma. Lightly <span class="hlt">cratered</span> surfaces on Ganymede are nominally of order 0.5-1.0 Ga. The uncertainty in these estimates is about a factor of five. Callisto is old, probably more than 4 Ga. It is too heavily <span class="hlt">cratered</span> to be accounted for by the current flux of JFCs. The lack of pronounced apex-antapex asymmetries on Ganymede may be compatible with <span class="hlt">crater</span> equilibrium, but it is more easily understood as evidence for nonsynchronous rotation of an icy carapace. c 1998 Academic Press.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/4045338-high-explosive-crater-studies-desert-alluvium','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/4045338-high-explosive-crater-studies-desert-alluvium"><span>HIGH EXPLOSIVE <span class="hlt">CRATER</span> STUDIES: DESERT ALLUVIUM</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Murphey, B.F.</p> <p>1961-05-01</p> <p><span class="hlt">Crater</span> dimensions were determined for 23 explosions of 256-pound spherical TNT charges buried in desert alluvium. As opposed to previous work covering depths of burst as great as 6 feet, the work presented in this report extends knowledge of apparent <span class="hlt">crater</span> radius and depth to depths of burst as great as 30 feet. Optimum depth of burst for apparent <span class="hlt">crater</span> radius was near 10 feet and for apparent <span class="hlt">crater</span> depth near 8 feet. Surface motion photography illustrated a very great slowing down of the surface motion between depths of burst of 9.5 and 15.9 feet. <span class="hlt">Crater</span> contours, profiles, snd overheadmore » photographs are presented as illustrations. (auth)« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4201638','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4201638"><span>The Mammalian Neuronal Sodium Channel Blocker μ-Conotoxin <span class="hlt">Bu</span>IIIB has a Structured N-terminus that Influences Potency</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Kuang, Zhihe; Zhang, Min-Min; Gupta, Kallol; Gajewiak, Joanna; Gulyas, Jozsef; Balaram, Padmanabhan; Rivier, Jean E.; Olivera, Baldomero M.; Yoshikami, Doju; Bulaj, Grzegorz; Norton, Raymond S.</p> <p>2014-01-01</p> <p>Among the μ-conotoxins that block vertebrate voltage-gated sodium channels (VGSCs), some have been shown to be potent analgesics following systemic administration in mice. We have determined the solution structure of a new representative of this family, μ-<span class="hlt">Bu</span>IIIB, and established its disulfide connectivities by direct mass spectrometric collision induced dissociation fragmentation of the peptide with disulfides intact. The major oxidative folding product adopts a 1-4/<span class="hlt">2</span>-5/3-6 pattern with the following disulfide bridges: Cys5-Cys17, Cys6-Cys23 and Cys13-Cys24. The solution structure reveals that the unique N-terminal extension in μ-<span class="hlt">Bu</span>IIIB, which is also present in μ-<span class="hlt">Bu</span>IIIA and μ-<span class="hlt">Bu</span>IIIC but absent in other μ-conotoxins, forms part of a short α-helix encompassing Glu3 to Asn8. This helix is packed against the rest of the toxin and stabilized by the Cys5-Cys17 and Cys6-Cys23 disulfide bonds. As such, the side chain of Val1 is located close to the aromatic rings of Trp16 and His20, which are located on the canonical helix that displays several residues found to be essential for VGSC blockade in related μ-conotoxins. Mutations of residues <span class="hlt">2</span> and 3 in the N-terminal extension enhanced the potency of μ-<span class="hlt">Bu</span>IIIB for NaV1.3. One analog, [d-Ala<span class="hlt">2</span>]<span class="hlt">Bu</span>IIIB, showed a 40-fold increase, making it the most potent peptide blocker of this channel characterized to date and thus a useful new tool with which to characterize this channel. Based on previous results for related μ-conotoxins, the dramatic effects of mutations at the N-terminus were unanticipated, and suggest that further gains in potency might be achieved by additional modifications of this region. PMID:23557677</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA104838','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA104838"><span>Explosive <span class="hlt">Cratering</span> Performance Tests</span></a></p> <p><a target="_blank" href="http://www.dtic.mil/">DTIC Science & Technology</a></p> <p></p> <p>1981-07-02</p> <p>0.25 cm) rain bucket Sling psychrometer ± 1%, ± 10 C 3 TOP 4-<span class="hlt">2</span>-830 <span class="hlt">2</span> July 1981 ITEM REQUIR•4ENT Instrumentation Range/Minimum Accuracy Wind indicator...burial depths. History of prior excavation or disturbance among the various <span class="hlt">crater</span> sites within the test area should be comparatively equal. However</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20030111111&hterms=TURTLES&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3DTURTLES','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20030111111&hterms=TURTLES&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3DTURTLES"><span>Numerical Simulations of Silverpit <span class="hlt">Crater</span> Collapse</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Collins, G. S.; Turtle, E. P.; Melosh, H. J.</p> <p>2003-01-01</p> <p>The Silverpit <span class="hlt">crater</span> is a recently discovered, 60-65 Myr old complex <span class="hlt">crater</span>, which lies buried beneath the North Sea, about 150 km east of Britain. High-resolution images of Silverpit's subsurface structure, provided by three-dimensional seismic reflection data, reveal an inner-<span class="hlt">crater</span> morphology similar to that expected for a 5-8 km diameter terrestrial <span class="hlt">crater</span>. The <span class="hlt">crater</span> walls show evidence of terracestyle slumping and there is a distinct central uplift, which may have produced a central peak in the pristine <span class="hlt">crater</span> morphology. However, Silverpit is not a typical 5-km diameter terrestrial <span class="hlt">crater</span>, because it exhibits multiple, concentric rings outside the main cavity. External concentric rings are normally associated with much larger impact structures, for example Chicxulub on Earth, or Orientale on the Moon. Furthermore, external rings associated with large impacts on the terrestrial planets and moons are widely-spaced, predominantly inwardly-facing, asymmetric scarps. However, the seismic data show that the external rings at Silverpit represent closely-spaced, concentric fault-bound graben, with both inwardly and outwardly facing faults-carps. This type of multi-ring structure is directly analogous to the Valhalla-type multi-ring basins found on the icy satellites. Thus, the presence and style of the multiple rings at Silverpit is surprising given both the size of the <span class="hlt">crater</span> and its planetary setting.