Science.gov

Sample records for active tectonic features

  1. Tectonic features on Titan

    NASA Astrophysics Data System (ADS)

    Cook, C.; Barnes, J.

    2011-10-01

    This research is based on the exploration of tectonic patterns on Titan from a global perspective. Several moons in the outer solar system display known stress fields driven or modified by global forces which affect patterns of tectonism. Patterns such as these are seen in Europa's tidal forces, Enceladus' tiger strips, and Ganymede's global expansion. Given its proximity to Saturn, as well as its eccentric orbit, tectonic features and global stresses may be present on Titan as well. Titan displays visible tectonic structures, such as mountain chains along its equator (Radebaugh et al. 2007), as well as the unexplored Virgae.

  2. Active tectonics

    SciTech Connect

    Not Available

    1986-01-01

    This study is part of a series of Studies in Geophysics that have been undertaken for the Geophysics Research Forum by the Geophysics Study Committee. One purpose of each study is to provide assessments from the scientific community to aid policymakers in decisions on societal problems that involve geophysics. An important part of such assessments is an evaluation of the adequacy of current geophysical knowledge and the appropriateness of current research programs as a source of information required for those decisions. The study addresses our current scientific understanding of active tectonics --- particularly the patterns and rates of ongoing tectonic processes. Many of these processes cannot be described reasonably using the limited instrumental or historical records; however, most can be described adequately for practical purposes using the geologic record of the past 500,000 years. A program of fundamental research focusing especially on Quaternary tectonic geology and geomorphology, paleoseismology, neotectonics, and geodesy is recommended to better understand ongoing, active tectonic processes. This volume contains 16 papers. Individual papers are indexed separately on the Energy Database.

  3. Elysium Region, Mars: Characterization of tectonic features

    NASA Technical Reports Server (NTRS)

    Hall, J. L.; Solomon, S. C.; Head, J. W.; Mouginis-Mark, P. J.

    1984-01-01

    In this paper the tectonic features of the Elysium region are identified and characterized. Identification of features was made using USGS controlled photomosaics (Elysium quadrangle, and portions of Amenthes and Cebrenia quadrangles); Viking Orbiter photographic data were used in individual cases to assist in identification. The positions and orientations of tectonic features can then be used, in conjunction with estimates of the mass of the volcanic load obtained from gravity modelling, to constrain the thickness of the elastic lithosphere in the region.

  4. Timing of ancient extensional tectonic features on Mars

    NASA Technical Reports Server (NTRS)

    Wichman, R.; Schultz, Peter H.

    1987-01-01

    Although numerous studies have delineated the Tharsis and post-Tharsis volcanic/tectonic history on Mars, only a few attempts have examined the earlier epochs. This is not an easy task since unambiguous crater ages for pre-Tharsis and early Tharsis units are difficult to determine owing to a variety of active surface processes. Ancient tectonic features, however, have a sufficiently large superposed crater population that should permit relative dating. A technique for crater counting along linear features analagous to areal crater density is proposed. A modification of this approach has been tested and applied to a variety of ancient tectonic features.

  5. Studies in geophysics: Active tectonics

    NASA Technical Reports Server (NTRS)

    1986-01-01

    Active tectonics is defined within the study as tectonic movements that are expected to occur within a future time span of concern to society. Such movements and their associated hazards include earthquakes, volcanic eruptions, and land subsidence and emergence. The entire range of geology, geophysics, and geodesy is, to some extent, pertinent to this topic. The needs for useful forecasts of tectonic activity, so that actions may be taken to mitigate hazards, call for special attention to ongoing tectonic activity. Further progress in understanding active tectonics depends on continued research. Particularly important is improvement in the accuracy of dating techniques for recent geologic materials.

  6. MEVTV Workshop on Tectonic Features on Mars

    NASA Technical Reports Server (NTRS)

    Watters, Thomas R. (Editor); Golombek, Matthew P. (Editor)

    1989-01-01

    The state of knowledge of tectonic features on Mars was determined and kinematic and mechanical models were assessed for their origin. Three sessions were held: wrinkle ridges and compressional structure; strike-slip faults; and extensional structures. Each session began with an overview of the features under discussion. In the case of wrinkle ridges and extensional structures, the overview was followed by keynote addresses by specialists working on similar structures on the Earth. The first session of the workshop focused on the controversy over the relative importance of folding, faulting, and intrusive volcanism in the origin of wrinkle ridges. The session ended with discussions of the origin of compressional flank structures associated with Martian volcanoes and the relationship between the volcanic complexes and the inferred regional stress field. The second day of the workshop began with the presentation and discussion of evidence for strike-slip faults on Mars at various scales. In the last session, the discussion of extensional structures ranged from the origin of grabens, tension cracks, and pit-crater chains to the origin of Valles Marineris canyons. Shear and tensile modes of brittle failure in the formation of extensional features and the role of these failure modes in the formation of pit-crater chains and the canyons of Valles Marineris were debated. The relationship of extensional features to other surface processes, such as carbonate dissolution (karst) were also discussed.

  7. Tectonism

    NASA Image and Video Library

    2011-10-24

    This image from NASA 2001 Mars Odyssey spacecraft shows evidence of tectonic stresses that deform and fracture rocks and planetary surfaces. Right angles seen here are a good indication that the feature was formed by tectonic stresses.

  8. Active tectonics and human survival strategies

    NASA Astrophysics Data System (ADS)

    King, Geoffrey; Bailey, Geoffrey; Sturdy, Derek

    1994-10-01

    Tectonic movements continuously remould the surface of Earth in response to plate motion. Yet such deformation is rarely taken into account when assessing landscape change and its impact on human land use, except perhaps as an occasional hazard to human life or a temporary disruption in the longer term patterns of human history. However, active tectonics also create and sustain landscapes that can be beneficial to human survival, forming a complex topography of potentially fertile sedimentary basins enclosed by mountain barriers that can facilitate the control and explotation of food resources, especially animal prey. We discuss the tectonic history of northwest Greece and show how the Paleolithic sites of the region are located to take advantage of tectonically created features at both a local and a regional scale. We suggest that the association of significant concentrations of early Paleolithic sites with tectonically acitve regions is not coincidental and that on the longer time spans of human biological evolution, active tectonics has been an important selective agent contributing to the development of the human species as an intelligent predator.

  9. Analysis of tectonic features in US southwest from Skylab photographs

    NASA Technical Reports Server (NTRS)

    Abdel-Gawad, M. (Principal Investigator); Tubbesing, L.

    1975-01-01

    The author has identified the following significant results. Skylab photographs were utilized to study faults and tectonic lines in selected areas of the U.S. Southwest. Emphasis was on elements of the Texas Zone in the Mojave Desert and the tectonic intersection in southern Nevada. Transverse faults believed to represent the continuation of the Texas Zone were found to be anomalous in strike. This suggests that the Mojave Desert block was rotated counterclockwise as a unit with the Sierra Nevada. Left-lateral strike-slip faults in Lake Mead area are interpreted as elements of the Wasatch tectonic zone; their anomalous trend indicates that the Lake Mead area has rotated clockwise with the Colorado Plateau. A tectonic model relating major fault zones to fragmentation and rotation of crustal blocks was developed. Detailed correlation of the high resolution S190B metric camera photographs with U-2 photographs and geologic maps demonstrates the feasibility of utilizing S190B photographs for the identification of geomorphic features associated with recent and active faults and for the assessment of seismic hazards.

  10. Ambient tectonic stress as fragile geological feature

    NASA Astrophysics Data System (ADS)

    Sleep, Norman H.

    2014-09-01

    seismic waves produce frictional failure within shallow pervasively cracked rocks. Distributed failure preferentially relaxes ambient tectonic stresses, providing a fragility measure of past strong shaking. Relaxation of the regional fault-normal compression appears to have occurred within granite from 768 m down to ˜1000-1600 m depth at the Pilot Hole near Parkfield, California. Subsequent movements on the main fault have imposed strike-slip stress within the relaxed region. Peak ground velocities of ˜2 m s-1 are inferred for infrequent (few 1000 yr recurrence) past earthquakes from stress relaxation within the granite and from the variation of S wave velocity with depth in the overlying sandstone. Conversely, frequent strong shaking in slowly deforming regions relaxes shallow ambient tectonic stress. This situation is expected beneath Whittier Narrows, where strong Love waves from numerous San Andreas events repeatedly produced nonlinear behavior.

  11. Geopotential field anomalies and regional tectonic features

    NASA Astrophysics Data System (ADS)

    Mandea, Mioara; Korte, Monika

    2016-07-01

    Maps of both gravity and magnetic field anomalies offer crucial information about physical properties of the Earth's crust and upper mantle, required in understanding geological settings and tectonic structures. Density and magnetization represent independent rock properties and thus provide complementary information on compositional and structural changes. Two regions are considered: southern Africa (encompassing South Africa, Namibia and Botswana) and Germany. This twofold choice is motivated firstly by the fact that these regions represent rather diverse geological and geophysical conditions (old Archean crust with strong magnetic anomalies in southern Africa, and much younger, weakly magnetized crust in central Europe) and secondly by our intimate knowledge of the magnetic vector ground data from these two regions. We take also advantage of the recently developed satellite potential field models and compare magnetic and gravity gradient anomalies of some 200 km resolution. Comparing short and long wavelength anomalies and the correlation of rather large scale magnetic and gravity anomalies, and relating them to known lithospheric structures, we generally find a better agreement over the southern African region than the German territory. This probably indicates a stronger concordance between near-surface and deeper structures in the former area, which can be perceived to agree with a thicker lithosphere.

  12. Lithospheric structure on Venus from tectonic modelling of compressional features

    NASA Technical Reports Server (NTRS)

    Banerdt, W. B.; Golombek, M. P.

    1987-01-01

    In previous studies, extensional models were used that incorporated realistic rheologies in order to constrain lithospheric structure. Lithospheric modelling is considered herein from the standpoint of compressional deformation. Features of presumed compressional tectonic origin are reviewed and a model for compressional folding based on lithospheric strength envelopes are presented that include the effects of both brittle and ductile yielding as well as finite elastic strength. Model predictions are then compared with the widths and spacings of observed tectonic features and it is concluded that the results are consistent with a thin crust overlying a relatively stronger mantle, with thermal gradients probably in the range of 10 to 15 deg/km.

  13. Complex Plate Tectonic Features on Planetary Bodies: Analogs from Earth

    NASA Astrophysics Data System (ADS)

    Stock, J. M.; Smrekar, S. E.

    2016-12-01

    We review the types and scales of observations needed on other rocky planetary bodies (e.g., Mars, Venus, exoplanets) to evaluate evidence of present or past plate motions. Earth's plate boundaries were initially simplified into three basic types (ridges, trenches, and transform faults). Previous studies examined the Moon, Mars, Venus, Mercury and icy moons such as Europa, for evidence of features, including linear rifts, arcuate convergent zones, strike-slip faults, and distributed deformation (rifting or folding). Yet, several aspects merit further consideration. 1) Is the feature active or fossil? Earth's active mid ocean ridges are bathymetric highs, and seafloor depth increases on either side; whereas, fossil mid ocean ridges may be as deep as the surrounding abyssal plain with no major rift valley, although with a minor gravity low (e.g., Osbourn Trough, W. Pacific Ocean). Fossil trenches have less topographic relief than active trenches (e.g., the fossil trench along the Patton Escarpment, west of California). 2) On Earth, fault patterns of spreading centers depend on volcanism. Excess volcanism reduced faulting. Fault visibility increases as spreading rates slow, or as magmatism decreases, producing high-angle normal faults parallel to the spreading center. At magma-poor spreading centers, high resolution bathymetry shows low angle detachment faults with large scale mullions and striations parallel to plate motion (e.g., Mid Atlantic Ridge, Southwest Indian Ridge). 3) Sedimentation on Earth masks features that might be visible on a non-erosional planet. Subduction zones on Earth in areas of low sedimentation have clear trench -parallel faults causing flexural deformation of the downgoing plate; in highly sedimented subduction zones, no such faults can be seen, and there may be no bathymetric trench at all. 4) Areas of Earth with broad upwelling, such as the North Fiji Basin, have complex plate tectonic patterns with many individual but poorly linked ridge

  14. Active strike-slip faulting history inferred from offsets of topographic features and basement rocks: a case study of the Arima Takatsuki Tectonic Line, southwest Japan

    NASA Astrophysics Data System (ADS)

    Maruyama, Tadashi; Lin, Aiming

    2002-01-01

    Geological, geomorphological and geophysical data have been used to determine the total displacement, slip rates and age of formation of the Arima-Takatsuki Tectonic Line (ATTL) in southwest Japan. The ATTL is an ENE-WSW-trending dextral strike-slip fault zone that extends for about 60 km from northwest of the Rokko Mountains to southwest of the Kyoto Basin. The ATTL marks a distinct topographic boundary between mountainous regions and basin regions. Tectonic landforms typically associated with active strike-slip faults, such as systematically-deflected stream channels, offset ridges and fault scarps, are recognized along the ATTL. The Quaternary drainage system shows progressive displacement along the fault traces: the greater the magnitude of stream channel, the larger the amount of offset. The maximum dextral deflection of stream channels is 600-700 m. The field data and detailed topographic analyses, however, show that pre-Neogene basement rocks on both sides of the ATTL are displaced by about 16-18 km dextrally and pre-Mio-Pliocene elevated peneplains are also offset 16-17 km in dextral along the ATTL. This suggests that the ATTL formed in the period between the development of the pre-Mio-Pliocene peneplains and deflection of the Quaternary stream channels. The geological, geomorphological and geophysical evidence presented in this study indicates that (1) the ATTL formed after the mid-Miocene, (2) the ATTL has moved as a dextral strike-slip fault with minor vertical component since its formation to late Holocene and (3) the ATTL is presently active with dextral slip rates of 1-3 mm/year and a vertical component of >0.3 mm/year. The formation of the ATTL was probably related to the opening of the Japan Sea, which is the dominant tectonic event around Japan since mid-Miocene. The case study of the ATTL provides insight into understanding the tectonic history and relationship between tectonic landforms and structures in active strike-slip faults.

  15. Photogeological analysis of Europan tectonic features

    NASA Technical Reports Server (NTRS)

    Tufts, B. R.

    1993-01-01

    Preliminary photogeological analyses of the Pelorus Linea and Sidon Flexus regions of Europa were conducted to explore the proposal by Schenk that lateral motion of crustal blocks has occurred in a 'rift zone' including possible strike-slip, tension fracturing, and geometric plate rotation about an Euler pole. These analyses revealed features interpreted as tensional structures and block rotation in a strike-slip regime consistent with the Schenk hypotheses and implied the presence of at least two stages of crustal deformation consistent with a chronology developed by Lucchitta. Confirmation of regional scale Euler pole rotation was ambiguous, however. Up to 80 kilometers of possible extension was identified in the rift zone; to accommodate this, 'cryosubduction' is speculatively proposed as a mechanism for recycling Europan 'ice lithosphere'. The cumulative width of wedge-shaped bands included in the rift zone was measured and plotted versus distance from the inferred rotation pole. Three sharp decreases in the total width were noted. These occur roughly where certain triple bands cross the rift zone suggesting that the bands are structural features that predate and influence the zone. While the curve hints at one or more sinusoidal relationships consistent with rotation geometry, given the low photographic resolution and the preliminary nature of this examination the question of whether the observations represent coherent regional rotation modified by crosscutting structures or instead imply independent local rotations separated by these structures is unanswered by this analysis.

  16. A global tectonic activity map with orbital photographic supplement

    NASA Technical Reports Server (NTRS)

    Lowman, P. D., Jr.

    1981-01-01

    A three part map showing equatorial and polar regions was compiled showing tectonic and volcanic activity of the past one million years, including the present. Features shown include actively spreading ridges, spreading rates, major active faults, subduction zones, well defined plates, and volcanic areas active within the past one million years. Activity within this period was inferred from seismicity (instrumental and historic), physiography, and published literature. The tectonic activity map was used for planning global geodetic programs of satellite laser ranging and very long base line interferometry and for geologic education.

  17. Active tectonic features and structural dynamics of the summit area of Mt. Etna (Italy) revealed by soil CO2 and soil temperature surveying

    NASA Astrophysics Data System (ADS)

    Giammanco, Salvatore; Melián, Gladys; Neri, Marco; Hernández, Pedro A.; Sortino, Francesco; Barrancos, José; López, Manuela; Pecoraino, Giovannella; Perez, Nemesio M.

    2016-02-01

    This work presents the results of an extensive geochemical survey aimed at measuring soil CO2 effluxes and soil temperatures over a large portion of Mt. Etna's summit area, coupled with an updated structural survey of the same area. The main goals of this study were i) to find concealed or hidden volcano-tectonic structures in the studied area by detecting anomalous soil gas emissions, ii) to investigate the origin of the emitted gas and the mechanism of gas and heat transport to the surface, iii) to produce a structural model based both on the surface geology and on the soil gas data and, lastly, iv) to contribute to the assessment of hazard from slope failure and crater collapses at Mt. Etna. The results revealed many concealed structural lines that followed the major directions of structural weakness in the summit area of Mt. Etna, mostly due to a combined action of gravitational spreading of the volcano and magma intrusions. Both recent and old volcano-tectonic lines were found to act as pathways for the leakage of magmatic gases to the surface. An important role in driving magmatic gases to the surface is also played by fracturing and faulting due to caldera-forming collapses and smaller crater collapses. Correlation between soil CO2 emissions and soil temperature allowed discriminating areas of active shallow hydrothermal circulation along deep fractures (characterized by high values of both parameters, but mostly soil temperature) from those affected by undeveloped fractures that did not reach the surface (characterized by high CO2 emissions at low temperature). The former corresponded to weak zones of the volcano edifice that were frequently site of past eruptions, indicating that those areas keep a high potential for future opening of eruptive fissures. The latter were likely related to sites where new eruptive fissures may open in the near future due to backward propagation of extensional tectonic stress.

  18. Comparative tectonic features on Ceres and other planetary bodies

    NASA Astrophysics Data System (ADS)

    Roatsch, T.; von der Gathen, I.; Jaumann, R.; Krohn, K.; Otto, K.; Schulzeck, F.; Williams, D. A.; Buczkowski, D.; De Sanctis, M. C.; Elgner, S.; Kersten, E.; Matz, K. D.; Naß, A.; Preusker, F.; Schenk, P.; Schroeder, S.; Stephan, K.; Wagner, R. J.; Raymond, C. A.; Russell, C. T.

    2015-12-01

    Dawn Framing Camera images of Ceres' surface indicate that tectonic processes have played an important role in the surface formation history and alterations. We study structures expected to be the result of tectonic deformation and crustal stresses, which may enable us to reconstruct the formation process of the surface and the topographic signature. Tectonic features on Ceres such as troughs, ridges, scarps, fractures, depressions and domes are analogous to those on other planetary bodies like Enceladus, Ganymede, Europa and Mercury. Comparing these surface features will provide additional information about possible scenarios of crustal formation on Ceres. First investigations show that craters, like Urvara (46°S and 249°E), display sets of trenches radiating from the craters interior. They were likely formed by extensional tectonics linked to the impact. Similar features were also found on Mercury's surface. It is expected that other tectonic deformations on Ceres also influence the appearance of craters and crater walls. Comparatively small scale fissures on Ceres' surface, frequently arranged subparallel, seem to appear in terrain that looks smooth in the images. Fractures, cracks and scarps on Ceres can be found on Enceladus, Europa and Mercury in similar patterns. The "tiger stripes" on Enceladus are possible large scale analogous. Ridges on Europa, Enceladus and Ganymede are lineaments that dominate their entire surface. Those on Ceres' however, are more irregularly shaped and less distinct. On Ceres surface troughs seem to be relatively rare. However, they show similarities to troughs on Enceladus and Mercury, and could also be related to those on Europa and Ganymede. Domes are distributed over Ceres' entire surface and have a relatively regular shape. Analogous exist on Europa (relatively irregular or with halos) and Ganymede in the crater interiors.

  19. System of tectonic features common to Earth, Mars, and Venus

    SciTech Connect

    Watters, T.R. )

    1992-07-01

    Investigations of landforms on the terrestrial planets have revealed a system of tectonic features consisting of long, narrow, regularly spaced folds and/or thrust faults, referred to as wrinkle ridges, and conjugate sets of cross-trending strike-slip faults. These are observed in the Yakima fold belt of the Columbia Plateau, Earth, the ridged plains of the Tharsis province, Mars, and the lowland plains of Lavinia Planitia, Venus. The wrinkle ridges and strike-slip faults reflect a relatively small amount of crustal shortening in these regions of distributed deformation. The observed geometric relations between the structures are consistent with those predicted by the Coulomb-Anderson model. Although the tectonic settings of the provinces studied on the three planets are very different, the crustal materials appear to have deformed in a similar manner.

  20. Lineaments on Ganymede: New evidence for late tectonic activity

    NASA Astrophysics Data System (ADS)

    Croft, S. K.

    1985-04-01

    Families of lineaments in the Gilomesh and Ninki basins of Ganymede imply post impact tectonic activity. The grooves, previously considered the youngest tectonic features, are estimated to have formed between 3.8 and 3.1 Gyr ago. One rayed crater however, is probably less than 1 Gyr old, implying tectonic activity on Ganymede has extended nearly to the present. Like the grooves, the lineaments appear to be extensional. The parallel trends and nearly contiguous associations of the lineaments with the grooves imply that both are products of the same stress systems. The young inferred age of the lineaments implies that they (and presumably also the grooves) are not associated with stresses in the cooling of fresh deposits of bright terrain, but are probably associated with underlying convective stress patterns, the long implied duration of an extensional stress regime in Ganymede's lithosphere is consistent with the stress models of derived assuming a differentiated interior.

  1. Lineaments on Ganymede: New Evidence for Late Tectonic Activity

    NASA Technical Reports Server (NTRS)

    Croft, S. K.

    1985-01-01

    Families of lineaments in the Gilomesh and Ninki basins of Ganymede imply post impact tectonic activity. The grooves, previously considered the youngest tectonic features, are estimated to have formed between 3.8 and 3.1 Gyr ago. One rayed crater however, is probably less than 1 Gyr old, implying tectonic activity on Ganymede has extended nearly to the present. Like the grooves, the lineaments appear to be extensional. The parallel trends and nearly contiguous associations of the lineaments with the grooves imply that both are products of the same stress systems. The young inferred age of the lineaments implies that they (and presumably also the grooves) are not associated with stresses in the cooling of fresh deposits of bright terrain, but are probably associated with underlying convective stress patterns, the long implied duration of an extensional stress regime in Ganymede's lithosphere is consistent with the stress models of derived assuming a differentiated interior.

  2. Preliminary correlations of MAGSAT anomalies with tectonic features of Africa

    USGS Publications Warehouse

    Hastings, David A.

    1982-01-01

    An overview of the MAGSAT scalar anomaly map for Africa has suggested a correlation of MAGSAT anomalies with major crustal blocks of uplift or depression and different degrees of regional metamorphism. The strongest MAGSAT anomalies in Africa are closely correlated spatially with major tectonic features. Although a magnetic anomaly caused by a rectangular crustal block would be offset from the block's center by the effects of magnetic inclination, an anomaly caused by real crustal blocks of varying uplift, depression, and degree of regional metamorphism would be located nearer to the locus of greatest vertical movement and highest grade of metamorphism. Thus, the Bangui anomaly may be caused by a central old Precambrian shield, flanked to the north and south by two relatively young sedimentary basins.

  3. Exploring Active Tectonics in the Dominican Republic

    NASA Astrophysics Data System (ADS)

    Carbó-Gorosabel, A.; Córdoba-Barba, D.; Martín-Dívila, J.; Granja-Bruña, J. L.; Llanes Estrada, P.; Muñoz-Martín, A.; ten Brink, U. S.

    2010-07-01

    The devastating 12 January 2010 Haiti earthquake (M = 7.0), which killed an estimated 230,000 people and caused extensive damage to homes and buildings, drew attention to the crucial need for improved knowledge of the active tectonics of the Caribbean region. But even before this disastrous event, interest in understanding the active and complex northeastern Caribbean plate boundary had been increasing, because this region has experienced significant seismic activity during the past century and has an extensively documented record of historical seismicity and tsunamis. Moreover, this is an easily accessible region in which to study the continuity of seismic faults offshore and to try to understand the transitions between strike-slip and convergent tectonic regimes. Interest in the region has led to several studies that have improved scientists' knowledge of subduction zone tectonics and earthquake and tsunami hazard assessments 005BMann et al., 2002; ten Brink et al., 2006, 2009; Grindlay et al., 2005; Manaker et al., 2008; Granja Bruña et al., 2009; Mondziel et al., 2010].

  4. Geomorphic Indices in the Assessment of Tectonic Activity in Forearc of the Active Mexican Subduction Zone

    NASA Astrophysics Data System (ADS)

    Gaidzik, K.; Ramirez-Herrera, M. T.

    2015-12-01

    Rapid development of GIS techniques and constant advancement of digital elevation models significantly improved the accuracy of extraction of information on active tectonics from landscape features. Numerous attempts were made to quantitatively evaluate recent tectonic activity using GIS and DEMs, and a set of geomorphic indices (GI), however these studies focused mainly on sub-basins or small-scale areal units. In forearc regions where crustal deformation is usually large-scale and do not concentrate only along one specific fault, an assessment of the complete basin is more accurate. We present here the first attempt to implement thirteen GI in the assessment of active tectonics of a forearc region of an active convergent margin using the entire river basins. The GIs were divided into groups: BTAI - basin geomorphic indices (reflecting areal erosion vs. tectonics) and STAI - stream geomorphic indices (reflecting vertical erosion vs. tectonics). We calculated selected indices for 9 large (> 450 km2) drainage basins. Then we categorized the obtained results of each index into three classes of relative tectonic activity: 1 - high, 2 - moderate, and 3 - low. Finally we averaged these classes for each basin to determine the tectonic activity level (TAI). The analysis for the case study area, the Guerrero sector at the Mexican subduction zone, revealed high tectonic activity in this area, particularly in its central and, to a lesser degree, eastern part. This pattern agrees with and is supported by interpretation of satellite images and DEM, and field observations. The results proved that the proposed approach indeed allows identification and recognition of areas witnessing recent tectonic deformation. Moreover, our results indicated that, even though no large earthquake has been recorded in this sector for more than 100 years, the area is highly active and may represent a seismic hazard for the region.

  5. Eastern Ishtar Terra: Tectonic evolution derived from recognized features

    NASA Technical Reports Server (NTRS)

    Vorderbruegge, R. W.; Head, James W.

    1989-01-01

    Previous analyses have recognized several styles and orientations of compressional deformation, crustal convergence, and crustal thickening in Eastern Ishtar Terra. An east to west sense of crustal convergence through small scale folding, thrusting, and buckling is reflected in the high topography and ridge-and-valley morphology of Maxwell Montes and the adjacent portion of Fortuna Tessera. This east to west convergence was accompanied by up to 1000 km of lateral motion and large scale strike-slip faulting within two converging shear zones which has resulted in the present morphology of Maxwell Montes. A more northeast to southwest sense of convergence through large scale buckling and imbrication is reflected in large, northwest-trending scarps along the entire northern boundary of Ishtar Terra, with up to 2 km of relief present at many of the scarps. It was previously suggested that both styles of compression have occurred at the expense of pre-existing tessera regions which have then been overprinted by the latest convergence event. The difference in style is attributed mostly to differences in the properties of the crust converging with the tessera blocks. If one, presumably thick, tessera block converges with another tessera region, then the widespread, distributed style of deformation occurs, as observed in western Fortuna Tessera. However, if relatively thin crust (such as suggested for the North Polar Plains converges with thicker tessera regions, then localized deformation occurs, as reflected in the scarps along Northern Ishtar Terra. The purpose is to identify the types of features observed in Eastern Ishtar Terra. Their potential temporal and spatial relationships, is described, possible origins for them is suggested, and how the interpretation of some of these features has led to the multiple-style tectonic evolution model described is shown.

  6. Tectonic Processes on Europa: Tidal Stresses and Visible Features

    NASA Astrophysics Data System (ADS)

    Greenberg, R.; Geissler, P. E.; Hoppa, G.; Tufts, B. R.; Durda, D. D.; Pappalardo, R.; Head, J. W.; Carr, M. H.; Galileo Imaging Team

    1997-07-01

    Europa's orbital eccentricity, driven by the resonance with Io and Ganymede, results in ``diurnal'' tides (3.5 day period) and possibly in non-synchronous rotation. Both diurnal variation and non-synchronous rotation can create significant stress fields on Europa's surface and both effects may produce cracking. Patterns and time-sequences of apparent tectonic features on Europa include lineaments that correlate with both sources of stress, if we take into account non-synchronous rotation after initial crack formation, by amounts ranging up to several tens of degrees. For example, the stratigraphic time sequence of features in the Cadmus and Minos Linea region is consistent with the diurnal tensile-stress field, as it evolves during tens of degrees of non-synchronous rotation. Constraints on the rotation rate from comparing Voyager and Galileo images show that significant rotation requires greater than ~ 10(5) yr, but not necessarily longer than the age of the surface as indicated by the sparse craters. Once cracking is initiated, diurnal tides work cracks so that they open and close daily. Although the daily effect is small, over 10(5) yr double ridges could plausibly be built along the cracks with sizes and morphologies consistent with observed structures, according to a model in which underlying liquid water fills the open cracks, partially freezes, and is extruded during the daily closing of the cracks. Thus several lines of observational and theoretical evidence can be integrated if we assume non-synchronous rotation and the existence of a liquid water layer.

  7. Measurements of Active Tectonic Deformation on the Guerrero Coast, Mexico

    NASA Astrophysics Data System (ADS)

    Ramirez, T.; Cundy, A.; Carranza-Edwards, A.; Morales, E.; Kostoglodov, V.; Urrutia-Fucugauchi, J.

    2004-12-01

    The study of tectonic deformation rates using displaced shoreline features is relatively well-established, and has provided much useful information on seismic hazard. Such studies have frequently been complemented by analysis of the coastal sedimentary record, where past marine to terrestrial environmental changes (and vice versa) may be recorded by clear changes in stratigraphy. Studies of this type are particularly valuable for tectonically-active areas where the preservation of former shoreline features is poor, or where long-term subsidence has resulted in their erosion, drowning or burial. The specific objective of this study is to derive rates of tectonic deformation from geomorphic and stratigraphic studies of the Guerrero coastal area, and to examine the feasibility of this stratigraphic approach in the coastal lagoons of the Mexican Pacific coast, in the Guerrero gap. The Guerrero gap coastal area, where a major earthquake is expected to occur, parallels the Cocos plate subduction zone. Here convergence rates vary from 5.2 cm/yr to 5.8 cm/yr. The Guerrero gap has experienced several historical earthquakes, notably the 1911 (7.8 Ms). However, no large magnitude events since the 1911 earthquake and only a few Ms~6 events have occurred near the Guerrero gap edges. It is expected that a major interplate earthquake of estimated magnitude Mw=8.1 to 8.4 has a high probability to occur. Landforms within the Guerrero gap indicate that the coast is subsiding. A series of key indicators such as elongated islands reminiscent of ancient barriers, submerged barriers island, extensive marshy environments, increased depths in the lagoons, and submerged anthropogenic features (shell mounds), among others, suggest active tectonic subsidence of the coast. In contrast, the adjacent northwest area off the Guerrero gap exhibits landforms characteristic of tectonic uplift (marine terraces and uplifted beach ridges), indicating a different seismo-tectonic regime northwest of the

  8. Mobilization of evaporites in tectonically active terrains

    NASA Astrophysics Data System (ADS)

    Stiros, Stathis C.

    2015-04-01

    The role of evaporites, mostly halite, during seismic sequences is investigated using evidence from certain earthquakes with magnitude between approximately 6.0 and 7.2 which occurred in the last 60 years in the Zagros Mts. (Iran) and the Ionian Sea (Greece); i.e. two seismically active areas, characterized by evaporite-associated decollements and more shallow decollements combined with mature, along-thrusts intrusions. Studied earthquakes produced either large scale surface deformation, or were covered by high-resolution and accuracy GPS and INSAR data, permitting to fully recognize the deformation pattern. In all cases an "atypical", tectonic deformation pattern was observed, ranging from apparently "impossible" patterns (thrust and normal faults, sub-parallel and homothetic; 1953 Cephalonia earthquake, Greece) to rather diffuse tectonic patterns, even to "phantom" earthquakes (Zagros). Careful analysis and modeling of the surface deformation data, in combination with the available geological, geophysical and seismological data permits to recognize, and even to quantify differences between deformation observed, and that expected in ordinary environments. In particular, it was found that during earthquakes evaporites were mobilized, and this led either to a secondary deformation of the overburden, fully detached from the basement, or to significant aseismic (post-seismic) deformation. Anomalies in the distribution of seismic intensities due to evaporitic intrusions along faults were also observed. Apart from seismological implications (unpredictable post-seismic deformation, possibly also in the far-field), these results deriving from regions at different levels of evaporitic evolution, may prove useful to understand patterns of mobilization of evaporites during periods of tectonic activity.

  9. Active tectonics coupled to fluvial erosion in the NW Himalaya

    NASA Astrophysics Data System (ADS)

    Vannay, J.-C.; Grasemann, B.; Rahn, M.; Frank, W.; Carter, A.

    2003-04-01

    Both syntaxial extremities of the Himalaya show a spatial correlation between active exhumation of deep crustal rocks and the presence of powerful rivers, the Indus and the Tsangpo-Brahmaputra, cutting across the range two of the deepest gorges on Earth. These features strongly suggests that vigorous fluvial erosion can locally enhance isostatic and tectonic uplift, which in turn contributes to heat advection and weakening of the crust, as well as to maintain steep topographic gradients [Zeitler et al., 2001]. In order to test this positive feedback model, we combined structural and geochronological data to constrain the tectono-thermal evolution along the Sutlej (NW India), the third largest river cross-cutting entirely the Himalaya. The Himalayan crystalline core zone exposed along the Sutlej Valley is composed of two gneiss sheets, that were successively underthrusted and tectonically extruded as a consequence of the foreland-directed propagation of deformation in the Indian plate margin. During Early to Middle Miocene, combined thrusting along the Main Central Thrust (MCT) and extension along the Sangla Detachment induced the rapid exhumation and cooling of the amphibolite facies to migmatitic High Himalayan Crystalline Sequence [Vannay &Grasemann, 2001]. Underthrusting beneath the MCT led to the creation of the amphibolite facies Lesser Himalayan Crystalline Sequence (LHCS). The LHCS cooled rapidly from Late Miocene to Pleistocene, as a consequence of tectonic extrusion controlled by thrusting along the Munsiari Thrust, and extension in the MCT hanging wall. This phase is still active, as indicated by: (1) cooling rates in excess of 100^oC/Myr during the past ˜3 Myr in the LHCS; (2) Holocene neo-tectonic activity; (3) present-day hydrothermal activity testifying to elevated near-surface geothermal gradients; and (4) seismic activity along the Munsiari Thrust. Modelling of fluvial erosion in the Himalaya indicate that the Sutlej Valley corresponds to the main

  10. Vertical tectonics at an active continental margin

    NASA Astrophysics Data System (ADS)

    Houlié, N.; Stern, T. A.

    2017-01-01

    Direct observations of vertical movements of the earth's surface are now possible with space-based GPS networks, and have applications to resources, hazards and tectonics. Here we present data on vertical movements of the Earth's surface in New Zealand, computed from the processing of GPS data collected between 2000 and 2015 by 189 permanent GPS stations. We map the geographical variation in vertical rates and show how these variations are explicable within a tectonic framework of subduction, volcanic activity and slow slip earthquakes. Subsidence of >3 mm/yr is observed along southeastern North Island and is interpreted to be due to the locked segment of the Hikurangi subduction zone. Uplift of 1-3 mm/yr further north along the margin of the eastern North Island is interpreted as being due to the plate interface being unlocked and underplating of sediment on the subduction thrust. The Volcanic Plateau of the central North Island is being uplifted at about 1 mm/yr, which can be explained by basaltic melts being injected in the active mantle-wedge at a rate of ∼6 mm/yr. Within the Central Volcanic Region there is a 250 km2 area that subsided between 2005 and 2012 at a rate of up to 14 mm/yr. Time series from the stations located within and near the zone of subsidence show a strong link between subsidence, adjacent uplift and local earthquake swarms.

  11. A Digital Tectonic Activity Map of the Earth

    NASA Technical Reports Server (NTRS)

    Lowman, Paul; Masuoka, Penny; Montgomery, Brian; OLeary, Jay; Salisbury, Demetra; Yates, Jacob

    1999-01-01

    The subject of neotectonics, covering the structures and structural activity of the last 5 million years (i.e., post-Miocene) is a well-recognized field, including "active tectonics," focussed on the last 500,000 years in a 1986 National Research Council report of that title. However, there is a cartographic gap between tectonic maps, generally showing all features regardless of age, and maps of current seismic or volcanic activity. We have compiled a map intended to bridge this gap, using modern data bases and computer-aided cartographic techniques. The maps presented here are conceptually descended from an earlier map showing tectonic and volcanic activity of the last one million years. Drawn by hand with the National Geographic Society's 1975 "The Physical World" map as a base, the 1981 map in various revisions has been widely reproduced in textbooks and various technical publications. However, two decades of progress call for a completely new map that can take advantage of new knowledge and cartographic techniques. The digital tectonic activity map (DTM), presented in shaded relief (Fig. 1) and schematic (Fig. 2) versions, is the result. The DTM is intended to show tectonism and volcanism of the last one million years, a period long enough to be representative of global activity, but short enough that features such as fault scarps and volcanos are still geomorphically recognizable. Data Sources and Cartographic Methods The DTM is based on a wide range of sources, summarized in Table 1. The most important is the digital elevation model, used to construct a shaded relief map. The bathymetry is largely from satellite altimetry, specifically the marine gravity compilations by Smith and Sandwell (1996). The shaded relief map was designed to match the new National Geographic Society world physical map (1992), although drawn independently, from the digital elevation model. The Robinson Projection is used instead of the earlier Van der Grinten one. Although neither

  12. Hydrocarbon Potential of the Southern Gulf of Mexico. Evidences from Tectonic Features and Oil Seeps

    NASA Astrophysics Data System (ADS)

    Padilla Y Sanch, R.

    2008-05-01

    The Gulf of Mexico has an enormous oil potential, about 104 billion barrels of oil equivalent (BBOE). From these, about 54 BBOE are in Mexican waters. Tectonic features in the sea-floor of the Gulf of Mexico (GOM) are closely related to oil seepage that have been mapped since the early 20 century, and are direct evidences of working petroleum systems, as well as that deep reservoirs are leaking oil to the surface. This could be considered an inconvenience by some, but it is known that the giant field Cantarell was named after a fisherman that reported frequently giant oil seeps offshore northward Ciudad del Carmen. Deep water exploration has become more and more important these days because of the continuously increasing oil prices. The northern half of the Gulf of Mexico today displays an unusual drilling activity, whereas in the southern part drilling activity is too low. In this research work the interest is focused on the satellite detected oil seeps, and ther coincident location with the tectonic structures shown in the new digital tectonic map of mexico.

  13. Seismic activation of tectonic stresses by mining

    NASA Astrophysics Data System (ADS)

    Marcak, Henryk; Mutke, Grzegorz

    2013-10-01

    Hard coal mining in the area of the Bytom Syncline (Upper Silesia Coal Basin, Poland) has been associated with the occurrence of high-energy seismic events (up to 109 J; local magnitude up to 4.0), which have been recorded by the local mining seismological network and regional seismological network. It has been noticed that the strongest seismic events occur when the mine longwall alignments coincide with the syncline axis. Data recorded by the improved local seismic network in the Bobrek Mine allow the estimation of the depths of the events’ hypocentres during excavation of longwall panel 3 as it approached the syncline axis. The recorded data were also used to estimate the location of the rupture surface and stress distribution in the seismic focus region. It was concluded that tectonic stresses, particularly horizontal stress components, are essential in the distribution of seismic tremors resulting from reverse faulting. The stresses induced by mining activity are only triggering tectonic deformations. The hypocentres of the strongest seismic events during mining of longwall panel 3/503 were located 300-800 m deeper than the level of coal seam 503.

  14. Active Tectonics and Seismic Potential of Alaska

    NASA Astrophysics Data System (ADS)

    Freymueller, Jeffrey T.; Haeussler, Peter J.; Wesson, Robert L.; Ekström, Göran

    This multidisciplinary monograph provides the first modern integrative summary focused on the most spectacular active tectonic systems in North America. Encompassing seismology, tectonics, geology, and geodesy, it includes papers that summarize the state of knowledge, including background material for those unfamiliar with the region; address global hypotheses using data from Alaska; and test important global hypotheses using data from this region. It is organized around four major themes: • subduction and great earthquakes at the Aleutian Arc, • the transition from strike slip to accretion and subduction of the Yakutat microplate, • the Denali fault and related structures and their role in accommodating permanent deformation of the overriding plate, and • regional integration and large-scale models and the use of data from Alaska to address important global questions and hypotheses. The book's publication near the beginning of the National Science Foundation's EarthScope project makes it especially timely because Alaska is perhaps the least understood area within the EarthScope footprint, and interest in the region can be expected to rise with time as more EarthScope data become available.