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li class="active"><span>24</span></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_24 --> <div id="page_25" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li class="active"><span>25</span></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="481"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://images.nasa.gov/#/details-PIA03794.html','SCIGOVIMAGE-NASA'); return false;" href="https://images.nasa.gov/#/details-PIA03794.html"><span>Reuyl <span class="hlt">Crater</span> Dust Avalanches</span></a></p> <p><a target="_blank" href="https://images.nasa.gov/">NASA Image and Video Library</a></p> <p></p> <p>2002-06-04</p> <p>The rugged, arcuate rim of the 90 km <span class="hlt">crater</span> Reuyl dominates this NASA Mars Odyssey image. Reuyl <span class="hlt">crater</span> is at the southern edge of a region known to be blanketed in thick dust based on its high albedo brightness and low thermal inertia values.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016HydJ...24..675F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016HydJ...24..675F"><span>Water availability and land <span class="hlt">subsidence</span> in the Central Valley, California, USA</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Faunt, Claudia C.; Sneed, Michelle; Traum, Jon; Brandt, Justin T.</p> <p>2016-05-01</p> <p>The Central Valley in California (USA) covers about 52,000 km<span class="hlt">2</span> and is one of the most productive agricultural regions in the world. This agriculture relies heavily on surface-water diversions and groundwater pumpage to meet irrigation water demand. Because the valley is semi-arid and surface-water availability varies substantially, agriculture relies heavily on local groundwater. In the southern two thirds of the valley, the San Joaquin Valley, historic and recent groundwater pumpage has caused significant and extensive drawdowns, aquifer-system compaction and <span class="hlt">subsidence</span>. During recent drought periods (2007-2009 and 2012-present), groundwater pumping has increased owing to a combination of decreased surface-water availability and land-use changes. Declining groundwater levels, approaching or surpassing historical low levels, have caused accelerated and renewed compaction and <span class="hlt">subsidence</span> that likely is mostly permanent. The <span class="hlt">subsidence</span> has caused operational, maintenance, and construction-design problems for water-delivery and flood-control canals in the San Joaquin Valley. Planning for the effects of continued <span class="hlt">subsidence</span> in the area is important for water agencies. As land use, managed aquifer recharge, and surface-water availability continue to vary, long-term groundwater-level and <span class="hlt">subsidence</span> monitoring and modelling are critical to understanding the dynamics of historical and continued groundwater use resulting in additional water-level and groundwater storage declines, and associated <span class="hlt">subsidence</span>. Modeling tools such as the Central Valley Hydrologic Model, can be used in the evaluation of management strategies to mitigate adverse impacts due to <span class="hlt">subsidence</span> while also optimizing water availability. This knowledge will be critical for successful implementation of recent legislation aimed toward sustainable groundwater use.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFMEP53B1683B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFMEP53B1683B"><span>Block Distribution Analysis of Impact <span class="hlt">Craters</span> in the Tharsis and Elysium Planitia Regions on Mars</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Button, N.; Karunatillake, S.; Diaz, C.; Zadei, S.; Rajora, V.; Barbato, A.; Piorkowski, M.</p> <p>2017-12-01</p> <p>The block distribution pattern of ejecta surrounding impact <span class="hlt">craters</span> reveals clues about their formation. Using images from High Resolution Imaging Science Experiment (HiRISE) image onboard the Mars Reconnaissance Orbiter (MRO), we indentified two rayed impact <span class="hlt">craters</span> on Mars with measurable ejecta fields to quantitatively investigate in this study. Impact <span class="hlt">Crater</span> 1 (HiRISE image PSP_008011_1975) is located in the Tharsis region at 17.41°N, 248.75°E and is 175 m in diameter. Impact <span class="hlt">Crater</span> <span class="hlt">2</span> (HiRISE image ESP_018352_1805) is located in Elysium Planitia at 0.51°N, 163.14°E and is 320 m in diameter. Our block measurements, used to determine the area, were conducted using HiView. Employing methods similar to Krishna and Kumar (2016), we compared block size and axis ratio to block distance from the center of the <span class="hlt">crater</span>, impact angle, and direction. Preliminary analysis of sixteen radial sectors around Impact <span class="hlt">Crater</span> 1 revealed that in sectors containing mostly small blocks (less than 10 m<span class="hlt">2</span>), the small blocks were ejected up to three times the diameter of the <span class="hlt">crater</span> from the center of the <span class="hlt">crater</span>. These small block-dominated sectors lacked blocks larger than 10 m<span class="hlt">2</span>. Contrastingly, in large block-dominated sectors (larger than 30 m<span class="hlt">2</span>) blocks rarely traveled farther than 200 m from the center of the <span class="hlt">crater</span>. We also seek to determine the impact angle and direction. Krishna and Kumar (2016) calculate the b-value (N(a) = Ca-b; "N(a) equals the number of fragments or <span class="hlt">craters</span> with a size greater than a, C is a constant, and -b is a power index") as a method to determine the impact direction. Our preliminary results for Impact <span class="hlt">Crater</span> 1 did not clearly indicate the impact angle. With improved measurements and the assessment of Impact <span class="hlt">Crater</span> <span class="hlt">2</span>, we will compare Impact <span class="hlt">Crater</span> 1 to Impact <span class="hlt">Crater</span> <span class="hlt">2</span> as well as assess the impact angle and direction in order to determine if the <span class="hlt">craters</span> are secondary <span class="hlt">craters</span>. Hood, D. and Karunatillake, S. (2017), LPSC, Abstract #2640 Krishna, N., and P. S</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70012357','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70012357"><span>Goat paddock cryptoexplosion <span class="hlt">crater</span>, Western Australia</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Harms, J.E.; Milton, D.J.; Ferguson, J.; Gilbert, D.J.; Harris, W.K.; Goleby, B.</p> <p>1980-01-01</p> <p>Goat Paddock, a <span class="hlt">crater</span> slightly over 5 km in diameter (18??20??? S, 126??40???E), lies at the north edge of the King Leopold Range/Mueller Range junction in the Kimberley district, Western Australia (Fig. 1). It was noted as a geological anomaly in 1964 during regional mapping by the Bureau of Mineral Resources, Geology and Geophysics and the Geological Survey of Western Australia. The possibility of its being a meteorite impact <span class="hlt">crater</span> has been discussed1, although this suggestion was subsequently ignored<span class="hlt">2</span>. Two holes were drilled by a mining corporation in 1972 to test whether kimberlite underlay the structure. Here we report the findings of five days of reconnaissance in August 1979 which established that Goat Paddock is a cryptoexplosion <span class="hlt">crater</span> containing shocked rocks and an unusually well exposed set of structural features. ?? 1980 Nature Publishing Group.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..1816516B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..1816516B"><span>Estimated Rock Abundance and Thermophysical Parameters in Oppenheimer <span class="hlt">Crater</span> on the Moon</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bauch, Karin E.; Hiesinger, Harald; Ivanov, Mikhail; van der Bogert, Carolyn H.; Pasckert, Jan-Hendrik; Weinauer, Julia</p> <p>2016-04-01</p> <p>Oppenheimer <span class="hlt">crater</span> is located in the north-east of the South Pole-Aitken basin (SPA), the largest impact structure on the Moon [e.g., 1]. The <span class="hlt">crater</span> is ˜215km in diameter and has an estimated age of ˜4.1 Ga [<span class="hlt">2</span>]. The floor of Oppenheimer shows evidence of dark mantling deposits and a concentric system of graben structures close to the rim of the <span class="hlt">crater</span> [3]. Image and topography data show that the floor is flat apart from the graben structures and subsequent impacts on the floor. Oppenheimer-<span class="hlt">U</span> (˜40km) and -H (˜35km) are floor-fractured <span class="hlt">craters</span> within the north-west and south-east portions of Oppenheimer <span class="hlt">crater</span> [3]. Dark mantling deposits on the floor are associated with the graben system. [3] estimated an age between ˜3.98Ga and ˜3.66Ga for the pyroclastic activity, based on <span class="hlt">crater</span> size-frequency distribution (CSFD) measurements on Lunar Reconnaissance Orbiter (LRO) WAC and NAC images. In this study we compare the mapping results of [3] with temperature data of the LRO Diviner experiment [4] using a numerical model [5, 6]. Nighttime temperature variations are directly influenced by the surface and subsurface thermophysical properties, namely bulk density, heat capacity, and thermal conductivity [7, 8]. These properties can be summarized to a thermal inertia, which represents the ability to conduct and store heat [8]. Low thermal inertia units, such as dust and other fine grained material, quickly respond to temperature changes, which results in large temperature amplitudes between the lunar day and night. On the other hand, high thermal inertia material, e.g. rocks or bedrock, take more time to heat up during the day and reradiate the heat during the night [8]. Relative rock abundances are derived from temperature measurements of the same location at different wavelengths. Brightness temperatures are a function of wavelength and increase with decreasing wavelength [9, 10]. This nonlinearity of the Planck radiance can be used to determine the amount of</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016NatSR...628160H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016NatSR...628160H"><span>Time-varying land <span class="hlt">subsidence</span> detected by radar altimetry: California, Taiwan and north China</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hwang, Cheinway; Yang, Yuande; Kao, Ricky; Han, Jiancheng; Shum, C. K.; Galloway, Devin L.; Sneed, Michelle; Hung, Wei-Chia; Cheng, Yung-Sheng; Li, Fei</p> <p>2016-06-01</p> <p>Contemporary applications of radar altimetry include sea-level rise, ocean circulation, marine gravity, and icesheet elevation change. Unlike InSAR and GNSS, which are widely used to map surface deformation, altimetry is neither reliant on highly temporally-correlated ground features nor as limited by the available spatial coverage, and can provide long-term temporal <span class="hlt">subsidence</span> monitoring capability. Here we use multi-mission radar altimetry with an approximately 23 year data-span to quantify land <span class="hlt">subsidence</span> in cropland areas. <span class="hlt">Subsidence</span> rates from TOPEX/POSEIDON, JASON-1, ENVISAT, and JASON-<span class="hlt">2</span> during 1992-2015 show time-varying trends with respect to displacement over time in California’s San Joaquin Valley and central Taiwan, possibly related to changes in land use, climatic conditions (drought) and regulatory measures affecting groundwater use. Near Hanford, California, <span class="hlt">subsidence</span> rates reach 18 cm yr-1 with a cumulative <span class="hlt">subsidence</span> of 206 cm, which potentially could adversely affect operations of the planned California High-Speed Rail. The maximum <span class="hlt">subsidence</span> rate in central Taiwan is 8 cm yr-1. Radar altimetry also reveals time-varying <span class="hlt">subsidence</span> in the North China Plain consistent with the declines of groundwater storage and existing water infrastructure detected by the Gravity Recovery And Climate Experiment (GRACE) satellites, with rates reaching 20 cm yr-1 and cumulative <span class="hlt">subsidence</span> as much as 155 cm.