  15. Problems of the active tectonics of the Eastern Black Sea

    NASA Astrophysics Data System (ADS)

    Javakhishvili, Z.; Godoladze, T.; Dreger, D. S.; Mikava, D.; Tvaliashvili, A.

    2016-12-01

    The Black Sea Basin is the part of the Arabian Eurasian Collision zone and important unit for understanding the tectonic process of the region. This complex basin comprises two deep basins, separated by the mid-Black Sea Ridge. The basement of the Black Sea includes areas with oceanic and continental crust. It was formed as a "back-arc" basin over the subduction zone during the closing of the Tethys Ocean. In the past decades the Black Sea has been the subject of intense geological and geophysical studies. Several papers were published about the geological history, tectonics, basement relief and crustal and upper mantle structure of the basin. New tectonic schemes were suggested (e. g. Nikishin et al 2014, Shillington et al. 2008, Starostenko et al. 2004 etc.). Nevertheless, seismicity of the Black Sea is poorly studied due to the lack of seismic network in the coastal area. It is considered, that the eastern basin currently lies in a compressional setting associated with the uplift of the Caucasus and structural development of the Caucasus was closely related to the evolution of the Eastern Black Sea Basin. Analyses of recent sequence of earthquakes in 2012 can provide useful information to understand complex tectonic structure of the Eastern Black Sea region. Right after the earthquake of 2012/12/23, National Seismic monitoring center of Georgia deployed additional 4 stations in the coastal area of the country, close to the epicenter area, to monitor aftershock sequence. Seismic activity in the epicentral area is continuing until now. We have relocated approximately 1200 aftershocks to delineate fault scarf using data from Georgian, Turkish and Russian datacenters. Waveforms of the major events and the aftershocks were inverted for the fault plane solutions of the events. For the inversion were used green's functions, computed using new 1D velocity model of the region. Strike-slip mechanism of the major events of the earthquake sequence indicates extensional

  16. Tectonics

    NASA Astrophysics Data System (ADS)

    John Dewey will complete his term as editor-in-chief of Tectonics at the end of 1984. Clark Burchfiel's term as North American Editor will also end. Tectonics is published jointly with the European Geophysical Society. This newest of AGU's journals has already established itself as an important journal bridging the concerns of geophysics and geology.James A. Van Allen, president of AGU, has appointed a committee to recommend candidates for both editor-in-chief and North American editor for the 1985-1987 term.

  17. Active Tectonics in crossroads of an evolving orogen and morphological consequences: Anatolia

    NASA Astrophysics Data System (ADS)

    Koral, Hayrettin

    2016-04-01

    Anatolia lies in a curved setting of the active Alpine Mountain Range and is located in crossroads of the European and Asian terrains. It is one of the fastest deforming land in the world, manifested by seismicity, characteristic landforms and GPS measurements. Active tectonics in Anatolia provides not only a comparable geological model for the past orogens, but also a laboratory case for morphological consequences of an orogenic processes. Anatolia comprise different tectonic subsettings with its own characteristics. Northern part is influenced by tectonic characteristics of the Black Sea Basin, the Pontides and the Caucasian Range; northwestern part by the Balkanides; eastern-southeastern part by the Bitlis-Zagros suture; and south-southwestern part by the eastern Mediterranean subduction setting. Much of its present tectonic complexity was inherited from the convergence dominant plate tectonic setting of the platelets prior to the Middle-Neogene. Beginning about 11 Ma ago, the deformed and uplifted landmass unable to accommodate further deformation in Anatolia and ongoing tectonic activity gave rise to rearrangement of tectonic forces and westerly translational movements. Formation of major strike-slip faults in Anatolia including the North and East Anatolian Faults and a new platelet called the Anatolian Plate are the consequences of this episode. Such change in the tectonic regime has led to modification of previously-formed landscape, modification and sometimes termination of previously-formed basins. Evidence is present in the Plio-Quaternary stratigraphy, tectonic characteristics and morphology of the well-studied areas. This presentation will discuss active tectonic features of the northwestern, southwestern and eastern Anatolian subsettings and their influence on morphology that is closely related to sites of pre-historical human settlement.

  18. Active tectonics at the Lower Yarmouk Gorge?

    NASA Astrophysics Data System (ADS)

    Inbar, Nimrod; Raggad, Marwan; Siebert, Christian; Möller, Peter; Rödiger, Tino; Rosenthal, Eliyaho; Guttman, Josseph; Magri, Fabien

    2017-04-01

    The Lower Yarmouk Gorge (LYG) extends on the eastern margin of the Jordan Rift Valley (JRV) adjacent to the Kinneret basin which makes part in the chain of pull-apart basins along the Dead Sea Transform (DST). The LYG is bounded to the south by the Ajloun Plateau (northern Jordan) and to the north by the Golan Heights (Israel). It acts as the outflow of the Yarmouk drainage basin into the Jordan River a few kilometers south of Lake Tiberias. Although topographically the Golan Heights and the Ajloun seem to be different provinces separated by the LYG, the northern Ajloun and southern Golan form the southern flank of a major synclinal structure. Morphologically, the LYG resembles the Sheikh-Ali strike-slip fault and other NE-SW striking faults related to the DST. However, the existence of faulting along that line is debatable. As the gorge serves also as state boundary, no seismic lines cross the LYG. Quaternary landslides, mostly on the southern flank of the LYG cover possible surface evidence of faulting although Quaternary basalts located at the gorge path may indicate possible vertical pathways. Moreover, hydrological studies (Siebert et al., 2014, Goretzki et al., 2016) show that permeability anisotropy along the LYG line allows heated groundwater to emerge along the gorge with temperatures rising up to 60°C. The presented study uses well data from northern Jordan and southern Golan Heights as well as seismic data from the southern Golan Heights to bridge over the information gap. Based on the available information we present our hypothesis on the geology of the LYG aiming to contribute to the discussion regarding active tectonics at the Lower Yarmouk Gorge. Our preliminary results show that a major fault along the gorge path is dubious however, perpendicular faulting is more likely to occur. We expect the results of current research to contribute to the understanding of the local complex geohydrological system. Furthermore, results are expected to deepen our

  19. Significant Centers of Tectonic Activity as Identified by Wrinkle Ridges for the Western Hemisphere of Mars

    NASA Technical Reports Server (NTRS)

    Anderson, R.C.; Haldemann, A. F. C.; Golombek, M. P.; Franklin, B. J.; Dohm, J. M.; Lias, J.

    2000-01-01

    The western hemisphere region of Mars has been the site of numerous scientific investigations regarding its tectonic evolution. For this region of Mars, the dominant tectonic region is the Tharsis province. Tharsis is characterized by an enormous system of radiating grabens and a circumferential system of wrinkle ridges. Past investigations of grabens associated with Tharsis have identified specific centers of tectonic activity. A recent structural analysis of the western hemisphere region of Mars which includes the Tharsis region, utilized 25,000 structures to determine the history of local and regional centers of tectonic activity based primarily on the spatial and temporal relationships of extensional features. This investigation revealed that Tharsis is more structurally complex (heterogeneous) than has been previously identified: it consists of numerous regional and local centers of tectonic activity (some are more dominant and/or more long lived than others). Here we use the same approach as Anderson et al. to determine whether the centers of tectonic activity that formed the extensional features also contributed to wrinkle ridge (compressional) formation.

  20. Seismic features of regional earthquakes around the Yellow Sea and their tectonic implications

    NASA Astrophysics Data System (ADS)

    Choi, H.; Hong, T.

    2012-12-01

    The Yellow Sea belongs to the eastern Eurasian plate. It is surrounded by the eastern China and Korean Peninsula. It is known that there is a collision belt between the North and South China blocks, which may be extended to the Korean Peninsula. The location of collision around the Korean Peninsula still remains under debate. In particular, the collision location in the Yellow Sea is unclear due to limitation in physical accessibility by presence of oceanic environment and national borders. We investigate seismic features including seismicity, focal mechanism solutions and ambient stress fields around the Yellow Sea, and identify the collision location in the Yellow Sea. The focal mechanism solutions are determined by the waveform inversion and seismic wave polarity analyses. The representative ambient stress fields are induced by interpolating individual P and T axes of single events. Compared to the southeastern China, Yellow Sea and Korean Peninsula, high seismicity is found in the northeastern China. The ambient stress field around the Yellow Sea displays ENE-WSW compressional direction, which is consistently observed in the eastern China and Korean Peninsula. The strike-slip faulting events are typically expected in the eastern China, Yellow Sea and Korean Peninsula which belong to the intraplate zone. However, unusual normal faulting events with ENE-WSW directional strikes are observed in a narrow region between the Shandong Peninsula (eastern China) and the central Korean Peninsula. The observation suggests that the collision belt is extended to the Korean Peninsula across the Yellow Sea. The normal faulting region around the Yellow Sea corresponds to the region that experienced the paleo-tectonic evolution. Moderate to large earthquakes may occur in such region due to the reverse activation of the paleo-tectonic structures by current tectonic forces in the future.

  1. Elysium region, mars: Tests of lithospheric loading models for the formation of tectonic features

    SciTech Connect

    Hall, J.L.; Solomon, S.C.; Head, J.W.

    1992-10-10

    The second largest volcanic province on Mars lies in the Elysium region. Like the larger Tharsis province, Elysium is marked by a topographic rise and a broad free air gravity anomaly and also exhibits a complex assortment of tectonic and volcanic features. We test the hypothesis that the tectonic features in the Elysium region are the product of stresses produced by loading of the Martian lithosphere. We consider loading at three different scales: local loading by individual volcanoes, regional loading of the lithosphere from above or below, and quasi-global loading by Tharsis. A comparison of flexural stresses with lithospheric strength and with the inferred maximum depth of faulting confirms that concentric graben around Elysium Mons can be explained as resulting from local flexure of an elastic lithosphere about 50 km thick in response to the volcano load. Volcanic loading on a regional scale, however, leads to predicted stresses inconsistent with all observed tectonic features, suggesting that loading by widespread emplacement of thick plains deposits was not an important factor in the tectonic evolution of the Elysium region. A number of linear extensional features oriented generally NW-SE may have been the result of flexural uplift of the lithosphere on the scale of the Elysium rise. The global stress field associated with the support of the Tharsis rise appears to have influenced the development of many of the tectonic features in the Elysium region, including Cerberus Rupes and the systems of ridges in eastern and western Elysium. The comparisons of stress models for Elysium with the preserved tectonic features support a succession of stress fields operating at different times in the region.

  2. Hydrothermal and tectonic activity in northern Yellowstone Lake, Wyoming

    USGS Publications Warehouse

    Johnson, S.Y.; Stephenson, W.J.; Morgan, L.A.; Shanks, Wayne C.; Pierce, K.L.

    2003-01-01

    Yellowstone National Park is the site of one of the world's largest calderas. The abundance of geothermal and tectonic activity in and around the caldera, including historic uplift and subsidence, makes it necessary to understand active geologic processes and their associated hazards. To that end, we here use an extensive grid of high-resolution seismic reflection profiles (???450 km) to document hydrothermal and tectonic features and deposits in northern Yellowstone Lake. Sublacustrine geothermal features in northern Yellowstone Lake include two of the largest known hydrothermal explosion craters, Mary Bay and Elliott's. Mary Bay explosion breccia is distributed uniformly around the crater, whereas Elliott's crater breccia has an asymmetric distribution and forms a distinctive, ???2-km-long, hummocky lobe on the lake floor. Hydrothermal vents and low-relief domes are abundant on the lake floor; their greatest abundance is in and near explosion craters and along linear fissures. Domed areas on the lake floor that are relatively unbreached (by vents) are considered the most likely sites of future large hydrothermal explosions. Four submerged shoreline terraces along the margins of northern Yellowstone Lake add to the Holocene record or postglacial lake-level fluctuations attributed to "heavy breathing" of the Yellowstone magma reservoir and associated geothermal system. The Lake Hotel fault cuts through northwestern Yellowstone Lake and represents part of a 25-km-long distributed extensional deformation zone. Three postglacial ruptures indicate a slip rate of ???0.27 to 0.34 mm/yr. The largest (3.0 m slip) and most recent event occurred in the past ???2100 yr. Although high heat flow in the crust limits the rupture area of this fault zone, future earthquakes of magnitude ???5.3 to 6.5 are possible. Earthquakes and hydrothermal explosions have probably triggered landslides, common features around the lake margins. Few high-resolution seismic reflection surveys have

  3. Basic tectonic features of the Knipovich Ridge (North Atlantic) and its neotectonic evolution

    NASA Astrophysics Data System (ADS)

    Peive, A. A.; Chamov, N. P.

    2008-01-01

    The geological and geophysical data primarily on the structure of the upper sedimentary sequence of the northern Knipovich Ridge (Norwegian-Greenland Basin) that were obtained during Cruise 24 of the R/V Akademik Nikolai Strakhov are considered. These data indicate that the recent kinematics of the northern Knipovich Ridge is determined by dextral strike-slip displacements along the Molloy Fracture Zone (315° NW). This stress field is superimposed by a system related to rifting and latitudinal opening of rifts belonging to the ridge proper. Thus, the structural elements formed under the effect of two stress fields are combined in this district. Several stages of tectonic movements are definable. The first stage (prior to 500 ka ago) is marked by the dominant normal faults, which are overlain by the lower and upper sedimentary sequences. The second stage (prior to 120-100 ka ago) is characterized by development of normal and reverse faults, which displace the lower sequence and are overlain by the upper sequence. Both younger and older structural features reveal peaks of tectonic activity separated by intermediate quiet periods 50-60 ka long. The stress field of the regional strike-slip faulting is realized in numerous oblique NE-trending normal and normal-strike-slip faults that divide the rift valley and its walls into the segments of different sizes. Their strike (20°-30° NE) is consistent with a system of secondary antithetic sinistral strike-slip faults. The system of depressions located 40 km west of the rift valley axis may be considered a paleorift zone that is conjugated at 78°07' N and 5°20' W with the NW-trending fault marked by the main dextral offset. The stress field that existed at this stage was identical to the recent one. The rift valley axis migrated eastward to its present-day position approximately 2 Ma ago (if the spreading rate of ˜0.7 cm/yr is accepted). The obtained data substantially refine the understanding of the initial breakup of

  4. Mesozoic tectonic features of the Floridan Plateau basement

    SciTech Connect

    Lord, K.M. . Dept. of Geology)

    1993-03-01

    Digitally-filtered Bouguer gravity anomaly maps of the Floridan Plateau delineate the Mesozoic extensional basins in the southwestern half of the plateau and suggest modification of existing basement models. The extension into Florida of the Triassic South Georgia Rift is marked by a gravity low and appears to have small ancillary rift basins paralleling its southeastern border. The Jurassic Apalachicola, Tampa, and South Florida Basins are delineated by positive anomalies, possibly attributable to the emplacement of hypabyssal rocks, and are separated by the negative anomalies of the Middle Ground and Sarasota Arches. The Tampa Basin is more aerially extensive than shown on previous basement maps, extending from the Jay Fault zone to the western edge of the plateau. The South Florida Basin is likely comprised of three separate NW-trending grabens sharing a common northwestern boundary. Existing seismic reflection profiles provide a characterization of some of the boundaries of these features. All of them, with the possible exception of the Apalachicola Basin, are bounded by the Jay Fault zone, a probable Paleozoic right-lateral strike-slip zone, segments of which were reactivated during the Mesozoic to accommodate differential vertical movement related to extension.

  5. The tectonics of Mercury

    NASA Technical Reports Server (NTRS)

    Melosh, H. J.; Mckinnon, W. B.

    1988-01-01

    The probable tectonic history of Mercury and the relative sequence of events are discussed on the basis of data collected by the Mariner-10 spacecraft. Results indicate that Mercury's tectonic activity was confined to its early history; its endogenic activity was principally due to a small change in the shape of its lithosphere, caused by tidal despinning, and a small change in area caused by shrinkage due to cooling. Exogenic processes, in particular the impact activity, have produced more abundant tectonic features. Many features associated with the Caloris basin are due to loading of Mercury's thick lithosphere by extrusive lavas or subsidence due to magma withdrawal. It is emphasized that tectonic features observed on Mercury yield insight into the earliest tectonic events on planets like Mars and, perhaps, the earth, where subsequent events obscured or erased the most ancient tectonic records.

  6. Tectonics

    NASA Image and Video Library

    2015-09-04

    The graben and collapse features in this image are part of Ceraunius Fossae, which is located south of Alba Mons. Orbit Number: 60406 Latitude: 27.0278 Longitude: 249.29 Instrument: VIS Captured: 2015-07-27 14:05 http://photojournal.jpl.nasa.gov/catalog/PIA19767

  7. Recent tectonic activity on Pluto driven by phase changes in the ice shell

    NASA Astrophysics Data System (ADS)

    Hammond, Noah P.; Barr, Amy C.; Parmentier, Edgar M.

    2016-07-01

    The New Horizons spacecraft has found evidence for geologic activity on the surface of Pluto, including extensional tectonic deformation of its water ice bedrock see Moore et al. (2016). One mechanism that could drive extensional tectonic activity is global surface expansion due to the partial freezing of an ocean. We use updated physical properties for Pluto and simulate its thermal evolution to understand the survival of a possible subsurface ocean. For thermal conductivities of rock less than 3 W m-1 K-1, an ocean forms and at least partially freezes, leading to recent extensional stresses in the ice shell. In scenarios where the ocean freezes and the ice shell is thicker than 260 km, ice II forms and causes global volume contraction. Since there is no evidence for recent compressional tectonic features, we argue that ice II has not formed and that Pluto's ocean has likely survived to present day.

  8. Importance of expansion and contraction in the formation of tectonic features on the Moon

    NASA Technical Reports Server (NTRS)

    Golombek, M. P.; Banerdt, W. B.

    1993-01-01

    The lack of globally distributed tectonic features on the lunar surface has been used to argue against significant changes in the radius of the Moon since the formation of the presently observed surface, which dates to the end of heavy bombardment about 3.9 Ga. This observation has been used previously to limit the maximum stresses to approximately 100 MPa that could be supported by the lunar lithosphere without the formation of globally distributed tectonic features, which in turn limits the maximum radius changes to plus or minus 1 km for a purely elastic lithosphere. In a previous abstract, limits on the elastic expansion or contraction of the Moon were reexamined with respect to realistic failure stresses necessary to produce actual lunar tectonic features. In addition, limits on the permanent (plastic) strain that could be accommodated by non-mascon grabens and wrinkle ridges were considered with more severe constraints placed on the total reasonable expansion and contraction of the Moon since 3.9 Ga. In this abstract, considerations of the distribution and mechanisms of formation due to a planetary radius change or their accommodating much permanent plastic planetary expansion or contraction.

  9. Relief Evolution in Tectonically Active Mountain Ranges

    NASA Technical Reports Server (NTRS)

    Whipple, Kelin X.

    2004-01-01

    The overall aims of this 3-yr project, as originally proposed were to: (1) investigate quantitatively the roles of fluvial and glacial erosion in the evolution of relief in mountainous regions, and (2) test rigorously the quality and accuracy of SRTM topographic data in areas of rugged relief - both the most challenging and of greatest interest to geomorphic, neotectonic, and hazards applications. Natural laboratories in both the western US and the Southern Alps of New Zealand were identified as most promising. The project has been both successful and productive, despite the fact that no SRTM data for our primary field sites in New Zealand were released on the time frame of the work effort. Given the delayed release of SRTM data, we pursued the scientific questions of the roles of fluvial and, especially, glacial erosion in the evolution of relief in mountainous regions using available digital elevation models (DEMs) for the Southern Alps of New Zealand (available at both 25m and 50m pixel sizes), and USGS 10m and 30m DEMs within the Western US. As emphasized in the original proposal, we chose the emphasis on the role of glacial modification of topographic relief because there has been little quantitative investigation of glacial erosion processes at landscape scale. This is particularly surprising considering the dramatic sculpting of most mid- and high-latitude mountain ranges, the prodigious quantities of glacially-derived sediment in terrestrial and marine basins, and the current cross-disciplinary interest in the role of denudational processes in orogenesis and the evolution of topography in general. Moreover, the evolution of glaciated landscapes is not only a fundamental problem in geomorphology in its own right, but also is at the heart of the debate over Late Cenozoic linkages between climate and tectonics.

  10. Geomorphic signatures of active tectonics in the Trans-Yamuna segment of the western Doon valley, northwest Himalaya, India

    NASA Astrophysics Data System (ADS)

    Philip, George; Sah, Madho P.

    Being involved in the late orogenic movements of the sub-Himalaya, the Doon valley and its Quaternary formations have received considerable attention from Earth scientists in the study of active tectonics and paleoseismic events. Study of aerial photographs and satellite data, and selected field checks not only confirmed neotectonic features already reported by various authors but also revealed the presence of more such features. In response to active tectonics, these features have affected very young terraces and Quaternary sediments in the Trans-Yamuna segment of the Doon valley in the western sub-Himalaya. In the present study, an attempt has been made to understand the neotectonic implications of these movements on landforms in and around Sataun-Sirmuri Tal. Ground evidence indicates that the area has experienced at least three major tectonic impulses since the generation of the Main Boundary Thrust. The major tectonic disturbances are most likely due to co-seismic activity along the ongoing Himalayan tectonic processes. In this paper, we discuss some of the strong geomorphic signatures, such as lineament and active fault traces, pressure ridges, sag ponds, alluvial fans, river terraces and finally landslides, which are indicative of active tectonics in this area. On the basis of the present-day geomorphic configuration of this sub-Himalayan basin, a possible evolutionary history is also presented.

  11. Structural features of northern Tarim basin: Implications for regional tectonics and petroleum traps

    SciTech Connect

    Dong Jia; Juafu Lu; Dongsheng Cai

    1998-01-01

    The rhombus-shaped Tarim basin in northwestern China is controlled mainly by two left-lateral strike-slip systems: the northeast-trending Altun fault zone along its southeastern side and the northeast-trending Aheqi fault zone along its northwestern side. In this paper, we discuss the northern Tarim basin`s structural features, which include three main tectonic units: the Kalpin uplift, the Kuqa depression, and the North Tarim uplift along the northern margin of the Tarim basin. Structural mapping in the Kalpin uplift shows that a series of imbricated thrust sheets have been overprinted by strike-slip faulting. The amount of strike-slip displacement is estimated to be 148 km by restoration of strike-slip structures in the uplift. The Kuqa depression is a Mesozoic-Cenozoic foredeep depression with well-developed flat-ramp structures and fault-related folds. The Baicheng basin, a Quaternary pull-apart basin, developed at the center of the Kuqa depression. Subsurface structures in the North Tarim uplift can be divided into the Mesozoic-Cenozoic and the Paleozoic lithotectonic sequences in seismic profiles. The Paleozoic litho-tectonic sequence exhibits the interference of earlier left-lateral and later right-lateral strike-slip structures. Many normal faults in the Mesozoic-Cenozoic litho-tectonic sequence form the negative flower structures in the North Tarim uplift; these structures commonly directly overlie the positive flower structures in the Paleozoic litho-tectonic sequence. The interference regions of the northwest-trending and northeast-trending folds in the Paleozoic tectonic sequence have been identified to have the best trap structures. Our structural analysis indicates that the Tarim basin is a transpressional foreland basin rejuvenated during the Cenozoic.

  12. Data for Quaternary faults, liquefaction features, and possible tectonic features in the Central and Eastern United States, east of the Rocky Mountain Front

    USGS Publications Warehouse

    Crone, Anthony J.; Wheeler, Russell L.

    2000-01-01

    The USGS is currently leading an effort to compile published geological information on Quaternary faults, folds, and earthquake-induced liquefaction in order to develop an internally consistent database on the locations, ages, and activity rates of major earthquake-related features throughout the United States. This report is the compilation for such features in the Central and Eastern United States (CEUS), which for the purposes of the compilation, is defined as the region extending from the Rocky Mountain Front eastward to the Atlantic seaboard. A key objective of this national compilation is to provide a comprehensive database of Quaternary features that might generate strong ground motion and therefore, should be considered in assessing the seismic hazard throughout the country. In addition to printed versions of regional and individual state compilations, the database will be available on the World-Wide Web, where it will be readily available to everyone. The primary purpose of these compilations and the derivative database is to provide a comprehensive, uniform source of geological information that can by used to complement the other types of data that are used in seismic-hazard assessments. Within our CEUS study area, which encompasses more than 60 percent of the continuous U.S., we summarize the geological information on 69 features that are categorized into four classes (Class A, B, C, and D) based on what is known about the feature's Quaternary activity. The CEUS contains only 13 features of tectonic origin for which there is convincing evidence of Quaternary activity (Class A features). Of the remaining 56 features, 11 require further study in order to confidently define their potential as possible sources of earthquake-induced ground motion (Class B), whereas the remaining features either lack convincing geologic evidence of Quaternary tectonic faulting or have been studied carefully enough to determine that they do not pose a significant seismic hazard

  13. Tectonic, a novel regulator of the Hedgehog pathway required for both activation and inhibition

    PubMed Central

    Reiter, Jeremy F.; Skarnes, William C.

    2006-01-01

    We report the identification of a novel protein that participates in Hedgehog-mediated patterning of the neural tube. This protein, named Tectonic, is the founding member of a previously undescribed family of evolutionarily conserved secreted and transmembrane proteins. During neural tube development, mouse Tectonic is required for formation of the most ventral cell types and for full Hedgehog (Hh) pathway activation. Epistasis analyses reveal that Tectonic modulates Hh signal transduction downstream of Smoothened (Smo) and Rab23. Interestingly, characterization of Tectonic Shh and Tectonic Smo double mutants indicates that Tectonic plays an additional role in repressing Hh pathway activity. PMID:16357211

  14. Tectonic, a novel regulator of the Hedgehog pathway required for both activation and inhibition.

    PubMed

    Reiter, Jeremy F; Skarnes, William C

    2006-01-01

    We report the identification of a novel protein that participates in Hedgehog-mediated patterning of the neural tube. This protein, named Tectonic, is the founding member of a previously undescribed family of evolutionarily conserved secreted and transmembrane proteins. During neural tube development, mouse Tectonic is required for formation of the most ventral cell types and for full Hedgehog (Hh) pathway activation. Epistasis analyses reveal that Tectonic modulates Hh signal transduction downstream of Smoothened (Smo) and Rab23. Interestingly, characterization of Tectonic Shh and Tectonic Smo double mutants indicates that Tectonic plays an additional role in repressing Hh pathway activity.

  15. The seismicity of Ethiopia; active plate tectonics

    USGS Publications Warehouse

    Mohr, P.

    1981-01-01

    Ethiopia, descended from the semimythical Kingdom of Punt, lies at the strategic intersection of Schmidt's jigsaw puzzle where the Red Sea, Gulf of Aden, and the African Rift System meet. Because of geologically recent uplift combined with rapid downcutting erosion by rivers, notably the Blue Nile (Abbay), Ethiopia is the most mountainous country in Africa. It is also the most volcanically active, while its historical seismicity matches that of the midocean ridges. And, in a sense, Ethiopia is host to an evoloving ocean ridge system. 

  16. Northeast Basin and Range province active tectonics: An alternative view

    SciTech Connect

    Westaway, R. )

    1989-09-01

    Slip rates and slip vector azimuths on major active oblique normal faults are used to investigate whether circulation associated with the Yellowstone upwelling plume is driving tectonic deformation in the northeast Basin and Range province. Observed deformation is consistent with this suggestion; the plume is sheared to the southwest by motion of the North American plate. Testable predictions are made for structure and evolution of the region.

  17. Active tectonic studies in the United States, 1987-1990

    SciTech Connect

    Weldon, R.J., II )

    1991-01-01

    The techniques and instrumentation used in active tectonic studies are discussed, and recent results are reviewed. It is suggested that a critical mass of data on several particular regions has been accumulated, making possible critical debates and attempts to assess earthquake hazards. Particular attention is given to studies of the Pacific Northwest region, basin and range deformation studies, and distributed deformation and hidden earthquake sources. Also included is a comprehensive bibliography for the period.

  18. Volcanic, tectonic, and hydrothermal features identified in the Lau Basin with near-bottom multibeam sonar data

    NASA Astrophysics Data System (ADS)

    Ferrini, V. L.; Tivey, M. K.; Carbotte, S. M.; Martinez, F.

    2007-12-01

    We present high-resolution bathymetric maps of six hydrothermal vent fields located along the Eastern Lau Spreading Center and Valu Fa Ridge in the Lau backarc basin. Generated with near-bottom SM2000 multibeam sonar data collected with ROV Jason 2, these maps provide sufficient detail to quantify tectonic, volcanic, and hydrothermal features that reveal important differences in these hydrothermal systems, their geologic settings, and the nature of their volcanic substrate. The Kilo Moana and Tow Cam vent fields, hosted in basaltic substrate, have bathymetric characteristics that distinguish them from the Mariner and Vai Lili fields that are hosted in andesitic substrate. The basalt-hosted vent fields are located on relatively flat seafloor crosscut by extensive faults and fissures. At these sites, the high-resolution bathymetry indicates that volcanic activity pre-dates tectonic activity. Pillow and lobate flows at these sites can be discerned as sub-meter roughness, with amplitudes of 0.1- 0.4 m over length scales of 0.5-1 m. Vent structures (5-15 m tall) are clearly identifiable. In contrast, the andesite- hosted vent fields have more relief, and roughness is evident as finger-like flow fronts related to more viscous andesitic flows. Volcanic domes (15-30 m diameter), some with collapse craters (10-20 m diameter), are also evident at these vent fields. Hydrothermal structures at Mariner are as tall as 25m, while at Vai Lili vents are smaller and difficult to distinguish from the rough seafloor that surrounds them. The detailed bathymetry at these vent fields is consistent with the tectonic activity pre-dating volcanic activity. The bathymetric features documented at the ABE and Tui Malila vent fields are transitional to the contrasting features observed to the north (at Kilo Moana and Tow Cam) and south (Mariner and Vai Lili). Bathymetric maps from ABE and Tui Malila reveal pillow and lobate flows, faults that post-date volcanic activity, finger-like flow fronts

  19. Constraints on the lithospheric structure of Venus from mechanical models and tectonic surface features

    NASA Technical Reports Server (NTRS)

    Zuber, Maria T.

    1987-01-01

    The evidence for the extensional or compressional origins of some prominent Venusian surface features disclosed by radar images is discussed. Using simple models, the hypothesis that the observed length scales (10-20 km and 100-300 km) of deformations are controlled by dominant wavelengths arising from unstable compression or extension of the Venus lithosphere is tested. The results show that the existence of tectonic features that exhibit both length scales can be explained if, at the time of deformation, the lithosphere consisted of a crust that was relatively strong near the surface and weak at its base, and an upper mantle that was stronger than or nearly comparable in strength to the upper crust.

  20. Geological evidence and future detection of active tectonics on Mars.

    NASA Astrophysics Data System (ADS)

    Pio Rossi, Angelo; Hauber, Ernst; Spagnuolo, Mauro; Fueten, Frank; Pondrelli, Monica; Breuer, Doris; Grott, Matthias; Knapmeyer, Martin; Quantin Nataf, Cathy; Unnithan, Vikram

    2013-04-01

    Accumulating evidence shows that recent tectonic deformation affected discrete areas on Mars (e.g. Spagnuolo et al., 2011; Roberts et al., 2012): Steep scarps cut bedrock and unconsolidated deposits, including mass wasting and eolian materials. The crater size frequency-based age estimate for some of these scarps, e.g. in Aureum Chaos is a few Myr only. The case for recent or very recent volcanism is sound on Mars (e.g. Hauber et al., 2011; Neukum et al., 2004), but comparably young tectonics on Mars had not been discovered until recently. Areas with linear or curvilinear, steep fault-like scarps (e.g., in Aureum or Aram Chaos) are relatively far from large volcanic edifices and provinces with recent effusive activity. Hence, a direct volcano-tectonic link, e.g., with Tharsis, seems unlikely. On the other hand, late collapses and subsidence in ~Hesperian or younger chaos/chasma areas could be responsible for the local deformation, which appears to be mainly extensional. Reactivation of older structures is also a possibility. Regardless the actual mechanism and geodynamic setting, present tectonic activity on Mars is a very real possibility, and it would open a range of opportunities for research such as geodynamics, hazards for future exploration, resources and exobiological potential: present faulting in chasmata and chaotic terrains could offer pathways for subsurface fluids to reach the surface or near subsurface, including potential degassing. Future missions such as InSight (NASA) and potentially Mars Network Science Mission (MNSM, ESA) could detect the first signs of Mars's tectonic activity. In addition, ESA ExoMars Trace Gas Orbiter could also investigate any potential outgassing in the vicinity of recently faulted candidate areas. References: Hauber et al. (2011) GLR, 38, 10, 1944-8007, doi:10.1029/2011GL047310 Neukum et al. (2004) Nature, 432, 971-979, doi:10.1038/nature03231 Roberts, G. P., et al. (2012), JGR, 117, E02009, doi:10.1029/2011JE003816

  1. Active Tectonics: Part 2: Epeirogenic and intraplate movements

    NASA Astrophysics Data System (ADS)

    Brown, L. D.; Reilinger, R. E.

    The major deformations of the Earth's surface are largely consistent with the tenets of plate tectonics, which predict that such activity should be focused at the various boundaries along which massive lithospheric plates collide, pull apart, or slide past one another. Yet crustal deformations also occur well into the interior of these plates. Some may represent the distributed effects of distant plate boundaries, as, for example, the earthquakes of the intermontane western United States. Some, such as the geodetically observed uplift over a deep magma chamber in the Rio Grande rift of New Mexico, may correspond to incipient foundation of a new plate boundary. Others, like the subtle, broad uplifts and subsidences in the nominally stable cratonic interiors, are much more puzzling. Such motions often appear estranged, if not divorced, from accepted plate-tectonic processes. Postglacial rebound, a well-known phenomenon in portions of North America and Europe, also appears to be an inadequate explanation for many observations. Understanding contemporary motions of plate interiors is often hindered by the paucity and uncertain accuracy of relevant geophysical and geodetic observations. Yet intraplate tectonics constitutes more than a scientific enigma. Even seemingly slow vertical motions may threaten river courses or seafront properties on socially relevant time scales, and the subtle strain accumulating elsewhere may portend future earthquakes or volcanoes in the least predictable places.

  2. Tectonic activity and the evolution of submarine canyons: The Cook Strait Canyon system, New Zealand

    NASA Astrophysics Data System (ADS)

    Micallef, Aaron; Mountjoy, Joshu; Barnes, Philip; Canals, Miquel; Lastras, Galderic

    2016-04-01

    Submarine canyons are Earth's most dramatic erosional features, comprising steep-walled valleys that originate in the continental shelf and slope. They play a key role in the evolution of continental margins by transferring sediments into deep water settings and are considered important biodiversity hotspots, pathways for nutrients and pollutants, and analogues of hydrocarbon reservoirs. Although comprising only one third of continental margins worldwide, active margins host more than half of global submarine canyons. We still lack of thorough understanding of the coupling between active tectonics and submarine canyon processes, which is necessary to improve the modelling of canyon evolution in active margins and derive tectonic information from canyon morphology. The objectives of this study are to: (i) understand how tectonic activity influences submarine canyon morphology, processes, and evolution in an active margin, and (2) formulate a generalised model of canyon development in response to tectonic forcing based on morphometric parameters. We fulfil these objectives by analysing high resolution geophysical data and imagery from Cook Strait Canyon system, offshore New Zealand. Using these data, we demonstrate that tectonic activity, in the form of major faults and structurally-generated tectonic ridges, leaves a clear topographic signature on submarine canyon location and morphology, in particular their dendritic and sinuous planform shapes, steep and linear longitudinal profiles, and cross-sectional asymmetry and width. We also report breaks/changes in canyon longitudinal slope gradient, relief and slope-area regression models at the intersection with faults. Tectonic activity gives rise to two types of knickpoints in the Cook Strait Canyon. The first type consists of low slope gradient, rounded and diffusive knickpoints forming as a result of short wavelength folds or fault break outs and being restored to an equilibrium profile by upstream erosion and

  3. Tectonic activity evolution of the Scotia-Antarctic Plate boundary from mass transport deposit analysis

    NASA Astrophysics Data System (ADS)

    Pérez, Lara F.; Bohoyo, Fernando; Hernández-Molina, F. Javier; Casas, David; Galindo-Zaldívar, Jesús; Ruano, Patricia; Maldonado, Andrés.

    2016-04-01

    The spatial distribution and temporal occurrence of mass transport deposits (MTDs) in the sedimentary infill of basins and submerged banks near the Scotia-Antarctic plate boundary allowed us to decode the evolution of the tectonic activity of the relevant structures in the region from the Oligocene to present day. The 1020 MTDs identified in the available data set of multichannel seismic reflection profiles in the region are subdivided according to the geographic and chronological distributions of these features. Their spatial distribution reveals a preferential location along the eastern margins of the eastern basins. This reflects local deformation due to the evolution of the Scotia-Antarctic transcurrent plate boundary and the impact of oceanic spreading along the East Scotia Ridge (ESR). The vertical distribution of the MTDs in the sedimentary record evidences intensified regional tectonic deformation from the middle Miocene to Quaternary. Intensified deformation started at about 15 Ma, when the ESR progressively replaces the West Scotia Ridge (WSR) as the main oceanic spreading center in the Scotia Sea. Coevally with the WSR demise at about 6.5 Ma, increased spreading rates of the ESR and numerous MTDs were formed. The high frequency of MTDs during the Pliocene, mainly along the western basins, is also related to greater tectonic activity due to uplift of the Shackleton Fracture Zone by tectonic inversion and extinction of the Antarctic-Phoenix Ridge and involved changes at late Pliocene. The presence of MTDs in the southern Scotia Sea basins is a relevant indicator of the interplay between sedimentary instability and regional tectonics.

  4. The nature and origin of periodically spaced tectonic features on Mars

    NASA Technical Reports Server (NTRS)

    Watters, Thomas R.

    1991-01-01

    The final report on the nature and origin of periodically spaced tectonic features on Mars is presented. The focus of this investigation was to characterize and model the periodically spaced wrinkle ridges observed in ridged plains material on Mars. The investigation centered on the wrinkle ridges in ridged plains material on the Tharsis Plateau. Wrinkle ridges are interpreted to be structural in origin, resulting from buckling followed by reverse or thrust faulting of the ridged plains material. The study extended beyond Tharsis to other ridged plains units, particularly those in Hesperia Planum. As a corollary, an analysis of the spacing of the anticlinal ridges of the Yakima Fold Belt of the Columbia Plateau in the NW United States was undertaken.

  5. Satellite Elevation Magnetic and Gravity Models of Major South American Plate Tectonic Features

    NASA Technical Reports Server (NTRS)

    Vonfrese, R. R. B.; Hinze, W. J.; Braile, L. W.; Lidiak, E. G.; Keller, G. R. (Principal Investigator); Longacre, M. B.

    1984-01-01

    Some MAGSAT scalar and vector magnetic anomaly data together with regional gravity anomaly data are being used to investigate the regional tectonic features of the South American Plate. An initial step in this analysis is three dimensional modeling of magnetic and gravity anomalies of major structures such as the Andean subduction zone and the Amazon River Aulacogen at satellite elevations over an appropriate range of physical properties using Gaus-Legendre quadrature integration method. In addition, one degree average free-air gravity anomalies of South America and adjacent marine areas are projected to satellite elevations assuming a spherical Earth and available MAGSAT data are processed to obtain compatible data sets for correlation. Correlation of these data sets is enhanced by reduction of the MAGSAT data to radial polarization because of the profound effect of the variation of the magnetic inclination over South America.

  6. Early thermal profiles and lithospheric strength of Ganymede from extensional tectonic features

    SciTech Connect

    Golombek, M.P.; Banerdt, W.B.

    1986-11-01

    The early thermal profiles and the lithospheric stability and strength of Ganymede are quantitatively determined on the basis of brittle lithosphere thickness estimates derived from the width and spacing of extensional tectonic features, together with lithospheric strength envelopes for ice. Plots of the brittle and ductile yield stress vs. depth for the icy lithosphere of Ganymede exhibit a linear increase in brittle strength with depth to a maximum at the brittle-ductile transition that is followed by an exponential decrease in ductile yield stress with depth. The results obtained imply that the thermal gradient and lithospheric strength have varied laterally by factor as great as 5, and that Ganymede underwent cooling in a highly inhomogeneous fashion with lateral thermal anomalies. The present analysis furnishes reasons for the stability of large cratered terrain remnants. 47 references.

  7. Early thermal profiles and lithospheric strength of Ganymede from extensional tectonic features

    NASA Technical Reports Server (NTRS)

    Golombek, Matthew P.; Banerdt, W. Bruce

    1986-01-01

    The early thermal profiles and the lithospheric stability and strength of Ganymede are quantitatively determined on the basis of brittle lithosphere thickness estimates derived from the width and spacing of extensional tectonic features, together with lithospheric strength envelopes for ice. Plots of the brittle and ductile yield stress vs. depth for the icy lithosphere of Ganymede exhibit a linear increase in brittle strength with depth to a maximum at the brittle-ductile transition that is followed by an exponential decrease in ductile yield stress with depth. The results obtained imply that the thermal gradient and lithospheric strength have varied laterally by factor as great as 5, and that Ganymede underwent cooling in a highly inhomogeneous fashion with lateral thermal anomalies. The present analysis furnishes reasons for the stability of large cratered terrain remnants.

  8. Seismic imaging of major tectonic features in the crust of Phanerozoic eastern Australia

    NASA Astrophysics Data System (ADS)

    Finlayson, D. M.; Wake-Dyster, K. D.; Leven, J. H.; Johnstone, D. W.; Murray, C. G.; Harrington, H. J.; Korsch, R. J.; Wellman, P.

    1990-02-01

    Crustal architecture can be recognised from Seismic fabric characteristics and velocity information. Across Phanerozoic eastern Australia, three major crustal sub-divisions are identified from data in southern Queensland. They occur under (west to east) the Nebine Ridge, Taroom Trough and New England Fold Belt, with each crustal sub-division having its own internal architecture but separated by major bounding structures (geosutures). These features are assessed against evolutionary models for the region. The significant conclusions are as follows: (1)The Nebine Ridge forms the southeastern part of the Thomson Fold Belt but has a crustal architecture distinctly different from that under the central part of the fold belt, tentatively supporting an evolutionary model involving fragmentation and eastward stretching and thinning of a Precambrian Australian craton. The ridge crust has possibly been considerably altered by Carboniferous plutonism and compressional events. (2)Between the Nebine Ridge and the crust under the Taroom Trough of the Bowen Basin there is a major low-angle (5-10°) geosuture (the Foyleview geosuture), which extends from upper to lower crustal levels along a series of prominent horizons. It was probably active during the major Carboniferous tectonism which severely structured Devonian basins west of the Nebine Ridge. The geosuture forms the southeastern boundary of the Thomson Fold Belt. (3)The crustal architecture under the Taroom Trough has little obvious structure above an outstanding Moho transition zone. However, the prominent Meandarra Gravity Ridge striking along the trough axis highlights the possibility of high-density mafic volcanics within the crust and the probability of a rift model being appropriate early in the trough's history. The sedimentary basin architecture supports the concept of an early extensional history for the crust within a poorly defined, N-S trending, strike-slip regime. (4)Between the Taroom Trough and the New

  9. Tectonic and Aqueous Processes in the Formation of Mass-wasting Features on Mars and Earth

    NASA Astrophysics Data System (ADS)

    Watkins, Jessica

    2015-10-01

    Fundamental to the advancement of planetary geology is an understanding of the interaction between tectonic and aqueous processes on planetary surfaces. This dissertation examines this interaction within two geomorphologic processes: landslide emplacement, on Mars and on Earth, and the formation of seasonal slope features on Mars. Long-runout landsliding in equatorial Valles Marineris, Mars is among the most prominent geomorphic occurrences shaping the canyon. However, the mechanism of landslide long-distance transport, and the highly debated role of water therein, remains elusive. Through systematic mapping of high-resolution satellite images, integrated with spectral analysis, we show that hydrated silicates played a decisive role in facilitating landslide transport by lubricating the basal sliding zone. This conclusion implies that clay minerals, generated by ancient water-rock interactions, exert a long-lasting influence on Mars surface processes. The Eureka Valley (EV) landslide is an unexamined, well-preserved long-runout landslide in arid southeast Eureka Valley, California. The field, photogeologic, spectral, and luminescence dating investigation presented here support initiation as a result of fault-generated fracture during the mid to early Holocene at minimum, and transport lubricated by the presence of basal clays, characterized by 3-D internal deformation, as the most likely EV landslide emplacement mechanism. This geomorphological characterization may be applied to long-runout landslides on Earth and other planetary surfaces, suggesting that their emplacement likely does not require the participation of water. Recurring slope lineae (RSL) are seasonal, narrow, low-albedo features extending down steep, equator-facing Mars slopes. RSL formation has been largely attributed to the seepage of near-surface water, though its source is not well understood. Through detailed analysis of high-resolution satellite images of RSL geologic contexts, we quantify the

  10. Inferring tectonic activity using drainage network and RT model: an example from the western Himalayas, India

    NASA Astrophysics Data System (ADS)

    Sahoo, Ramendra; Jain, Vikrant

    2017-04-01

    Morphology of the landscape and derived features are regarded to be an important tool for inferring about tectonic activity in an area, since surface exposures of these subsurface processes may not be available or may get eroded away over time. This has led to an extensive research in application of the non-planar morphological attributes like river long profile and hypsometry for tectonic studies, whereas drainage network as a proxy for tectonic activity has not been explored greatly. Though, significant work has been done on drainage network pattern which started in a qualitative manner and over the years, has evolved to incorporate more quantitative aspects, like studying the evolution of a network under the influence of external and internal controls. Random Topology (RT) model is one of these concepts, which elucidates the connection between evolution of a drainage network pattern and the entropy of the drainage system and it states that in absence of any geological controls, a natural population of channel networks will be topologically random. We have used the entropy maximization principle to provide a theoretical structure for the RT model. Furthermore, analysis was carried out on the drainage network structures around Jwalamukhi thrust in the Kangra reentrant in western Himalayas, India, to investigate the tectonic activity in the region. Around one thousand networks were extracted from the foot-wall (fw) and hanging-wall (hw) region of the thrust sheet and later categorized based on their magnitudes. We have adopted the goodness of fit test for comparing the network patterns in fw and hw drainage with those derived using the RT model. The null hypothesis for the test was, the drainage networks in the fw are statistically more similar than those on the hw, to the network patterns derived using the RT model for any given magnitude. The test results are favorable to our null hypothesis for networks with smaller magnitudes (< 9), whereas for larger

  11. Drilling to investigate processes in active tectonics and magmatism

    NASA Astrophysics Data System (ADS)

    Shervais, J.; Evans, J.; Toy, V.; Kirkpatrick, J.; Clarke, A.; Eichelberger, J.

    2014-12-01

    Coordinated drilling efforts are an important method to investigate active tectonics and magmatic processes related to faults and volcanoes. The US National Science Foundation (NSF) recently sponsored a series of workshops to define the nature of future continental drilling efforts. As part of this series, we convened a workshop to explore how continental scientific drilling can be used to better understand active tectonic and magmatic processes. The workshop, held in Park City, Utah, in May 2013, was attended by 41 investigators from seven countries. Participants were asked to define compelling scientific justifications for examining problems that can be addressed by coordinated programs of continental scientific drilling and related site investigations. They were also asked to evaluate a wide range of proposed drilling projects, based on white papers submitted prior to the workshop. Participants working on faults and fault zone processes highlighted two overarching topics with exciting potential for future scientific drilling research: (1) the seismic cycle and (2) the mechanics and architecture of fault zones. Recommended projects target fundamental mechanical processes and controls on faulting, and range from induced earthquakes and earthquake initiation to investigations of detachment fault mechanics and fluid flow in fault zones. Participants working on active volcanism identified five themes: the volcano eruption cycle; eruption sustainability, near-field stresses, and system recovery; eruption hazards; verification of geophysical models; and interactions with other Earth systems. Recommended projects address problems that are transferrable to other volcanic systems, such as improved methods for identifying eruption history and constraining the rheological structure of shallow caldera regions. Participants working on chemical geodynamics identified four major themes: large igneous provinces (LIPs), ocean islands, continental hotspot tracks and rifts, and

  12. Active tectonics of central-western Caucasus, Georgia

    NASA Astrophysics Data System (ADS)

    Tsereteli, N.; Tibaldi, A.; Alania, V.; Gventsadse, A.; Enukidze, O.; Varazanashvili, O.; Müller, B. I. R.

    2016-11-01

    This work contributes to a better knowledge of potentially seismogenic faults of the Georgia Greater and Lesser Caucasus by evaluating the distribution of earthquake foci, active tectonic stress field, kinematics and geometry of main fault planes. We consider all the information coming from field structural geology, geomorphology, seismological data from historical and instrumental catalogues, seismic reflection sections, as well as new focal mechanism solutions. These data enable recognizing some active ENE-WSW reverse faults in the core of the Greater Caucasus that are parallel to the mountain range. At the southernmost front of the Greater Caucasus, a series of main thrusts dipping towards NNE are active, with up to hundreds-km-long segments; along this thrust zone, a potentially locked segment is present, about 90 km long. The studied section of the Lesser Caucasus has active structures along the northern front given by south-dipping thrusts, as well as in the central core where strike-slip and oblique faults coexist. The Transcaucasian depression between the two mountain ranges shows an ongoing inversion tectonics of the central part of the Rioni Basin where active N- to NE-dipping reverse faults are present, accompanied by clear evidence of uplift of a wide area. The data are coherent with a N-S to NNE-SSW contraction of the central-western Greater Caucasus and Lesser Caucasus. Although in general the seismicity decreases westward in terms of number of earthquakes and magnitude, seismological and geological structural data in the Rioni Basin indicate here a Quaternary propagation of deformation towards the west.

  13. Areas of Unsolved Problems in Caribbean Active Tectonics

    NASA Astrophysics Data System (ADS)

    Mann, P.

    2015-12-01

    I review some unsolved problems in Caribbean active tectonics. At the regional and plate scale: 1) confirm the existence of intraplate deformation zones of the central Caribbean plate that are within the margin of error of ongoing GPS measurements; 2) carry out field studies to evaluate block models versus models for distributed fault shear on the densely populated islands of Jamaica, Hispaniola, Puerto Rico, and the Virgin Islands; 3) carry out paleoseismological research of key plate boundary faults that may have accumulated large strains but have not been previously studied in detail; 4) determine the age of onset and far-field effects of the Cocos ridge and the Central America forearc sliver; 4) investigate the origin and earthquake-potential of obliquely-sheared rift basins along the northern coast of Venezuela; 5) determine the age of onset and regional active, tectonic effects of the Panama-South America collision including the continued activation of the Maracaibo block; and 6) validate longterm rates on active subduction zones with improving, tomographic maps of subducted slabs. At the individual fault scale: 1) determine the mode of termination of large and active strike -slip faults and application of the STEP model (Septentrional, Polochic, El Pilar, Bocono, Santa Marta-Bucaramanaga); 2) improve the understanding of the earthquake potential on the Enriquillo-Plantain Garden fault zone given "off-fault" events such as the 2010 Haiti earthquake; how widespread is this behavior?; and 3) estimate size of future tsunamis from studies of historic or prehistoric slump scars and mass transport deposits; what potential runups can be predicted from this information?; and 4) devise ways to keep rapidly growing, circum-Caribbean urban populations better informed and safer in the face of inevitable and future, large earthquakes.

  14. Piazzi On Ceres and Pacific On Earth Are Tectonically Comparable Features

    NASA Astrophysics Data System (ADS)

    Kochemasov, G.

    Earth is more than 10 times larger than Ceres but the wave planetary tectonics [1] is not perplexed with this. Theorem 1 states that "Celestial bodies are dichotomic". This theorem is valid for bodies of various sizes, compositions and physical states. What is common for all of them that they are moving, moving in non-circular orbits, and rotate. These properties are sufficient for invoking inertia forces making celestial bodies oscillate and acquire a convexo-concave shape. of the recent planetological achievements three should be mentioned particularly as they concern small celestial bodies where general rules of body shaping are expressed very sharply. A small aster- oid 433 Eros, the largest asteroid 1 Ceres and Borrelli comet were studied in different scales but all of them have essential features predicted by the wave planetology. The convexo-concave shape of asteroid Eros (stony, 33 km long) is repeated in comet Bor- relli (icy, 8 km long). Borrelli's convex hemisphere is sharply jagged because of exten- sion. The same is observed on Eros ("saddle") but in a lesser degree. Borrelli's concave strongly contracted hemisphere is a source of a large complexly built tail of expulsion. This extruded material samples interior of the comet and leaves whitish spots in the centre of the concave side. Eros also have many signes of past degassing in a form of regular net of pits (craters); in the centre of the concave side is a large complexly built crater Psych. Both oblong bodies -Eros and Borrelli - have different opposite ends: blunt and sharp, predicted by the wave planetology (the Arctic-Antarctic symp- tom). The oblong body of Ceres (major/minor axes of 898/788 km [2] and 970/ 930 km,[Parker &Stern]) according to HST (J.Parker &Stern) has a prominent dusky dark spot (Piazzi) from one side. It occupies a significant part of the asteroid (about 250 km, more than a quarter the size of Ceres) and probably might be assigned to a depression. Tectonically one may compare

  15. Magnetotelluric impedance tensor analysis for identification of transverse tectonic feature in the Wagad uplift, Kachchh, northwest India

    NASA Astrophysics Data System (ADS)

    Pavan Kumar, G.; Kumar, Virender; Nagar, Mehul; Singh, Dilip; Mahendar, E.; Patel, Pruthul; Mahesh, P.

    2017-07-01

    The 2001 Bhuj earthquake (Mw 7.7) occurred in northwestern region of Indian peninsula has reactivated a couple of transverse faults to its surroundings. Intermediate to moderate magnitude earthquakes are occurring along these faults which includes recent Dholavira earthquake (Mw 5.1, 2012) suggesting distinct tectonic scenario in the region. We present the results of magnetotelluric (MT) impedance tensors analyses of 18 sites located along a profile cutting various faults in the uplifted Wagad block of the Kachchh basin. The MT time series of 4-5 days recording duration have been processed and the earth response functions are estimated in broad frequency range (0.01-1000 s). The observed impedance tensors are analyzed by using three decomposition techniques as well as by the phase tensor method constraining with the induction arrows. The analyses suggest distinct tectonic feature within the block bounded by the South Wagad Fault (SWF) and the North Wagad Fault (NWF) particularly in the period band of 1-10 s. In the south of NWF, the telluric vectors and the major axes of the phase ellipses are aligned in the NNW-SSE to NW-SE direction where as a dominant E-W strike is obtained for northern side of the NWF. The transverse geo-electric strike coincides with the prominent clustering of seismicity after the Bhuj earthquake and trend of the Manfara transverse fault is located in close vicinity of the study area. We therefore suggest the presence NNW-SSE trending transverse structural feature in the Wagad uplift of the basin appears to play significant role in the current seismicity of the active intraplate region.

  16. Elastic lithosphere thickness on the moon from mare tectonic features - A formal inversion

    NASA Technical Reports Server (NTRS)

    Comer, R. P.; Solomon, S. C.; Head, J. W.

    1979-01-01

    The thickness (T) of the lunar elastic lithosphere at the time (3.6 to 3.8 billion years ago) of the earliest preserved basalt flows in circular mare basins can be estimated by inverting the observed locations of extensional tectonic features in and surrounding the maria. In performing the inversion, the lithosphere is modeled as an elastic shell with a liquid interior, and the basalt load for each mare is approximated by a set of concentric cylinders. To permit solving the forward problem of placing radial limits on the positions of the rilles around a given mare, an additional parameter F, the ratio of the radial stress at the radial limits to the maximum radial stress, is introduced. T and F are chosen to give the best weighted-squares fit of the radial limits to the observations, and are used as the initial values in a linearized matrix inversion to check the resolution and estimate errors. The application of the procedure to three maria with prominent extensional features, Humorum, Orientale, and Serenitatis, gives values of T from about 40 + or - 10 to 50 + or - 10 km, and in each case the linearized matrix equation has an exact inverse.

  17. Elastic lithosphere thickness on the moon from mare tectonic features - A formal inversion

    NASA Technical Reports Server (NTRS)

    Comer, R. P.; Solomon, S. C.; Head, J. W.

    1979-01-01

    The thickness (T) of the lunar elastic lithosphere at the time (3.6 to 3.8 billion years ago) of the earliest preserved basalt flows in circular mare basins can be estimated by inverting the observed locations of extensional tectonic features in and surrounding the maria. In performing the inversion, the lithosphere is modeled as an elastic shell with a liquid interior, and the basalt load for each mare is approximated by a set of concentric cylinders. To permit solving the forward problem of placing radial limits on the positions of the rilles around a given mare, an additional parameter F, the ratio of the radial stress at the radial limits to the maximum radial stress, is introduced. T and F are chosen to give the best weighted-squares fit of the radial limits to the observations, and are used as the initial values in a linearized matrix inversion to check the resolution and estimate errors. The application of the procedure to three maria with prominent extensional features, Humorum, Orientale, and Serenitatis, gives values of T from about 40 + or - 10 to 50 + or - 10 km, and in each case the linearized matrix equation has an exact inverse.

  18. Activities for Plate Tectonics using GeoMapApp

    NASA Astrophysics Data System (ADS)

    Goodwillie, A. M.

    2016-12-01

    The concept of plate tectonics is a fundamental component of our understanding of how Earth works yet authentic, high-quality geoscience data related to plate tectonics may not be readily available to all students. To compound matters, when data is accessible, students may not possess the skills or resources necessary to explore and analyse it. As a result, much emphasis at federal and state level is now placed upon encouraging students to work with more data and more technology more often and more rigourously. Easy-to-use digital platforms offer much potential for promoting inquiry-based learning at all levels of education. GeoMapApp is one such tool. Developed at Columbia University's Lamont-Doherty Earth Observatory, GeoMapApp (http://www.geomapapp.org) is a free resource that integrates a wide range of research-grade geoscience data in one intuitive map-based interface. Simple strategies for data manipulation, visualisation and presentation allow uses to explore the data in meaningful ways. Layering and transparency capabilities further allow learners to use GeoMapApp to compare multiple data sets at once, and high-impact Save Session functionality allows a GeoMapApp project to be saved for sharing or later use. In this presentation, activities related to plate tectonics will be highlighted. One GeoMapApp activity helps students investigate plate boundaries by exploring earthquake and volcano locations. Another requires students to calculate the rate of seafloor spreading using crustal age data in various ocean basins. A third uses the GeoMapApp layering technique to explore the influence of geological forces in shaping the landscape. Each activity shown can be done by students on an individual basis, as pairs, or as groups. Educators report that student use of GeoMapApp fosters an increased sense of data "ownership" amongst students, promotes STEM skills, and provides them with access to authentic research-grade geoscience data using the same cutting

  19. Detection and Analysis of Deep Seated Gravitational Slope Deformation and Relations with the Active Tectonics

    NASA Astrophysics Data System (ADS)

    Moro, M.; Saroli, M.; Lancia, M.; Albano, M.; Lo Sardo, L.; Stramondo, S.

    2015-12-01

    Modern geomorphological investigations focused on the definition of major factors conditioning the landscape evolution. The interaction of some of these factors as the litho-structural setting, the local relief, the tectonic activity, the climatic conditions and the seismicity plays a key-role in determining large scale slope instability phenomena which display the general morphological features of deep seated gravitational deformations (DSGD). The present work aims to detect the large scale gravitational deformation and relations with the active tectonics affecting the Abruzzo Region and to provide a description of the morphologic features of the deformations by means of aerial photograph interpretation, geological/geomorphological field surveys and DInSAR data. The investigated areas are morphologically characterized by significant elevation changes due to the presence of high mountain peaks, separated from surrounding depressed areas by steep escarpments, frequently represented by active faults. Consequently, relief energy favours the development of gravity-driven deformations. These deformations seem to be superimposed on and influenced by the inherited structural and tectonic pattern, related to the sin- and post-thrusting evolution. The morphological evidences of these phenomena, are represented by landslides, sackungen or rock-flows, lateral spreads and block slides. DInSAR analysis measured deformation of the large scale gravitative phenomena previously identified through aerial-photo analysis. DSGD may evolve in rapid, catastrophic mass movements and this paroxistic evolution of the deformations may be triggered by high magnitude seismic events. These assumptions point out the great importance of mapping in detail large scale slope instability phenomena in relation to the active faults, in a perspective of land-use planning such as the Abruzzo Region characterized by a high magnitude historical seismicity.

  20. Hydrothermal fluids circulation and travertine deposition in an active tectonic setting: Insights from the Kamara geothermal area (western Anatolia, Turkey)

    NASA Astrophysics Data System (ADS)

    Brogi, Andrea; Alçiçek, M. Cihat; Yalçıner, Cahit Çağlar; Capezzuoli, Enrico; Liotta, Domenico; Meccheri, Marco; Rimondi, Valentina; Ruggieri, Giovanni; Gandin, Anna; Boschi, Chiara; Büyüksaraç, Aydin; Alçiçek, Hülya; Bülbül, Ali; Baykara, Mehmet Oruç; Shen, Chuan-Chou

    2016-06-01

    Coexistence of thermal springs, travertine deposits and tectonic activity is a recurring feature for most geothermal areas. Although such a certainty, their relationships are debated mainly addressing on the role of the tectonic activity in triggering and controlling fluids flow and travertine deposition. In this paper, we present the results of an integrated study carried out in a geothermal area located in western Anatolia (Turkey), nearby the well-known Pamukkale area (Denizli Basin). Our study focused on the relationships among hydrothermal fluids circulation, travertine deposition and tectonic activity, with particular emphasis on the role of faults in controlling fluids upwelling, thermal springs location and deposition of travertine masses. New field mapping and structural/kinematics analyses allowed us to recognize two main faults systems (NW- and NE-trending), framed in the Neogene-Quaternary extensional tectonic evolution of western Anatolia. A geo-radar (GPR) prospection was also provided in a key-area, permitting us to reconstruct a buried fault zone and its relationships with the development of a fissure-ridge travertine deposit (Kamara fissure-ridge). The integration among structural and geophysical studies, fluids inclusion, geochemical, isotopic data and 230 Th/238 U radiometric age determination on travertine deposits, depict the characteristics of the geothermal fluids and their pathway, up to the surface. Hydrological and seismological data have been also taken in account to investigate the relation between local seismicity and fluid upwelling. As a main conclusion we found strict relationships among tectonic activity, earthquakes occurrence, and variation of the physical/chemical features of the hydrothermal fluids, presently exploited at depth, or flowing out in thermal springs. In the same way, we underline the tectonic role in controlling the travertine deposition, making travertine (mainly banded travertine) a useful proxy to reconstruct the

  1. Glacial reorganization of topography in a tectonically active mountain range

    NASA Astrophysics Data System (ADS)

    Adams, Byron; Ehlers, Todd

    2016-04-01

    Tests of the interactions between tectonic and climate forcing on Earth's topography often focus on the concept of steady-state whereby processes of rock deformation and erosion are opposing and equal. However, when conditions change such as the climate or tectonic rock uplift, then surface processes act to restore the balance between rock deformation and erosion by adjusting topography. Most examples of canonical steady-state mountain ranges lie within the northern hemisphere, which underwent a radical change in the Quaternary due to the onset of widespread glaciation. The activity of glaciers changed erosion rates and topography in many of these mountain ranges, which likely violates steady-state assumptions. With new topographic analysis, and existing patterns of climate and rock uplift, we explore a mountain range previously considered to be in steady-state, the Olympic Mountains, USA. The details of our analysis suggest the dominant topographic signal in the Olympic Mountains is a spatial, and likely temporal, variation in erosional efficiency dictated by orographic precipitation, and Pleistocene glacier ELA patterns, and not tectonic rock uplift rates. Alpine glaciers drastically altered the relief structure of the Olympic Mountains. The details of these relief changes are recorded in channel profiles as overdeepenings, reduced slopes, and associated knickpoints. We find the position of these relief changes within the orogen is dependent on the position of the Pleistocene ELA. While alpine glaciers overdeepened valleys in regions near the Pleistocene ELA (which has a tendency to increase relief), headward erosion of west and north flowing glacier systems captured significant area from opposing systems and caused drainage divide lowering. This divide lowering reduced relief throughout the range. We demonstrate similar topographic effects recorded in the basin hypsometries of other Cenozoic mountain ranges around the world. The significant glacial overprint on

  2. Tectonic features of the southern Sumatra-western Java forearc of Indonesia

    NASA Astrophysics Data System (ADS)

    Schlüter, H. U.; Gaedicke, C.; Roeser, H. A.; Schreckenberger, B.; Meyer, H.; Reichert, C.; Djajadihardja, Y.; Prexl, A.

    2002-10-01

    Multichannel reflection seismic profiles along the active Sunda Arc, where the Indo-Australian plate subducts under the overriding Eurasian margin revealed two accretionary wedges: The inner wedge I is of assumed Paleogene age, and the outer wedge II is of Neogene to Recent age. The inner wedge I is composed of tectonic flakes stretching from southeast Sumatra across the Sunda Strait to northwest Java, implying a similar plate tectonic regime in these areas at the time of flake development during upper Oligocene. Today, wedge I forms the outer arc high and the backstop for the younger outer wedge II. The missing outer arc high of the southern Sunda Strait is explained by a combination of Neogene transtension due to a clockwise rotation of Sumatra with respect to Java and by arc-parallel strike-slip movements. The rotation created transtensional pull-apart basins along the western Sunda Strait (Semangka Graben) as opposed to transpression and inversion on the eastern Sunda Strait, within the new detected Krakatau Basin. The arc-parallel transpressional Mentawai strike-slip fault zone (MFZ) was correlated from the Sumatra forearc basin to the northwest Java forearc basin. Off the Sunda Strait, northward bending branches of the MFZ are connected with the right-lateral Sumatra fault zone (SFZ) along the volcanic arc segment on Sumatra. It is speculated that the SFZ was attached to the Cimandiri-Pelabuhan Ratu strike-slip fault of Java prior to the presumed rotation of Sumatra, and that since the late lower Miocene the main slip movement shifted from the volcanic arc position to the forearc basin area due to increasingly oblique plate convergence.

  3. Integrated geophysical and geological studies of selected major tectonic features in south-central U.S

    NASA Astrophysics Data System (ADS)

    Alrefaee, Hamed

    southern continent during the Grenville orogeny. The extensional tectonism associated with the Cambrian rifting and the opening of the Gulf of Mexico played a pronounced role in the evolution of the Llano uplift. The compressional tectonism of the Late Paleozoic Ouachita orogeny as well as the Ouachita related foreland basins contributed to the rise of the Llano uplift area. The complete Bouguer gravity and reduced to pole total magnetic intensity (RTP) maps of the Llano uplift show anomalously high values. A number of short wavelengths maxima superimposed on a relatively broad, high gravity anomaly coincide with Llano uplift area. The sources of the short wavelength anomalies can be related to shallow mafic bodies that were intruded into the uppermost crust during subduction of the Laurentia (North America continent) beneath a southern continent during the Grenville orogeny. The source of the broad, circular gravity anomaly appears to be related to a deeper geologic body situated in the middle crust. The RTP map reveals NW-SE trending magnetic highs that coincide with metamorphic rock exposures. Based on the gravity signature, the Llano uplift is interpreted to be independent terrane with physical and geological properties that differ distinctly from its surroundings. The Meers fault is the southernmost element of the complex and frontal fault zone which separates the uplifted igneous rocks of the Wichita Mountains, and the Anadarko basin in southwest Oklahoma. Motion on the Meers fault represents continued activity on one of the largest structural features in North America. The Wichita uplift and the Anadarko basin, which are separated by the Meers fault and related subparallel fault strands, indicate significant intra-plate deformation along the trend of the Southern Oklahoma aulacogen. The interpretation of the gravity and magnetic data reveals clearer variations in the magnetic properties than densities of the rocks on both sides of the Meers fault. The high magnetic

  4. Scanning electron microscope-cathodoluminescence (SEM-CL) imaging of planar deformation features and tectonic deformation lamellae in quartz

    NASA Astrophysics Data System (ADS)

    Hamers, M. F.; Drury, M. R.

    2011-12-01

    Planar deformation features (PDFs) in quartz are essential proof for the correct identification of meteorite impact structures and related ejecta layers, but can be confused with tectonic deformation lamellae. The only completely reliable method to demonstrate the shock origin of suspected (sub-) planar microstructures, transmission electron microscope (TEM) observations, is costly and time consuming. We have used a cathodoluminescence (CL) detector attached to a scanning electron microscope (SEM) to image both PDFs and tectonic deformation lamellae in quartz to demonstrate the potential of a simple method to identify PDFs and define characteristics that allow their distinction from tectonic deformation lamellae. In both limited wavelength grayscale and composite color SEM-CL images, PDFs are easily identified. They are straight, narrow, well-defined features, whereas tectonic deformation lamellae are thicker, slightly curved, and there is often no clear boundary between lamella and host quartz. Composite color images reveal two types of CL behavior in PDFs: either they emit a red to infrared CL signal or they are nonluminescent. The color of the CL signal emitted by tectonic deformation lamellae ranges from blue to red. For comparison, we also imaged several shocked quartz grains at cryogenic temperature. In most cases, the PDF characteristics in cryo-CL images do not differ significantly from those in images recorded at room temperature. We conclude that SEM-CL imaging, especially when color composites are used, provides a promising, practical, low cost, and nondestructive method to distinguish between PDFs and tectonic lamellae, even when the simplest CL techniques available are used.

  5. Climate dominated topography in a tectonically active mountain range

    NASA Astrophysics Data System (ADS)

    Adams, B. A.; Ehlers, T. A.

    2015-12-01

    Tests of the interactions between tectonic and climate forcing on Earth's topography often focus on the concept of steady-state whereby processes of rock deformation and erosion are opposing and equal. However, when conditions change such as the climate or tectonic rock uplift, then surface processes act to restore the balance between rock deformation and erosion by adjusting topography. Most examples of canonical steady-state mountain ranges lie within the northern hemisphere, which underwent a radical change in the Quaternary due to the onset of widespread glaciation. The activity of glaciers changed erosion rates and topography in many of these mountain ranges, which likely violates steady-state assumptions. With new topographic analysis, and existing patterns of climate and rock uplift, we explore a mountain range previously considered to be in steady-state, the Olympic Mountains, USA. The broad spatial trend in channel steepness values suggests that the locus of high rock uplift rates is coincident with the rugged range core, in a similar position as high temperature and pressure lithologies, but not in the low lying foothills as has been previously suggested by low-temperature thermochronometry. The details of our analysis suggest the dominant topographic signal in the Olympic Mountains is a spatial, and likely temporal, variation in erosional efficiency dictated by orographic precipitation, and Pleistocene glacier ELA patterns. We demonstrate the same topographic effects are recorded in the basin hypsometries of other Cenozoic mountain ranges around the world. The significant glacial overprint on topography makes the argument of mountain range steadiness untenable in significantly glaciated settings. Furthermore, our results suggest that most glaciated Cenozoic ranges are likely still in a mode of readjustment as fluvial systems change topography and erosion rates to equilibrate with rock uplift rates.

  6. Tectonic tremor activity associated with teleseismic and nearby earthquakes

    NASA Astrophysics Data System (ADS)

    Chao, K.; Obara, K.; Peng, Z.; Pu, H. C.; Frank, W.; Prieto, G. A.; Wech, A.; Hsu, Y. J.; Yu, C.; Van der Lee, S.; Apley, D. W.

    2016-12-01

    Tectonic tremor is an extremely stress-sensitive seismic phenomenon located in the brittle-ductile transition section of a fault. To better understand the stress interaction between tremor and earthquake, we conduct the following studies: (1) search for triggered tremor globally, (2) examine ambient tremor activities associated with distant earthquakes, and (3) quantify the temporal variation of ambient tremor activity before and after nearby earthquakes. First, we developed a Matlab toolbox to enhance the searching of triggered tremor globally. We have discovered new tremor sources in the inland faults in Kyushu, Kanto, and Hokkaido in Japan, southern Chile, Ecuador, and central Colombia in South America, and in South Italy. Our findings suggest that tremor is more common than previously believed and indicate the potential existence of ambient tremor in the triggered tremor active regions. Second, we adapt the statistical analysis to examine whether the long-term ambient tremor rate may affect by the dynamic stress of teleseismic earthquakes. We analyzed the data in Nankai, Hokkaido, Cascadia, and Taiwan. Our preliminary results did not show an apparent increase of ambient tremor rate after the passing of surface waves. Third, we quantify temporal changes in ambient tremor activity before and after the occurrence of local earthquakes under the southern Central Range of Taiwan with magnitudes of >=5.5 from 2004 to 2016. For a particular case, we found a temporal variation of tremor rate before and after the 2010/03/04 Mw6.3 earthquake, located about 20 km away from the active tremor source. The long-term increase in the tremor rate after the earthquake could have been caused by an increase in static stress following the mainshock. For comparison, clear evidence from seismic and GPS observations indicate a short-term increase in the tremor rate a few weeks before the mainshock. The increase in the tremor rate before the mainshock could correlate with stress changes

  7. Tectonic Processes on Europa: Tidal Stresses, Mechanical Response, and Visible Features

    NASA Astrophysics Data System (ADS)

    Greenberg, Richard; Geissler, Paul; Hoppa, Gregory; Tufts, B. Randall; Durda, Daniel D.; Pappalardo, Robert; Head, James W.; Greeley, Ronald; Sullivan, Robert; Carr, Michael H.

    1998-09-01

    Europa's orbital eccentricity, driven by the resonance with Io and Ganymede, results in "diurnal" tides (3.5-day period) and possibly in nonsynchronous rotation. Both diurnal variation and nonsynchronous rotation can create significant stress fields on Europa's surface, and both effects may produce cracking. Patterns and time sequences of apparent tectonic features on Europa include lineaments that correlate with both sources of stress, if we take into account nonsynchronous rotation, after initial crack formation, by amounts ranging up to several tens of degrees. For example, the crosscutting time sequence of features in the Cadmus and Minos Linea region is consistent with a combined diurnal and nonsynchronous tensile-stress field, as it evolves during tens of degrees of nonsynchronous rotation. Constraints on the rotation rate from comparing Voyager and Galileo images show that significant rotation requires >104yr, but could be fast enough to have allowed significant rotation since the last global resurfacing, even if such resurfacing was as recent as a few million years ago. Once cracking is initiated, diurnal tides work cracks so that they open and close daily. Although the daily effect is small, over 105yr double ridges could plausibly be built along the cracks with sizes and morphologies consistent with observed structures, according to a model in which underlying liquid water fills the open cracks, partially freezes, and is extruded during the daily closing of the cracks. Thus, several lines of observational and theoretical evidence can be integrated if we assume nonsynchronous rotation and the existence of a liquid water layer.

  8. Tectonic Processes on Europa: Tidal Stresses, Mechanical Response, and Visible Features

    USGS Publications Warehouse

    Greenberg, R.; Geissler, P.; Hoppa, G.; Tufts, B.R.; Durda, D.D.; Pappalardo, R.; Head, J.W.; Greeley, R.; Sullivan, R.; Carr, M.H.

    1998-01-01

    Europa's orbital eccentricity, driven by the resonance with Io and Ganymede, results in "diurnal" tides (3.5-day period) and possibly in nonsynchronous rotation. Both diurnal variation and nonsynchronous rotation can create significant stress fields on Europa's surface, and both effects may produce cracking. Patterns and time sequences of apparent tectonic features on Europa include lineaments that correlate with both sources of stress, if we take into account nonsynchronous rotation, after initial crack formation, by amounts ranging up to several tens of degrees. For example, the crosscutting time sequence of features in the Cadmus and Minos Linea region is consistent with a combined diurnal and nonsynchronous tensile-stress field, as it evolves during tens of degrees of nonsynchronous rotation. Constraints on the rotation rate from comparing Voyager and Galileo images show that significant rotation requires 104yr, but could be fast enough to have allowed significant rotation since the last global resurfacing, even if such resurfacing was as recent as a few million years ago. Once cracking is initiated, diurnal tides work cracks so that they open and close daily. Although the daily effect is small, over 105yr double ridges could plausibly be built along the cracks with sizes and morphologies consistent with observed structures, according to a model in which underlying liquid water fills the open cracks, partially freezes, and is extruded during the daily closing of the cracks. Thus, several lines of observational and theoretical evidence can be integrated if we assume nonsynchronous rotation and the existence of a liquid water layer. ?? 1998 Academic Press.

  9. Topographic representation using DEMs and its applications to active tectonics research

    NASA Astrophysics Data System (ADS)

    Oguchi, T.; Lin, Z.; Hayakawa, Y. S.

    2016-12-01

    Identifying topographic deformations due to active tectonics has been a principal issue in tectonic geomorphology. It provides useful information such as whether a fault has been active during the recent past. Traditionally, field observations, conventional surveying, and visual interpretation of topographic maps, aerial photos, and satellite images were the main methods for such geomorphological investigations. However, recent studies have been utilizing digital elevation models (DEMs) to visualize and quantitatively analyze landforms. There are many advantages to the use of DEMs for research in active tectonics. For example, unlike aerial photos and satellite images, DEMs show ground conditions without vegetation and man-made objects such as buildings, permitting direct representation of tectonically deformed landforms. Recent developments and advances in airborne LiDAR also allow the fast creation of DEMs even in vegetated areas such as forested lands. In addition, DEMs enable flexible topographic visualization based on various digital cartographic and computer-graphic techniques, facilitating identification of particular landforms such as active faults. Further, recent progress in morphometric analyses using DEMs can be employed to quantitatively represent topographic characteristics, and objectively evaluate tectonic deformation and the properties of related landforms. This paper presents a review of DEM applications in tectonic geomorphology, with attention to historical development, recent advances, and future perspectives. Examples are taken mainly from Japan, a typical tectonically active country. The broader contributions of DEM-based active tectonics research to other fields, such as fluvial geomorphology and geochronology, will also be discussed.

  10. Topographyc metrics in the southern sector of the Marche foothills: implication for active tectonic analysis

    NASA Astrophysics Data System (ADS)

    Materazzi, Marco; Aringoli, Domenico; Carducci, Tamara; Cavitolo, Paolo; Farabollini, Piero; Giacopetti, Marco; Pambianchi, Gilberto; Tondi, Emanuele; Troiani, Francesco

    2016-04-01

    Quantitative geomorphic analysis can be provided a useful contribution to the study of recent tectonics. Some parameters, that quantify the channels morphology, as the Stream Length-Gradient (SL) Index (Hack, 1973) and the Steepness (Ks) Index (Flint, 1974), are generally used to detect anomalies on the expected concave-up equilibrium stream-profile, which can result in local abrupt changes in stream gradient (i.e., knickpoints) and/or broad convexities on stream long-profiles extending for tens of kilometres (i.e., knickzones). The main goal of this work is the study of the morphological and morphometrical features in the southern sector of the Marche Region, with the aim to gain new knowledge on the influences of rock resistance and rock uplift on the fluvial and topographic system. The investigated area is situated in central Italy and it extends from the axial zone of the Umbria-Marche Apennines to the Adriatic Sea, including the southern sector of the Marche Region and belongs to the foredeep domain of the Apennines orogenic system, which has affected by tectonic activity up to very recent times. The rheology of outcropping deposits doesn't allow the strain to be easily recorded at the outcrop scale. The analyses have been aimed at to test the sensitivity of both SL and Ks for evaluating active crustal deformations, acting at different wavelengths on land surface, within a low tectonically active thrust-and-fold belt. Additional purpose was the understanding of the pattern of regional differential crustal activity in the topographic arrangement of the study area In this research project two sets of analysis were conducted. References Hack J.T. 1973. Stream-profile analysis and stream-gradient index. Journal of Research of the U.S. Geological Survey, 1, 421-429. Flint J.J. 1974. Stream gradient as a function of order, magnitude and discharge. Water Resources Research, 10, 969-973.

  11. New constraints on the active tectonic deformation of the Aegean

    USGS Publications Warehouse

    Nyst, M.; Thatcher, W.

    2004-01-01

    revealed by seismicity, active faulting, fault geomorphology, and earthquake fault plane solutions, continental tectonics, at least in the Aegean, is to first order very similar to global plate tectonics and obeys the same simple kinematic rules. Although the widespread distribution of Aegean seismicity and active faulting might suggest a rather spatially homogeneous seismic hazard, the focusing of deformation near microplate boundaries implies the highest hazard is comparably localized.

  12. Tectonic Features of the Out-of-Sequence Thrust Offshore Southwest Taiwan

    NASA Astrophysics Data System (ADS)

    Chuang, C.; Liu, C.; Lin, A. T.