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4914853','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4914853"><span>Time-varying land <span class="hlt">subsidence</span> detected by radar altimetry: California, Taiwan and north China</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Hwang, Cheinway; Yang, Yuande; Kao, Ricky; Han, Jiancheng; Shum, C. K.; Galloway, Devin L.; Sneed, Michelle; Hung, Wei-Chia; Cheng, Yung-Sheng; Li, Fei</p> <p>2016-01-01</p> <p>Contemporary applications of radar altimetry include sea-level rise, ocean circulation, marine gravity, and icesheet elevation change. Unlike InSAR and GNSS, which are widely used to map surface deformation, altimetry is neither reliant on highly temporally-correlated ground features nor as limited by the available spatial coverage, and can provide long-term temporal <span class="hlt">subsidence</span> monitoring capability. Here we use multi-mission radar altimetry with an approximately 23 year data-span to quantify land <span class="hlt">subsidence</span> in cropland areas. <span class="hlt">Subsidence</span> rates from TOPEX/POSEIDON, JASON-1, ENVISAT, and JASON-<span class="hlt">2</span> during 1992–2015 show time-varying trends with respect to displacement over time in California’s San Joaquin Valley and central Taiwan, possibly related to changes in land use, climatic conditions (drought) and regulatory measures affecting groundwater use. Near Hanford, California, <span class="hlt">subsidence</span> rates reach 18 cm yr−1 with a cumulative <span class="hlt">subsidence</span> of 206 cm, which potentially could adversely affect operations of the planned California High-Speed Rail. The maximum <span class="hlt">subsidence</span> rate in central Taiwan is 8 cm yr−1. Radar altimetry also reveals time-varying <span class="hlt">subsidence</span> in the North China Plain consistent with the declines of groundwater storage and existing water infrastructure detected by the Gravity Recovery And Climate Experiment (GRACE) satellites, with rates reaching 20 cm yr−1 and cumulative <span class="hlt">subsidence</span> as much as 155 cm. PMID:27324935</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27324935','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27324935"><span>Time-varying land <span class="hlt">subsidence</span> detected by radar altimetry: California, Taiwan and north China.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Hwang, Cheinway; Yang, Yuande; Kao, Ricky; Han, Jiancheng; Shum, C K; Galloway, Devin L; Sneed, Michelle; Hung, Wei-Chia; Cheng, Yung-Sheng; Li, Fei</p> <p>2016-06-21</p> <p>Contemporary applications of radar altimetry include sea-level rise, ocean circulation, marine gravity, and icesheet elevation change. Unlike InSAR and GNSS, which are widely used to map surface deformation, altimetry is neither reliant on highly temporally-correlated ground features nor as limited by the available spatial coverage, and can provide long-term temporal <span class="hlt">subsidence</span> monitoring capability. Here we use multi-mission radar altimetry with an approximately 23 year data-span to quantify land <span class="hlt">subsidence</span> in cropland areas. <span class="hlt">Subsidence</span> rates from TOPEX/POSEIDON, JASON-1, ENVISAT, and JASON-<span class="hlt">2</span> during 1992-2015 show time-varying trends with respect to displacement over time in California's San Joaquin Valley and central Taiwan, possibly related to changes in land use, climatic conditions (drought) and regulatory measures affecting groundwater use. Near Hanford, California, <span class="hlt">subsidence</span> rates reach 18 cm yr(-1) with a cumulative <span class="hlt">subsidence</span> of 206 cm, which potentially could adversely affect operations of the planned California High-Speed Rail. The maximum <span class="hlt">subsidence</span> rate in central Taiwan is 8 cm yr(-1). Radar altimetry also reveals time-varying <span class="hlt">subsidence</span> in the North China Plain consistent with the declines of groundwater storage and existing water infrastructure detected by the Gravity Recovery And Climate Experiment (GRACE) satellites, with rates reaching 20 cm yr(-1) and cumulative <span class="hlt">subsidence</span> as much as 155 cm.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70174830','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70174830"><span>Time-varying land <span class="hlt">subsidence</span> detected by radar altimetry: California, Taiwan and north China</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Hwang, Cheinway; Yang, Yuande; Kao, Ricky; Han, Jiancheng; Shum, C.K.; Galloway, Devin L.; Sneed, Michelle; Hung, Wei-Chia; Cheng, Yung-Sheng; Li, Fei</p> <p>2016-01-01</p> <p>Contemporary applications of radar altimetry include sea-level rise, ocean circulation, marine gravity, and ice sheet elevation change. Unlike InSAR and GNSS, which are widely used to map surface deformation, altimetry is neither reliant on highly temporally-correlated ground features nor as limited by the available spatial coverage, and can provide long-term temporal <span class="hlt">subsidence</span> monitoring capability. Here we use multi-mission radar altimetry with an approximately 23 year data-span to quantify land <span class="hlt">subsidence</span> in cropland areas. <span class="hlt">Subsidence</span> rates from TOPEX/POSEIDON, JASON-1, ENVISAT, and JASON-<span class="hlt">2</span> during 1992–2015 show time-varying trends with respect to displacement over time in California’s San Joaquin Valley and central Taiwan, possibly related to changes in land use, climatic conditions (drought) and regulatory measures affecting groundwater use. Near Hanford, California, <span class="hlt">subsidence</span> rates reach 18 cm/yr with a cumulative <span class="hlt">subsidence</span> of 206 cm, which potentially could adversely affect operations of the planned California High-Speed Rail. The maximum <span class="hlt">subsidence</span> rate in central Taiwan is 8 cm/yr. Radar altimetry also reveals time-varying <span class="hlt">subsidence</span> in the North China Plain consistent with the declines of groundwater storage and existing water infrastructure detected by the Gravity Recovery And Climate Experiment (GRACE) satellites, with rates reaching 20 cm/yr and cumulative <span class="hlt">subsidence</span> as much as 155 cm.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.usgs.gov/sir/2006/5218/','USGSPUBS'); return false;" href="https://pubs.usgs.gov/sir/2006/5218/"><span>Interferograms showing land <span class="hlt">subsidence</span> and uplift in Las Vegas Valley, Nevada, 1992-99</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Pavelko, Michael T.; Hoffmann, Jörn; Damar, Nancy A.</p> <p>2006-01-01</p> <p>The <span class="hlt">U</span>.S. Geological Survey, in cooperation with the Nevada Department of Conservation and Natural Resources-Division of Water Resources and the Las Vegas Valley Water District, compiled 44 individual interferograms and 1 stacked interferogram comprising 29 satellite synthetic aperture radar acquisitions of Las Vegas Valley, Nevada, from 1992 to 1999. The interferograms, which depict short-term, seasonal, and long-term trends in land <span class="hlt">subsidence</span> and uplift, are viewable with an interactive map. The interferograms show that land <span class="hlt">subsidence</span> and uplift generally occur in localized areas, are responsive to ground-water pumpage and artificial recharge, and, in part, are fault controlled. Information from these interferograms can be used by water and land managers to mitigate land <span class="hlt">subsidence</span> and associated damage. Land <span class="hlt">subsidence</span> attributed to ground-water pumpage has been documented in Las Vegas Valley since the 1940s. Damage to roads, buildings, and other engineered structures has been associated with this land <span class="hlt">subsidence</span>. Land uplift attributed to artificial recharge and reduced pumping has been documented since the 1990s. Measuring these land-surface changes with traditional benchmark and Global Positioning System surveys can be costly and time consuming, and results typically are spatially and temporally sparse. Interferograms are relatively inexpensive and provide temporal and spatial resolutions previously not achievable. The interferograms are viewable with an interactive map. Landsat images from 1993 and 2000 are viewable for frames of reference to locate areas of interest and help determine land use. A stacked interferogram for 1992-99 is viewable to visualize the cumulative vertical displacement for the period represented by the individual interferograms. The interactive map enables users to identify and estimate the magnitude of vertical displacement, visually analyze deformation trends, and view interferograms and Landsat images side by side. The</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2002GeCoA..66..487L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2002GeCoA..66..487L"><span>Uranium-series dating of pedogenic silica and carbonate, <span class="hlt">Crater</span> Flat, Nevada</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ludwig, K. R.; Paces, J. B.</p> <p>2002-02-01</p> <p>A 230Th-234<span class="hlt">U</span>-238<span class="hlt">U</span> dating study on pedogenic silica-carbonate clast rinds and matrix laminae from alluvium in <span class="hlt">Crater</span> Flat, Nevada was conducted using small-sample thermal-ionization mass spectrometry (TIMS) analyses on a large suite of samples. Though the 232Th content of these soils is not particularly low (mostly 0.1-9 ppm), the high <span class="hlt">U</span> content of the silica component (mostly 4-26 ppm) makes them particularly suitable for 230Th/<span class="hlt">U</span> dating on single, 10 to 200 mg totally-digested samples using TIMS. We observed that (1) both micro- (within-rind) and macro-stratigraphic (mappable deposit) order of the 230Th/<span class="hlt">U</span> ages were preserved in all cases; (<span class="hlt">2</span>) back-calculated initial 234<span class="hlt">U</span>/238<span class="hlt">U</span> fall in a restricted range (typically 1.67±0.19), so that 234<span class="hlt">U</span>/238<span class="hlt">U</span> ages with errors of about 100 kyr (<span class="hlt">2</span>σ) could be reliably determined for the oldest, 400 to 1000 ka rinds; and (3) though 13 of the samples were >350 ka, only three showed evidence for an open-system history, even though the sensitivity of such old samples to isotopic disruption is very high. An attempt to use leach-residue techniques to separate pedogenic from detrital <span class="hlt">U</span> and Th failed, yielding corrupt 230Th/<span class="hlt">U</span> ages. We conclude that 230Th/<span class="hlt">U</span> ages determined from totally dissolved, multiple sub-mm size subsamples provide more reliable estimates of soil chronology than methods employing larger samples, chemical enhancement of 238<span class="hlt">U</span>/232Th, or isochrons.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19820038852&hterms=projectile+motion&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dprojectile%2Bmotion','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19820038852&hterms=projectile+motion&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dprojectile%2Bmotion"><span>Calculational investigation of impact <span class="hlt">cratering</span> dynamics - Material motions during the <span class="hlt">crater</span> growth period</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Austin, M. G.; Thomsen, J. M.; Ruhl, S. F.; Orphal, D. L.; Schultz, P. H.