    2011-12-01

    Large splay faults developed in an accretionary wedge have been linked to seismogenic processes in a subduction zone. The Luzon subduction system between Taiwan and Luzon islands has been categorized as one of the highest tsunami risk zones in the circum-Pacific region. Bathymetry and seismic reflection profile data collected offshore south and southwest Taiwan reveal that there is a prominent out-of-sequence thrust (OOST) developed in the frontal portion of the Luzon accretionary wedge. This OOST forms the boundary separating a fold-and-thrust belt lower slope domain of the accretionary wedge from an intensely deformed upper slope domain. This OOST extends laterally over 250 km in the offshore region, from south of 20oN northward to the onshore structure of southwestern Taiwan, and is suggested to be the major branch of the splay fault system of the Luzon subduction zone. In order to better understand the structure features of this OOST and its variations from south to north as the tectonic processes changes from subduction in the area offshore south Taiwan to collision on land Taiwan, we analyze a series of large-offset deep seismic reflection profiles collected during the TAIGER survey in 2009 that ran across this OOST. The shallow part of the fault plane can be identified easily on the seismic profiles, however, due to the presence of strong multiples, the deeper part of the fault plane is poorly imaged. We are reprocessing the seismic profiles to improve the deep crustal images. Furthermore, we use seismic attribute analysis techniques to help identify the OOST. Finally, we propose a new evolution model of OOST from subduction to collision, and discuss its potential seismic risks.

  13. Tectonic Activity on Enceladus in the Context of a Pressurized Global Ocean or Regional Sea

    NASA Astrophysics Data System (ADS)

    Montesi, Laurent; Johnston, Stephanie

    2017-04-01

    The rich history of tectonic activity on Enceladus has the potential to provide constraints on the internal structure of the satellite. The South Polar region is dominated by tectonic extension whereas the Southern Curvilinear Terrain surrounding it is interpreted as a compressional feature. Other tectonised terrains in the leading hemisphere and the trailing hemisphere of the satellite may constitute ancient analogues to the South Polar Terrain. The North Pole also presents evidence for recent tectonic extension. To explain the origin of the tectonic pattern featuring regions of extension at both poles, one of them being surrounded by an annulus of compressive tectonics, we study the stress field generated by a pressurized internal water reservoir. Recent geodetic data show that Enceladus likely features a global ocean, although the ice is thinner at the poles, especially the South Pole. Earlier models proposed that water is limited to a regional sea at the South pole. We consider both cases. Regardless of its geometry, the internal water body is likely to be overpressurised as it loses heat and water expands upon freezing. Our model considers an axisymmetric ice shell with an indentation representing the region of thinned ice at the South Pole. The regional sea and the global ocean (when present) exert a uniform pressure of 10 kPa to the base of the ice shell. If the base of the ice shell is fixed, failure takes place only at the South Pole. If the base of the ice shell is sliding, failure also takes place at the North Pole as the shell is pushed against the rigid core. This is the only case where failure at mid-latitude takes place by shear faulting without tensile cracking at the surface. If the base of the ice shell is in contact with the overpressurised ocean, the entire surface of the satellite undergoes failure by tensile cracking. If the intensity of the overpressure is reduced, failure concentrates at the South Pole. There is no local maximum in tension

  14. Tectonic activity on Pluto after the Charon-forming impact

    NASA Astrophysics Data System (ADS)

    Barr, Amy C.; Collins, Geoffrey C.

    2015-01-01

    The Pluto-Charon system, likely formed from an impact, has reached the endpoint of its tidal evolution. During its evolution into the dual-synchronous state, the equilibrium tidal figures of Pluto and Charon would have also evolved as angular momentum was transferred from Pluto's spin to Charon's orbit. The rate of tidal evolution is controlled by Pluto's interior physical and thermal state. We examine three interior models for Pluto: an undifferentiated rock/ice mixture, differentiated with ice above rock, and differentiated with an ocean. For the undifferentiated case without an ocean, the Pluto-Charon binary does not evolve to its current state unless its internal temperature Ti > 200K , which would likely lead to strong tidal heating, melting, and differentiation. Without an ocean, Pluto's interior temperature must be higher than 240 K for Charon to evolve on a time scale less than the age of the Solar System. Further tidal heating would likely create an ocean. If New Horizons finds evidence of ancient tidally-driven tectonic activity on either body, the most likely explanation is that Pluto had an internal ocean during Charon's orbital evolution.

  15. Tectonic and Hydrological Activities on Xanadu, Hotei and Tui Regions on Titan

    NASA Astrophysics Data System (ADS)

    Mitri, G.; Di Marco, C.; Di Achille, G.; Lunine, J. I.; Flamini, E.; Meriggiola, R.; Poggiali, V.

    2012-12-01

    Xanadu (~10°S, 120°W), Tui (~24°S, 125°W) and Hotei (~26°S, 78°W) regions are three adjacent geomorphic provinces located on Titan's leading hemisphere. The interpretation of the geological activities of these regions is not unique. Radebaugh et al. (2010) proposed that complex geological activity occurred to form the highlands regions of Xanadu where first compression occurred, and subsequently extensional tectonism and erosion by methane precipitation. However, Brown et al. (2011) proposed that Xanadu is a wide and ancient impact crater basin. Nelson et al. (2009) observed surface reflectance variability at the Hotei region suggesting that such surface variability might be due to surface activity potentially related to cryovolcanic activity. Wide lobate features in the Tui and Hotei regions were identified using Cassini VIMS (Barnes et al. 2009) and RADAR observations (Walls et al. 2009) and were interpreted as cryovolcanic flows. However, Moore and Howard (2010) suggested that the observed lobate features in both regions might be paleolakes. We produced a geomorphological map encompassing the Xanadu, Tui and Hotei regions. Our geomorphological analysis is based on the Synthetic Aperture Radar images from the Cassini RADAR. We also used topographic data from radar altimeter and SAR-Topography technique datasets. We show that Xanadu is a dissected plateau whose formation most likely involved crustal uplift produced by compressional tectonic activity. We also show that both the Tui and Hotei regions present characteristics of closed drainage basins with an inflow of liquids from the highlands of Xanadu and a lack of outflow, suggesting that Hotei and Tui are endorheic basins that might contain ephemeral lakes currently appearing as dry lakebeds. Such lakebeds are likely filled with liquid hydrocarbons only during rare periods of significant rainfall and dry out due to evaporation.

  16. Expression of Active Tectonics in Erosional Landscapes (Invited)

    NASA Astrophysics Data System (ADS)

    Whipple, K. X.; McDermott, J. A.; Adams, B. A.

    2010-12-01

    Landform analysis has become a standard tool in neotectonic studies. Most commonly the offset, tilting, and warping of abandoned depositional landforms is used to infer deformation rates and patterns. The timescales recorded in deformed landforms importantly bridge the gap between geodetic and geologic methods. Whereas such analyses of static landforms has become well developed, complementary approaches to extract quantitative information about tectonics from erosional landscapes are relatively new, rapidly evolving, and can provide powerful insight. Over the last decade, some useful general rules about the expression of rock uplift rate in erosional landscapes have been developed that can guide and augment studies of the spatial distribution of active rock uplift. At catchment scale, the relationship between landscape form and rock uplift is dictated largely by the response of stream profiles to rock uplift (particularly in rocky landscapes where uplift exceeds soil production), which is largely one of changing channel steepness (gradient adjusted for drainage area). Changes in channel steepness along stream can be either abrupt (discrete slope-break knickpoints) or gradual (expressed as zones of enhanced or reduced river profile concavity) depending on the deformation pattern. Landforms can record information about both spatial and temporal patterns in rock uplift rate. Landscapes in various parts of the Himalaya exemplify both spatial and temporal influences. The Siwalik Hills in the Himalayan foreland are a type locality for the topographic expression of spatial patterns in rock uplift rate. Here an independently known pattern of rock uplift rate over a fault-bend fold affords an opportunity to study landscape response and test landscape evolution models. Once calibrated, such models can be used to evaluate along-strike variability in the rate and pattern of rock uplift far more effectively and efficiently than can be achieved with other methods. Applying these

  17. Tectonic activity revealed by morphostructural analysis: Development of the Sierra de la Candelaria range, northwestern Argentina

    NASA Astrophysics Data System (ADS)

    Barcelona, H.; Peri, G.; Tobal, J.; Sagripanti, L.; Favetto, A.

    2014-12-01

    The tectonically active broken foreland of NW Argentina is a recent analog of the eastern margin of the Puna plateau during Mio-Pliocene times and likely of other broken forelands worldwide. In order to evaluate active tectonism in the broken foreland of the NW Argentine Andes, we examined the complex geomorphology in the vicinity of the basement-cored Sierra de la Candelaria range at ˜26°S and deciphered multiple episodes of crustal deformation spanning the Pliocene to the Quaternary. Digital elevation models, satellite images and geological data within a GIS environment allowed us to analyze the terrain, drainage networks, river dynamics and structure, as well as to obtain detailed geomorphological mapping, active tectonic indices, longitudinal river profiles and structural sections. Three morphostructural segments were defined based on the structural features, the differential vertical dissection pattern over the basement, the faulted Pliocene to recent deposits, the stepwise propagation of anticlines and the distortion over the fluvial system. By combining the several lines of evidence, we concluded that the Sierra de la Candelaria range was subjected to a multi-stage development. The first stage uplifted the central segment concomitant with the formation of the surrounding ranges and with the main partition phase of the foreland. After a significant time lapse, the mountain range was subjected to southward thick-skinned growth and northward growth via stepwise thin-skinned deformation and exerted control over the dynamics of the Río Rosario. Taking into account the surrounding basins and ranges of the Sierra de la Candelaria, the southern Santa Bárbara System is characterized by partially isolated intramontane basins (Choromoro and Rosario) limited by shielded ranges that caused moisture block and shows continuous deformation. These features were related to early stages of a broken foreland evolution model and modern analogs were found at the northern

  18. Collecting Inexpensive High Resolution Aerial and Stereo Images of Small- to Mid-Scale Geomorphic and Tectonic Features

    NASA Astrophysics Data System (ADS)

    Wheelwright, R. J.; White, W. S.; Willis, J. B.

    2010-12-01

    Methods for collecting accurate, mm- to cm-scale stereoscopic aerial imagery of both small- and mid-scale geomorphic features are developed for a one-time cost of under $1500. High resolution aerial images are valuable for documenting and analyzing small- to mid-scale geomorphic and tectonic features. However, collecting images of mid-scale features such as landslides, rock glaciers, fault scarps, and cinder cones is expensive and makes studies that rely on high resolution repeat imagery prohibitive for undergraduate geology departments with limited budgets. In addition to cost, collecting images of smaller scale geomorphic features such as gravel bars is often impeded by overhanging vegetation or other features in the immediate environment that make impractical the collection of aerial images using standard airborne techniques. The methods provide high resolution stereo photos suitable for image processing and stereographic analysis; the images are potentially suitable for change analyses, velocity tracking, and construction of lidar-resolution digital elevation models. We developed two techniques. The technique suitable for small-scale features (such as gravel bars) utilizes two Nikon D3000 digital single-lens reflex (DSLR) cameras attached to a system of poles that suspends the cameras at a height of 4 meters with a variable camera separation of 0.6 to 0.9 m. The poles are oriented such that they do not appear in the photographs. The cameras are simultaneously remotely activated to collect stereo pairs at a resolution of 64 pixels/cm2 (pixel length is 1.2 mm). Ground control on the images is provided by pegs placed 5 meters apart, GPS positioning, and a meter-stick included in each photograph. Initial photo data gathered of a gravel bar on the Henry’s Fork of the Snake River, north of Rexburg, Idaho is sharp and readily segmented using the MatLab-based CLASTS image processing algorithm. The technique developed for imaging mid-scale features (such as cinder

  19. The role of space-based observation in understanding and responding to active tectonics and earthquakes

    NASA Astrophysics Data System (ADS)

    Elliott, J. R.; Walters, R. J.; Wright, T. J.

    2016-12-01

    The quantity and quality of satellite-geodetic measurements of tectonic deformation have increased dramatically over the past two decades improving our ability to observe active tectonic processes. We now routinely respond to earthquakes using satellites, mapping surface ruptures and estimating the distribution of slip on faults at depth for most continental earthquakes. Studies directly link earthquakes to their causative faults allowing us to calculate how resulting changes in crustal stress can influence future seismic hazard. This revolution in space-based observation is driving advances in models that can explain the time-dependent surface deformation and the long-term evolution of fault zones and tectonic landscapes.

  20. Drainage response to active tectonics and evolution of tectonic geomorphology across the Himalayan Frontal Thrust, Kumaun Himalaya

    NASA Astrophysics Data System (ADS)

    Luirei, Khayingshing; Bhakuni, Surendra S.; Kothyari, Girish Ch.

    2015-06-01

    We present the results of integrated studies of geomorphic indices of drainage networks and landforms developed across the mountain front along the Himalayan Frontal Thrust (HFT) between the Dabka and Baur rivers, Kumaun Himalaya. The HFT is a morphogenic structure in nature, creating a 100-m-high E-W trending escarpment that extends ~ 21 km. Geomorphological evidence indicates ~ 10.5 km westward migration of the Dabka River and ~ 5.2 km eastward migration of the Baur River. These migrations are a result of uplift of the hanging wall along the HFT. The HFT is offset by a transverse fault, which suggests that the latter postdates the reactivation of the HFT between 500 and 100 ka. Presence of different levels of strath terraces along the mountain front suggests the active nature of the HFT. To assess the relative tectonic activity, morphometric indices such as stream-gradient (SL) index, mountain front sinuosity (Smf) index, and ratio of valley floor width to valley height (Vf) have been analyzed. Results of the former two are consistent with the tectonic landforms developed in thrust zones. Paleochannels of the Dabka and Baur rivers are characterized by high Vf values while other valleys show low Vf values. Quaternary alluvial sediments have been deformed along the Pawalgarth Thrust, a splay of the HFT. Deformation has resulted in the formation of the Pawalgarh Anticline, a thrust-related asymmetric fold.

  1. Active landsliding and landscape denudation in response to transient tectonic uplift, Northern California.

    NASA Astrophysics Data System (ADS)

    Bennett, G. L.; Roering, J. J.; Miller, S. R.; Kirby, E.; Schmidt, D. A.

    2014-12-01

    The northern Californian Coast ranges present a unique area to study landscape response to transient tectonic uplift. Studies have shown that an increase in uplift may be balanced by the rate of landsliding in settings of steady uplift. However, the landsliding response to transient tectonic uplift remains to be elucidated. The Californian Coast ranges are shaped by the northward migration of the Mendocino Triple Junction (MTJ), which geodynamic modeling suggests produces a transient double-humped uplift field. A major research question is whether we can detect a signature of this transient tectonic uplift in landslide activity and document how the channel network communicates this signal to hillslopes. Using air photos and Worldview imagery, we manually mapped more than 2000 earthflows and debris slides in the Eel and surrounding catchments that span the ~400 km-long region. The velocities of active earthflows were estimated by visually tracking features between images spanning 1993 to 2013. We mapped channel steepness from 10m NED DEMs in Topotoolbox 2 and developed a new tool to automatically define knickpoints along the channel network. Earthflows occur almost exclusively in a band of Franciscan mélange oriented along the MTJ transect whilst debris slides are more evenly distributed by lithology. Both earthflows and debris slides are clustered in the Eel catchment around the proposed uplift peaks and are largely absent outside of these zones. Within these areas of high landslide densities, we observe peaks in active earthflows adjacent to peaks in dormant earthflows to the south, suggesting that the signature of earthflow activity remains for a period of time once the uplift peak has passed. Landslide density, mean landslide area, and earthflow velocity all increase rapidly above threshold values of channel steepness and local relief. In the Eel catchment, where the zone of rapid uplift is commencing, landslides, particularly earth flows, are concentrated

  2. Electrical structure of the tectonically active Kalabsha Fault, Aswan, Egypt [rapid communication

    NASA Astrophysics Data System (ADS)

    Mekkawi, Mahmoud; Schnegg, Pierre-André; Arafa-Hamed, Tarek; Elathy, Essam

    2005-12-01

    In this work, we use the magnetotelluric (MT) method to detect geoelectrical conductivity anomalies in the Earth's crust and link them to local seismic activity. This application affords the unusual opportunity to study the percolation of water from a lake into a fault system and its effect on the induced seismicity. MT measurements were carried out in the period range 0.0046-420 s at nine sites along a 15 km-long North-South profile crossing the Kalabsha Fault, on the western bank of Lake Aswan. Data were analysed by 2D simultaneous inversion of both polarisations. The resulting model is compared with the local seismicity map and reveals the conductive signature of the fault, as well as geological and tectonic stresses prevailing in the Aswan area. Our MT investigations show the following features: The measured MT strike aligns with the seismic epicentre axis corresponding to the Kalabsha Fault. While crossing the Fault, enhanced conductivity is found down to depths of 5 km on a 1-2 km profile segment. At mid-crustal depths (20 km), a very high conductive body is found to coincide with the main seismic cluster in the Aswan area. These observations indicate that seismic activity and high electrical conductivity are related. The link between them is the presence of crustal fluids which are presumably the cause of the high conductivity observed. Their presence is also required to trigger the observed seismicity. In addition, we explain the lower conductivity of the local upper crust in terms of stress-modulated rock porosity. We believe that these results are of general significance, as they could explain the mid-crustal seismicity of tectonically active zones.

  3. The Geomorphological Evolution of a Landscape in a Tectonically Active Region: the Sennwald Landslide

    NASA Astrophysics Data System (ADS)

    Aksay, Selçuk; Ivy-Ochs, Susan; Hippe, Kristina; Graemiger, Lorenz; Vockenhuber, Christof

    2016-04-01

    The Säntis nappe is a fold-and-thrust structure in eastern Switzerland consisting of numerous tectonic discontinuities that make rocks vulnerable to rock failure. The Sennwald landslide is one of those events that occurred due to the failure of Lower Cretaceous Helvetic limestones. This study reveals the surface exposure age of the event in relation to geological and tectonic setting, earthquake frequency of the Central Alps, and regional scale climate/weather influence. Our study comprises detailed mapping of landform features, thin section analysis of landslide boulder lithologies, landslide volume estimation, numerical DAN-3D run-out modelling, and the spatial and temporal relationship of the event. In the Sennwald landslide, 92 million m3 of limestones detached from the south-eastern wall of the Säntis nappe and slid with a maximum travel distance of ~4'500 m and a "fahrboeschung" angle of 15° along the SE-dipping sliding plane almost parallel to the orientation of the bedding plane. Numerical run-out modelling results match the extent and the thickness of landslide deposits as observed in the field. The original bedrock stratigraphy was preserved as geologically the top layer in the bedrock package travelled the farthest and the bottom layer came to rest closest to the release bedrock wall during the landslide. Velocities of maximum 90 m/s were obtained from the numerical run-out modelling. Total Cl and 36Cl were determined at ETH AMS facility with isotope dilution methods defined in the literature (Ivy-Ochs et al., 2004). Surface exposure ages of landslide deposits in the accumulation area are revealed from twelve boulders. The distribution of limestone boulders in the accumulation area, the exposure ages, and the numerical run-out modelling support the hypothesis that the Sennwald landslide was a single catastrophic event. The event is likely to have been triggered by at least light to moderate earthquakes (Mw=4.0-6.0). The historical and the last 40-year

  4. Active tectonic characteristics of river terraces along the Tianquan River, Sichuan, China

    NASA Astrophysics Data System (ADS)

    Cai, Y. M.; Shyu, J. B. H.; Chang, C. P.

    2015-12-01

    The Longmenshan fold-and-thrust belt at the western edge of the Sichuan Basin has long been identified as an active tectonic belt. This has been clearly illustrated by the disastrous Wenchuan and Lushan earthquakes in the recent decade. The two earthquakes, however, have distinctive characters. In the north, the Wenchuan event occurred on major fault zones identified previously. But in the south, the Lushan event was not accompanied by surface ruptures, and the seismogenic structure is still under debate. In order to further understand the neotectonic characteristics of the Lushan earthquake region, we analyzed fluvial terraces, in the hope that such geomorphic features would provide information of active structures of the area. Along the Tianquan River, river terraces are particularly well developed near two cities, Tianquan and Shiyang. Since the terraces appear to be very wide and limited in these two basin-like areas, we suspected that they formed as filled-up lakes. However, after detailed field investigations, we found that underneath these terraces, early Tertiary bedrocks crop out below river sediments that are only several meters thick. This indicates that the Tianquan River has incised into bedrocks. The slope of the terrace surfaces is similar to that of the present-day riverbed, and the river sediments in the terrace outcrops have similar grain size distribution as current riverbed sediments. Therefore, we suggest that the terraces along the Tianquan River are not related to dammed lake, but were produced by tectonic uplift. Combining the age of terrace sediments dated by optically stimulated luminescence (OSL) and detailed topography of the terrace surfaces, we aim to establish a model for the formation mechanism of these two terrace groups. We hope the results of this study would provide more information of neotectonic characteristics of the southwestern Sichuan Basin, as well as future earthquake hazards in this densely populated region.

  5. Robust and exploratory analysis of active mesoscale tectonic zones in Japan utilizing the nationwide GPS array

    NASA Astrophysics Data System (ADS)

    Toya, Yuzo; Kasahara, Minoru

    2005-05-01

    A monitoring GPS array recently developed in Japan can yield nationwide maps of active inland tectonic zones (ATZs) on a mesoscale, approximately 70 to several hundred kilometers in lateral extent. But it has been difficult to characterize ATZs in Japan, as they are in fact operational on multiple scales and our efforts are often hindered by various irregularities in the data. The key to overcoming these problems would be to gain an insight into the available data before any precise kinematic modeling is performed with indefinite assumptions. In this study, horizontal velocity fields, deduced from the nationwide GPS array, were treated with a set of techniques in robust smoothing and exploratory data analysis that brought out exceptionally powerful mesoscale ATZs, and made them easier to characterize. The resolved ATZs were then retrospectively monitored to study their regional and temporal variations, using a set of approx. 840 observation stations, about 30 km apart, for a 4-year series of fixed observation time-intervals, 810 days each. The smoothing operation involved three steps: (1) imputation of the velocity fields for the purpose of anti-aliasing, (2) robust smoothing of the velocity fields with the median operative, and (3) visualization of deformation-rate distributions in several coordinate independent parameters, and post-filtering. The geometrical resolvability of mesoscale ATZs was confirmed by calibrating the smoothing scheme against synthetic tectonic boundary models before it was applied to the case study in Japan. ATZs in Japan, which are essentially visible as systematic deviations in the velocity fields on the International Terrestrial Reference Frame (ITRF) and as strain rate anomalies, were highlighted sharply along some known tectonic zones, chains of active volcanoes, and areas above low seismic velocity anomalies in the crust and upper mantle, all of which generally paralleled the offshore trench axes. The geometrical agreements among the

  6. Identification and interpretation of tectonic features from ERTS-1 imagery. [Coastal Ranges of California

    NASA Technical Reports Server (NTRS)

    Abdel-Gawad, M. (Principal Investigator)

    1974-01-01

    The author has identified the following significant results. The transverse faults observed in the central Coast Ranges of California are believed to represent the remnants of a major system of shear faults older than the San Andreas system. The transverse shear system is believed to have developed in the Mesozoic when the Pacific Plate was advancing under the North American Plate. Shear faults thus developed due to unequal rates of underthrusting. This tectonic model indicates that the intrusive belt of the proto-Sierra Nevada and the belt of eugeosynclinal sedimentary belt (Franciscan group) which lay to the west were both subjected to regional left-handed shear. Later development of the San Andreas system as transform faults of the East Pacific Rise changes the tectonic style to right-lateral tangential. The model explains the peculiar distribution of the Franciscan rocks in the Diablo Range east of the San Andreas fault and in Santa Lucia Range west of Nacimiento fault and the presence of Sierra Nevada type granitic blocks in between the two faults in the Salinia block. This model is also consistent with an analysis of the Texas and Parras shears which indicates that the southwestern part of North America has been subjected to a major left-lateral regional shear before the development of the San Andreas fault system.

  7. Charon tectonics

    PubMed Central

    Beyer, Ross A.; Nimmo, Francis; McKinnon, William B.; Moore, Jeffrey M.; Binzel, Richard P.; Conrad, Jack W.; Cheng, Andy; Ennico, K.; Lauer, Tod R.; Olkin, C.B.; Robbins, Stuart; Schenk, Paul; Singer, Kelsi; Spencer, John R.; Stern, S. Alan; Weaver, H.A.; Young, L.A.; Zangari, Amanda M.

    2017-01-01

    New Horizons images of Pluto’s companion Charon show a variety of terrains that display extensional tectonic features, with relief surprising for this relatively small world. These features suggest a global extensional areal strain of order 1% early in Charon’s history. Such extension is consistent with the presence of an ancient global ocean, now frozen. PMID:28919640

  8. Charon tectonics

    NASA Astrophysics Data System (ADS)

    Beyer, Ross A.; Nimmo, Francis; McKinnon, William B.; Moore, Jeffrey M.; Binzel, Richard P.; Conrad, Jack W.; Cheng, Andy; Ennico, K.; Lauer, Tod R.; Olkin, C. B.; Robbins, Stuart; Schenk, Paul; Singer, Kelsi; Spencer, John R.; Stern, S. Alan; Weaver, H. A.; Young, L. A.; Zangari, Amanda M.

    2017-05-01

    New Horizons images of Pluto's companion Charon show a variety of terrains that display extensional tectonic features, with relief surprising for this relatively small world. These features suggest a global extensional areal strain of order 1% early in Charon's history. Such extension is consistent with the presence of an ancient global ocean, now frozen.

  9. Charon tectonics.

    PubMed

    Beyer, Ross A; Nimmo, Francis; McKinnon, William B; Moore, Jeffrey M; Binzel, Richard P; Conrad, Jack W; Cheng, Andy; Ennico, K; Lauer, Tod R; Olkin, C B; Robbins, Stuart; Schenk, Paul; Singer, Kelsi; Spencer, John R; Stern, S Alan; Weaver, H A; Young, L A; Zangari, Amanda M

    2017-05-01

    New Horizons images of Pluto's companion Charon show a variety of terrains that display extensional tectonic features, with relief surprising for this relatively small world. These features suggest a global extensional areal strain of order 1% early in Charon's history. Such extension is consistent with the presence of an ancient global ocean, now frozen.

  10. Tectonic Maps of the Poles

    NASA Technical Reports Server (NTRS)

    2002-01-01

    These tectonic relief maps of the north (left, view large [540k]) and south (right, view large [411k]) poles are the result of new satellite-based technologies which are being used to analyze tectonic activity in the Earth's crust. These maps, known as Digital Tectonic Activity Maps (DTAMs), synoptically depict the architecture of the Earth's crust including current and past tectonic activity. This is significant because it permits researchers to view broad zones of activity over the entire surface of the Earth, rather than focusing on single boundary features. By looking at these 'big pictures,' scientists can possibly identify regions of activity which were not previously recognized or mapped using traditional methods. For more information, see: DTAM web site Putting Earthquakes in Their Place Images courtesy Brian Montgomery, NASA GSFC; data by Paul Lowman and Jacob Yates, NASA GSFC

  11. Tectonic Maps of the Poles

    NASA Technical Reports Server (NTRS)

    2002-01-01

    These tectonic relief maps of the north (left, view large [540k]) and south (right, view large [411k]) poles are the result of new satellite-based technologies which are being used to analyze tectonic activity in the Earth's crust. These maps, known as Digital Tectonic Activity Maps (DTAMs), synoptically depict the architecture of the Earth's crust including current and past tectonic activity. This is significant because it permits researchers to view broad zones of activity over the entire surface of the Earth, rather than focusing on single boundary features. By looking at these 'big pictures,' scientists can possibly identify regions of activity which were not previously recognized or mapped using traditional methods. For more information, see: DTAM web site Putting Earthquakes in Their Place Images courtesy Brian Montgomery, NASA GSFC; data by Paul Lowman and Jacob Yates, NASA GSFC

  12. Evidence for a major, tectonically active structure beneath the coastal plain of North and South Carolina

    SciTech Connect

    Marple, R.T.; Talwani, P. . Geology Dept.); Olson, O.

    1994-03-01

    Evaluation of Landsat imagery, aerial photography, potential field data, and topographic maps have revealed a linear, [approximately]400-km-long, NNE-trending zone in the coastal plain of North and South Carolina. This zone is composed of subtle topographic highs, aeromagnetic anomalies, and in some locations mapped and inferred faults. It is also associated with a zone of river anomalies (ZRA). Various data suggest that the ZRA may be associated with tectonic activity on a large right-lateral strike-slip fault system. The ZRA in the South Carolina coastal plain is defined by an [approximately]15-km-wide NNE-trending zone that crosses NW-SE-flowing rivers. Along this zone the rivers are characterized by river bends that are convex toward the NNE, incised channels, changes in river patterns, and convex-upward longitudinal profiles. In the coastal plain and eastern Slate Belt of North Carolina the ZRA (width yet to be determined) displays a slightly more northeasterly trend that is highlighted by linear aeromagnetic anomalies and right-lateral offsets of larger rivers crossing its trend. This feature is not traceable across the southern flank of the Cape Fear Arch and north of this area the ZRA's trend is offset [approximately]15 km toward the east (right step geometry) from that of the ZRA in South Carolina. Analyses of geologic and geophysical data further indicate that these two zones may be the result of ongoing tectonic uplift along a NNE-trending right-lateral strike-slip fault zone possibly associated with recent seismicity near Charleston.

  13. Late Quaternary tectonics and active ground deformation in the Catania urban area (eastern Sicily): New constraints from a geological investigation

    NASA Astrophysics Data System (ADS)

    Catalano, Stefano; Pavano, Francesco; Romagnoli, Gino; Tortorici, Giuseppe

    2017-08-01

    New surface and subsurface geological data on the Catania urban area, in eastern Sicily, are here illustrated by a detailed geological map of the city and by four significant cross-sections. Our study aims at defining the prolongation of the principal regional Late Quaternary tectonic features, beneath the city. The resulting geometry of the investigated structures completes the tectonic pictures of two different stages of deformation. The earlier structural association, ranging in age from 600 to 125 ka, consists of a transpressive dextral belt that include E-W oblique thrust ramp, located to the south and the north of the city respectively, connected by a wide NE-SW oriented anticline crossing the urban area. The younger structural association developed since the Late Pleistocene and includes a set of ENE-trending folds that originated at the hangingwall of a main thrust ramp running just beneath the old town (Catania Thrust Ramp). These contractional features have been active during the last 60 ka and their geometry is consistent with the active ground deformation observed by the available geodetic data (GPS vectors and DInSAR analyses). The entire set of the recent structures are bordered to the north by a dextral transfer zone, reactivating part of the previous E-W alignment, that now represents the tectonic boundary with the Mt. Etna Volcano transtensional domain. Our data suggest that the Catania Thrust Ramp could play a main role in the active deformation pattern of the region, thus representing a potential seismotectonic feature to be carefully investigated for the re-evaluation of the seismic hazard of the area.

  14. Quantifying submarine landslide processes driven by active tectonic forcing: Cook Strait submarine canyon, New Zealand.

    NASA Astrophysics Data System (ADS)

    Mountjoy, J. J.; Barnes, P. M.; Pettinga, J. R.

    2006-12-01

    The Cook Strait submarine canyon system is a multi-branched, deeply incised and highly sinuous feature of New Zealand's active margin, covering some 1500km2 of sea floor between the North and South Islands and spanning water depths of between 50 and 2700m. The canyon occurs at the transition from the westward dipping oblique subduction zone adjacent to the SE North Island and the zone of continental transpression in NE South Island. The recent acquisition of high resolution (5-10m) SIMRAD EM300 bathymetric data allows active tectonic and geomorphic processes to be assessed and quantified at a level of detail previously not possible. While multiple active submarine fault traces have been identified in the Cook Strait by previous studies, quantitative information on their activity has been limited. Cook Strait is structurally characterized by westward dipping thrust faults and E-W trending dextral strike slip faults. The multiple large magnitude high frequency earthquake sources define zones of very high ground shaking expected to contribute to triggering of extensive submarine slope failures. Landslide activity within the canyon system is widespread and represents the dominant mass movement process affecting canyon heads and walls, redistributing material into valley fills. Complexes of large (km3) multi-stepped, deep-seated (100m) translational bedding plane failures represented by gently sloping (<3°) evacuated slide-scar areas with associated blocky valley fill deposits are numerous. Steep catchment heads, channel walls and the leading edges of asymmetric thrust-fault driven anticlines are dominated by gulley and rill systems with associated eroded and/or incipient slump features. Large (107m3+) slide blocks are recognized in discrete failures with quantifiable displacement vectors. Tsunamigenic landslides in this environment are inevitable. This study will provide quantification of landslide models including triggering mechanisms, discrete geometries and

  15. Applications of Morphochronology to the Active Tectonics of Tibet

    SciTech Connect

    Ryerson, F J; Tapponnier, P; Finkel, R C; Meriaux, A; der Woerd, J V; Lasserre, C; Chevalier, M; Xiwei, X; Haibing, L; King, G P

    2005-01-28

    The Himalayas and the Tibetan Plateau were formed as a result of the collision of India and Asia, and provide an excellent opportunity to study the mechanical response of the continental lithosphere to tectonic stress. Geophysicists are divided in their views on the nature of this response advocating either (1) homogeneously distributed deformation with the lithosphere deforming as a fluid continuum or (2) deformation is highly localized with the lithosphere that deforms as a system of blocks. The resolution of this issue has broad implications for understanding the tectonic response of continental lithosphere in general. Homogeneous deformation is supported by relatively low decadal, geodetic slip-rate estimates for the Altyn Tagh and Karakorum Faults. Localized deformation is supported by high millennial, geomorphic slip-rates constrained by both cosmogenic and radiocarbon dating on these faults. Based upon the agreement of rates determined by radiocarbon and cosmogenic dating, the overall linearity of offset versus age correlations, and on the plateau-wide correlation of landscape evolution and climate history, the disparity between geomorphic and geodetic slip-rate determinations is unlikely to be due to the effects of surface erosion on the cosmogenic age determinations. Similarly, based upon the consistency of slip-rates over various observation intervals, secular variations in slip-rate appear to persist no longer than 2000 years and are unlikely to provide reconciliation. Conversely, geodetic and geomorphic slip-rate estimates on the Kunlun fault, which does not have significant splays or associated thrust faults, are in good agreement, indicating that there is no fundamental reason why these complementary geodetic and geomorphic methods should disagree. Similarly, the geodetic and geomorphic estimates of shortening rates across the northeastern edge of the plateau are in reasonable agreement, and the geomorphic rates on individual thrust faults demonstrate

  16. Copernican tectonic activities in the northwestern Imbrium region of the Moon

    NASA Astrophysics Data System (ADS)

    Daket, Yuko; Yamaji, Atsushi; Sato, Katsushi

    2015-04-01

    Mare ridges and lobate scarps are the manifestations of horizontal compression in the shallow part of the Moon. Conventionally, tectonism within mascon basins has been thought to originate from mascon loading which is syndepositional tectonics (e.g., Solomon and Head, 1980). However, Ono et al. (2009) have pointed out that the subsurface tectonic structures beneath some mare ridges in Serenitatis appeared to be formed after the deposition of mare strata. Watters et al. (2010) also reported Copernican lobate scarps. Those young deformations cannot be explained by the mascon loading and are possibly ascribed to global cooling, orbital evolution and/or regional factors. Since mare ridges are topographically larger than lobate scarps, they might have large contribution to the recent contraction. In this study, we estimated until when the tectonic activities of mare ridges lasted in the northwestern Imbrium region. In order to infer the timing of the latest ages of tectonic activities, we used craters dislocated by the thrust faults that run along to the mare ridges in the study area. The ages of dislocated craters indicate the oldest estimate of the latest tectonic activity of the faults, because those craters must have existed during the tectonic activities. The ages of craters are inferred by the degradation levels classified by Trask (1971). We found ~450 dislocated craters in the study area. About 40 of them are smaller than 100 meter in diameter. Sub-hundred-meter-sized craters that still maintain their morphology sharp are classified into Copernican Period. Those small dislocated craters are interspersed all over the region, indicating that the most of the mare ridges in the study area were tectonically active in Copernican Period. In addition, we also found two sub-hundred-meter-sized craters dislocated by a graben at the west of Promontorium Laplace, indicating horizontal extension existed at Copernican Period. Consequently, tectonic activities in the study

  17. Active tectonics of the Northern Rif (Morocco) from geomorphic and geochronological data

    NASA Astrophysics Data System (ADS)

    Poujol, A.; Ritz, J.-F.; Tahayt, A.; Vernant, P.; Condomines, M.; Blard, P.-H.; Billant, J.; Vacher, L.; Tibari, B.; Hni, L.; Idrissi, A. Koulali

    2014-07-01

    We present results of a geomorphological and morphotectonic analysis of the northeastern part of the Rif. We show that the present day kinematics of the Rif is characterized by active deformation along the Trougout and Nekor faults in the North-East. Digital Elevation Models of offset drainage features (streams, fluvial terraces) allow determining a normal-left-lateral motion along the Trougout fault and a left-lateral strike-slip motion along the Nekor fault. Preliminary 3He cosmogenic dates of tectonic markers yield vertical and horizontal slip rates of ∼0.9 mm/yr and ∼0.5 mm/yr, respectively along the Trougout fault. The present-day localized transtension seen in the north-eastern Rif morphology (Ras Tarf) is coeval with uplifted marine terraces near the Al Hoceima Bay. U/Th dating of shells yield an average uplift rate of ∼0.2 mm/yr during the past 500 ka. These data show that active transtension in the northeastern Rif is also associated with uplift. These new morphotectonic constraints are consistent with the GPS measurements showing southwestward overall motion of most of the Rif belt with respect to stable Africa.

  18. Salts as indicators of tectonic activity along Nesson anticline, North Dakota

    SciTech Connect

    Lefever, J.A.; Lefever, R.D.; Anderson, S.B.

    1988-07-01

    The Nesson anticline is the major north-south-trending structure in the North Dakota portion of the Williston basin. The trace of the anticline is marked by nearly continuous production for 110 mi (175 km) from the Canadian border south to Dunn County; production is from 13 different stratigraphic zones. Previous studies have shown that the central and southern parts of the anticline, from Beaver Lodge field south to Rattlesnake Point field, consist of at least nine structurally independent areas, each of which has an individual tectonic history. Isopach patterns indicate that most of the areas underwent their greatest tectonic activity during the Devonian and Early Mississippian, although a few areas were active during the early Mesozoic as well. Ten traceable salts are present along the anticline in the Prairie (Devonian), Charles (Mississippian), Opeche (Permian), Spearfish (Triassic), and Pipe Formations (Jurassic). The isopach patterns of the individual salts indicate contemporaneous tectonic activity through thickening or thinning of the salt. Postdepositional activity is indicated by the absence of a salt; the timing of the activity may be estimated from the presence of compensating section above the level of the salt. Their results indicate that, in addition to the times given above, significant tectonic activity took place along the anticline during the Late Mississippian, late Jurassic, and Early Cretaceous.

  19. Morphometric analysis of relative tectonic activity in the Baturagung Mountain, Central Java, Indonesia

    NASA Astrophysics Data System (ADS)

    Mulyasari, Rahmi; Brahmantyo, Budi; Supartoyo

    2017-06-01

    Special Region of Yogyakarta and Klaten district, Central Java is one of areas in Indonesia that is prone to earthquake caused by subduction in Indian Ocean and active fault in land. The earthquake sources from active fault probable from Opak and other faults located in Baturagung Mountain. Active faults controlling landform development in tectonically active regions, and it has significantly affected fluvial systems and mountain - front landscapes in the Baturagung Mountain. To assess tectonic activities in the area used quantitative analysis (morphometric). Morphometric analysis consists of 5 parameters geomorphic indices: drainage basin asymmetry (AF), hypsometric curve and integral (Hc and Hi), stream length gradient (SL) index, basin shape index (Bs), and mountain-front sinuosity (Smf). These indices were combined to yield the relative tectonic activity index (RTAI) using geographic information systems (GIS). The result found that RTAI in the study area are divided into three classes: Class 2 (high 0.6% of the watershed area (1.32 km2)); Class 3 (moderate 58.9% (122.1 km2)); and Class 4 (low 40.4% (83.75 km2)). All of morphometric analysis generally indicates this area more influenced by tectonics than erosion. The results are consistent with geomorphological observations.

  20. Icy Satellite Tectonic, Geodynamic and Mass Wasting Surface Features: Constraints on Interior Processes and Evolution

    NASA Astrophysics Data System (ADS)

    Singer, Kelsi Nab

    Empirical data collected from mapping campaigns combined with modeling of geologic processes improves our understanding of planetary geology. Many planet- or satellite-scale processes cannot be reproduced in labs, thus analyzing surface features provides insights to confirm, discount, or improve models. I present the methods used to map and characterize the morphometry of several types of geologic features found on three icy satellites of Jupiter and Saturn, and the resulting data. Trends in the data provide insight into feature formation, and to both surface and interior processes occurring in icy satellites. Topics include: i) linear features and despinning stresses on Iapetus, ii) long-runout landslides and friction reduction on Iapetus, iii) pits, uplifts, and small chaos regions on Europa and what they reveal about ice shell thickness, iv) relaxed impact craters and the thermal history of Ganymede, and v) the size-velocity distribution of ejecta fragments from large cratering events on Europa and Ganymede.