</p> <p>1980-01-01</p> <p>The considered investigation was conducted in connection with studies which are to provide a better understanding of the detailed dynamics of impact <span class="hlt">cratering</span> processes. Such an understanding is vital for a comprehension of planetary surfaces. The investigation is the continuation of a study of impact dynamics in a uniform, nongeologic material at impact velocities achievable in laboratory-scale experiments conducted by Thomsen et al. (1979). A calculation of a 6 km/sec impact of a 0.3 g spherical 2024 aluminum projectile into low strength (50 kPa) homogeneous plasticene clay has been continued from 18 microseconds to past 600 microseconds. The <span class="hlt">cratering</span> flow field, defined as the material flow field in the target beyond the transient cavity but well behind the outgoing shock wave, has been analyzed in detail to see how applicable the Maxwell Z-Model, developed from analysis of near-surface explosion <span class="hlt">cratering</span> calculations, is to impact <span class="hlt">cratering</span></p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009Icar..203...77S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009Icar..203...77S"><span>Machine cataloging of impact <span class="hlt">craters</span> on Mars</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Stepinski, Tomasz F.; Mendenhall, Michael P.; Bue, Brian D.</p> <p>2009-09-01</p> <p>This study presents an automated system for cataloging impact <span class="hlt">craters</span> using the MOLA 128 pixels/degree digital elevation model of Mars. <span class="hlt">Craters</span> are detected by a two-step algorithm that first identifies round and symmetric topographic depressions as <span class="hlt">crater</span> candidates and then selects <span class="hlt">craters</span> using a machine-learning technique. The system is robust with respect to surface types; <span class="hlt">craters</span> are identified with similar accuracy from all different types of martian surfaces without adjusting input parameters. By using a large training set in its final selection step, the system produces virtually no false detections. Finally, the system provides a seamless integration of <span class="hlt">crater</span> detection with its characterization. Of particular interest is the ability of our algorithm to calculate <span class="hlt">crater</span> depths. The system is described and its application is demonstrated on eight large sites representing all major types of martian surfaces. An evaluation of its performance and prospects for its utilization for global surveys are given by means of detailed comparison of obtained results to the manually-derived Catalog of Large Martian Impact <span class="hlt">Craters</span>. We use the results from the test sites to construct local depth-diameter relationships based on a large number of <span class="hlt">craters</span>. In general, obtained relationships are in agreement with what was inferred on the basis of manual measurements. However, we have found that, in Terra Cimmeria, the depth/diameter ratio has an abrupt decrease at ˜38°S regardless of <span class="hlt">crater</span> size. If shallowing of <span class="hlt">craters</span> is attributed to presence of sub-surface ice, a sudden change in its spatial distribution is suggested by our findings.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70012020','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70012020"><span>Earth fissures and localized differential <span class="hlt">subsidence</span></span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Holzer, Thomas L.; Pampeyan, Earl H.</p> <p>1981-01-01</p> <p>Long linear tension cracks associated with declining groundwater levels at four sites in <span class="hlt">subsiding</span> areas in south-central Arizona, Fremont Valley, California, and Las Vegas Valley, Nevada, occur near points of maximum convex-upward curvature in <span class="hlt">subsidence</span> profiles oriented perpendicular to the cracks. Profiles are based on repeated precise vertical control surveys of lines of closely spaced bench marks. Association of these fissures with zones of localized differential <span class="hlt">subsidence</span> indicates that linear earth fissures are caused by horizontal tensile strains probably resulting from localized differential compaction. Horizontal tensile strains across the fissures at the point of maximum convex-upward curvature, ranging from approximately 100 to 700 microstrains (0.01 to 0.07% per year), were indicated based on measurements with a tape or electronic distance meter.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/3871217','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/3871217"><span>Synergistic effect of concanavalin A and <span class="hlt">Bu</span>-WSA on DNA synthesis in human peripheral blood lymphocytes.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Nitta, T; Okumura, S; Nakano, M</p> <p>1985-02-01</p> <p>Butanol-extracted water soluble adjuvant (<span class="hlt">Bu</span>-WSA) obtained from Bacterionema matruchotii was not mitogenic for human peripheral blood mononuclear cells (PBM) but was capable of enhancing (3H) thymidine uptake of T cells stimulated by concanavalin A (Con A) in the presence of B cells or macrophages (M phi) in vitro. The mechanisms of the synergy of Con A and <span class="hlt">Bu</span>-WSA were studied by using separated cell populations from PBM. Both subfractioned OKT4+ and OKT8+ cells were responsive to co-stimulation by Con A and <span class="hlt">Bu</span>-WSA in the presence of an accessory cell population. Allogeneic B cells and M phi as well as autologous cells had helper function as accessory cells. Heavy irradiation with gamma-rays did not affect the function of the accessory cells, but previous treatment of B cells with anti-Ig serum plus complement (C) or treatment of M phi with anti-M phi serum plus C deprived them of their function. The treatment of accessory cells with anti-HLA-DR serum, regardless of the presence or absence of C, resulted in loss of their helper function. Cultures in Marbrook-type vessels showed that a mixed cell population of T cells and accessory cells in the lower chamber produced some active factor(s) after co-stimulation with Con A and <span class="hlt">Bu</span>-WSA, and by passing through the membrane filter separating the chambers, the factor(s) enhanced the proliferation of the Con A-activated T cell population in the upper chamber. The factor(s) was presumed to be interleukin <span class="hlt">2</span> (IL <span class="hlt">2</span>), because it supported the growth of IL <span class="hlt">2</span>-dependent CTLL cells. These results indicate that the synergy of Con A and <span class="hlt">Bu</span>-WSA on the proliferative response of human PBM is due to the elevation of growth factor production from T cells stimulated by those mitogens.