  1. Preliminary study on hydrogeology in tectonically active areas.

    SciTech Connect

    Lowry, Thomas Stephen; Lappin, Allen R.; Gettemy, Glen L.; Jensen, Richard Pearson; Arnold, Bill Walter; James, Scott Carlton; Lee, Moo Yul; Meier, Diane A.

    2006-09-01

    This report represents the final product of a background literature review conducted for the Nuclear Waste Management Organization of Japan (NUMO) by Sandia National Laboratories, Albuquerque, New Mexico, USA. Internationally, research of hydrological and transport processes in the context of high level waste (HLW) repository performance, has been extensive. However, most of these studies have been conducted for sites that are within tectonically stable regions. Therefore, in support of NUMO's goal of selecting a site for a HLW repository, this literature review has been conducted to assess the applicability of the output from some of these studies to the geological environment in Japan. Specifically, this review consists of two main tasks. The first was to review the major documents of the main HLW repository programs around the world to identify the most important hydrologic and transport parameters and processes relevant in each of these programs. The review was to assess the relative importance of processes and measured parameters to site characterization by interpretation of existing sensitivity analyses and expert judgment in these documents. The second task was to convene a workshop to discuss the findings of Task 1 and to prioritize hydrologic and transport parameters in the context of the geology of Japan. This report details the results and conclusions of both of these Tasks.

  2. Geopotential field anomalies and regional tectonic features - two case studies: southern Africa and Germany

    NASA Astrophysics Data System (ADS)

    Korte, Monika; Mandea, Mioara

    2016-05-01

    Maps of magnetic and gravity field anomalies provide information about physical properties of the Earth's crust and upper mantle, helpful in understanding geological conditions and tectonic structures. Depending on data availability, whether from the ground, airborne, or from satellites, potential field anomaly maps contain information on different ranges of spatial wavelengths, roughly corresponding to sources at different depths. Focussing on magnetic data, we compare amplitudes and characteristics of anomalies from maps based on various available data and as measured at geomagnetic repeat stations. Two cases are investigated: southern Africa, characterized by geologically old cratons and strong magnetic anomalies, and the smaller region of Germany with much younger crust and weaker anomalies. Estimating lithospheric magnetic anomaly values from the ground stations' time series (repeat station crustal biases) reveals magnetospheric field contributions causing time-varying offsets of several nT in the results. Similar influences might be one source of discrepancy when merging anomaly maps from different epochs. Moreover, we take advantage of recently developed satellite potential field models and compare magnetic and gravity gradient anomalies of ˜ 200 km resolution. Density and magnetization represent independent rock properties and thus provide complementary information on compositional and structural changes. Comparing short- and long-wavelength anomalies and the correlation of rather large-scale magnetic and gravity anomalies, and relating them to known lithospheric structures, we generally find a better agreement in the southern African region than the German region. This probably indicates stronger concordance between near-surface (down to at most a few km) and deeper (several kilometres down to Curie depth) structures in the former area, which can be seen to agree with a thicker lithosphere and a lower heat flux reported in the literature for the southern

  3. Mapping Active Faults and Tectonic Geomorphology offshore central California

    NASA Astrophysics Data System (ADS)

    Johnson, S. Y.; Watt, J. T.; Hart, P. E.; Sliter, R. W.; Wong, F. L.

    2009-12-01

    In June 2008, and July 2009, the USGS conducted two high-resolution, marine, seismic-reflection surveys across the continental shelf and upper slope between Piedras Blancas and Point Sal, central California, in order to better characterize regional earthquake sources. More than 1,300 km of single-channel seismic data were acquired aboard the USGS R/V Parke Snavely using a 500-joule mini-sparker source fired at a 0.5-second shot interval and recorded with a 15-meter streamer. Most tracklines were run perpendicular to the coast at 800-meter spacing, extending from the nearshore (~ 10-15 m water depth) to as far as 20 km offshore. Sub-bottom imaging varies with substrate, ranging from outstanding (100 to 150 m of penetration) in inferred Quaternary shallow marine, shelf and upper slope deposits to poor (0 to 10 m) in the Mesozoic basement rocks. Marine magnetic data were collected simultaneously on this survey, and both data sets are being integrated with new aeromagnetic data, publicly available industry seismic-reflection data, onshore geology, seismicity, and high-resolution bathymetry. Goals of the study are to map geology, structure, and sediment distribution; to document fault location, length, segmentation, shallow geometry and structure; and to identify possible sampling targets for constraining fault slip rates, earthquake recurrence, and tsunami hazard potential. The structure and tectonic geomorphology of the >100-km-long, right-lateral, Hosgri fault zone and its connections to the Los Osos, Pecho, Oceano and other northwest-trending inboard faults are the focus of this ongoing work. The Hosgri fault forms the eastern margin of the offshore Santa Maria basin and coincides in places with the outer edge of the narrow (5- to 15-km-wide), structurally complex continental shelf. The Hosgri is imaged as a relatively continuous, vertical fault zone that extends upward to the seafloor; varies significantly and rapidly along strike; and incorporates numerous

  4. Middle proterozoic tectonic activity in west Texas and eastern New Mexico and analysis of gravity and magnetic anomalies

    SciTech Connect

    Adams, D.C.; Keller, G.R. )

    1994-03-01

    The Precambrian history of west Texas and eastern New Mexico is complex, consisting of four events: Early Proterozoic orogenic activity (16309-1800 Ma), formation of the western granite-rhyolite province (WGRP) (1340-1410 Ma), Grenville age tectonics (1116-1232 Ma), and middle Proterozoic extension possibly related to mid-continent rifting (1086-1109 Ma). Pre-Grenville tectonics, Grenville tectonics, and mid-continent rifting are represented in this area by the Abilene gravity minimum (AGM) and bimodal igneous rocks, which are probably younger. We have used gravity modeling and the comparison of gravity and magnetic anomalies with rock types reported from wells penetrating Precambrian basement to study the AGM and middle Proterozoic extension in this area. The AGM is an east-northeast-trending, 600 km long, gravity low, which extends from the Texas-Oklahoma border through the central basin platform (CBP) to the Delaware basin. This feature appears to predate formation of the mafic body in the CBP (1163 Ma) and is most likely related to Pre-Grenville tectonics, possibly representing a continental margin arc batholith. Evidence of middle Proterozoic extension is found in the form of igneous bodies in the CBP, the Van Horn uplift, the Franklin Mountains, and the Sacramento Mountains. Analysis of gravity and magnetic anomalies shows that paired gravity and magnetic highs are related to mafic intrusions in the upper crust. Mapping of middle Proterozoic igneous rocks and the paired anomalies outlines a 530 km diameter area of distributed east-west-oriented extension. The Debaca-Swisher terrain of shallow marine and clastic sedimentary rocks is age correlative with middle Proterozoic extension. These rocks may represent the lithology of possible Proterozoic exploration targets. Proterozoic structures were reactivated during the Paleozoic, affecting both the structure and deposition in the Permian basin.

  5. Impact-related Events on Active Tectonic Regions Defined by Its Age, Shocked Minerals and Compositions

    NASA Astrophysics Data System (ADS)

    Miura, Y.; Hirota, A.; Gorton, M.; Kedves, M.

    2002-03-01

    New type of impact-related event is defined at active tectonic region by using semi-circular structure, bulk XRF compositions with mixed data, shocked quartz grains with the PDFs texture, and Fe-Ni content. Example is discussed in Takamatsu MKT crater in Japan.

  6. Assessment of relative tectonic activity in the Trichonis Lake graben (Western Greece) using geomorphometry

    NASA Astrophysics Data System (ADS)

    Karymbalis, Efthimios; Valkanou, Kanella; Fubelli, Giandomenico; Ferentinou, Maria; Giles, Philip; Papanastassiou, Dimitris; Gaki-Papanastassiou, Kalliopi; Tsanakas, Konstantinos

    2016-04-01

    In tectonically active areas fluvial systems and mountain fronts are controlled by the type, geometry, and recent activity of faults. The aim of this study is to investigate the contribution of neotectonics to the development of the fluvial landscape of the broader Trichonis Lake area (located in western continental Greece) through quantitative geomorphological analysis. The Trichonis Lake graben is a well-known tectonic depression of Quaternary age, which cuts across the early Tertiary NW-SE fold and thrust structures of the Pindos Mountain belt. It strikes WNW-ESE for a distance of 32 km and has a width of 10 km. The graben at the north and south flanks of the lake is bounded by E-W and NW-SE trending faults. Recent seismic activity (a shallow earthquake sequence in 1975 and a 2007 earthquake swarm) showed the existence of a NNW-SSE normal fault that dips to the NE and bounds the south-eastern shore of the lake. The studied catchments are developed on the hanging walls of these active normal faults. To evaluate the relative tectonic activity in the study area, various morphometric indices were measured for 35 catchments (slope of the valley sides of the catchment, hypsometric integral, catchment asymmetry factor, relief ratio, Melton's ruggedness number, stream-gradient index, ratio of valley floor width to valley height, and catchment shape) and 20 mountain fronts (mountain-front sinuosity index) around the lake. For the measurement of the geomorphometric variables a digital elevation model (DEM) with 2-m spatial resolution was derived from topographic maps at 1:5000 scale with 4-m contour lines, and a series of maps showing the spatial distribution of the variables were produced in a GIS environment. For each morphometric variable the catchments were classified into three classes. The combination of these morphometric variables allowed us to yield two new indices of relative tectonic activity (named IRTA - Index of Relative Tectonic Activity and IAT - Index of

  7. Debris Flow Architecture and Processes in Offshore Trinidad: Implications for basin fill in tectonically active margins

    NASA Astrophysics Data System (ADS)

    Moscardelli, L.; Wood, L.; Mann, P.

    2004-12-01

    The eastern continental margin of Trinidad is situated along the tectonically active oblique converging southeastern boundary of the Caribbean and South American plates and proximal to the Orinoco Delta. Factors that have contributed to gravitational instabilities in the shelf edge include high sedimentation accumulation rates, high frequency sea-level fluctuations during the Quaternary, frequent earthquakes and the abundance of methane hydrate. This volatile mix of factors favor the formation of episodic gravity induced deposits that have affected thousands of square kilometers of the deep marine environment. Debris flows are the predominant type of gravity induced deposits in the area. Multiple episodes of debris flow occurrence have been identified using nearly 10,000 square kilometers of three-dimensional seismic data that cover the entire eastern margin. Units can reach up to 250 meters in thickness and occur over 100's of kilometer square areas. Maps that have been generated for the uppermost flow show significant basal scour, up to 33 meters deep generated during passage of the flow. Scours also show divergent patterns in map view indicating changes in the flow conditions. Flow scour erosional shadows around prominent seafloor mud volcanoes preserving evacuated strata on the downslope side of these obstructions. Internal architecture shows high amplitude discontinuous and chaotic seismic facies, and stacked thrust imbricates association with compressional bends in the flow path. The scale and occurrence frequency of these features suggest that they may form a significant threat to submarine installations and possibly generate tsunamigenic waves that can threaten shipping and coastal communities.

  8. The feedback between active tectonics, fluid flow and mineralization in an Andean geotermal reservoir

    NASA Astrophysics Data System (ADS)

    Reich, M.; Arancibia, G.; Perez, P.; Sanchez, P.; Cembrano, J. M.; Stimac, J. A.; Lohmar, S.

    2012-12-01

    regarding the role of faults and fractures networks on the chemical evolution and migration pattern of hydrothermal fluids in the reservoir. More than 120 structural measurements of faults, veins and fault-veins were performed along the drillcore, and 47 samples were taken for petrography and fluid inclusions studies. Detailed mapping of structures, including dip and kinematic indicators from mineral sealing reveal a strong correlation between abundance of structures and rock type. Lava intervals exhibit more intense fracturing and veining than tuff and volcanoclastic intervals. In the upper 300 m of the core, structures are primarily steeply dipping with a dominant normal sense of displacement (some dextral component). Below a cataclastic zone at 300 m, structures are more variable in dip and sense of motion, with some reverse faults. Considering the fact that tectonic activity defines the nature, geometry and kinematics of fault/fracture networks, a better understanding of the structural pattern and its link with the chemical evolution of fluids may give significant insights into the processes governing the dynamics of the geothermal system. This is particularly critical for continuing research into the understanding of geothermal reservoirs in Chile, where the links between structural features and fluid evolution remain largely unconstrained.

  9. Active inversion tectonics, simple shear folding and back-thrusting at Rioni Basin, Georgia

    NASA Astrophysics Data System (ADS)

    Tibaldi, A.; Alania, V.; Bonali, F. L.; Enukidze, O.; Tsereteli, N.; Kvavadze, N.; Varazanashvili, O.

    2017-03-01

    The Rioni Basin, located between the Greater and Lesser Caucasus in Georgia, is an outstanding example of ongoing inversion tectonics. Marine and continental deposits of Cretaceous-Neogene age have been locally uplifted since the end of Miocene. The uplifted area totals 1300 km2, and Plio-Quaternary river deposits have been raised up to 200 m above the surrounding plains. Inversion tectonics has been accompanied by the development of south-vergent asymmetrical folds and strike-slip faults along the border of the uplifted area. The folds have locally an en-échelon geometry and microtectonic data indicate rotation of the paleostress direction over time, suggesting simple shear deformation. In the interiors of the uplifted area, there are gentle symmetrical folds and one main active south-dipping reverse fault, corresponding to a backthrust. Morphostructural evidence, as well as the tilting of Quaternary strata, the offset of Quaternary alluvial deposits and the presence of crustal seismic activity, indicate that compressional tectonics is still active. The combination of field data with seismic reflection sections shows that inversion tectonics took place through a series of north-dipping blind thrusts and a wedge with passive back-thrusting. Uplift and contraction are more developed along the eastern part of the study area, suggesting the westward propagation of the closure of the Transcaucasian depression.

  10. Lithospheric strength of Ganymede: Clues to early thermal profiles from extensional tectonic features

    NASA Technical Reports Server (NTRS)

    Golombek, M. P.; Banerdt, W. B.

    1985-01-01

    While it is generally agreed that the strength of a planet's lithosphere is controlled by a combination of brittle sliding and ductile flow laws, predicting the geometry and initial characteristics of faults due to failure from stresses imposed on the lithospheric strength envelope has not been thoroughly explored. Researchers used lithospheric strength envelopes to analyze the extensional features found on Ganymede. This application provides a quantitative means of estimating early thermal profiles on Ganymede, thereby constraining its early thermal evolution.

  11. Geomorphology, tectonics, and exploration

    NASA Technical Reports Server (NTRS)

    Sabins, F. F., Jr.

    1985-01-01

    Explorationists interpret satellite images for tectonic features and patterns that may be clues to mineral and energy deposits. The tectonic features of interest range in scale from regional (sedimentary basins, fold belts) to local (faults, fractures) and are generally expressed as geomorphic features in remote sensing images. Explorationists typically employ classic concepts of geomorphology and landform analysis for their interpretations, which leads to the question - Are there new and evolving concepts in geomorphology that may be applicable to tectonic analyses of images?

  12. The Central-Western Mediterranean: Anomalous igneous activity in an anomalous collisional tectonic setting

    NASA Astrophysics Data System (ADS)

    Lustrino, Michele; Duggen, Svend; Rosenberg, Claudio L.

    2011-01-01

    plate (Sardinia, Corsica, Balearic Islands, Kabylies, Calabria, Peloritani Mountains). The bulk of igneous activity in the central-western Mediterranean is believed to have tapped mantle 'wedge' regions, metasomatized by pressure-related dehydration of the subducting slabs. The presence of subduction-related igneous rocks with a wide range of chemical composition has been related to the interplay of several factors among which the pre-metasomatic composition of the mantle wedges (i.e., fertile vs. refractory mineralogy), the composition of the subducting plate (i.e., the type and amount of sediment cover and the alteration state of the crust), the variable thermo-baric conditions of magma formation, coupled with variable molar concentrations of CO 2 and H 2O in the fluid phase released by the subducting plates are the most important. Compared to classic collisional settings (e.g., Himalayas), the central-western Mediterranean area shows a range of unusual geological and magmatological features. These include: a) the rapid formation of extensional basins in an overall compressional setting related to Africa-Europe convergence; b) centrifugal wave of both compressive and extensional tectonics starting from a 'pivotal' region around the Gulf of Lyon; c) the development of concomitant Cenozoic subduction zones with different subduction and tectonic transport directions; d) subduction 'inversion' events (e.g., currently along the Maghrebian coast and in northern Sicily, previously at the southern paleo-European margin); e) a repeated temporal pattern whereby subduction-related magmatic activity gives way to magmas of intraplate geochemical type; f) the late-stage appearance of magmas with collision-related 'exotic' (potassic to ultrapotassic) compositions, generally absent from simple subduction settings; g) the relative scarcity of typical calcalkaline magmas along the Italian peninsula; h) the absence of igneous activity where it might well be expected (e.g., above the

  13. Evaluating influence of active tectonics on spatial distribution pattern of floods along eastern Tamil Nadu, India

    NASA Astrophysics Data System (ADS)

    Selvakumar, R.; Ramasamy, SM.

    2014-12-01

    Flooding is a naturally recurrent phenomenon that causes severe damage to lives and property. Predictions on flood-prone zones are made based on intensity-duration of rainfall, carrying capacity of drainage, and natural or man-made obstructions. Particularly, the lower part of the drainage system and its adjacent geomorphic landforms like floodplains and deltaic plains are considered for analysis, but stagnation in parts of basins that are far away from major riverine systems is less unveiled. Similarly, uncharacteristic flooding in the upper and middle parts of drainage, especially in zones of an anomalous drainage pattern, is also least understood. Even though topographic differences are attributed for such anomalous spatial occurrence of floods, its genetic cause has to be identified for effective management practice. Added to structural and lithological variations, tectonic movements too impart micro-scale terrain undulations. Because active tectonic movements are slow-occurring, long-term geological processes, its resultant topographical variations and drainage anomalies are least correlated with floods. The recent floods of Tamil Nadu also exhibit a unique distribution pattern emphasizing the role of tectonics over it. Hence a detailed geoinformatics-based analysis was carried out to envisage the relationship between spatial distribution of flood and active tectonic elements such as regional arches and deeps, block faults, and graben and drainage anomalies such as deflected drainage, compressed meander, and eyed drainages. The analysis reveals that micro-scale topographic highs and lows imparted by active tectonic movements and its further induced drainage anomalies have substantially controlled the distribution pattern of flood.

  14. Active tectonics of the Rif Mountains (Morocco) from geomorphic and geochronological data

    NASA Astrophysics Data System (ADS)

    Ritz, Jean-François; Poujol, Antoine; Tahayt, Abdelilah; Vernant, Philippe; Condomines, Michel; Blard, Pierre-Henri; Braucher, Régis; Benedetti, Lucilla; Bourles, Didier; Leroux-Mallouf, Romain; Ferry, Matthieu; Maate, Soufian

    2014-05-01

    We present results of a geomorphological and morphotectonic analysis of the Rif Mountains (Morocco). We show that the present day kinematics of the Rif is characterized by active deformation along normal and left-lateral strike-slip faults in the North-East (Trougout, Rouadi, Boujibar and Nekor faults), reverse fault in the South (the South Rif Front) and inherited fold structures in the West. Digital Elevation Models of offset drainage features (streams, fluvial terraces) allow determining horizontal cumulative displacements of ~25-35m along the Trougout fault and ~40m along the Nekor fault. 14C dating of tectonic markers yields vertical and horizontal slip rates of ~2.8 mm/yr and ~2.3 mm/yr respectively, along the Trougout fault. For the first time, cosmogenic 3He method is used on volcanic rocks to date the successive exposure of the fault plane. Along the Trougout fault, this yields recurrence time between 3,1 and 4,1 ka. The present-day localized transtension seen in the northeastern Rif morphology (Ras Tarf) is coeval with uplifted marine terraces near the Al Hoceima Bay. U/Th dating of shells yields an average uplift rate of ~0.2 mm/yr during the past 500 Ka. These data show that active transtension in the northeastern Rif is also associated with uplift. Comparison with cosmogenic 10Be/3He dating of perched fluvial surface located above these marine terraces is in progress and may allow us to confirm or not this uplift rate. In the western Rif, geomorphic markers allow us to suggest that active deformation is accommodated along blind thrust and NNW-SSE inherited folds. These new morphotectonic constraints are consistent with the GPS measurements showing southwestward overall motion of most of the Rif belt with respect to stable Africa and suggest a continuum of the deformation from the Pliocene.

  15. The link between tectonics and sedimentation in the Pannonian basin: seismic analysis of structural and stratigraphic features and compaction effects

    NASA Astrophysics Data System (ADS)

    Balázs, Attila; Matenco, Liviu; Magyar, Imre; Sztanó, Orsolya; Horváth, Ferenc; Cloetingh, Sierd

    2017-04-01

    The architecture of sedimentary basins reflects the relationship between accommodation space and sediment supply, their rates and localization being variable during basin evolution. A novel kinematic and seismic sequence stratigraphic interpretation calibrated by wells allows the quantification of the link between the formation of half-grabens and coeval sedimentation in the Great Hungarian Plain part of the basin. While the lower order tectonic induced cycles characterize the main phases of extension in various sub-basins, the higher order cyclicity and associated unconformities define individual moments of fault (re-)activation. The combined kinematic and depositional model at the scale of the entire basin infers that the cumulated amounts of Early to Late Miocene extension were much higher than previously thought, reaching about 220-290 km. The post-rift phase of the basin is associated with the evolution of Lake Pannon: an initial underfilled, balance fill and a final stage of overfilled large lacustrine basin. Paleobathymetric calculations based on the decompacted thickness of the prograding shelf-margin slope clinoforms indicate water depth values typically a few 100s meters up to 1 kilometer between the bottomsets and topsets. Additional 0-75 meters of water column covered the shelf controlled by climatically driven lake level variations. Sedimentary transport routes were primarily determined by inherited and/or local active tectonics including the control of the Miocene shelf-margin progradation directions and affecting recent fluvial geometries as well. Sediments up to 6 km thick are affected by continuous differential vertical movements and compaction creating gentle fold geometries and differential compaction induced faults, playing a major role in hydrocarbon migration and trapping.

  16. Tree Tectonics

    NASA Astrophysics Data System (ADS)

    Vogt, Peter R.

    2004-09-01

    Nature often replicates her processes at different scales of space and time in differing media. Here a tree-trunk cross section I am preparing for a dendrochronological display at the Battle Creek Cypress Swamp Nature Sanctuary (Calvert County, Maryland) dried and cracked in a way that replicates practically all the planform features found along the Mid-Oceanic Ridge (see Figure 1). The left-lateral offset of saw marks, contrasting with the right-lateral ``rift'' offset, even illustrates the distinction between transcurrent (strike-slip) and transform faults, the latter only recognized as a geologic feature, by J. Tuzo Wilson, in 1965. However, wood cracking is but one of many examples of natural processes that replicate one or several elements of lithospheric plate tectonics. Many of these examples occur in everyday venues and thus make great teaching aids, ``teachable'' from primary school to university levels. Plate tectonics, the dominant process of Earth geology, also occurs in miniature on the surface of some lava lakes, and as ``ice plate tectonics'' on our frozen seas and lakes. Ice tectonics also happens at larger spatial and temporal scales on the Jovian moons Europa and perhaps Ganymede. Tabletop plate tectonics, in which a molten-paraffin ``asthenosphere'' is surfaced by a skin of congealing wax ``plates,'' first replicated Mid-Oceanic Ridge type seafloor spreading more than three decades ago. A seismologist (J. Brune, personal communication, 2004) discovered wax plate tectonics by casually and serendipitously pulling a stick across a container of molten wax his wife and daughters had used in making candles. Brune and his student D. Oldenburg followed up and mirabile dictu published the results in Science (178, 301-304).

  17. Response of Cenozoic turbidite system to tectonic activity and sea-level change off the Zambezi Delta

    NASA Astrophysics Data System (ADS)

    Castelino, Jude A.; Reichert, Christian; Jokat, Wilfried

    2017-09-01

    Submarine fans and turbidite systems are important and sensitive features located offshore from river deltas that archive tectonic events, regional climate, sea level variations and erosional process. Very little is known about the sedimentary structure of the 1800 km long and 400 km wide Mozambique Fan, which is fed by the Zambezi and spreads out into the Mozambique Channel. New multichannel seismic profiles in the Mozambique Basin reveal multiple feeder systems of the upper fan that have been active concurrently or consecutively since Late Cretaceous. We identify two buried, ancient turbidite systems off Mozambique in addition to the previously known Zambezi-Channel system and another hypothesized active system. The oldest part of the upper fan, located north of the present-day mouth of the Zambezi, was active from Late Cretaceous to Eocene times. Regional uplift caused an increased sediment flux that continued until Eocene times, allowing the fan to migrate southwards under the influence of bottom currents. Following the mid-Oligocene marine regression, the Beira High Channel-levee complex fed the Mozambique Fan from the southwest until Miocene times, reworking sediments from the shelf and continental slope into the distal abyssal fan. Since the Miocene, sediments have bypassed the shelf and upper fan region through the Zambezi Valley system directly into the Zambezi Channel. The morphology of the turbidite system off Mozambique is strongly linked to onshore tectonic events and the variations in sea level and sediment flux.

  18. Response of Cenozoic turbidite system to tectonic activity and sea-level change off the Zambezi Delta

    NASA Astrophysics Data System (ADS)

    Castelino, Jude A.; Reichert, Christian; Jokat, Wilfried

    2017-03-01

    Submarine fans and turbidite systems are important and sensitive features located offshore from river deltas that archive tectonic events, regional climate, sea level variations and erosional process. Very little is known about the sedimentary structure of the 1800 km long and 400 km wide Mozambique Fan, which is fed by the Zambezi and spreads out into the Mozambique Channel. New multichannel seismic profiles in the Mozambique Basin reveal multiple feeder systems of the upper fan that have been active concurrently or consecutively since Late Cretaceous. We identify two buried, ancient turbidite systems off Mozambique in addition to the previously known Zambezi-Channel system and another hypothesized active system. The oldest part of the upper fan, located north of the present-day mouth of the Zambezi, was active from Late Cretaceous to Eocene times. Regional uplift caused an increased sediment flux that continued until Eocene times, allowing the fan to migrate southwards under the influence of bottom currents. Following the mid-Oligocene marine regression, the Beira High Channel-levee complex fed the Mozambique Fan from the southwest until Miocene times, reworking sediments from the shelf and continental slope into the distal abyssal fan. Since the Miocene, sediments have bypassed the shelf and upper fan region through the Zambezi Valley system directly into the Zambezi Channel. The morphology of the turbidite system off Mozambique is strongly linked to onshore tectonic events and the variations in sea level and sediment flux.

  19. Active tectonics of the Oran (Algeria) Quaternary plain

    NASA Astrophysics Data System (ADS)

    youcef, Bouhadad; rabah, Bensalem; e-hadi, oubaiche

    2016-04-01

    The Oran region, in north-western Algeria, has been hit several times in the past by destructive moderate-sized and strong earthquakes. The Oran October 9th , 1790 (I0= X) was among the strongest seismic events in the western Mediterranean area comparable, if we consider the described effects, to the El- Asnam (1980, Ms=7.3) and Zemmouri (2003, Mw=6.8) earthquakes. Such strong seismic events requires the presence of major active geological structures that are re-activated several times in the past. In this work we present results of a multi- disciplinary study combining geomorphic analysis, field earthquake geological investigations and geophysical methods, undertaken to study the southern border of the Oran Quaternary plain. A 50 km long, SW-dipping and NE-SW trending active fault has been identified that showing clear quaternary deformation. Keywords: earthquake geology, active fault, geomorphic, geophysics, Algeria.

  20. Relationship between Mesozoic and Cenozoic tectonic features in west central Arizona and adjacent southeastern California

    SciTech Connect

    Spencer, J.E.; Reynolds, S.J. )

    1990-01-10

    The Maria fold-and-thrust belt (MFTB) is a narrow belt of Mesozoic crustal shortening that is characterized by generally south vergent folds and thrusts that commonly displace Proterozoic crystalline rocks over deformed and metamorphosed Paleozoic and Mesozoic strata. The MFTB is cut by a south to southeast trending belt of mid-Tertiary extensional deformation. Extension was characterized by large displacements on low-angle normal faults, known as detachment faults, and by isostatic uplift of mylonitic midcrustal rocks now exposed in metamorphic core complexes. The geometry and style of extensional deformation change along the extensional belt and reveal the influence of the MFTB. Several extensional features are spatially coincident with the root zone of MFTB thrusts: (1) an areally extensive west-northwest trending belt of denuded Tertiary mylonitic fabrics in the Whipple and Harcuvar metamorphic core complexes, (2) a style of extension characterized by minimum extensional dismemberment of the upper plate and maximum denudation and uplift of deep-seated lower plate rocks, (3) an abrupt bend in the belt of arched, uplifted rocks below detachment faults, and (4) an abrupt bend in the trend of the breakaway zone of the detachment faults and an associated lateral ramp in the detachment fault system.

  1. Identification and interpretation of tectonic features from Skylab imagery. [California to Arizona

    NASA Technical Reports Server (NTRS)

    Abdel-Gawad, M. (Principal Investigator)

    1974-01-01

    The author has identified the following significant results. S190-B imagery confirmed previous conclusions from S190-A that the Garlock fault does not extend eastward beyond its known termination near the southern end of Death Valley. In the Avawatz Mountains, California, two faults related to the Garlock fault zone (Mule Spring fault and Leach Spring fault) show evidence of recent activity. There is evidence that faulting related to Death Valley fault zone extends southeastward across the Old Dad Mountains. There, the Old Dad fault shows evidence of recent activity. A significant fault lineament has been identified from McCullough Range, California southeastward to Eagle Tail Mountains in southwestern Arizona. The lineament appears to control tertiary and possible cretaceous intrusives. Considerable right lateral shear is suspected to have taken place along parts of this lineament.

  2. Tectonic features of out-of-sequence-thrusts in central Nankai accretionary prism

    NASA Astrophysics Data System (ADS)

    Saito, S.; Kuramoto, S.; Ashi, J.; Kinoshita, M.; Ujiie, K.; Sagaguchi, A.; Lallemant, S.; Toki, T.; Kubo, Y.; Misawa, N.

    2002-12-01

    During NT02-02 and YK02-02 cruises, deep-tow camera, multi-beam bathymetry, and diving survey were conducted in central Nankai accretionary prism, off Kii Peninsula. A system of out-of-sequence thrusts (OOST) defines high ridges, roughly parallel to the deformation front. The surface manifestation of the OOST is characterized by right-stepped en-echelon arrangement of ridges, which suggests a dextral slip component along the OOST. A series of deep-tow camera and dive surveys were conducted on the sites of OOST. Observation of outcrops and rock-sampling documented that the ridges are composed dominantly of stratified shale, siltstone and partly of sandstone covered by present talus debris and clayey ooze. Exposures along the southern limb of the ridges indicate that the beddings of the sediments dip generally northwestward at an angle of about 20 to 30 degree. In contrast to the southern limb of the ridge, outcrops along the northern limb of the ridge show southward dipping bedding. Active cold seepages with Calyptogena colony, bacteria mat, and carbonate chimney were observed at several sites on the slope of OOST ridges. All the active cold seepages observed from the submersible are located on the gentle foot of the slope. High heat flow, low chlorinity of interstitial water chemistry, and high natural gamma radiation at the active colony suggests seepage from the inside of the basement.

  3. The Meers Fault: Tectonic activity in southwestern Oklahoma

    SciTech Connect

    Ramelli, A.R.; Slemmons, D.B.; Brocoum, S.J.

    1987-03-01

    The Meers Fault in Southwestern Oklahoma is capable of producing large, damaging earthquakes. By comparison to historical events, a minimum of M = 6-3/4 to 7-1/4 could be expected. The most recent surface rupturing event occurred in the late Holocene, and it appears that one or more pre-Holocene events preceded it. Surface rupture length is at least 37 km. Displacements comprising the present-day scarp have left-lateral and high-angle reverse components. Vertical separation of the ground surface reaches 5 m, while lateral separation exceeds the vertical by a ratio of about 3:1 to 5:1, reaching about 20 m. Individual events apparently had maximum displacements of several meters. The Meers Fault may be part of a larger active zone. Based on surface expressions, the Washita Valley, Oklahoma and Potter County, Texas Faults may also have ruptures during the late Quaternary, although not as recently as the Meers Fault. Low sun angle photography in Southwestern Oklahoma revealed no evidence of fault activity, other than that of the Meers Fault, although activity may be concealed by poor preservation or ductile surface deformation. This suggests that additional areas of activity may be sparse and rupture infrequently.

  4. Morphotectonic evolution of triangular facets and wine-glass valleys in the Noakoh anticline, Zagros, Iran: Implications for active tectonics

    NASA Astrophysics Data System (ADS)

    Bahrami, Shahram

    2012-07-01

    The Noakoh anticline is located in Kermanshah province and is part of the Simply Folded Belt of Zagros. Boundaries of 97 triangular facets and 67 wine-glass (W-G) valleys, which formed on anticline limbs, were delineated using Quickbird satellite imagery. The strata dip (D), area (A), base length (BL), topographic slope (S) of facets, the maximum width (M), outlet width (O) and ratio of maximum width to outlet width (W index) of W-G valleys were analysed in detail. Noakoh anticline was subdivided into 9 tectonic zones on the basis of dip, topographic slopes and width of limbs. Results show that there are strong positive correlations between means of D-BL and S-BL pairs. Poor positive correlations exist between means of D-A and S-A pairs. Among W-G valley metrics, the W index has strong relations with D and S parameters. Based on the results, steep facets with long bases and well developed W-G valleys with narrow outlets and wide upper parts are associated with more rotated limbs having steep slopes. Facets on the northeastern slope have more forest cover, micro-organism activity, karstic features and soil cover, whereas facets on relatively drier southwestern slope are characterized by physical weathering processes and minor karstic landforms. This study demonstrates that, apart from tectonic activity as a major control on the morphometry of facets and valleys, climate and slope aspect have also acted as secondary factors on the development of the studied landforms.

  5. Physical mechanism of the vertical electric field generation over active tectonic faults

    NASA Astrophysics Data System (ADS)

    Pulinets, S. A.

    2009-09-01

    The concept of the Global Electric Circuit (GEC) provides an explanation of the existence of a vertical atmospheric electric field and coupling between the ground and ionosphere. Presently, ionospheric physics pays more attention to electric fields and coupling processes in the polar and auroral regions, whereas in other areas the potential difference between the ground and ionosphere usually is not taken into account. Regional processes exist, however, that are able to significantly affect the GEC parameters and through modification of the ionospheric potential to create plasma density irregularities of different scales within the ionosphere. One such source of ionosphere modification is air ionization in the vicinity of active tectonic faults, which takes place due to increased radon emanation. This paper considers the process of local modification of the GEC and corresponding ionospheric variability due to tectonic activity.

  6. Linking Europa's plume activity to tides, tectonics, and liquid water

    NASA Astrophysics Data System (ADS)

    Rhoden, Alyssa Rose; Hurford, Terry A.; Roth, Lorenz; Retherford, Kurt

    2015-06-01

    Much of the geologic activity preserved on Europa's icy surface has been attributed to tidal deformation, mainly due to Europa's eccentric orbit. Although the surface is geologically young (30-80 Myr), there is little information as to whether tidally-driven surface processes are ongoing. However, a recent detection of water vapor near Europa's south pole suggests that it may be geologically active. Initial observations indicated that Europa's plume eruptions are time-variable and may be linked to its tidal cycle. Saturn's moon, Enceladus, which shares many similar traits with Europa, displays tidally-modulated plume eruptions, which bolstered this interpretation. However, additional observations of Europa at the same time in its orbit failed to yield a plume detection, casting doubt on the tidal control hypothesis. The purpose of this study is to analyze the timing of plume eruptions within the context of Europa's tidal cycle to determine whether such a link exists and examine the inferred similarities and differences between plume activity on Europa and Enceladus. To do this, we determine the locations and orientations of hypothetical tidally-driven fractures that best match the temporal variability of the plumes observed at Europa. Specifically, we identify model faults that are in tension at the time in Europa's orbit when a plume was detected and in compression at times when the plume was not detected. We find that tidal stress driven solely by eccentricity is incompatible with the observations unless additional mechanisms are controlling the eruption timing or restricting the longevity of the plumes. The addition of obliquity tides, and corresponding precession of the spin pole, can generate a number of model faults that are consistent with the pattern of plume detections. The locations and orientations of these hypothetical source fractures are robust across a broad range of precession rates and spin pole directions. Analysis of the stress variations across

  7. Magnetic fields over active tectonic zones in ocean

    USGS Publications Warehouse

    Kopytenko, Yu. A.; Serebrianaya, P.M.; Nikitina, L.V.; Green, A.W.

    2002-01-01

    The aim of our work is to estimate the electromagnetic effects that can be detected in the submarine zones with hydrothermal activity. It is known that meso-scale flows appear in the regions over underwater volcanoes or hot rocks. Their origin is connected with heat flux and hot jets released from underwater volcanoes or faults in a sea bottom. Values of mean velocities and turbulent velocities in plumes were estimated. Quasiconstant magnetic fields induced by a hot jet and a vortex over a plume top are about 1-40 nT. Variable magnetic fields are about 0.1-1 nT. These magnetic disturbances in the sea medium create an additional natural electromagnetic background that must be considered when making detailed magnetic surveys. ?? 2002 Elsevier Science Ltd. All rights reserved.

  8. Seafloor morphology of the Eurasia-Nubia (Africa) plate boundary between the Tore-Madeira Rise and the Straits of Gibraltar: a case of coexistent Mesozoic through Present day features of tectonic, oceanographic and sedimentary origin

    NASA Astrophysics Data System (ADS)

    Terrinha, Pedro; Duarte, João.; Valadares, Vasco; Batista, Luis; Zitellini, Nevio; Grácia, Eulalia; Lourenço, Nuno; Rosas, Filipe; Roque, Cristina

    2010-05-01

    The joint use of more than 10.000 km multichannel seismic reflection profiles and 180.000km2 of multibeam swath bathymetry and backscatter allowed for a new vision of the seafloor tectonic and geomorphic processes of the area that encompasses the present day plate boundary between Africa and Eurasia, between the Gibraltar Straits and the Tore-Madeira Rise, in the southern sector of the North Atlantic Ocean. The interpretation of this data allowed for the detailed description of the seafloor morphology (i.e. a morphologic map) and the classification of the morphologic features in what respects the genetic process and age. It can be seen that in the same region coexist morphologic features that result from tectonic processes associated with the Triassic-Cretaceous break-up of Pangea, the Paleogene-Miocene compressive phase, the Miocene through Present subduction under the Gibraltar Arc (Gutscher et al., 2002), the Pliocene-Quaternary wrench tectonics and possible coeval plate boundary (Zitellini et al., 2009), the Present day mud volcanism and propagation of the compressive deformation along the West Continental Margin of Portugal (Terrinha et al., 2009). Interpretation of the seismic profiles together with the bathymetry allows the understanding of endogenous and exogenous processes that creates reliefs associated with active structures (related to the Miocene through Present compressive stress field). Other reliefs generated in Mesozoic times by analogous processes can be as well preserved as these active ones. In what concerns exogenous processes, the analysis of the two datasets (reflection seismics and bathymetry) allowed for the description of morphologic features associated with oceanic currents that interact with the seafloor forming these important features. As is the case of the well known active contourites but also less known features, like giant scours at 4 km water depth that have recently been described, suggesting the interaction of deep currents and

  9. Study provides data on active plate tectonics in southeast Asia region

    NASA Astrophysics Data System (ADS)

    Wilson, P.; Rais, J.; Reigber, Ch.; Reinhart, E.; Ambrosius, B. A. C.; Le Pichon, X.; Kasser, M.; Suharto, P.; Majid, Dato'Abdul; Yaakub, Dato'Paduka Awang Haji Othman Bin Haji; Almeda, R.; Boonphakdee, C.

    A major geodynamic study has provided significant new information about the location of active plate boundaries in and around Southeast Asia, as well as deformation processes in the Sulawesi region of Indonesia and tectonic activity in the Philippine archipelago. Results also have confirmed the existence of the so-called Sunda Block, which appears to be rotating with respect to adjacent plates.The study, known as the Geodynamics of South and South-East Asia (GEODYSSEA) project, has been a joint venture of the European Commission and the Association of South- East Asian Nations. It began in 1991 and involved a large team of European and Asian scientists and technicians studying the complex geodynamic processes and natural hazards of the region from the Southeast Asia mainland to the Philippines to northern Australia. Earthquakes, volcanic eruptions, tsunamis, and tectonically induced landslides endanger the lives of millions of people in the region, and the tectonic activity behind these natural hazards results from the convergence and collision of the Eurasian, Philippine, and Indo-Australian Plates at relative velocities of up to 10 cm per year.

  10. Energy of relief as useful geomorphic index to record seabed tectonic activity: preliminary results from the Sardinia Basin (Tyrrhenian Sea).

    NASA Astrophysics Data System (ADS)

    Baioni, Davide; Tramontana, Mario

    2017-04-01

    A morphostructural investigation in the seafloor of the Tyrrhenian sea has been carried on using the analysis of the energy of relief (Er). On the dry land the energy of relief is calculated to detect the intensity of denudation processes on the landscape and it is used as useful geomorphic index in the morphotectonic and morphostructural investigations. In fact, when it is calculated for single cells of small size this parameter may reveal zones affected by tectonic movements that control the development of the relief, by measuring unit cells of equal areas and assuming that for such cells mass and gravity acceleration can be treated as constant values. The energy of relief quantitative parameter is thus expressed by the maximum difference in elevation between the highest point and the lowest point measured in a given area. On the sea bottom this geomorphic index has not been well and intensively applied. In fact, the study of this quantitative index was applied only by few authors to the Adriatic seabed; however we believe that because the absent or low erosion of seabed, it can be even more useful and easier to be interpreted as a tectonic activity marker too. Further researches, however, are needed to better understand the sensitivity of this parameter in detecting neo-tectonic features in marine environment. Our research focuses on the calculation and evaluation of energy of relief in the Sardinia Basin, the peri-Tyrrhenian Basin located in the western passive margin of the Tyrrhenian Sea, and bounded offshore to the north by the Baronie Seamounts and to the south by the Ichnusa Seamount. The distribution of the energy of relief was obtained by subdividing the study area into square cells of 25 km2, which were numbered by orthographic coordinates. Highest and lowest elevation for each cell was obtained from the bathymetric map "Tyrrhenian Sea Bathymetry", with 100 m contour lines. Within each cell, the value of the energy of relief was calculated, so obtaining

  11. Using the salt tectonics as a proxy to reveal post-rift active crustal tectonics: The example of the Eastern Sardinian margin

    NASA Astrophysics Data System (ADS)

    Lymer, Gaël; Vendeville, Bruno; Gaullier, Virginie; Chanier, Frank; Gaillard, Morgane

    2017-04-01

    The Western Tyrrhenian Basin, Mediterranean Sea, is a fascinating basin in terms of interactions between crustal tectonics, salt tectonics and sedimentation. The METYSS (Messinian Event in the Tyrrhenian from Seismic Study) project is based on 2100 km of HR seismic data acquired in 2009 and 2011 along the Eastern Sardinian margin. The main aim is to study the Messinian Salinity Crisis (MSC) in the Western Tyrrhenian Basin, but we also investigate the thinning processes of the continental crust and the timing of crustal vertical motions across this complex domain. Our first results allowed us to map the MSC seismic markers and to better constrain the timing of the rifting, which ended before the MSC across the upper and middle parts of the margin. We also evidenced that crustal activity persisted long after the end of rifting. This has been particularly observed on the upper margin, where several normal faults and a surprising compressional structure were recently active. In this study we investigate the middle margin, the Cornaglia Terrace, where the Mobile Unit (MU, mobile Messinian salt) accumulated during the MSC and acts as a décollement. Our goal is to ascertain whether or not crustal tectonics existed after the pre-MSC rift. This is a challenge where the MU is thick, because potential basement deformations could be first accommodated by the MU and therefore would not find any expression in the supra-salt layers (Upper Unit, UU and Plio-Quaternary, PQ). However our investigations clearly reveal interactions between crustal and salt tectonics along the margin. We thus evidence gravity gliding of the salt and its brittle sedimentary cover along basement slopes generated by the post-MSC tilting of some basement blocks bounded by crustal normal faults, formerly due to the rifting. Another intriguing structure also got our interest. It corresponds to a wedge-shaped of MU located in a narrow N-S half graben bounded to the west by a major, east-verging, crustal

  12. Seismotectonics of Northeastern Sicily and Southern Calabria (Italy): New constraints on the tectonic structures featuring in a crucial sector for the Central Mediterranean geodynamics

    NASA Astrophysics Data System (ADS)

    Scarfì, Luciano; Barberi, Graziella; Musumeci, Carla; Patanè, Domenico

    2016-04-01

    The purpose of this study is to gain a better understanding on the tectonic structures featuring in a crucial sector of central Mediterranean area, including the Aeolian Islands, southern Calabria and northeastern Sicily, where the convergence between Eurasian and African plates has given rise to a complicated collisional/subduction complex. A high quality dataset of about 3000 earthquakes has been exploited for local earthquake tomography and focal mechanisms computation. Results depict undiscovered details of a network of faults which enables the contemporary existence of adjacent compressional and extensional domains. In particular, tomographic images, seismic events distribution and focal mechanisms pinpoint the geometry and activity of a lithospheric-scale tear faults system which, with a NW-SE trend through Sicily and the Tyrrhenian and Ionian Seas, represents the southern edge of the Ionian subduction trench zone. At crustal depth, this tearing is well highlighted by a rotation of the maximum horizontal stress, moving across the area from west toward east. In addition, the shallow normal fault regime, characterising the northeastern Sicily mainland, south of the NW-SE lineament, changes in the deeper part of the crust. Indeed, a NE-SW earthquake distribution, NW gently dipping, and inverse fault solutions indicate a still active contractional deformation in the eastern Sicily, caused by the Africa-Eurasia convergence and well framed with the current compressive regime along the southern Tyrrhenian zone and at the front of the Sicilian Chain-Foreland.

  13. Seismotectonics of northeastern Sicily and southern Calabria (Italy): New constraints on the tectonic structures featuring in a crucial sector for the central Mediterranean geodynamics

    NASA Astrophysics Data System (ADS)

    Scarfı, L.; Barberi, G.; Musumeci, C.; Patanè, D.

    2016-03-01

    The purpose of this study is to gain a better understanding on the tectonic structures featuring in a crucial sector of central Mediterranean area, including the Aeolian Islands, southern Calabria, and northeastern Sicily, where the convergence between Eurasian and African Plates has given rise to a complicated collisional/subduction complex. A high-quality data set of about 3000 earthquakes has been exploited for local earthquake tomography and focal mechanisms computation together with available source mechanisms from published catalogues. The results depict new details of a network of faults which enables the concurrent existence of adjacent compressional and extensional domains. In particular, tomographic images, seismic events distribution, and focal mechanisms pinpoint the geometry and activity of a lithospheric-scale tear faults system which, with a NW-SE trend through Sicily and the Tyrrhenian and Ionian Seas, represents the southern edge of the Ionian subduction trench zone. At crustal depth, this tearing is well highlighted by a rotation of the maximum horizontal stress, moving across the area from west toward east. In addition, the shallow normal fault regime, characterizing the southern Calabria and northeastern Sicily mainland, south of the NW-SE lineament, changes in the deeper part of the crust. Indeed, a NE-SW earthquake distribution, gently dipping NW, and inverse fault solutions indicate a still active contractional deformation in eastern Sicily, caused by the Africa-Eurasia convergence and well framed with the current compressive regime along the southern Tyrrhenian zone and at the front of the Sicilian Chain-Foreland.

  14. Recent tectonic activity on Mercury revealed by small thrust fault scarps

    NASA Astrophysics Data System (ADS)

    Watters, Thomas R.; Daud, Katie; Banks, Maria E.; Selvans, Michelle M.; Chapman, Clark R.; Ernst, Carolyn M.

    2016-10-01

    Large tectonic landforms on the surface of Mercury, consistent with significant contraction of the planet, were revealed by the flybys of Mariner 10 in the mid-1970s. The MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) mission confirmed that the planet's past 4 billion years of tectonic history have been dominated by contraction expressed by lobate fault scarps that are hundreds of kilometres long. Here we report the discovery of small thrust fault scarps in images from the low-altitude campaign at the end of the MESSENGER mission that are orders of magnitude smaller than the large-scale lobate scarps. These small scarps have tens of metres of relief, are only kilometres in length and are comparable in scale to small young scarps on the Moon. Their small-scale, pristine appearance, crosscutting of impact craters and association with small graben all indicate an age of less than 50 Myr. We propose that these scarps are the smallest members of a continuum in scale of thrust fault scarps on Mercury. The young age of the small scarps, along with evidence for recent activity on large-scale scarps, suggests that Mercury is tectonically active today and implies a prolonged slow cooling of the planet's interior.

  15. New Insights into the Active Tectonics of Eastern Indonesia from GPS Measurements

    NASA Astrophysics Data System (ADS)

    Susilo, S.; Koulali Idrissi, A.; McClusky, S.; Meilano, I.; Cummins, P. R.; Tregoning, P.; Syafii, A.

    2014-12-01

    The Indonesian archipelago encompasses a wide range of tectonic environments, including island arc volcanism, subduction zones, and arc-continent collision. Many of the details of this tectonic activity are still poorly understood, especially where the Australian continent collides with Indonesia, separating the Sunda Arc in west from that at the Banda Arc in the east. While it seems clear that the Australian plate is subducted under both the Sunda and Banda Arcs, it is not clear what happens along the 1000 km -long stretch in between. The question of just where the plate motion is accommodated is of major importance to assessments of earthquake and tsunami hazard in the region. To help resolve these questions the Geospatial Information Agency of Indonesia has collaborated with the Australian National University and the Bandung Institute of Technology in a GPS campaign spanning much of eastern Indonesia, from Lombok in the west to Alor in the east. We have combined these data with those from previous campaigns, resulting in over 27 campaign and 18 continuous GPS sites being used in the analysis. The improvement in site density allowed us to develop of a more complete description of tectonic activity in this region than has been obtained in previous studies. Our preliminary results suggests that there is a relatively simple transition from subduction at the Java Trench off east Java, to a partitioned convergence along both the Timor Trough and the Flores Thrust in the Nusa Tenggara region.

  16. ANALYSIS ON THE GROUND DESTROYED FEATURES AND TECTONIC STRESS FIELD OF THE 2008 WENCHUAN EARTHQUAKE AND OUR TREATING TACTICS

    NASA Astrophysics Data System (ADS)

    Guo, Y.; Wang, H.; Deng, Z.; You, H.

    2009-12-01

    To research the ground destroyed features and tectonic stress field of the 2008 Wenchuan Earthquake, we went the earthquake-hazard area, Hongkou Town in Dujiangyan City, Yingxiu Town in Wenchuan County, Bailu Town in Pengzhou City, Yinghua Town in Shifang City, Hanwang Town in Mianzhu City and Beichuan Cit early and late twice in 2008. The geological survey was made. Firstly, the ground destroyed features of the Wenchuan Earthquake around both Yingxiu - Beichuan Fracture and Guanxian - Jiangyou Fracture were analyzed. They mainly display as the ground crack ground, road steep slope, ground deformation, road rise high and deformation, road staggering and rupture, etc. Besides, the Wenchuan Earthquake resulted in the great deal of building collapse and lots of bridges damage even break down; It can be seen that the first floor of the building disappeared or damaged seriously; Some building still stood there although damaged by the earthquake; A few of building was damaged slightly and kept intact structure. Furthermore, the earthquake caused earth slide, mudflow and rolling stone, which lead to the building destroyed seriously, river blocked up, the life line engineering destroyed. Secondly, the phenomena of the ground destroy were analyzed preliminarily. The seismic intensity was determined based on the field investigation. The damaged situation of the construction was concluded. Based on the principle of structure geology and making use of the Stereographic projection, the stress field was analyzed according to the attitude, structural nature and relations among the fracture, fault scratch and joint fissure as well as the characteristics of ground deformation thirdly. The geodynamics of the 2008 Wenchuan Earthquake are probed into preliminarily. The main compressive stress (the maximum main stress) σ1 took Northeast by east direction, and the main tensile stress (the minimum main stress)σ3 took Northwest by north direction. The main fracture shows as the right

  17. Late cretaceous extensional tectonics and associated igneous activity on the northern margin of the Gulf of Mexico Basin

    NASA Technical Reports Server (NTRS)

    Bowen, R. L.; Sundeen, D. A.

    1985-01-01

    Major, dominantly compressional, orogenic episodes (Taconic, Acadian, Alleghenian) affected eastern North America during the Paleozoic. During the Mesozoic, in contrast, this same region was principally affected by epeirogenic and extensional tectonism; one episode of comparatively more intense tectonic activity involving extensive faulting, uplift, sedimentation, intrusion and effusion produced the Newark Series of eposits and fault block phenomena. This event, termed the Palisades Disturbance, took place during the Late Triassic - Earliest Jurassic. The authors document a comparable extensional tectonic-igneous event occurring during the Late Cretaceous (Early Gulfian; Cenomanian-Santonian) along the southern margin of the cratonic platform from Arkansas to Georgia.

  18. Active tectonics on Lanzarote (Canary Islands) from the analysis of CGPS data

    NASA Astrophysics Data System (ADS)

    Riccardi, Umberto; Arnoso, Jose; Benavent, María Teresa; Velez, Emilio; Tammaro, Umberto; González Montesinos, Fuensanta

    2017-04-01

    We report on the analysis of about three years of CGPS data collected on a small network consisting in five permanent stations, with the largest baseline up to 40 km, spread over Timanfaya National Park in Lanzarote Island. The GPS stations are operated by different institutions, as follows: CAME is co-operated by the Institute of Geosciences (CSIC-UCM), DiSTAR and the Geodesy Research Group of University Complutense of Madrid (GRG-UCM), while LACV is operated by (CSIC-UCM and GRG-UCM). Stations HRIA, TIAS, YAIZ, belong to GRAFCAN (Cartographical Service of the Government of Canary Islands). Lanzarote is the most Northeast and the oldest island of the Canarian Archipelago (Spain), which is located on a transitional zone, a passive margin, between oceanic and continental crust. Due to some peculiarities in geochemistry and geochronology of the rocks as well as tectonics, the origin of the archipelago from a hot spot is still debated. In fact, the most recent Holocenic volcanism is scattered over the islands and the last eruption was a submarine one, occurred in October 2011 at El Hierro Island. The last eruption in Lanzarote was a 7 years voluminous eruptive cycle, occurred during the 18th century. Historical seismicity registered in the region, is customarily attributed to diffuse tectonic activity. This study is intended to contributing to shed light on the active tectonics on Lanzarote island and to separate between local and regional strain fields. With the aid of Gamit 10.6 software, we compute from the GPS observations the "ionofree" linear combinations in order to obtain the positions of the stations in ITRF2008 frame using daily sessions, and IGS precise ephemeris. The frame referencing of the network is realized by eleven IGS GPS stations. Then through a Kalman filtering procedure, implemented in GLOBK software, we obtain the final daily solutions by constraining the fiducial GPS stations to their ITRF2008 coordinates. For a reliable strain field retrieval

  19. Spatial analysis of Budovar stream catchment (Srem Loess Plateau, Serbia) in a tectonically active region

    NASA Astrophysics Data System (ADS)

    Jovanovic, Mladjen; Rvovic, Ivan; Sorak, Rada; Petrovic, Milos

    2016-04-01

    Budovar is the far longest stream on Srem Loess Plateau, with a length of a 52 km, and catchment area of 245 km2. Budovar stream drains a quite complex landscape in terms of generally flat loess plateau, with elevations decreasing gradually southeastward - from 213 m at slopes of Fru\\vska Gora Mountain to 70,9 m at the confluence with Danube river. The youngest (Pleistocene/Holocene) sedimentary formations in the catchment vary from slope loess on Fru\\vska Gora Mtn. in upper part, through typical plateau loess in middle part, and the finest bog-sediments in tectonic depressions in lower part. These deposits lie over the bog-lake-terrestrial sediments with thickness over 100 m. According the geodetic measurements, uplift of Fru\\vska Gora Mtn., which has been the strongest during the Middle Pleistocene, is still present, with rates of up to 1 mm/y in contrast of general uplift of the area, subsidence is recorded in two distinct parts of the catchment. Spatial analysis is done using a DEM, generated in ArcGIS 10.0 from the elevation points, 10 m contours and stream coverage available in 1:25.000 topographical maps. Both longitudinal and cross-section profiles of the valley reflect the influence of tectonic distortions and climatic fluctuations. Valleys in Budovar catchment have composite character - the valleys cross-sections vary from deep incised V-shape, reversed trapezoid shape and completely flat valleys in tectonic depressions. Moreover, there is almost no correlation between the shape of cross-sectional profiles and the direction of curvature of the main valley's long axis (left/right or straight), suggesting that the tectonic activity has the key role in shaping. The width of valleys in Budovar catchment area is in sharp contrast with present stream discharge, which suggests strong climate fluctuations since Upper Pleistocene. The longitudinal profiles also shows signs of kickpoints and some short reaches with increasing elevation in the flow direction. Key

  20. Paleoseismic and geomorphologic evidence of recent tectonic activity of the Pozohondo Fault (Betic Cordillera, SE Spain)

    USGS Publications Warehouse

    Rodríguez-Pascua, M.A.; Pérez-López, R.; Garduño-Monroy, V.H.; Giner-Robles, J.L.; Silva, P.G.; Perucha-Atienza, M.A.; Hernández-Madrigal, V.M.; Bischoff, J.

    2012-01-01

    Instrumental and historical seismicity in the Albacete province (External Prebetic Zone) has been scarcely recorded. However, major strike-slip faults showing NW-SE trending provide geomorphologic and paleoseismic evidence of recent tectonic activity (Late Pleistocene to Present). Moreover, these faults are consistently well oriented under the present stress tensor and therefore, they can trigger earthquakes of magnitude greater than M6, according to the lengths of surface ruptures and active segments recognized in fieldwork. Present landscape nearby the village of Hellin (SE of Albacete) is determined by the recent activity of the Pozohondo Fault (FPH), a NW-SE right-lateral fault with 90 km in length. In this study, we have calculated the Late Quaternary tectonic sliprate of the FPH from geomorphological, sedimentological, archaeoseimological, and paleoseismological approaches. All of these data suggest that the FPH runs with a minimum slip-rate of 0.1 mm/yr during the last 100 kyrs (Upper Pleistocene-Holocene). In addition, we have recognized the last two major paleoearthquakes associated to this fault. Magnitudes of these paleoearthquakes were gretarer than M6 and their recurrence intervals ranged from 6600 to 8600 yrs for the seismic cycle of FPH. The last earthquake was dated between the 1st and 6th centuries, though two earthquakes could be interpreted in this wide time interval, one at the FPH and other from a far field source. Results obtained here, suggest an increasing of the tectonic activity of the Pozohondo Fault during the last 10,000 yrs.

  1. Plate Tectonics: A Framework for Understanding Our Living Planet.

    ERIC Educational Resources Information Center

    Achache, Jose

    1987-01-01

    Discusses some of the events leading to the development of the theory of plate tectonics. Describes how seismic, volcanic, and tectonic features observed at the surface of the planet are now seen as a consequence of intense internal activity, and makes suggestions about their further investigation. (TW)

  2. Plate Tectonics: A Framework for Understanding Our Living Planet.

    ERIC Educational Resources Information Center

    Achache, Jose

    1987-01-01

    Discusses some of the events leading to the development of the theory of plate tectonics. Describes how seismic, volcanic, and tectonic features observed at the surface of the planet are now seen as a consequence of intense internal activity, and makes suggestions about their further investigation. (TW)

  3. Recent Advances in Mars Tectonics

    NASA Technical Reports Server (NTRS)

    Golombek, M. P.; Banerdt, W. B.

    1999-01-01

    Since the publication of the "Stress and Tectonics on Mars" chapter in the Mars book (the last comprehensive summary of our knowledge on the topic) considerable advances have been made in certain areas of Martian tectonics and significant advances are expected with the return of Mars Global Surveyor data. This abstract will summarize the advances in our knowledge of tectonic features and processes on Mars since the Mars book and point towards new areas of research that can be expected from the Mars Global Surveyor data. Two out of three areas of study that were discussed as future directions of work in the Mars chapter have had significant work directed towards them. One area is the field of structural mapping and understanding the timing of tectonic activity on Mars in the framework of the global stratigraphy. Although the general development and relative timing of the development of the Tharsis province on Mars had been understood for some time, actual placement of mapped tectonic features in a global stratigraphic framework has only recently been completed. The second area of study mentioned in the Mars chapter was the impact of improved topography and gravity on modeling loads and deriving stresses in the Martian lithosphere. Mars Global Surveyor is on the brink of returning vastly improved topographic and gravity fields and these newer data sets can be used to better define the size and shape of Tharsis and to quantify loads and derived stresses in the Martian lithosphere. Additional information is contained in the original extended abstract.

  4. Recent Advances in Mars Tectonics

    NASA Technical Reports Server (NTRS)

    Golombek, M. P.; Banerdt, W. B.

    1999-01-01

    Since the publication of the "Stress and Tectonics on Mars" chapter in the Mars book (the last comprehensive summary of our knowledge on the topic) considerable advances have been made in certain areas of Martian tectonics and significant advances are expected with the return of Mars Global Surveyor data. This abstract will summarize the advances in our knowledge of tectonic features and processes on Mars since the Mars book and point towards new areas of research that can be expected from the Mars Global Surveyor data. Two out of three areas of study that were discussed as future directions of work in the Mars chapter have had significant work directed towards them. One area is the field of structural mapping and understanding the timing of tectonic activity on Mars in the framework of the global stratigraphy. Although the general development and relative timing of the development of the Tharsis province on Mars had been understood for some time, actual placement of mapped tectonic features in a global stratigraphic framework has only recently been completed. The second area of study mentioned in the Mars chapter was the impact of improved topography and gravity on modeling loads and deriving stresses in the Martian lithosphere. Mars Global Surveyor is on the brink of returning vastly improved topographic and gravity fields and these newer data sets can be used to better define the size and shape of Tharsis and to quantify loads and derived stresses in the Martian lithosphere. Additional information is contained in the original extended abstract.

  5. Identification and interpretation of tectonic features from ERTS-1 imagery: Southwestern North America and the Red Sea area

    NASA Technical Reports Server (NTRS)

    Abdel-Gawad, M. (Principal Investigator); Tubbesing, L.

    1975-01-01

    The author has identified the following significant results. The ERTS-1 imagery was utilized to study major fault and tectonic lines and their intersections in southwestern North America. A system of transverse shear faults was recognized in the California Coast Ranges, the Sierra Nevada, the Great Basin, and Mexico. They are interpreted as expressions of a major left-lateral shear which predated the San Andreas system, the opening of the Gulf of California and Basin and Range rift development. Tectonic models for Basin and Range, Coast Ranges, and Texas-Parras shears were developed. Geological structures and Precambrian metamorphic trend lines of schistosity were studied across the Red Sea rift.

  6. Geomorphic signature of active tectonics in the southern Abruzzi Periadriatic hilly belt (Central Italy)

    NASA Astrophysics Data System (ADS)

    Racano, Simone; Fubelli, Giandomenico; Centamore, Ernesto; Dramis, Francesco

    2016-04-01

    The geo-structural setting of the southern Abruzzi hilly belt that stretches from the northeastern front of the Maiella Massif to the Adriatic coast is characterized by deep-seated northeast verging thrusts masked by a thick cover of Late Pliocene-Middle Pleistocene marine deposits. Most authors consider this area tectonically inactive while only few of them support the hypothesis of its recent activity from the analysis of the river network pattern. Geological and geomorphological investigations carried out in the area have clearly shown the occurrence of surface deformations resulting from the continued activity of compressive tectonics up to recent times. The analysis of the study area by of a 10 m resolution DTM (using the open-source QGIS software) confirmed and supplemented field observations. Particularly significant in this context is the topographic setting of the alluvial strath terraces in the river valleys that develop transversally to the buried thrusts. In correspondence of these structures, topographic highs have grown up displacing the middle-Pleistocene planation surface developed on top of the hilly belt, from the Maiella piedmont to the coastal zone, and diverting laterally the river courses uphill. In the same places, as along the Alento and Foro rivers that cross by antecedence the grown up topographic highs, the long profiles of terraces bend eastward and the height difference between the terrace orders, essentially related all around the area to the Quaternary regional uplift, strongly increases. In some cases, surficial faults have lowered the terraces into graben troughs or have displaced them until assuming an uphill trend. This recent tectonic activity should be taken in account in assessing the seismic hazard of the study area.

  7. Soil radon measurements as a potential tracer of tectonic and volcanic activity

    NASA Astrophysics Data System (ADS)

    Neri, Marco; Ferrera, Elisabetta; Giammanco, Salvatore; Currenti, Gilda; Cirrincione, Rosolino; Patanè, Giuseppe; Zanon, Vittorio

    2016-04-01

    In Earth Sciences there is a growing interest in studies concerning soil-radon activity, due to its potential as a tracer of numerous natural phenomena. Our work marks an advance in the comprehension of the interplay between tectonic activity, volcanic eruptions and gas release through faults. Soil-radon measurements, acquired on Mt. Etna volcano in 2009–2011, were analyzed. Our radon probe is sensitive to changes in both volcanic and seismic activity. Radon data were reviewed in light of the meteorological parameters. Soil samples were analyzed to characterize their uranium content. All data have been summarized in a physical model which identifies the radon sources, highlights the mechanism of radon transport and envisages how such a mechanism may change as a consequence of seismicity and volcanic events. In the NE of Etna, radon is released mainly from a depth of <1400 m, with an ascent speed of >50 m/day. Three periods of anomalous gas release were found (February 2010, January and February 2011). The trigger of the first anomaly was tectonic, while the second and third had a volcanic origin. These results mark a significant step towards a better understanding of the endogenous mechanisms that cause changes in soil-radon emission at active volcanoes.

  8. Soil radon measurements as a potential tracer of tectonic and volcanic activity.

    PubMed

    Neri, Marco; Ferrera, Elisabetta; Giammanco, Salvatore; Currenti, Gilda; Cirrincione, Rosolino; Patanè, Giuseppe; Zanon, Vittorio

    2016-04-15

    In Earth Sciences there is a growing interest in studies concerning soil-radon activity, due to its potential as a tracer of numerous natural phenomena. Our work marks an advance in the comprehension of the interplay between tectonic activity, volcanic eruptions and gas release through faults. Soil-radon measurements, acquired on Mt. Etna volcano in 2009-2011, were analyzed. Our radon probe is sensitive to changes in both volcanic and seismic activity. Radon data were reviewed in light of the meteorological parameters. Soil samples were analyzed to characterize their uranium content. All data have been summarized in a physical model which identifies the radon sources, highlights the mechanism of radon transport and envisages how such a mechanism may change as a consequence of seismicity and volcanic events. In the NE of Etna, radon is released mainly from a depth of <1400 m, with an ascent speed of >50 m/day. Three periods of anomalous gas release were found (February 2010, January and February 2011). The trigger of the first anomaly was tectonic, while the second and third had a volcanic origin. These results mark a significant step towards a better understanding of the endogenous mechanisms that cause changes in soil-radon emission at active volcanoes.

  9. Soil radon measurements as a potential tracer of tectonic and volcanic activity

    PubMed Central

    Neri, Marco; Ferrera, Elisabetta; Giammanco, Salvatore; Currenti, Gilda; Cirrincione, Rosolino; Patanè, Giuseppe; Zanon, Vittorio

    2016-01-01

    In Earth Sciences there is a growing interest in studies concerning soil-radon activity, due to its potential as a tracer of numerous natural phenomena. Our work marks an advance in the comprehension of the interplay between tectonic activity, volcanic eruptions and gas release through faults. Soil-radon measurements, acquired on Mt. Etna volcano in 2009–2011, were analyzed. Our radon probe is sensitive to changes in both volcanic and seismic activity. Radon data were reviewed in light of the meteorological parameters. Soil samples were analyzed to characterize their uranium content. All data have been summarized in a physical model which identifies the radon sources, highlights the mechanism of radon transport and envisages how such a mechanism may change as a consequence of seismicity and volcanic events. In the NE of Etna, radon is released mainly from a depth of <1400 m, with an ascent speed of >50 m/day. Three periods of anomalous gas release were found (February 2010, January and February 2011). The trigger of the first anomaly was tectonic, while the second and third had a volcanic origin. These results mark a significant step towards a better understanding of the endogenous mechanisms that cause changes in soil-radon emission at active volcanoes. PMID:27079264

  10. Coevolution of active vision and feature selection.

    PubMed

    Floreano, Dario; Kato, Toshifumi; Marocco, Davide; Sauser, Eric

    2004-03-01

    We show that complex visual tasks, such as position- and size-invariant shape recognition and navigation in the environment, can be tackled with simple architectures generated by a coevolutionary process of active vision and feature selection. Behavioral machines equipped with primitive vision systems and direct pathways between visual and motor neurons are evolved while they freely interact with their environments. We describe the application of this methodology in three sets of experiments, namely, shape discrimination, car driving, and robot navigation. We show that these systems develop sensitivity to a number of oriented, retinotopic, visual-feature-oriented edges, corners, height, and a behavioral repertoire to locate, bring, and keep these features in sensitive regions of the vision system, resembling strategies observed in simple insects.

  11. Threshold bedrock channels in tectonically active mountains with frequent mass wasting

    NASA Astrophysics Data System (ADS)

    Korup, O.; Hayakawa, Y. S.; Codilean, A.; Oguchi, T.

    2013-12-01

    Models of how mountain belts grow and erode through time largely rely on the paradigm of fluvial bedrock incision as the main motor of response to differences in rock uplift, thus setting base levels of erosion in tectonically active landscapes. Dynamic feedbacks between rock uplift, bedrock river geometry, and mass wasting have been encapsulated within the concept of threshold hillslopes that attain a mechanically critical inclination capable of adjusting to fluvial incision rates via decreased stability and commensurately more frequent landsliding. Here we provide data that challenge the widely held view that channel steepness records tectonic forcing more faithfully than hillslope inclination despite much robust empirical evidence of such links between bedrock-river geometry and hillslope mass wasting. We show that the volume mobilized by mass wasting depends more on local topographic relief and the sinuosity of bedrock rivers than their mean normalized channel steepness. We derive this counterintuitive observation from an unprecedented inventory of ~300,000 landslides covering the tectonically active Japanese archipelago with substantial differences in seismicity, lithology, vertical surface deformation, topography, and precipitation variability. Both total landslide number and volumes increase nonlinearly with mean local relief even in areas where the fraction of steepest channel segments attains a constant threshold well below the maximum topographic relief. Our data document for the first time that mass wasting increases systematically with preferential steepening of flatter channel segments. Yet concomitant changes in mean channel steepness are negligible such that it remains a largely insensitive predictor of landslide denudation. Further, minute increases in bedrock-river sinuosity lead to substantial reduction in landslide abundance and volumes. Our results underline that sinuosity (together with mean local relief) is a key morphometric variable for

  12. Geomorphology, active tectonics, and landscape evolution in the Mid-Atlantic region: Chapter

    USGS Publications Warehouse

    Pazzaglia, Frank J.; Carter, Mark W.; Berti, Claudio; Counts, Ronald C.; Hancock, Gregory S.; Harbor, David; Harrison, Richard W.; Heller, Matthew J.; Mahan, Shannon; Malenda, Helen; McKeon, Ryan; Nelson, Michelle S.; Prince, Phillip; Rittenour, Tammy M.; Spotilla, James; Whittecar, G. Richard

    2015-01-01

    In 2014, the geomorphology community marked the 125th birthday of one of its most influential papers, “The Rivers and Valleys of Pennsylvania” by William Morris Davis. Inspired by Davis’s work, the Appalachian landscape rapidly became fertile ground for the development and testing of several grand landscape evolution paradigms, culminating with John Hack’s dynamic equilibrium in 1960. As part of the 2015 GSA Annual Meeting, the Geomorphology, Active Tectonics, and Landscape Evolution field trip offers an excellent venue for exploring Appalachian geomorphology through the lens of the Appalachian landscape, leveraging exciting research by a new generation of process-oriented geomorphologists and geologic field mapping. Important geomorphologic scholarship has recently used the Appalachian landscape as the testing ground for ideas on long- and short-term erosion, dynamic topography, glacial-isostatic adjustments, active tectonics in an intraplate setting, river incision, periglacial processes, and soil-saprolite formation. This field trip explores a geologic and geomorphic transect of the mid-Atlantic margin, starting in the Blue Ridge of Virginia and proceeding to the east across the Piedmont to the Coastal Plain. The emphasis here will not only be on the geomorphology, but also the underlying geology that establishes the template and foundation upon which surface processes have etched out the familiar Appalachian landscape. The first day focuses on new and published work that highlights Cenozoic sedimentary deposits, soils, paleosols, and geomorphic markers (terraces and knickpoints) that are being used to reconstruct a late Cenozoic history of erosion, deposition, climate change, and active tectonics. The second day is similarly devoted to new and published work documenting the fluvial geomorphic response to active tectonics in the Central Virginia seismic zone (CVSZ), site of the 2011 M 5.8 Mineral earthquake and the integrated record of Appalachian

  13. Channel morphometry, sediment transport, and implications for tectonic activity and surficial ages of Titan basins

    USGS Publications Warehouse

    Cartwright, R.; Clayton, J.A.; Kirk, R.L.

    2011-01-01

    Fluvial features on Titan and drainage basins on Earth are remarkably similar despite differences in gravity and surface composition. We determined network bifurcation (Rb) ratios for five Titan and three terrestrial analog basins. Tectonically-modified Earth basins have Rb values greater than the expected range (3.0-5.0) for dendritic networks; comparisons with Rb values determined for Titan basins, in conjunction with similarities in network patterns, suggest that portions of Titan's north polar region are modified by tectonic forces. Sufficient elevation data existed to calculate bed slope and potential fluvial sediment transport rates in at least one Titan basin, indicating that 75mm water ice grains (observed at the Huygens landing site) should be readily entrained given sufficient flow depths of liquid hydrocarbons. Volumetric sediment transport estimates suggest that ???6700-10,000 Titan years (???2.0-3.0??105 Earth years) are required to erode this basin to its minimum relief (assuming constant 1m and 1.5m flows); these lowering rates increase to ???27,000-41,000 Titan years (???8.0-12.0??105 Earth years) when flows in the north polar region are restricted to summer months. ?? 2011 Elsevier Inc.

  14. Channel morphometry, sediment transport, and implications for tectonic activity and surficial ages of Titan basins

    USGS Publications Warehouse

    Cartwright, Richard; Clayton, Jordan A.; Kirk, Randolph L.

    2011-01-01

    Fluvial features on Titan and drainage basins on Earth are remarkably similar despite differences in gravity and surface composition. We determined network bifurcation (Rb) ratios for five Titan and three terrestrial analog basins. Tectonically-modified Earth basins have Rb values greater than the expected range (3.0–5.0) for dendritic networks; comparisons with Rb values determined for Titanbasins, in conjunction with similarities in network patterns, suggest that portions of Titan's north polar region are modified by tectonic forces. Sufficient elevation data existed to calculate bed slope and potential fluvial sedimenttransport rates in at least one Titanbasin, indicating that 75 mm water ice grains (observed at the Huygens landing site) should be readily entrained given sufficient flow depths of liquid hydrocarbons. Volumetric sedimenttransport estimates suggest that ~6700–10,000 Titan years (~2.0–3.0 x 105 Earth years) are required to erode this basin to its minimum relief (assuming constant 1 m and 1.5 m flows); these lowering rates increase to ~27,000–41,000 Titan years (~8.0–12.0 x 105 Earth years) when flows in the north polar region are restricted to summer months.

  15. Active tectonics and Quaternary landscape evolution across the western Panama block, Costa Rica, Central America

    NASA Astrophysics Data System (ADS)

    Marshall, Jeffrey Scott

    Three aspects of active tectonism are examined across central Costa Rica: (1) fault kinematics; (2) volcanic arc retreat; and (3) spatially variable coastal uplift. Diffuse faulting along the Central Costa Rica Deformed Belt (CCRDB) defines the western margin of the Panama block and aligns with the rough-smooth boundary (RSB) on the subducting Cocos plate. Sub-horizontal subduction of rough, hotspot thickened crust (Cocos Ridge and seamounts) shifts active shortening into the volcanic arc along the CCRDB. Mesoscale faults express variable kinematics across three domains: transtension in the forearc, transcurrent motion across the volcanic arc, and transpression in the back arc. Fault kinematics agree with seismicity and GPS data, and isotopic ages confirm that faulting postdates the late Neogene onset of shallow subduction. Stratigraphic correlation augmented by 40Ar/39Ar dating constrain the timing of Quaternary arc migration from the Neogene Aguacate range to the modern Cordillera Central. The Valle Central basin, between the cordilleras, filled with thick sequences of lavas, pyroclastic flows, and lahars. Middle Pleistocene drainage capture across the Aguacate arc linked the Valle Central with the Pacific slope and ash flows descended onto the coastal Orotina debris fan. Arc retreat reflects slab shallowing and enhanced tectonic erosion as rough crust entered the subduction zone. Differing subduction parameters across the RSB (crustal age, slab dip, roughness) produce marked contrasts in coastal tectonism. Varying uplift rates across coastal faults reflect sub-horizontal subduction of seamount roughness. Three groups (I--III) of fluvial terraces are correlated along the coast by isotopic ages and geomorphic characteristics. Base level fluctuations and terrace genesis reflect interaction between eustatic sea level and spatially variable rock uplift. Low uplift rates (north of RSB), yield one surface per terrace group, whereas moderate rates (south of RSB

  16. Evaluation of the relative tectonic activity in the eastern Lake Van basin, East Turkey

    NASA Astrophysics Data System (ADS)

    Sağlam Selçuk, Azad

    2016-10-01

    The eastern part of the Lake Van basin (Van region, Turkey) is controlled by reverse faults, such as the Gürpınar, Everek and Alaköy faults. These represent the major tectonic structures within the Van region and have caused many devastating earthquakes. Based on quantitative analyses, the Quaternary activity and topographic relief control of each of these faults was investigated. The Gürpınar, Everek and Alaköy faults are restricted to the southern slopes of the Güzelsu, Everek, and Karasu basins, respectively. Analyses of the mountain front sinuosity (Smf) and valley floor width-to-height ratio (Vf) suggest high activity along the Gürpınar fault, the Everek fault, and the western part of the Alaköy fault. Furthermore, based on the integration between Smf and Vf, the estimated uplift rates were observed to increase from north to south. The Gürpınar and Everek hanging-wall blocks are characterized by uplift rates of > 0.5 mm yr- 1, whereas the Alaköy fault exhibited a rate of 0.05 to 0.5 mm yr- 1. These faults produce knickpoints or knickzones, complex basin hypsometric curves, and high values of the stream length-gradient index. Based on these geomorphic analyses, it was established that the tectonic activity of both the Gürpınar and Everek faults is greater than that of the Alaköy fault.

  17. Volcanic activity before and after large tectonic earthquakes: Observations and statistical significance

    NASA Astrophysics Data System (ADS)

    Eggert, Silke; Walter, Thomas R.

    2009-06-01

    The study of volcanic triggering and interaction with the tectonic surroundings has received special attention in recent years, using both direct field observations and historical descriptions of eruptions and earthquake activity. Repeated reports of clustered eruptions and earthquakes may imply that interaction is important in some subregions. However, the subregions likely to suffer such clusters have not been systematically identified, and the processes responsible for the observed interaction remain unclear. We first review previous works about the clustered occurrence of eruptions and earthquakes, and describe selected events. We further elaborate available databases and confirm a statistically significant relationship between volcanic eruptions and earthquakes on the global scale. Moreover, our study implies that closed volcanic systems in particular tend to be activated in association with a tectonic earthquake trigger. We then perform a statistical study at the subregional level, showing that certain subregions are especially predisposed to concurrent eruption-earthquake sequences, whereas such clustering is statistically less significant in other subregions. Based on this study, we argue that individual and selected observations may bias the perceptible weight of coupling. The activity at volcanoes located in the predisposed subregions (e.g., Japan, Indonesia, Melanesia), however, often unexpectedly changes in association with either an imminent or a past earthquake.

  18. Relationship between observed upper mantle structures and recent tectonic activity across the Southeastern United States

    NASA Astrophysics Data System (ADS)

    Biryol, C. Berk; Wagner, Lara S.; Fischer, Karen M.; Hawman, Robert B.

    2016-05-01

    The lithospheric structure of the Southeastern United States is a product of earlier episodes of continental collision and breakup. The region is located in the interior of the North American Plate, away from active plate margins. However, there is ongoing tectonism in the region with multiple zones of seismicity, uplifting arches, and Cenozoic intraplate volcanism. The mechanisms controlling this activity and the state of stress remain enigmatic. Two important factors are plate strength and preexisting, inherited structures. Here we present new tomographic images of the upper mantle beneath the Southeastern United States, revealing large-scale structural variations in the upper mantle. Examples include the relatively thick lithospheric mantle of stable North America that abruptly thins beneath the Paleozoic Appalachian orogeny, and the slow upper mantle of the Proterozoic Reelfoot rift. Our results also indicate fast seismic velocity patterns that can be interpreted as ongoing lithospheric foundering. This provides a viable explanation for seismicity, uplifting, and young intraplate volcanism. We postulate that not only tectonic inheritance but also continuing lithospheric foundering may control the ongoing activity of the region long after it became a passive margin. Based on distinct variations in the geometry and thickness of the lithospheric mantle and foundered lithosphere, we propose that piecemeal delamination has occurred beneath the region throughout the Cenozoic, removing a significant amount of reworked/deformed mantle lithosphere. Ongoing lithospheric foundering beneath the eastern margin of stable North America explains significant variations in thickness of lithospheric mantle across the former Grenville deformation front.