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19940016309&hterms=missing&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dmissing','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19940016309&hterms=missing&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dmissing"><span>The missing impact <span class="hlt">craters</span> on Venus</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Speidel, D. H.</p> <p>1993-01-01</p> <p>The size-frequency pattern of the 842 impact <span class="hlt">craters</span> on Venus measured to date can be well described (across four standard deviation units) as a single log normal distribution with a mean <span class="hlt">crater</span> diameter of 14.5 km. This result was predicted in 1991 on examination of the initial Magellan analysis. If this observed distribution is close to the real distribution, the 'missing' 90 percent of the small <span class="hlt">craters</span> and the 'anomalous' lack of surface splotches may thus be neither missing nor anomalous. I think that the missing <span class="hlt">craters</span> and missing splotches can be satisfactorily explained by accepting that the observed distribution approximates the real one, that it is not <span class="hlt">craters</span> that are missing but the impactors. What you see is what you got. The implication that Venus crossing impactors would have the same type of log normal distribution is consistent with recently described distribution for terrestrial <span class="hlt">craters</span> and Earth crossing asteroids.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018JGRE..123..763C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018JGRE..123..763C"><span>An Assessment of Regional Variations in Martian Modified Impact <span class="hlt">Crater</span> Morphology</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Craddock, Robert A.; Bandeira, Lourenço.; Howard, Alan D.</p> <p>2018-03-01</p> <p>Impact <span class="hlt">craters</span> on Mars have been extensively modified by ancient geologic processes that may have included rainfall and surface runoff, snow and ice, denudation by lava flows, burial by eolian material, or others. Many of these processes can leave distinct signatures on the morphometry of the modified impact <span class="hlt">crater</span> as well as the surrounding landscape. To look for signs of potential regional differences in <span class="hlt">crater</span> modification processes, we conducted an analysis of different morphometric parameters related to modified impact <span class="hlt">craters</span> located in the Margaritifer Sinus, Sinus Sabaeus, Iapygia, Mare Tyrrhenum, Aeolis, and Eridania quadrangles, including depth, <span class="hlt">crater</span> wall slope, <span class="hlt">crater</span> floor slope, the curvature between the interior wall and the <span class="hlt">crater</span> floor slope, and the curvature between the interior wall and surrounding landscape. A Welch's t test analysis comparing these parameters shows that fresh impact <span class="hlt">craters</span> (Type 4) have consistent morphologies regardless of their geographic location examined in this study, which is not unexpected. Modified impact <span class="hlt">craters</span> both in the initial (Type 3) and terminal stages (Type 1) of modification also have statistically consistent morphologies. This would suggest that the processes that operated in the late Noachian were globally ubiquitous, and that modified <span class="hlt">craters</span> eventually reached a stable <span class="hlt">crater</span> morphology. However, <span class="hlt">craters</span> preserved in advanced (but not terminal) stages of modification (Type <span class="hlt">2</span>) have morphologies that vary across the quadrangles. It is possible that these variations reflect spatial differences in the types and intensity of geologic processes that operated during the Noachian, implying that the ancient climate also varied across regions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70036029','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70036029"><span>Coral reef evolution on rapidly <span class="hlt">subsiding</span> margins</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Webster, J.M.; Braga, J.C.; Clague, D.A.; Gallup, C.; Hein, J.R.; Potts, D.C.; Renema, W.; Riding, R.; Riker-Coleman, K.; Silver, E.; Wallace, L.M.</p> <p>2009-01-01</p> <p>A series of well-developed submerged coral reefs are preserved in the Huon Gulf (Papua New Guinea) and around Hawaii. Despite different tectonics settings, both regions have experienced rapid <span class="hlt">subsidence</span> (<span class="hlt">2</span>-6??m/ka) over the last 500??ka. Rapid <span class="hlt">subsidence</span>, combined with eustatic sea-level changes, is responsible for repeated drowning and backstepping of coral reefs over this period. Because we can place quantitative constraints on these systems (i.e., reef drowning age, eustatic sea-level changes, <span class="hlt">subsidence</span> rates, accretion rates, basement substrates, and paleobathymetry), these areas represent unique natural laboratories for exploring the roles of tectonics, reef accretion, and eustatic sea-level changes in controlling the evolution of individual reefs, as well as backstepping of the entire system. A review of new and existing bathymetric, radiometric, sedimentary facies and numerical modeling data indicate that these reefs have had long, complex growth histories and that they are highly sensitive, recording drowning not only during major deglaciations, but also during high-frequency, small-amplitude interstadial and deglacial meltwater pulse events. Analysis of five generalized sedimentary facies shows that reef