  19. Tectonics on Triton

    NASA Technical Reports Server (NTRS)

    Croft, Steven K.

    1993-01-01

    Tectonic features on Triton have been mapped as part of a larger study of the geology of Triton. Few purely tectonic structures are found on Triton: some grabens and possibly some compressive ridges. However, most of the other structures seen (primarily cryovolcanic in origin) exhibit tectonic control. A regional tectonic network has the following dominant orientations: N-S, E-W, NE-SW, and NW-SE. Most of the orientations are consistent with tidal deformations related to Triton's decreasing orbital radius. Localized quasi-concentric patterns may be due to interior processes such as mantle plumes.

  20. Tectonics on Triton

    NASA Technical Reports Server (NTRS)

    Croft, Steven K.

    1993-01-01

    Tectonic features on Triton have been mapped as part of a larger study of the geology of Triton. Few purely tectonic structures are found on Triton: some grabens and possibly some compressive ridges. However, most of the other structures seen (primarily cryovolcanic in origin) exhibit tectonic control. A regional tectonic network has the following dominant orientations: N-S, E-W, NE-SW, and NW-SE. Most of the orientations are consistent with tidal deformations related to Triton's decreasing orbital radius. Localized quasi-concentric patterns may be due to interior processes such as mantle plumes.

  1. An Integrated Geospatial System for earthquake precursors assessment in Vrancea tectonic active zone in Romania

    NASA Astrophysics Data System (ADS)

    Zoran, Maria A.; Savastru, Roxana S.; Savastru, Dan M.

    2015-10-01

    With the development of space-based technologies to measure surface geophysical parameters and deformation at the boundaries of tectonic plates and large faults, earthquake science has entered a new era. Using time series satellite data for earthquake prediction, it is possible to pursue the behaviors of earthquake precursors in the future and to announce early warnings when the differences between the predicted value and the observed value exceed the pre-define threshold value. Starting with almost one week prior to a moderate or strong earthquake a transient thermal infrared rise in LST of several Celsius degrees (oC) and the increased OLR values higher than the normal have been recorded around epicentral areas, function of the magnitude and focal depth, which disappeared after the main shock. Also are recorded associated geomagnetic and ionospheric distrurbances. Vrancea tectonic active zone in Romania is characterized by a high seismic hazard in European- Mediterranean region, being responsible of strong or moderate intermediate depth and normal earthquakes generation on a confined epicentral area. Based on recorded geophysical parameters anomalies was developed an integrated geospatial system for earthquake precursors assessment in Vrancea active seismic zone. This system integrates derived from time series MODIS Terra/Aqua, NOAA-AVHRR, ASTER, Landsat TM/ETM satellite data multi geophysical parameters (land surface temperature -LST, outgoing long-wave radiation- OLR, and mean air temperature- AT as well as geomagnetic and ionospheric data in synergy with in-situ data for surveillance and forecasting of seismic events.

  2. Coseismic landslides reveal near-surface rock strength in a high-relief tectonically active setting

    USGS Publications Warehouse

    Gallen, Sean F; Clark, Marin K; Godt, Jonathan W.

    2014-01-01

    We present quantitative estimates of near-surface rock strength relevant to landscape evolution and landslide hazard assessment for 15 geologic map units of the Longmen Shan, China. Strength estimates are derived from a novel method that inverts earthquake peak ground acceleration models and coseismic landslide inventories to obtain material proper- ties and landslide thickness. Aggregate rock strength is determined by prescribing a friction angle of 30° and solving for effective cohesion. Effective cohesion ranges are from 70 kPa to 107 kPa for 15 geologic map units, and are approximately an order of magnitude less than typical laboratory measurements, probably because laboratory tests on hand-sized specimens do not incorporate the effects of heterogeneity and fracturing that likely control near-surface strength at the hillslope scale. We find that strength among the geologic map units studied varies by less than a factor of two. However, increased weakening of units with proximity to the range front, where precipitation and active fault density are the greatest, suggests that cli- matic and tectonic factors overwhelm lithologic differences in rock strength in this high-relief tectonically active setting.

  3. Sediment yield from the tectonically active semiarid Western Transverse Ranges of California

    USGS Publications Warehouse

    Warrick, J.A.; Mertes, L.A.K.

    2009-01-01

    Sediment yields from the world's rivers are generally highest from steep drainage basins with weak lithology, active tectonics, or severe land-use impacts. Here, we evaluate sediment yields from the Western Transverse Ranges of California in an attempt to explain why they are two- to tenfold greater than the surrounding areas of California. We found that suspended-sediment yields across the gauged basins of the Western Transverse Range during 1969-1999 varied by approximately an order of magnitude (740-5300 t/km2/yr). Similarly, fine-sediment concentrations for normalized discharge rates varied by almost two orders of magnitude (e.g., 1.3-110 g/L for the mean annual flood) for 11 previously unmonitored drainages of the Santa Ynez Mountains. Areas with high sediment yields consistently have weakly consolidated bedrock (Quaternary-Pliocene marine formations) and are associated with the highest rates of tectonic uplift of the region (>5 mm/yr). These regions are important to the sediment discharge budgets, because ???50% of the total suspended-sediment discharge from the Western Transverse Range is estimated to be generated within these regions, even though they represent only ???10% of the total watershed area. Previous estimates of suspended-sediment discharge from the Ventura River have likely been underestimated by ???50% because the gauging station is located immediately upstream of a high sediment yield region. We also found a significant and positive correlation between sediment yield and the percentage of a watershed with grassland and agricultural land use. These results suggest that there is adequate variation within the lithology, tectonics, and land use of the broader Western Transverse Range geologic province to induce large variations in sediment yield at the local scale. ?? 2009 Geological Society of America.

  4. Active tectonics in Eastern Lunana (NW Bhutan): Implications for the seismic and glacial hazard potential of the Bhutan Himalaya

    NASA Astrophysics Data System (ADS)

    Meyer, M. C.; Wiesmayr, G.; Brauner, M.; HäUsler, H.; Wangda, D.

    2006-06-01

    Paleoseismological investigations, brittle fault analysis, and paleostrain calculations combined with the interpretation of satellite imagery and flood wave modeling were used to investigate the seismic and associated glacial hazard potential in Eastern Lunana, a remote area in NW Bhutan. Seismically induced liquefaction features, cracked pebbles, and a surface rupture of about 6.8 km length constrain the occurrence of M ≥ 6 earthquakes within this high-altitude periglacial environment, which are the strongest earthquakes ever been reported for the Kingdom of Bhutan. Seismicity occurs along conjugate sets of faults trending NE-SW to NNW-SSE by strike-slip and normal faulting mechanism indicating E-W extension and N-S shortening. The strain field for these conjugate sets of active faults is consistent with widespread observations of young E-W expansion throughout southern Tibet and the north Himalaya. We expect, however, that N-S trending active strike-slip faults may even reach much farther to the south, at least into southern Bhutan. Numerous glacial lakes exist in the investigation area, and today more than 100 × 106 m3 of water are stored in moraine-dammed and supraglacial lakes which are crosscut by active faults. Strong earthquakes may trigger glacial lake outburst floods, and the impact of such flash floods may be worst 80 km downstream where the valley is broad and densely populated. Consequently, tectonic models of active deformation have to be closely linked with glacial hazard evaluation and require rethinking and modification.

  5. Discrimination and Assessment of Induced Seismicity in Active Tectonic Zones: A Case Study from Southern California

    NASA Astrophysics Data System (ADS)

    Bachmann, C. E.; Lindsey, N.; Foxall, W.; Robertson, M.

    2014-12-01

    Earthquakes induced by human activity have become a matter of heightened public concern during recent years. Of particular concern is seismicity associated with wastewater injection, which has included events having magnitudes greater than 5. The causes of the induced events are primarily changes in pore-pressure, fluid volume and perhaps temperature due to injection. Recent research in the US has focused on mid-continental regions having low rates of naturally-occurring seismicity, where induced events can be identified by relatively straightforward spatial and temporal correlation of seismicity with high-volume injection activities. Recent examples include events correlated with injection of wastewater in Oklahoma, Arkansas, Texas and Ohio, and long-term brine injection in the Paradox Valley in Colorado. Even in some of the cases where there appears at first sight to be a clear spatial correlation between seismicity and injection, it has been difficult to establish causality definitively. Here, we discuss methods to identify induced seismicity in active tectonic regions. We concentrate our study on Southern California, where large numbers of wastewater injection wells are located in oil-producing basins that experience moderate to high rates of naturally-occurring seismicity. Using the catalog of high-precision CISN relocations produced by Hauksson et al. (BSSA, 2012), we aim to discriminate induced from natural events based on spatio-temporal patterns of seismicity occurrence characteristics and their relationships to injection activities, known active faults and other faults favorably oriented for slip under the tectonic stress field. Since the vast majority of induced earthquakes are very small, it is crucial to include all events above the detection threshold of the CISN in each area studied. In addition to exploring the correlation of seismicity to injection activities in time and space, we analyze variations in frequency-magnitude distributions, which can

  6. Regional Paleoseismology Within Tectonic Complexity of Plate Interior and Island Arcs: the Itoigawa-Shizuoka Tectonic Line Active Fault System in Central Japan

    NASA Astrophysics Data System (ADS)

    Okumura, K.

    2008-12-01

    Structural simplicity of a highly-active fault system is a requisite for characteristic recurrence of large earthquakes. Recent paleoseismological studies on timing and repeated slips on the North Anatolian fault and the San Andreas fault have evidenced the condition. Regular recurrent earthquakes of similar size in a fault segment seems to be real under certain cirucumstances. However, paleoseismology in fault systems of structural complexity usually exhibit rather irregular recurrence of earthquakes in space and time. These observations tend to make seismologists skeptical about time-dependent risk assessment. In order to better evaluate the risks from actual data on active faulting, we need to reject simplistic mind in zones of complexity. In this paper, long-term behavior of the Itoigawa-Shizuoka tectonic line active fault system (ISTL), paleoseismologically the riskiest major active fault system in central Japan is analyzed together with rupture history of adjacent major fault zone within regional tectonic framework. Low-acitivity (< 4 mm/yr, R>2000 yr) Northern ISTL juxtaposes the high-heatflow basement block of Hida Mountains with overthrusting Neogene sediments in Saikawa Hills, the other flank of which is also bordered by active ( 5 mm/yr, R=~1000 yr) Nagano fault zone. Low-activity (< 2 mm/yr, R>3000 yr) Southern ISTL fringes only for 30 km along northeastern corner of the 100 km by 50 km the Akaishi Mesozoic-Neogene accretion block, that is presumably more affected by PHS-EUR plate boundary. There is another major moderate fault zone (~1 mm/yr, R=5000 yr) of Ina faults in west of Akaishi block. Further west are conjugate strike-slip fault systems of Kiso and Atera. Between these two low-activity portions of the ISTL, the Middle ISTL shows very high activity (5 to 10 mm/yr, R < 800 yr) and the evaluation as the riskiest faults derive only from this Middle ISTL. The rupture history of the ISTL will be analyzed together with that of adjacent fault zones in

  7. Archaeological evidences of the tectonic activity of Shueib Structure (NW Jordan)

    NASA Astrophysics Data System (ADS)

    Al-Awabdeh, Mohammad; Azañón, J. Miguel; Pérez-Peña, J. Vicente; Booth-Rea, Gillermo

    2014-05-01

    Archaeological damage in buried ruins often offers an excellent record of recent tectonic activity. The lower Jordan valley has experienced a continuous occupation in the last 5000 year, being frequent archaeological remains of human settlements along the valley. In this work we studied the Early Neolithic-to-Middle Islamic Periods archaeological site of Tall al-Hammam (Arabic name, ¨Hill of Baths¨). This ruin is located 27 km southwest of Amman city and it constitutes the largest Bronze Age archaeological site in Jordan. It consists of two main parts; the Upper Tall and the Lower Tall. This ruin lies within the southwestern termination of the Shueib structure (SHS); a Cretaceous fold-bend fault structure thought inactive through the entire Cenozoic. The relics, in the lower Tall, show clear fault-related damage in some walls. Two Middle Bronze Age (MBA) walls are displaced 26 and 20 cm respectively, according with a NNE-SSW fault plane. Apart of wall displacements, hundreds of joints and cracks in boulders of the walls are present. They strike generally NW-SE and NE-SW. Both archaeological evidences, boulder fractures and walls distortion, are coherent with the present-day tectonic setting of the Dead Sea Transform Fault in the region, and suggest a Quaternary reactivation of the SHS.

  8. Drainage - Structure Correlation in tectonically active Regions: Case studies in the Bolivian and Colombian Andes

    NASA Astrophysics Data System (ADS)

    Zeilinger, Gerold; Parra, Mauricio; Kober, Florian

    2017-04-01

    It is widely accepted, that drainage patterns are often controlled by tectonics/climate and geology/rheology. Classical drainage patterns can be found 1) in fault-and-thrust belt, where rives follow the valleys parallel or cut perpendicular to strike trough the ridges, forming a trellis pattern, 2) at dome structures where the drainage form a radial pattern or 3) rectangular patterns in strongly fractured regions. In this study, we focus on fault-and-thrust belts, that undergone different phases of tectonic activity. According to classical models, the deformation is propagating into the foreland, hence being youngest at the frontal part and getting successively older towards the axis of the orogen. Drainage patterns in the more interior parts of the orogenic wedge should be then less influenced by the direction of structures, as landscape evolution is changing to a tectonic passive stage. This relationship might represent the transience and maturity of drainage pattern evolution. Here we study drainage patterns of the Bolivian and the eastern Colombian Andes by comparing the relative orientation of the drainage network with the orogen structural grain. The drainage is extracted from Digital Elevation Models (SRTM 30 m) and indexed by their Strahler Order. Order 1 channels have an upstream area of 1 km2. The direction of all segments is analyzed by linear directional mean function that results in the mean orientation of input channels with approx. 500 m average length. The orientation of structures for different structural domains is calculated using the same function on digitized faults and fold-axis. Rose diagrams show the length-weighted directional distribution of structures, of higher (>= 4) and of lower order (<= 3) channels. The structural trend in the Bolivian Andes is controlled by the orocline, where a predominant NW-SE trend turns into an N-S trend at 18°S and where the eastern orogen comprise from west to east, the Eastern Cordillera (EC), the

  9. Simulation of active tectonic processes for a convecting mantle with moving continents

    USGS Publications Warehouse

    Trubitsyn, V.; Kaban, M.; Mooney, W.; Reigber, C.; Schwintzer, P.

    2006-01-01

    Numerical models are presented that simulate several active tectonic processes. These models include a continent that is thermally and mechanically coupled with viscous mantle flow. The assumption of rigid continents allows use of solid body equations to describe the continents' motion and to calculate their velocities. The starting point is a quasi-steady state model of mantle convection with temperature/ pressure-dependent viscosity. After placing a continent on top of the mantle, the convection pattern changes. The mantle flow subsequently passes through several stages, eventually resembling the mantle structure under present-day continents: (a) Extension tectonics and marginal basins form on boundary of a continent approaching to subduction zone, roll back of subduction takes place in front of moving continent; (b) The continent reaches the subduction zone, the extension regime at the continental edge is replaced by strong compression. The roll back of the subduction zone still continues after closure of the marginal basin and the continent moves towards the upwelling. As a result the ocean becomes non-symmetric and (c) The continent overrides the upwelling and subduction in its classical form stops. The third stage appears only in the upper mantle model with localized upwellings. ?? 2006 The Authors Journal compilation ?? 2006 RAS.

  10. Tectonic history and thrust-fold deformation style of seismically active structures near Coalinga

    SciTech Connect

    Namson, J.S. ); Davis, T.L.; Lagoe, M.B.

    1990-01-01

    The stratigraphy of the Coalinga region can be divided into tectostratigraphic facies whose boundaries delineate two major tectonic events - one in the mid-Cenozoic (38-17 Ma) and one in the late Cenozoic (less than 3 Ma). The succession of these tectostratigraphic facies, and an integration of geology, subsurface well data, a seismic-reflection profile, and earthquake seismicity on a retrodeformable cross section, yield a model for the tectonic evolution of the Coalinga region. This model suggests that the structural style of both deformational events is characteristic of fold and thrust belts. The model also indicates that the causative fault of the May 2 earthquake is a ramped thrust. The results of this study, in combination with regional geologic relations, suggest that the Coalinga region is part of an active fold and thrust belt which borders the west and south sides of the San Joaquin Valley. The potential for future earthquakes due to movement of other blind thrust faults within this belt should be evaluated.

  11. Implications for the tectonic transition zone of active orogeny in Hoping drainage basin, by landscape evolution at the multi-temporal timescale

    NASA Astrophysics Data System (ADS)

    Chang, Q.; Chen, R. F.; Lin, W.; Hsieh, P. S.

    2015-12-01

    In an actively orogeny the landscape are transient state of disequilibrium in response to climatic and tectonic inputs. At the catchment scale, sensitivity of river systems plays an important role in landscape evolution. Hoping drainage basin is located at the tectonic transition zone in the north-eastern Taiwan, where the behavior of Philippine Sea plate switches from overriding above the east-dipping Eurasian Continental plate to northward subducting under the Ryukyu arc. However, extensive deep-seated landslides, debris flow, and numerous large alluvial terraces can be observed, suggesting strong surface processes in this watershed. This effect on regional climate fundamentally changed the landscape by reconfiguring drainage patterns and creating a vast influx of sediments into the basin. In this study we review the morphological evidence from multi-temporal timescale, including in-situ cosmogenic nuclides denudation rate and suspension load data, coupled with the analysis of the longitudinal profiles. The main goal of this study is to compare Holocene erosion rates with thermochronology and radiometric dating of river terraces to investigate the erosion history of Hoping area. The result shows that short-term erosion rate is around twice as large as the long-term denudation rate, which might due to the climate-driven erosion events such as typhoon-induced landslide. We've also mapped detail morphological features by using the high-resolution LiDAR image, which help us to identify not only the landslide but also tectonic features such as lineation, fault scarps, and fracture zones. The tectonic surface features and field investigation results show that the drainage basin is highly fractured, suggesting that even though the vertical tectonic activity rate is small, the horizontal shortening influenced by both southward opening of the back-arc Okinawa trough and the north-western collision in this area is significant. This might cause the reducing in rock strength

  12. Sea Level Changes and Active Tectonics of the Guerrero Coast, Mexico

    NASA Astrophysics Data System (ADS)

    Ramirez-Herrera, M.; Cundy, A. B.; Sedor, M.; Kostoglodov, V.

    2003-12-01

    Understanding the interaction between sea-level changes and tectonic activity during the Holocene is essential in determining long-term tectonic deformation rates and in identifying prehistorical earthquake events along active margins. The Guerrero coast extends along the active Pacific margin of southwest Mexico and parallels the trench where the Cocos Plate subducts beneath the North American Plate. The last major earthquakes occurred in Guerrero in 1899, 1907, 1909, 1911, and 1957, but none have occurred since the major 1911 (Ms=7.6) earthquake in the northwest segment of the Guerrero seismic gap. The Guerrero gap is currently considered to be matured for a severe earthquake of estimated Mw= 8.1 to 8.4. We present preliminary results of geomorphic field surveying, sediment coring, and geochemical and microfaunal analyses of cored sediments on the Guerrero coast. The Coyuca lagoon strip of the Guerrero coast consists of long barrier beaches, behind which extends a lagoon, beach ridges, extensive swamps, mangrove swamps, salt pans, floodplains, alluvial plains, fluvial terraces, and abandoned meanders. Abandoned meanders and fluvial terraces indicate that the Coyuca River has migrated to the southeast. This migration, and changes in hill elevations near the coast, suggest a southeast tilting of this coastal segment. The morphology of the Guerrero coast has no evidence of long-term coastal uplift. This is consistent with short- term tide gauge measurements (1953-1999) and GPS data (1992-2000) indicative of subsidence rates of ~3 mm/yr (Kostoglodov et al., 2001) in this area. Five cores up to 5.5 m depth were taken nearby the Mitla, Coyuca, Tres Palos and Tecomate lagoons. Core stratigraphies show clear sequences of interbedded peats and clays, interspersed with sand units. The peat-clay sequences are similar to those observed along active margins elsewhere, and indicate fluctuations between marine and brackish/freshwater conditions. Two cores included sediments

  13. Using Digital Topography to Differentiate Erosionally Exhumed and Tectonically Active Mountains Fronts

    NASA Astrophysics Data System (ADS)

    Frankel, K. L.; Pazzaglia, F. J.

    2003-12-01

    Mountain ranges in the southern Rocky Mountains have departed on unique landscape evolutionary pathways in the late Cenozoic that are directly dependent upon the degree of post-orogenic tectonic activity they have experienced. The topography of Sierra Nacimiento, a Laramide uplift in west-central New Mexico lacking an active range-front fault, is shaped primarily by erosional exhumation that is continuous, but not steady, being driven by distal base level fall from Rio Grande incision and resultant south to north knickpoint migration. In contrast, the topography of the Taos Range, a rift flank uplift in north-central New Mexico is shaped by contrasting active stream incision and aggradation astride an active range front normal fault. The distinction between exhumation-dominated and tectonically-dominated mountain fronts is best quantified by analyses of a new metric we call the drainage basin volume to drainage basin area ratio (V-A ratio) as well as the gradients of first-order streams. Drainage basin volume and area are calculated by constructing topographic envelope maps from 10 m resolution digital elevation models (DEM). The envelope maps are pinned by the watershed divide and cover the maximum elevations in each drainage basin. Subtracting the original DEM from the maximum elevation envelope map produces a topographic residual map from which area and volume data can be obtained. The erosionally exhumed Sierra Nacimiento has a mean V-A ratio of 88 m while the tectonically active Taos Range has a mean V-A ratio of 140 m. Similarly, there are systematic differences in the gradients of first order streams measured both in the range block and approximately 5 km of adjacent piedmont. Streams were defined and subsequently Strahler ordered by a flow accumulation threshold of 250 water-equivalent grid cell units. First order stream channel long profiles were extracted from the DEM at 30 meter increments and gradients were calculated by a FORTRAN program. Gradients of

  14. Lasting mantle scars lead to perennial plate tectonics.

    PubMed

    Heron, Philip J; Pysklywec, Russell N; Stephenson, Randell

    2016-06-10

    Mid-ocean ridges, transform faults, subduction and continental collisions form the conventional theory of plate tectonics to explain non-rigid behaviour at plate boundaries. However, the theory does not explain directly the processes involved in intraplate deformation and seismicity. Recently, damage structures in the lithosphere have been linked to the origin of plate tectonics. Despite seismological imaging suggesting that inherited mantle lithosphere heterogeneities are ubiquitous, their plate tectonic role is rarely considered. Here we show that deep lithospheric anomalies can dominate shallow geological features in activating tectonics in plate interiors. In numerical experiments, we found that structures frozen into the mantle lithosphere through plate tectonic processes can behave as quasi-plate boundaries reactivated under far-field compressional forcing. Intraplate locations where proto-lithospheric plates have been scarred by earlier suturing could be regions where latent plate boundaries remain, and where plate tectonics processes are expressed as a 'perennial' phenomenon.

  15. Lasting mantle scars lead to perennial plate tectonics

    PubMed Central

    Heron, Philip J.; Pysklywec, Russell N.; Stephenson, Randell

    2016-01-01

    Mid-ocean ridges, transform faults, subduction and continental collisions form the conventional theory of plate tectonics to explain non-rigid behaviour at plate boundaries. However, the theory does not explain directly the processes involved in intraplate deformation and seismicity. Recently, damage structures in the lithosphere have been linked to the origin of plate tectonics. Despite seismological imaging suggesting that inherited mantle lithosphere heterogeneities are ubiquitous, their plate tectonic role is rarely considered. Here we show that deep lithospheric anomalies can dominate shallow geological features in activating tectonics in plate interiors. In numerical experiments, we found that structures frozen into the mantle lithosphere through plate tectonic processes can behave as quasi-plate boundaries reactivated under far-field compressional forcing. Intraplate locations where proto-lithospheric plates have been scarred by earlier suturing could be regions where latent plate boundaries remain, and where plate tectonics processes are expressed as a ‘perennial' phenomenon. PMID:27282541

  16. Lasting mantle scars lead to perennial plate tectonics

    NASA Astrophysics Data System (ADS)

    Heron, Philip J.; Pysklywec, Russell N.; Stephenson, Randell

    2016-06-01

    Mid-ocean ridges, transform faults, subduction and continental collisions form the conventional theory of plate tectonics to explain non-rigid behaviour at plate boundaries. However, the theory does not explain directly the processes involved in intraplate deformation and seismicity. Recently, damage structures in the lithosphere have been linked to the origin of plate tectonics. Despite seismological imaging suggesting that inherited mantle lithosphere heterogeneities are ubiquitous, their plate tectonic role is rarely considered. Here we show that deep lithospheric anomalies can dominate shallow geological features in activating tectonics in plate interiors. In numerical experiments, we found that structures frozen into the mantle lithosphere through plate tectonic processes can behave as quasi-plate boundaries reactivated under far-field compressional forcing. Intraplate locations where proto-lithospheric plates have been scarred by earlier suturing could be regions where latent plate boundaries remain, and where plate tectonics processes are expressed as a `perennial' phenomenon.

  17. Geodetic component of the monitoring of tectonic and hydrogeological activities in Kopacki Rit Nature Park

    NASA Astrophysics Data System (ADS)

    Dapo, Almin; Pribicevic, Bosko

    2013-04-01

    Based on the European and global experience, the amplitude change in the structural arrangement caused by recent tectonic movements, can be most accurately determined by repeated precise GPS measurements on specially stabilized geodetic and geodynamic points. Because of these reasons, the GPS method to determine the movements on specially stabilized points in the Nature park Kopacki rit is also applied in this project. Kopacki rit Nature Park is the biggest preserved natural flooded area on the Danube. It is spread over 23 000 hectares between the rivers Danube and Drava and is one of the biggest fluvial wetland valleys in Europe. In 1993 it was listed as one of internationally valuable wetlands according to the Ramsar Convention. By now in Kopacki rit there have been sights of about 295 bird species, more than 400 species of invertebrates and 44 types of fish. Many of them are globally endangered species like, white tailed eagle, black stork and prairie hawk. It's not rare to come across some deer herds, wild boars or others. Today's geological and geomorphological relations in the Nature park Kopacki rit are largely the result of climate, sedimentary, tectonic and anthropogenic activity in the last 10,000 years. Unfortunately the phenomenon of the Kopacki rit Nature park is in danger to be over in the near future due to those and of course man made activities on the Danube river. It is trough scientific investigations of tectonic and hydrogeological activities that scientist from University of Zagreb are trying to contribute to wider knowledge and possible solutions to this problem. In the year 2009 the first GPS campaign was conducted, and the first set of coordinates of stabilized points was determined which can be considered zero-series measurements. In 2010 a second GPS campaign was conducted and the first set of movements on the Geodynamic Network of Kopacki Rit Nature Park was determined. Processing GPS measurements from 2009 and 2010 was carried out in a

  18. Primary centers and secondary concentrations of tectonic activity through time in the western hemisphere of Mars

    USGS Publications Warehouse

    Anderson, R.C.; Dohm, J.M.; Golombek, M.P.; Haldemann, A.F.C.; Franklin, B.J.; Tanaka, K.L.; Lias, J.; Peer, B.

    2001-01-01

    Five main stages of radial and concentric structures formed around Tharsis from the Noachian through the Amazonian as determined by geologic mapping of 24,452 structures within the stratigraphic framework of Mars and by testing their radial and concentric orientations. Tectonic activity peaked in the Noachian (stage 1) around the largest center, Claritas, an elongate center extending more than 20?? in latitude and defined by about half of the total grabens which are concentrated in the Syria Planum, Thaumasia, and Tempe Terra regions. During the Late Noachian and Early Hesperian (stage 2), extensional structures formed along the length of present-day Valles Marineris and in Thaumasia (with a secondary concentration near Warrego Vallis) radial to a region just to the south of the central margin of Valles Marineris. Early Hesperian (stage 3) radial grabens in Pavonis, Syria, Ulysses, and Tempe Terra and somewhat concentric wrinkle ridges in Lunae and Solis Plana and in Thaumasia, Sirenum, Memnonia, and Amazonis are centered northwest of Syria with secondary centers at Thaumasia, Tempe Terra, Ulysses Fossae, and western Valles Marineris. Late Hesperian/Early Amazonian (stage 4) structures around Alba Patera, the northeast trending alignment of Tharsis Montes, and Olympus Mons appears centered on Alba Patera. Stage 5 structures (Middle-Late Amazonian) represent the last pulse of Tharsis-related activity and are found around the large shield volcanoes and are centered near Pavonis Mons. Tectonic activity around Tharsis began in the Noachian and generally decreased through geologic time to the Amazonian. Statistically significant radial distributions of structures formed during each stage, centered at different locations within the higher elevations of Tharsis. Secondary centers of radial structures during many of the stages appear related to previously identified local magmatic centers that formed at different times and locations throughout Tharsis. Copyright 2001 by

  19. An attempt to monitor tectonic forces in the Vrancea active geodynamic zone: The Baspunar experiment

    NASA Astrophysics Data System (ADS)

    Besutiu, Lucian; Zlagnean, Luminita; Plopeanu, Marin

    2013-04-01

    (sparsely) run in the area, have provided inconsistent results on the PCF current dynamics. The Baspunar Geodynamic Observatory (BGO) has been designed and implemented by the Solid Earth Dynamics Department in the Institute of Geodynamics of the Romanian Academy in order to reveal and monitor eventual motions along PCF in the attempt to correlate variations in the slip rate with changes in the seismicity released within Vrancea zone. The first BGO records were strongly affected by changes in the atmospheric parameters. Consequently, technical measures and special corrections for the removal or at least mitigation of the effects created by changes in temperature, air pressure and humidity have been applied to the observations. In order to improve the signal to noise ratio, some mathematical filters have been applied too. The paper is aimed at revealing results of the geodetic observations along with preliminary geodynamic considerations. On the overall, after about two years of monitoring, PCF appears as an active tectonic contact. It mainly behaves as a left-lateral fault, but some short episodes with a reverse slip (dextral) were also pointed out. Correlations with crustal and intermediate-depth earthquakes occurring in both cases within the bending zone of East Carpathians are illustrated and discussed.

  20. Identifying induced seismicity in active tectonic regions: A case study of the San Joaquin Basin, California

    NASA Astrophysics Data System (ADS)

    Aminzadeh, F.; Göbel, T.

    2013-12-01

    Understanding the connection between petroleum-industry activities, and seismic event occurrences is essential to monitor, quantify, and mitigate seismic risk. While many studies identified anthropogenically-induced seismicity in intraplate regions where background seismicity rates are generally low, little is known about how to distinguish naturally occurring from induced seismicity in active tectonic regions. Further, it is not clear how different oil and gas operational parameters impact the frequency and magnitude of the induced seismic events. Here, we examine variations in frequency-size and spatial distributions of seismicity within the Southern Joaquin basin, an area of both active petroleum production and active fault systems. We analyze a newly available, high-quality, relocated earthquake catalog (Hauksson et al. 2012). This catalog includes many seismic events with magnitudes up to M = 4.5 within the study area. We start by analyzing the overall quality and consistence of the seismic catalog, focusing on temporal variations in seismicity rates and catalog completeness which could indicate variations in network sensitivity. This catalog provides relatively homogeneous earthquake recordings after 1981, enabling us to compare seismicity rates before and after the beginning of more pervasive petroleum-industry activities, for example, hydraulic-fracturing and waste-water disposals. We conduct a limited study of waste-water disposal wells to establish a correlation between seismicity statistics (i.e. rate changes, fractal dimension, b-value) within specific regions and anthropogenic influences. We then perform a regional study, to investigate spatial variations in seismicity statistics which are then correlated to oil field locations and well densities. In order to distinguish, predominantly natural seismicity from induced seismicity, we perform a spatial mapping of b-values and fractal dimensions of earthquake hypocenters. Seismic events in the proximity to

  1. The QuakeSim Project: Numerical Simulations for Active Tectonic Processes

    NASA Technical Reports Server (NTRS)

    Donnellan, Andrea; Parker, Jay; Lyzenga, Greg; Granat, Robert; Fox, Geoffrey; Pierce, Marlon; Rundle, John; McLeod, Dennis; Grant, Lisa; Tullis, Terry

    2004-01-01

    In order to develop a solid earth science framework for understanding and studying of active tectonic and earthquake processes, this task develops simulation and analysis tools to study the physics of earthquakes using state-of-the art modeling, data manipulation, and pattern recognition technologies. We develop clearly defined accessible data formats and code protocols as inputs to the simulations. these are adapted to high-performance computers because the solid earth system is extremely complex and nonlinear resulting in computationally intensive problems with millions of unknowns. With these tools it will be possible to construct the more complex models and simulations necessary to develop hazard assessment systems critical for reducing future losses from major earthquakes.

  2. The QuakeSim Project: Numerical Simulations for Active Tectonic Processes

    NASA Technical Reports Server (NTRS)

    Donnellan, Andrea; Parker, Jay; Lyzenga, Greg; Granat, Robert; Fox, Geoffrey; Pierce, Marlon; Rundle, John; McLeod, Dennis; Grant, Lisa; Tullis, Terry

    2004-01-01

    In order to develop a solid earth science framework for understanding and studying of active tectonic and earthquake processes, this task develops simulation and analysis tools to study the physics of earthquakes using state-of-the art modeling, data manipulation, and pattern recognition technologies. We develop clearly defined accessible data formats and code protocols as inputs to the simulations. these are adapted to high-performance computers because the solid earth system is extremely complex and nonlinear resulting in computationally intensive problems with millions of unknowns. With these tools it will be possible to construct the more complex models and simulations necessary to develop hazard assessment systems critical for reducing future losses from major earthquakes.

  3. Tectonics of Neyterkob corona on Venus

    NASA Technical Reports Server (NTRS)

    Kauhanen, K.

    1993-01-01

    Neyterkob double corona (50 deg N 202 deg) presents an area of corona-related interfering tectonic patterns which are formed in different phases of evolution of the corona and modified by regional stresses. Analyzing the patterns can reveal something about the coronal formation. Tectonic features form distinct units on topographic depressions, slopes, and volcanic flows extending over one radius of the corona. A remarkable amount of compressional features were found near the rim and related to interaction between adjacent coronae. Radial extension was mainly observed on a peculiar NE-SW trending high crossing the corona. Concentric fractures were found to the east partly connected to the lithospheric flexure. Tectonic features indicate movements of volcanic activity and modification of the area by more regional stresses.

  4. The global tectonic pattern

    NASA Astrophysics Data System (ADS)

    Doglioni, Carlo

    1990-07-01

    The relative motion vectors between the lithosphere and the underlying mantle appear to follow global flow lines which can be constructed by linking axes of extension and compression over the Earth's surface. The flow lines for the last 40 Ma are generally WNW-ESE (E-W), with an undulation of an about 15,000 km wavelength, showing a gradual and progressive variation in orientation. The undulation, which is sharper to the east, may reflect the mantle flow around an unstable rotation axis. The westward motion of the lithospheric plates could be interpreted as a result of differential angular velocity induced by the deceleration of the earth's rotation or, in a toroidal field, by the effects induced by lateral heterogeneities both in the lithosphere and in the mantle. In this light, plate tectonics is a consequence of variable decoupling at the base of the lithosphere as a function of mantle anisotropies. Simply stated, when there is compression or transpression between two plates, it is the eastern plate which moves more rapidly westwards relative to the underlying mantle. If there is extension or transtension, it is the western plate that moves faster westwards. Lithospheric subduction, especially if it dips westward, produces an obstacle to the eastward flow of the mantle. This is referred to as the Nail Effect. The eastward roll-back of the subduction hinge due to the mantle push will generate back-arc extension. Subductions following the mantle flow (E or NE-dipping) are associated to thicker thrust belts with huge exposures of basement rocks in the hinterland and shallow foreland basins. The subductions contrasting the mantle flow (W or SW-dipping) are characterized by shallow thrust belts with deep foreland basin and coeval extension in the back. E-dipping subductions are passive responses to actively thrusting plates: the base plate and intra-lithospheric decollements are connected to the surface and can uplift deep rocks. The W-dipping subductions are

  5. Active tectonics and mud diapirism in the Gulf of Squillace (Crotone Basin, Calabrian Arc, Italy)

    NASA Astrophysics Data System (ADS)

    Artoni, A.; Capozzi, R.; Lorenzini, S.; Oppo, D.; Polonia, A.; Torelli, L.

    2009-04-01

    The Calabrian arc is a prominent accretionary prism in the Mediterranean sea that contains alpine metamorphic rocks and connects the southern Apennine chain of Calabria, to the north, with the Maghrebian chain of Sicily, to the southwest. Recent active deformation inside the prism is testified by the earthquakes records and by submarine mud volcanism. The latter, not yet well defined within the accretionary prism, is generally associated to deeper active tectonic structures. In order to unravel the relationships between mud volcanoes and deeper deformations a study has been carried out in the Gulf of Squillace, located in the central portion of the backstop zone of the Calabrian arc and inside the Crotone basin. The deeper tectono-stratigraphic frame has been defined by using 10 well logs, 330 kms of public seismic reflection lines and three CROP seismic lines (the project for deep crust of Italy) recently processed with prestack depth migration. The study has been carried out within the Italian PRIN 2006 Project: "Tectonic and Sedimentation in the Accretionary Complex at the Front of the Calabrian Arc (Ionian Sea)". Three major tectonic units could be distinguished; from the top to the bottom, they are: 1) a metamorphic basement nappe (Alpine/Calabrian units); 2) a complex and east-verging Apenninic-Maghrebian prism, that can be subdivided in an outer prism sealed by middle Eocene(?)/Oligocene deposits and an inner prism sealed by middle/late Miocene deposits; 3) a deeper Mesozoic to Neogene relatively undeformed block interpreted as a thinned block of continental crust that preserves Mesozoic extensional fault. Subsurface mapping of Alpine/Calabrian and Apenninic-Maghrebian units show that their leading edges are oriented NNE-SSW and their tectonic stack was completed at least in the late Miocene; since then, WNW-ESE trending Catanzaro-Squillace transcurrent faults system and out-of-sequence thrusting started to locally reshape the backstop. The Cantanzaro

  6. Hazard analysis of active tectonics through geomorphometric parameters to cultural heritage conservation: the case of Paphos in Cyprus

    NASA Astrophysics Data System (ADS)

    Argyriou, A. V.; Sarris, A.; Alexakis, D.; Agapiou, A.; Themistocleous, K.; Lysandrou, V.; Hadjimitsis, D.

    2014-08-01

    Natural hazards, such as earthquakes, can have a large destructive effect on cultural heritage sites conservation. This study aims to assess from a geospatial perspective the risk from natural hazards for the archaeological sites and monuments and evaluate the potential tectonic activity impact on the cultural and historic heritage. Geomorphometric data derivatives that can be extracted from Digital Elevation Models (DEMs) provide information relevant with active tectonics. The specific extracted tectonic information when being used on the basis of analytical hierarchy process and weighted linear combination approach can offer an important robust approach. The ranking of the derived information relatively to specific criteria of weights can enhance the interrelationships and assemblages over neotectonics aspects. The outcomes of that methodological framework can propose an assessment approach for the spatial distribution of neotectonic activity and can become a useful tool to assessing seismic hazard for disaster risk reduction. The risk assessment aspects of such a hazard are being interlinked with the archaeological sites in order to highlight and examine those that are exposed on ongoing tectonic activity and seismic hazard. Paphos area in Cyprus has been used as the test bed for the particular analysis. The results show an important number of archaeological sites being located within zones of high degree of neotectonic activity.