drowning is characterized by a distinct biological and sedimentary sequence. Observational and numerical modeling data indicate that on precessional (20??ka) and sub-orbital timescales, the rate and amplitude of eustatic sea-level changes are critical in controlling initiation, growth, drowning or sub-aerial exposure, subsequent re-initiation, and final drowning. However, over longer timescales (> 100-500??ka) continued tectonic <span class="hlt">subsidence</span> and basement substrate morphology influence broad scale reef morphology and backstepping geometries. Drilling of these reefs will yield greatly expanded stratigraphic sections compared with similar reefs on slowly <span class="hlt">subsiding</span>, stable and uplifting margins, and thus they represent a unique archive of sea-level and climate</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..18.7294S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..18.7294S"><span>Proclus <span class="hlt">crater</span>: what a fresh, small <span class="hlt">crater</span> can tell about the composition of lunar Highlands</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Serventi, Giovanna; Carli, Cristian; Giacomini, Lorenza; Sgavetti, Maria</p> <p>2016-04-01</p> <p>Proclus <span class="hlt">crater</span> is a Copernican age (Apollo 15 PSR), simple and fresh <span class="hlt">crater</span>, with a diameter of 28 km. It is located on the northwest rim of Crisium basin and east of Palus Somni (16.1° N, 47.0° E). Here, we have analyzed a M3 (onboard Chandrayaan-1 mission) image (m3g20090202t024131 image) to study the composition of Proclus <span class="hlt">crater</span>. We first classified the <span class="hlt">crater</span> in different spectral regions applying the Spectral Angle Mapper (Kruse et al., 1993) method and using image-driven end-members; subsequently, the spectra representative of each region have been deconvolved applying the Modified Gaussian Model (Sunshine et al., 1990) algorithm and compared to spectral libraries consisting of well characterized terrestrial analogues, both mafic (olivine, OL, and pyroxenes, PX) and plagioclase (PL)-bearing. We recognized 5 spectral units into the <span class="hlt">crater</span>: 1) spectral unit A, characterized by an absorption band at 1250 nm, is interpreted as dominated by PL; <span class="hlt">2</span>) spectral unit B, with three absorption bands at ca. 900, 1250 and 1800 nm, where the band depth ratio between the 900 and 1250 nm bands decreases from spectral sub-unit B5 to B1, can be compared with mixtures composed with high PL content (>90%) and PX; 3) spectral unit C, characterized by two absorption bands at 900 and 1800 nm, can be interpreted as PX affected from space weathering (the band depth is less deep than band depth in PX analyzed in the laboratory) or as a mixture of 90% PL and 10% PX; 4) spectral unit D shows a broad absorption centered at 1050 nm with a shoulder at ca. 1600 nm and can be compared with OL affected from space weathering or with a mixture of 90% PL and 10% OL; 5) spectral unit E, characterized by a broad absorption with a shoulder at shorter wavelengths than in the previous unit, can be compared to the spectrum of a mixture composed of PL, OL, PX and Mg-spinel (from Gross et al., 2104). Moreover, spectral unit F has been recognized widespread into the <span class="hlt">crater</span>; this unit shows flat, red</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19950054277&hterms=epr&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Depr','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19950054277&hterms=epr&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Depr"><span>Scaling <span class="hlt">craters</span> in carbonates: Electron paramagnetic resonance analysis of shock damage</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Polanskey, Carol A.; Ahrens, Thomas J.</p> <p>1994-01-01</p> <p>Carbonate samples from the 8.9-Mt nuclear (near-surface explosion) <span class="hlt">crater</span>, OAK, and a terrestrial impact <span class="hlt">crater</span>, Meteor <span class="hlt">Crater</span>, were analyzed for shock damage using electron paramagnetic resonance (EPR). Samples from below the OAK apparent <span class="hlt">crater</span> floor were obtained from six boreholes, as well as ejecta recovered from the <span class="hlt">crater</span> floor. The degree of shock damage in the carbonate material was assessed by comparing the sample spectra to the spectra of Solenhofen and Kaibab limestone, which had been skocked to known pressures. Analysis of the OAK <span class="hlt">Crater</span> borehole samples has identified a thin zone of allocthonous highly shocked (10-13 GPa) carbonate material underneath the apparent <span class="hlt">crater</span> floor. This approx. 5- to 15-m-thick zone occurs at a maximum depth of approx. 125 m below current seafloor at the borehole, sited at the initial position of the OAK explosive, and decreases in depth towards the apparent <span class="hlt">crater</span> edge. Because this zone of allocthonous shocked rock delineates deformed rock below, and a breccia of mobilized sand and collapse debris above, it appears to outline the transient <span class="hlt">crater</span>. The transient <span class="hlt">crater</span> volume inferred in this way is found to by 3.<span class="hlt">2</span> +/- 0.<span class="hlt">2</span> times 10(exp 6)cu m, which is in good agreement with a volume of 5.3 times 10(exp 6)cu m inferred from gravity scaling of laboratory experiments. A layer of highly shocked material is also found near the surface outside the <span class="hlt">crater</span>. The latter material could represent a fallout ejecta layer. The ejecta boulders recovered from the present <span class="hlt">crater</span> floor experienced a range of shock pressures from approx. 0 to 15 GPa with the more heavily shocked samples all occurring between radii of 360 and approx. 600 m. Moreover, the fossil content, lithology and Sr isotopic composition all demonstrate that the initial position of the bulk of the heavily shocked rock ejecta sampled was originally near surface rock at initial depths in the 32 to 45-m depth (below sea level) range. 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