  7. Active tectonic deformation along rejuvenated faults in tropical Borneo: Inferences obtained from tectono-geomorphic evaluation

    NASA Astrophysics Data System (ADS)

    Mathew, Manoj Joseph; Menier, David; Siddiqui, Numair; Kumar, Shashi Gaurav; Authemayou, Christine

    2016-08-01

    The island of Borneo is enveloped by tropical rainforests and hostile terrain characterized by high denudation rates. Owing to such conditions, studies pertaining to neotectonics and consequent geomorphic expressions with regard to surface processes and landscape evolution are inadequately constrained. Here we demonstrate the first systematic tectono-geomorphic evaluation of north Borneo through quantitative and qualitative morphotectonic analysis at sub-catchment scale, for two large drainage basins located in Sarawak: the Rajang and Baram basins. The extraction of morphometric parameters utilizing digital elevation models arranged within a GIS environment focuses on hypsometric curve analysis, distribution of hypsometric integrals through spatial autocorrelation statistics, relative uplift values, the asymmetry factor and the normalized channel steepness index. Hypsometric analysis suggests a young topography adjusting to changes in tectonic boundary conditions. Autocorrelation statistics show clusters of high values of hypsometric integrals as prominent hotspots that are associated with less eroded, young topography situated in the fold and thrust belts of the Interior Highlands of Borneo. High channel steepness and gradients (> 200 m0.9) are observed in zones corresponding to the hotspots. Relative uplift values reveal the presence of tectonically uplifted blocks together with relatively subsided or lesser uplifted zones along known faults. Sub-catchments of both basins display asymmetry indicating tectonic tilting. Stream longitudinal profiles demonstrate the presence of anomalies in the form of knickzones without apparent lithological controls along their channel reaches. Surfaces represented by cold spots of low HI values and low channel gradients observed in the high elevation headwaters of both basins are linked to isolated erosional planation surfaces that could be remnants of piracy processes. The implication of our results is that Borneo experiences

  8. Along-strike Deformation in Quaternary Valleys of Tropical NW Borneo: Implications for Active Tectonics, Seismicity and Geomorphology

    NASA Astrophysics Data System (ADS)

    Sautter, B.; Mathew, M. J.; Menier, D.; Pubellier, M. F.; Sapin, F.; Siddiqui, N.

    2015-12-01

    In the wee hours of 5th June, 2015, NW Borneo was jolted by a 6.0 magnitude earthquake, caused by fault movement at a shallow depth of 10 km. The quake that originated from near the foot of the picturesque Mount Kinabalu, Sabah, was felt as far as 350 km away from the epicentre and has produced more than 90 aftershocks to date; ranging in magnitudes from 1.6 to 5.2. Although the geologically complex NW Borneo has experienced more than 60 mainshocks and numerous aftershocks since 1970 to present; research pertaining to active tectonics, morphotectonics analysis and subsequent geomorphic response to resulting transient dynamic topography remains inadequate.Here, we show evidences of active tectonics in tropical Sabah, NW Borneo, using morphometric indices, geomorphic indicators and report our results of morphotectonic analysis and consequent feedback of landscape and topography. Results from stream length gradient index, normalized channel steepness index and spatial distribution of hypsometric integral showed evidences of fault rejuvenation during Quaternary and recent periods. River longitudinal profiles showed the presence of several knickpoints indicating fault reactivations as the study area lacks lithological contrasts and similar climatic conditions along the channel reach. Field survey revealed the presence of highly elevated Quaternary fluvial terraces illustrating recent and important tectonic uplift rates in the trend of the exhumation rates calculated on Mt. Kinabalu by means of thermochronology. The uplifted terraces show a positive correlation with geomorphic analysis along the main valleys and other areas of active tectonics. Our analysis show the competition between important uplifts related to the dynamics of the NW Borneo Wedge and active normal faulting. These faults are in trend to the major earthquakes that occurred recently in this area, which have a normal faulting mechanism. The cause of the mechanism for recent tectonism and/or decoupling

  9. Marine and land active-source seismic investigation of geothermal potential, tectonic structure, and earthquake hazards in Pyramid Lake, Nevada

    SciTech Connect

    Eisses, A.; Kell, A.; Kent, G.; Driscoll, N.; Karlin, R.; Baskin, R.; Louie, J.; Pullammanappallil, S.

    2016-08-01

    Amy Eisses, Annie M. Kell, Graham Kent, Neal W. Driscoll, Robert E. Karlin, Robert L. Baskin, John N. Louie, Kenneth D. Smith, Sathish Pullammanappallil, 2011, Marine and land active-source seismic investigation of geothermal potential, tectonic structure, and earthquake hazards in Pyramid Lake, Nevada: presented at American Geophysical Union Fall Meeting, San Francisco, Dec. 5-9, abstract NS14A-08.

  10. Active Seismicity and Tectonics in Central Asia from Seismological Data Recorded in the Pamir and Tien Shan Mountain Ranges

    NASA Astrophysics Data System (ADS)

    Sippl, Christian; Schurr, Bernd; Schneider, Felix M.; Yuan, Xiaohui; Mechie, James; Minaev, Vladislav; Abdybachaev, Ulan A.; Gadoev, Mustafo; Oimahmadov, Ilhomjon

    2010-05-01

    Active tectonics in the Pamir mountains in central Asia, the westernmost part of the India-Eurasia collision zone, are controlled by ongoing convergence (about 20 mm/yr), causing substantial crustal shortening and compressional deformation. This leads to high seismicity rates throughout the region. Whereas seismic activity along the rim of the Pamir plateau is mostly compressional and concentrated along the Main Pamir Thrust, the distribution and focal mechanisms of earthquakes in its interior are more diffuse, with extensional events occurring along North-South trending rift zones (Kara Kul, Wachan). Seismicity in the south-western Pamir and in the Hindu Kush features frequent intermediate-depth earthquakes, reaching hypocentral depths of 300 km, which is rare for regions not obviously related to active subduction of oceanic lithosphere. These mantle earthquakes, which are not observed beneath the Himalayas and Tibet further east, form a rather well-defined Wadati-Benioff zone that was readily interpreted as subducted lithosphere present below the current collisional orogen. Earlier seismological studies showed the presence of a northward-dipping lithospheric slab under the Hindu Kush and a southward-dipping one beneath the Pamirs, with a small seismic gap in-between. Different hypotheses concerning the nature of these slabs (oceanic or continental lithosphere) and tectonic geometry in general (two slabs subducting in opposite directions or a single, hugely contorted slab) have been proposed in literature. Political instability in the region in the last two decades hampered on-site studies and field work, leaving many key issues poorly understood. In the framework of the multidisciplinary project TIPAGE (Tien Shan Pamir Geodynamic Programme), for the first time, new field campaigns collecting high quality data have been made possible. Local seismicity in the Pamir and Tien Shan mountain ranges (Tajikistan and Kyrgyzstan) is currently being recorded by a temporary

  11. Relative tectonic activity assessment along the East Anatolian strike-slip fault, Eastern Turkey

    NASA Astrophysics Data System (ADS)

    Khalifa, Abdelrahman

    2016-04-01

    The East Anatolian transform fault is a morphologically distinct and seismically active left-lateral strike-slip fault that extends for ~ 500 km from Karlıova to the Maraş defining the boundary between the Anatolian Block and Syrian Foreland. Deformed landforms along the East Anatolian fault provide important insights into the nature of landscape development within an intra-continental strike-slip fault system. Geomorphic analysis of the East Anatolian fault using geomorphic indices including mountain front sinuosity, stream length-gradient index, drainage density, hypsometric integral, and the valley-width to valley height ratio helped differentiate the faulting into segments of differing degrees of the tectonic and geomorphic activity. Watershed maps for the East Anatolian fault showing the relative relief, incision, and maturity of basins along the fault zone help define segments of the higher seismic risk and help evaluate the regional seismic hazard. The results of the geomorphic indices show a high degree of activity, reveal each segment along the fault is active and represent a higher seismic hazard along the entire fault.

  12. Impact of the Yakutat indentor corner on present-day tectonics and fault activity in SE Alaska - SW Yukon

    NASA Astrophysics Data System (ADS)

    Mazzotti, S.; Marechal, A.; Ritz, J. F.; Ferry, M. A.

    2015-12-01

    We present an active tectonic model of the SE Alaska - SW Yukon region based principally on the integration of recent GPS velocity data and new fault-slip rates derived from geomorphology. In this region, the Yakutat collision results in complex tectonics with patterns of strain localization and strain partitioning that strongly vary across the various mountain ranges and active faults. We propose that deformation and fault activity in the St. Elias and Chugach Mountains are primarily controlled by the eastern syntaxis of the Yakutat collision, which produces a semi-radial tectonic pattern: Velocities, principal horizontal shortening rates, and maximum horizontal stress orientations rotate by 60 - 80 ° around the syntaxis, from roughly parallel to the relative Pacific - North America motion at the front of the collision to roughly orthogonal southeast of the syntaxis. The interaction between this strain pattern and major inherited tectonic structures inland of the collision zone (i.e., Denali and Duke River Faults) results in various reactivation modes of these structures. Specifically, the Denali Fault shows a very pronounced lateral variations of activity from ~12 mm/a of dextral slip rate in its central section to ~1 mm/a of mostly shortening slip rate along its southern section. This marked change of activity is associated with a possible relay system where the Duke River and Totschunda Faults accommodate a major part (8 - 12 mm/a) of the inland strain transfer directly in front of the syntaxis. This new tectonic model retains some questions, in particular regarding the mechanisms of deformation and strain transfer (1) from the syntaxis to the Duke River - Totschunda system and (2) at the junction between Totschunda and Denali Faults. Numerical models of present-day deformation may help address these issues and provide information about relative strength of the various crustal and inherited fault elements of this system.

  13. Hidden faults in the Gobi Desert (Inner Mongolia, China) - evidence for fault activity in a previously tectonically stable zone

    NASA Astrophysics Data System (ADS)

    Rudersdorf, Andreas; Haedke, Hanna; Reicherter, Klaus

    2013-04-01

    The Gaxun Nur Basin (GNB, also Ejina Basin, Hei River Basin, Ruoshui Basin) north of the Tibetan Plateau and the Hexi Corridor is an endorheic basin bounded by the Bei Shan ranges in the west, the Gobi Altai mountains in the north and the Badain Jaran sand desert in the east. The basin is fed from the south by the braided drainage system of the Hei He (Hei River) and its tributaries, which originate in the Qilian Shan; terminal lakes like the dried Gaxun Nur and Sogo Nur are and have been temporal. The sedimentary succession of up to 300 m comprises intercalations of not only alluvial deposits but also lake sediments and playa evaporites. The basin has been regarded as tectonically inactive by earlier authors; however, the dating of sediments from an earlier drill core in the basin center provided some implications for tectonic activity. Subsequent remote sensing efforts revealed large lineaments throughout the basin which are now considered as possible fault line fingerprints. We investigated well preserved Yardangs (clay terraces) in the northeastern part of the GNB, in the vicinity of the Juyanze (paleo) lake, and found evidence for Holocene active tectonics (seismites). We present a lithological analysis of the relevant sequences and conclusions on the recent tectonic activity within the study area.

  14. Anisotropy and tectonic deformation in the Ordos basin revealed by an active source seismic experiment

    NASA Astrophysics Data System (ADS)

    Jun, W. S.; Wang, F.; Xu, T.

    2016-12-01

    With the purpose of exploring the Ordos block, western North China Craton, two controlled-source deep seismic transects were conducted across this region. The first one is a 650 km long profile oriented N-S; the second is 1530 km and is oriented E-W. The upper mantle P wave-velocity derived from these profiles features a 0.25 km/s difference between them. Being the E-W higher that the N-S. The results obtained from both seismic profiles indicate that the upper mantle beneath the Ordos block presents seismic anisotropy in terms of discrepancy in Pn-wave velocity, such as the apparent seismic velocities observed along the two reference profiles demonstrate. This result is consistent with SKS-wave splitting measurements in the interior of the Ordos block. This indicates that the compressive stress state in Ordos during the Mesozoic became an extensional stress state in the Cenozoic. The high-velocity anomaly in the uppermost mantle under the west-east profile suggests that the lithospheric mantle is still not water-rich. Unlike what happened in the NCC to east of the Taihang Mountains, where the lithosphere experienced its thinning and destruction since the Mesozoic, the lithosphere in the interior of Ordos has suffered less deformation and remained tectonically stable. Keywords: wide-angle seismic profiling, Pn phase, high-velocity anomaly, upper mantle anisotropy, Ordos block, North China Craton. ReferencesChen L., 2009. Lithospheric structure variations between the eastern and central North China Craton from S- and P-receiver function migration. Phys. Earth Planet. Inter. 173, 216-227. Gao S., Rudnick R.L., Xu W.L., et al., 2008. Recycling deep cratonic lithosphere and generation of intraplate magmatism in the North China Craton. Earth Planet. Sci. Lett. 270, 41-53. Xu T., Zhang Z.J., Gao E.G., et al., 2010. Segmentally iterative ray tracing in complex 2D and 3D heterogeneous block models. Bull. Seism. Soc. Am. 100, 841-850. Zhu R.X., Zheng T.Y., 2009. Destruction

  15. Quaternary active tectonic structures in the offshore Bajo Segura basin (SE Iberian Peninsula - Mediterranean Sea)

    NASA Astrophysics Data System (ADS)

    Perea, H.; Gràcia, E.; Alfaro, P.; Bartolomé, R.; Lo Iacono, C.; Moreno, X.; Masana, E.; Event-Shelf Team

    2012-10-01

    The Bajo Segura fault zone (BSFZ) is the northern terminal splay of the Eastern Betic shear zone (EBSZ), a large left-lateral strike-slip fault system of sigmoid geometry stretching more than 450 km from Alicante to Almería. The BSFZ extends from the onshore Bajo Segura basin further into the Mediterranean Sea and shows a moderate instrumental seismic activity characterized by small earthquakes. Nevertheless, the zone was affected by large historical earthquakes of which the largest was the 1829 Torrevieja earthquake (IEMS98 X). The onshore area of the BSFZ is marked by active transpressive structures (faults and folds), whereas the offshore area has been scarcely explored from the tectonic point of view. During the EVENT-SHELF cruise, a total of 10 high-resolution single-channel seismic sparker profiles were obtained along and across the offshore Bajo Segura basin. Analysis of these profiles resulted in (a) the identification of 6 Quaternary seismo-stratigraphic units bounded by five horizons corresponding to regional erosional surfaces related to global sea level lowstands; and (b) the mapping of the active sub-seafloor structures and their correlation with those described onshore. Moreover, the results suggest that the Bajo Segura blind thrust fault or the Torrevieja left-lateral strike-slip fault, with prolongation offshore, could be considered as the source of the 1829 Torrevieja earthquake. These data improve our understanding of present deformation along the BSFZ and provide new insights into the seismic hazard in the area.

  16. Geomorphic assessment of the tectonic activity of Qiulitagh fold-belt, Kuqa foreland basin, Xinjiang, China

    NASA Astrophysics Data System (ADS)

    Saint Carlier, Dimitri; Graveleau, Fabien; Delcaillau, Bernard; Hurtrez, Jean-Emmanuel; Vendeville, Bruno

    2014-05-01

    The Qiulitagh fold belt is an anticline structure located in the Kuqa fold-and-thrust belt (southern Tian Shan, China), whose active folding is well documented by structural and palaeomagnetic studies (Chen et al., 2007; Hubert-Ferrari et al., 2007; Li et al., 2012; Wang et al., 2011). The topography of Quilitagh fold belt can be divided into two SW-NE parallel ridges: 1) a 90 km long northern ridge, composed of the Northern Qiulitagh anticline and the Yakelike anticline, and 2) a 165km long southern ridge, composed of the Southern Qiulitagh anticline and the Mishikantage anticline. Due to the current absence of vegetation and relative homogeneity of outcropping lithologies (mainly Neogene detrital sandstone and silstone), these anticlines provide exceptional field cases for investigating the dynamic relationships between fold growth mechanisms, the subsurface structures, the geomorphic entities and the drainage network evolution. We used free topographic and satellite image datasets to carry out a morphometric study of the Quilitagh fold-belt and investigate the kinematics of active folding. Topographic datasets include Digital Elevation Models (DEM) from the NASA SRTM V.4.0 and ASTER programs, whereas satellite images are extracted from Landsat 7 shots and Google Earth. These datasets were incorporated in GIS software where three scales of observation were investigated: 1) a global fold scale, 2) a drainage basin scale and 3) a valley scale. At the drainage basin scale, we selected about 250 items and quantified several geomorphic indices of relative active tectonic growth. These are the basin mean slope, hypsometric integral, basin asymmetry and local relief. We also used published seismic profiles to link the 3D subsurface geometry of the salt-related Qiulitagh fold belt with the geomorphic signal. Results indicate that the morphometry of Quilitagh drainage basins (hypsometry, drainage basin asymmetry, local relief, valley incision, steepness index) change

  17. Pore-pressure sensitivities to dynamic strains: observations in active tectonic regions

    USGS Publications Warehouse

    Barbour, Andrew

    2015-01-01

    Triggered seismicity arising from dynamic stresses is often explained by the Mohr-Coulomb failure criterion, where elevated pore pressures reduce the effective strength of faults in fluid-saturated rock. The seismic response of a fluid-rock system naturally depends on its hydro-mechanical properties, but accurately assessing how pore-fluid pressure responds to applied stress over large scales in situ remains a challenging task; hence, spatial variations in response are not well understood, especially around active faults. Here I analyze previously unutilized records of dynamic strain and pore-pressure from regional and teleseismic earthquakes at Plate Boundary Observatory (PBO) stations from 2006 through 2012 to investigate variations in response along the Pacific/North American tectonic plate boundary. I find robust scaling-response coefficients between excess pore pressure and dynamic strain at each station that are spatially correlated: around the San Andreas and San Jacinto fault systems, the response is lowest in regions of the crust undergoing the highest rates of secular shear strain. PBO stations in the Parkfield instrument cluster are at comparable distances to the San Andreas fault (SAF), and spatial variations there follow patterns in dextral creep rates along the fault, with the highest response in the actively creeping section, which is consistent with a narrowing zone of strain accumulation seen in geodetic velocity profiles. At stations in the San Juan Bautista (SJB) and Anza instrument clusters, the response depends non-linearly on the inverse fault-perpendicular distance, with the response decreasing towards the fault; the SJB cluster is at the northern transition from creeping-to-locked behavior along the SAF, where creep rates are at moderate to low levels, and the Anza cluster is around the San Jacinto fault, where to date there have been no statistically significant creep rates observed at the surface. These results suggest that the strength

  18. Late Quaternary loess landscape evolution on an active tectonic margin, Charwell Basin, South Island, New Zealand

    NASA Astrophysics Data System (ADS)

    Hughes, Matthew W.; Almond, Peter C.; Roering, Joshua J.; Tonkin, Philip J.

    2010-10-01

    Loess deposits constitute an important archive of aeolian deposition reflecting wider patterns of glacial atmospheric circulation, and more localised interactions between riverine source areas, loess trapping efficiency and geomorphic controls on erosion rate. Conceptual models have been formulated to explain the coeval evolution of loess mantles and associated landscapes (loess landscape models) but none apply to areas of tectonically induced base-level lowering. This study uses an age sequence of alluvial fill terraces in the Charwell Basin, north-eastern South Island New Zealand, which straddles the transpressive Hope Fault, to investigate geomorphic controls on loess landscape evolution in an active tectonic region. We hypothesize that the more evolved drainage networks on older terraces will more effectively propagate base-level lowering by way of a greater areal proportion of steep and convex hillslopes and a smaller proportion of non-eroding interfluves. Eventually, as the proportion of interfluves diminishes and hillslope convexity increases, terraces shift from being net loess accumulators to areas of net loess erosion. We investigate the nature of erosion and the geomorphic thresholds associated with this transition. Morphometric analysis of alluvial terraces and terrace remnants of increasing age demonstrated geomorphic evolution through time, with a decrease in extent of original planar terrace tread morphology and an increase in frequency of steeper slopes and convexo-concave land elements. The number of loess sheets and the thickness of loess increased across the three youngest terraces. The next oldest (ca. 150 ka) terrace remnant had the greatest maximum number of loess sheets (3) and loess thickness (8 m) but the loess mantle was highly variable. A detailed loess stratigraphic analysis and the morphometric analysis place this terrace in a transition between dominantly planar, uniformly loess-mantled landforms and loess-free ridge and valley terrain

  19. Slip sense inversion on active strike-slip faults in southwest Japan and its implications for Cenozoic tectonic evolution

    NASA Astrophysics Data System (ADS)

    Maruyama, Tadashi; Lin, Aiming

    2004-05-01

    Analyses of deflected river channels, offset of basement rocks, and fault rock structures reveal that slip sense inversion occurred on major active strike-slip faults in southwest Japan such as the Yamasaki and Mitoke fault zones and the Median Tectonic Line (MTL). Along the Yamasaki and Mitoke fault zones, small-size rivers cutting shallowly mountain slopes and Quaternary terraces have been deflected sinistrally, whereas large-size rivers which deeply incised into the Mio-Pliocene elevated peneplains show no systematically sinistral offset or complicated hairpin-shaped deflection. When the sinistral offsets accumulated on the small-size rivers are restored, the large-size rivers show residual dextral deflections. This dextral offset sense is consistent with that recorded in the pre-Cenozoic basement rocks. S-C fabrics of fault gouge and breccia zone developed in the active fault zones show sinistral shear sense compatible with earthquake focal mechanisms, whereas those of the foliated cataclasite indicate a dextral shear sense. These observations show that the sinistral strike-slip shear fabrics were overprinted on dextral ones which formed during a previous deformation phase. Similar topographic and geologic features are observed along the MTL in the central-eastern part of the Kii Peninsula. Based on these geomorphological and geological data, we infer that the slip sense inversion occurred in the period between the late Tertiary and mid-Quaternary period. This strike-slip inversion might result from the plate rearrangement consequent to the mid-Miocene Japan Sea opening event. This multidisciplinary study gives insight into how active strike-slip fault might evolves with time.

  20. Peculiar Active-Tectonic Landscape Within the Sanctuary of Zeus at Mt. Lykaion (Peloponnese, Greece)

    NASA Astrophysics Data System (ADS)

    Davis, G. H.

    2008-12-01

    The Sanctuary of Zeus (Mt. Lykaion) lies in the Peloponnese within the Pindos fold and thrust belt. It is the object of investigation of the Mt. Lykaion Excavation and Survey (http://lykaionexcavation.org/). Mt. Lykaion is a thrust klippe, on the summit of which is an upper sanctuary marked by an ash altar, temenos, and column bases. Earliest objects recovered from the ash altar go back to 3000 BCE, leading Dr. David Romano (University of Pennsylvania), a principal leader of the project, to conclude that worship of divinities on the summit is ancient. Detailed structural geological mapping reveals one dimension of the "power" of the site. Crisscrossing the upper sanctuary are scree bands that mark the traces of active normal faults, which are expressions of tectonic stretching of the Aegean region. The scree bands, composed of cinder-block-sized limestone blocks, range up to 10 m in outcrop breadth, 100 m in length, and 5 m in thickness. Though discontinuous, most of the scree bands lie precisely on the traces of through-going faults, which cut and displace the sedimentary formations of the Pindos group. Some cut the thrust fault, whose elliptical trace defines the Lykaion klippe. What makes the scree bands of this active-tectonic landscape "peculiar" is that there are no cliffs from which the scree descends. Rather, the bands of scree occur along flanks of smooth, rounded hillslopes and ridges. The scree bands coincide with modest steps in the topography, ranging from tens of centimeters to several tens of meters. The specific bedrock formation where the bands are best developed is an Upper Cretaceous limestone whose average platy-bedding thickness (approximately 20 cm) matches closely the average joint spacing. The limestone has little mechanical integrity. It cannot support itself as a scarp footwall and instead collapses into a pile of scree, whose upper-surface inclination conforms to a stable angle of repose. Evidence of the contemporary nature of this

  1. Insights into the evolution of tectonically-active glaciated mountain ranges from digital elevation model analyses

    NASA Astrophysics Data System (ADS)

    Brocklehurst, S. H.; Whipple, K. X.

    2003-12-01

    Glaciers have played an important role in the development of most active mountain ranges around the world during the Quaternary, but the interaction between glacial erosion (as modulated by climate change) and tectonic processes is poorly understood. The so-called glacial buzzsaw hypothesis (Brozovic et al., 1997) proposes that glaciers can incise as rapidly as the most rapid rock uplift rates, such that glaciated landscapes experiencing different rock uplift rates but the same snowline elevation will look essentially the same, with mean elevations close to the snowline. Digital elevation model-based analyses of the glaciated landscapes of the Nanga Parbat region, Pakistan, and the Southern Alps, New Zealand, lend some support to this hypothesis, but also reveal considerably more variety to the landscapes of glaciated, tectonically-active mountain ranges. Larger glaciers in the Nanga Parbat region maintain a low downvalley gradient and valley floor elevations close to the snowline, even in the face of extremely rapid rock uplift. However, smaller glaciers steepen in response to rapid uplift, similar to the response of rivers. A strong correlation between the height of hillslopes rising from the cirque floors and rock uplift rates implies that erosion processes on hillslopes cannot initially keep up with more rapid glacial incision rates. It is these staggering hillslopes that permit mountain peaks to rise above 8000m. The glacial buzzsaw hypothesis does not describe the evolution of the Southern Alps as well, because here mean elevations rise in areas of more rapid rock uplift. The buzzsaw hypothesis may work well in the Nanga Parbat region because the zone of rapid rock uplift is structurally confined to a narrow region. Alternatively, the Southern Alps may not have been rising sufficiently rapidly or sufficiently long for the glacial buzzsaw to be imposed outside the most rapidly uplifting region, around Mount Cook. The challenge now is to understand in detail

  2. Large historical earthquakes and tsunamis in a very active tectonic rift: the Gulf of Corinth, Greece

    NASA Astrophysics Data System (ADS)

    Triantafyllou, Ioanna; Papadopoulos, Gerassimos

    2014-05-01

    The Gulf of Corinth is an active tectonic rift controlled by E-W trending normal faults with an uplifted footwall in the south and a subsiding hangingwall with antithetic faulting in the north. Regional geodetic extension rates up to about 1.5 cm/yr have been measured, which is one of the highest for tectonic rifts in the entire Earth, while seismic slip rates up to about 1 cm/yr were estimated. Large earthquakes with magnitudes, M, up to about 7 were historically documented and instrumentally recorded. In this paper we have compiled historical documentation of earthquake and tsunami events occurring in the Corinth Gulf from the antiquity up to the present. The completeness of the events reported improves with time particularly after the 15th century. The majority of tsunamis were caused by earthquake activity although the aseismic landsliding is a relatively frequent agent for tsunami generation in Corinth Gulf. We focus to better understand the process of tsunami generation from earthquakes. To this aim we have considered the elliptical rupture zones of all the strong (M≥ 6.0) historical and instrumental earthquakes known in the Corinth Gulf. We have taken into account rupture zones determined by previous authors. However, magnitudes, M, of historical earthquakes were recalculated from a set of empirical relationships between M and seismic intensity established for earthquakes occurring in Greece during the instrumental era of seismicity. For this application the macroseismic field of each one of the earthquakes was identified and seismic intensities were assigned. Another set of empirical relationships M/L and M/W for instrumentally recorded earthquakes in the Mediterranean region was applied to calculate rupture zone dimensions; where L=rupture zone length, W=rupture zone width. The rupture zones positions were decided on the basis of the localities of the highest seismic intensities and co-seismic ground failures, if any, while the orientation of the maximum

  3. Groundwater study using drill holes in the Abukuma granitic province, NE Japan: chemical and isotopic features in the fracture zone around the geological tectonic line

    NASA Astrophysics Data System (ADS)

    Takahashi, H. A.; Tsukamoto, H.; Kazahaya, K.; Takahashi, M.; Morikawa, N.; Yasuhara, M.; Inamura, A.; Handa, H.; Nakamura, T.

    2010-12-01

    Chemical and isotopic features of groundwater in a granitic province are considered to be controlled by water origin, water-rock reaction and/or fracture connection in rocks. Under the depth of a weathering layer, groundwater is existed only in cracks of granite, and its chemical nature or origin has been poorly understood because of difficulties on collection of water samples preserving its natural conditions. On the other hand, a geological tectonic line in a granitic province might provide an influence to groundwater as a path for ascending deep fluid. We conducted a study for chemical processes of groundwater in cracks with investigation of an influence of tectonic line by drilling three bore holes at two sites in a same rock body; Miharu site is located ca. 1.2km west from the Morioka-Shirakawa tectonic line, and Shirasawa site is ca. 5km west. In situ sampling of waters in cracks of granite are done with the single and double packer methods. The drill holes were made 305m and 135m at the Miharu site and 230m at the Shirasawa site. Using these bole holes, groundwater features in the fracture zone around the geological tectonic line can be compared with those outside it. Chemical type of groundwater has a variety with depth; the shallower groundwater is categorized as Ca-HCO3- type with slight NO3 contamination whereas deeper groundwater has Na-HCO3- type. Stable isotope composition of water showed that all the sample water is meteoric origin. Those have significantly low values (ca. 10‰ of δD lower than shallow groundwater) obviously indicating that the groundwater does not originate from the present meteoric water. Groundwater with low δD and δ18O values is likely recharged in an ice age consistent with the 14C date showing the age of carbon ranging from 10000 to 15000 yrBP. The vertical trends of chemical and isotopic components are similar between the two holes at the Miharu site, but different between the two sites, Miharu and Shirasawa. The

  4. Tectonics of the Outer Planet Satellites

    NASA Technical Reports Server (NTRS)

    McKinnon, W. B.; Collins, G. C.; Moore, J. M.; Nimmo, F.; Pappalardo, R. T.; Prockter, L. M.; Schenk, P. M.

    2010-01-01

    Tectonic features on the satellites of the outer planets range from the familiar, such as clearly recognizable graben on many satellites, to the bizarre, such as the ubiquitous double ridges on Europa, the twisting sets of ridges on Triton, or the isolated giant mountains rising from Io's surface. All of the large and middle-sized outer planet satellites except Io are dominated by water ice near their surfaces. Though ice is a brittle material at the cold temperatures found in the outer solar system, the amount of energy it takes to bring it close to its melting point is lower than for a rocky body. Therefore, some unique features of icy satellite tectonics may be influenced by a near-surface ductile layer beneath the brittle surface material, and several of the icy satellites may possess subsurface oceans. Sources of stress to drive tectonism are commonly dominated by the tides that deform these satellites as they orbit their primary giant planets. On several satellites, the observed tectonic features may be the result of changes in their tidal figures, or motions of their solid surfaces with respect to their tidal figures. Other driving mechanisms for tectonics include volume changes due to ice or water phase changes in the interior, thermoelastic stress, deformation of the surface above rising diapirs of warm ice, and motion of subsurface material toward large impact basins as they fill in and relax. Most satellites exhibit evidence for extensional deformation, and some exhibit strike-slip faulting, whereas contractional tectonism appears to be rare. Io s surface is unique, exhibiting huge isolated mountains that may be blocks of crust tilting and foundering into the rapidly emptying interior as the surface is constantly buried by deposits from hyperactive volcanoes. Of the satellites, diminutive Enceladus is spectacularly active; its south polar terrain is a site of young tectonism, copious heat flow, and tall plumes venting into space. Europa's surface is

  5. Tectonics of the Outer Planet Satellites

    NASA Technical Reports Server (NTRS)

    McKinnon, W. B.; Collins, G. C.; Moore, J. M.; Nimmo, F.; Pappalardo, R. T.; Prockter, L. M.; Schenk, P. M.

    2010-01-01

    Tectonic features on the satellites of the outer planets range from the familiar, such as clearly recognizable graben on many satellites, to the bizarre, such as the ubiquitous double ridges on Europa, the twisting sets of ridges on Triton, or the isolated giant mountains rising from Io's surface. All of the large and middle-sized outer planet satellites except Io are dominated by water ice near their surfaces. Though ice is a brittle material at the cold temperatures found in the outer solar system, the amount of energy it takes to bring it close to its melting point is lower than for a rocky body. Therefore, some unique features of icy satellite tectonics may be influenced by a near-surface ductile layer beneath the brittle surface material, and several of the icy satellites may possess subsurface oceans. Sources of stress to drive tectonism are commonly dominated by the tides that deform these satellites as they orbit their primary giant planets. On several satellites, the observed tectonic features may be the result of changes in their tidal figures, or motions of their solid surfaces with respect to their tidal figures. Other driving mechanisms for tectonics include volume changes due to ice or water phase changes in the interior, thermoelastic stress, deformation of the surface above rising diapirs of warm ice, and motion of subsurface material toward large impact basins as they fill in and relax. Most satellites exhibit evidence for extensional deformation, and some exhibit strike-slip faulting, whereas contractional tectonism appears to be rare. Io s surface is unique, exhibiting huge isolated mountains that may be blocks of crust tilting and foundering into the rapidly emptying interior as the surface is constantly buried by deposits from hyperactive volcanoes. Of the satellites, diminutive Enceladus is spectacularly active; its south polar terrain is a site of young tectonism, copious heat flow, and tall plumes venting into space. Europa's surface is

  6. Formation and evolution of yardangs activated by Late Pleistocene tectonic movement in Dunhuang, Gansu Province of China

    NASA Astrophysics Data System (ADS)

    Wang, Yanjie; Wu, Fadong; Zhang, Xujiao; Zeng, Peng; Ma, Pengfei; Song, Yuping; Chu, Hao

    2016-12-01

    Developed in the Anxi-Dunhuang basin, the yardangs of Dunhuang (western China) are clearly affected by tectonic movement. Based on fieldwork, this study ascertained three levels of river terrace in the area for the first time. Through the analysis of river terraces formation and regional tectonic movement, the study ascertained that the river terraces were formed mainly by Late Pleistocene tectonic uplift, which had activated the evolution of yardangs in the study area. By electron spin resonance (ESR) dating and optically stimulated luminescence (OSL) dating, the starting time and periodicity of the evolution of the yardangs were determined. The river terraces designated T3, T2 and T1 began to evolve at 109.0 ˜98.5, 72.9 ˜66.84 and 53.2 ˜38.0 kaBP, respectively, which is the evidence of regional neotectonic movement. And, the formation of the yardangs was dominated by tectonic uplift during the prenatal stage and mainly by wind erosion in the following evolution, with relatively short stationary phases. This research focused on the determination of endogenic processes of yardangs formation, which would contribute to further understanding of yardangs formation from a geological perspective and promote further study of yardang landform.

  7. Current Magmato-Tectonic Activity in the Asal-Ghoubbet Rift (Afar Depression, Republic of Djibouti)

    NASA Astrophysics Data System (ADS)

    Doubre, C.; Doubre, C.; Dorbath, L.; Manighetti, I.; Jacques, E.; Geoffroy, L.

    2001-12-01

    The Asal-Ghoubbet rift, the most active, emerged segment of the Aden ridge, opens at 16+/-2 mm/yr. Although normal faulting operates in the rift, it does not accommodate the entire extension, so that dyking must occur at depth. In order to investigate the current relationship between tectonics and magmatism, we installed 11 seismometers (3 3C + one broad band; plus 6 permanent stations) in the northeastern part of the rift, site of the most active faults and of the Fieale volcano caldera, and monitored the seismic activity during 5 months. About 200 small-magnitude (time, <= 3) events could be accurately ( ~ 300m) localized in the emerged part of the rift, using an appropriate velocity model. All fall within the temporary network, forming three major clusters. Nine % of the events spread in the outermost part of the rift northern shoulder, where clear active faults and volcanic structures are lacking. All seem to nucleate at a similar depth, of 6-8 km. Seven % of the events nucleate at a shallow depth ( ~1 km) in the northern Disa Le Mallo subrift, zone of intense active faulting and fissuring. Finally, the majority of events (70%) cluster below the Fieale caldera, at a mean depth of 3 km, hence just above the inferred magma chamber. The analysis of the broader-scale seismological data acquired in the rift over the last 20 years, points to a similar distribution. Thirty five out of 50 focal mechanisms we calculated using P wave polarities, are consistent with a double-couple source model, and reveal predominant normal faulting on NW-SE-striking planes parallel to the faults which structure the rift. Fifteen events, however, show non-double couple radiation pattern, particularly in the Fieale area. These particular events may result from magmatic activity (filling or collapse of the magma chamber) and/or geothermal processes. In the other two areas, where they are also found, their origin is possibly related to fissuring or dyking. One seismic sequence also occurred

  8. Active tectonics of northwestern U.S. inferred from GPS-derived surface velocities

    SciTech Connect

    Robert McCaffrey; Robert W. King; Suzette J. Payne; Matthew Lancaster

    2013-02-01

    Surface velocities derived from GPS observations from 1993 to 2011 at several hundred sites across the deforming northwestern United States are used to further elucidate the region's active tectonics. The new velocities reveal that the clockwise rotations, relative to North America, seen in Oregon and western Washington from earlier GPS observations, continue to the east to include the Snake River Plain of Idaho and south into the Basin and Range of northern Nevada. Regional-scale rotation is attributed to gravitationally driven extension in the Basin and Range and Pacific-North America shear transferred through the Walker Lane belt aided by potentially strong pinning below the Idaho Batholith. The large rotating section comprising eastern Oregon displays very low internal deformation rates despite seismological evidence for a thin crust, warm mantle, organized mantle flow, and elevated topography. The observed disparity between mantle and surface kinematics suggests that either little stress acts between them (low basal shear) or that the crust is strong relative to the mantle. The rotation of the Oregon block impinges on Washington across the Yakima fold-thrust belt where shortening occurs in a closing-fan style. Elastic fault locking at the Cascadia subduction zone is reevaluated using the GPS velocities and recently published uplift rates. The 18 year GPS and 80 year leveling data can both be matched with a common locking model suggesting that the locking has been stable over many decades. The rate of strain accumulation is consistent with hundreds of years between great subduction events.

  9. Taiwan: a perfect field trip to study active tectonics and erosion processes

    NASA Astrophysics Data System (ADS)

    Bigot-Cormier, Florence; Beauval, Véronique; Martinez, Claire-Marie; Seyeux, Jana

    2014-05-01

    Taiwan is located at the boundary between the Philippine Sea Plate to the East and the Eurasian Plate to the West. This plate boundary is rather complex since it comprises two subduction zones of reverse polarities. Due to this specific geodynamic context, this field is a perfect area to answer the French program in 5th grade (erosion processes) and 4th grade (active tectonics) in Earth Science class. That's why for the second year, students from the Lycée Français de Shanghai (LFS) in 4th grade will go for a 4-day field trip to discover volcanoes (in the Yangminshan National Park) and para-seismic constructions in the 101 Tower at Taipei. It will remind them the program of their previous class (5ème) through the visit of Yehliu Geographic Park and some other areas in the North of the Island where they will be able to observe different erosion processes (wind or water) carving the landscape. The aim of this field trip is first to show them that Earth Sciences cannot be studied only in class but also on the field to get a better understanding of the processes. In this manner, after having understood the internal thermal system of our Earth in class, they will see its manifestations on the surface of the Earth, by seeing an active explosive volcano with gas ejection, specific mineralization, and hot springs. Furthermore on the field, they will be able to do a link between the external and internal geodynamics processes usually studied separately in middle school. The poster presented will detail the first field trip in Taiwan realized in May 2013 by the LFS 4th grade students and will be made by the students going in June 2014. Thus, this activity will allow them to get a perspective of the topic that they will discover on the field trip.

  10. Volcanic activity before and after large tectonic earthquakes: Observations and statistical significance

    NASA Astrophysics Data System (ADS)

    Eggert, S.; Walter, T. R.

    2009-04-01

    The study of volcanic triggering and coupling to the tectonic surroundings has received special attention in recent years, using both direct field observations and historical descriptions of eruptions and earthquake activity. Repeated reports of volcano-earthquake interactions in, e.g., Europe and Japan, may imply that clustered occurrence is important in some regions. However, the regions likely to suffer clustered eruption-earthquake activity have not been systematically identified, and the processes responsible for the observed interaction are debated. We first review previous works about the correlation of volcanic eruptions and earthquakes, and describe selected local clustered events. Following an overview of previous statistical studies, we further elaborate the databases of correlated eruptions and earthquakes from a global perspective. Since we can confirm a relationship between volcanic eruptions and earthquakes on the global scale, we then perform a statistical study on the regional level, showing that time and distance between events follow a linear relationship. In the time before an earthquake, a period of volcanic silence often occurs, whereas in the time after, an increase in volcanic activity is evident. Our statistical tests imply that certain regions are especially predisposed to concurrent eruption-earthquake pairs, e.g., Japan, whereas such pairing is statistically less significant in other regions, such as Europe. Based on this study, we argue that individual and selected observations may bias the perceptible weight of coupling. Volcanoes located in the predisposed regions (e.g., Japan, Indonesia, Melanesia), however, indeed often have unexpectedly changed in association with either an imminent or a past earthquake.

  11. Seismicity and active tectonics at Coloumbo Reef (Aegean Sea, Greece): Monitoring an active volcano at Santorini Volcanic Center using a temporary seismic network

    NASA Astrophysics Data System (ADS)

    Dimitriadis, I.; Karagianni, E.; Panagiotopoulos, D.; Papazachos, C.; Hatzidimitriou, P.; Bohnhoff, M.; Rische, M.; Meier, T.

    2009-02-01

    The volcanic center of Santorini Island is the most active volcano of the southern Aegean volcanic arc. Α dense seismic array consisting of fourteen portable broadband seismological stations has been deployed in order to monitor and study the seismo-volcanic activity at the broader area of the Santorini volcanic center between March 2003 and September 2003. Additional recordings from a neighbouring larger scale temporary network (CYCNET) were also used for the relocation of more than 240 earthquakes recorded by both arrays. A double-difference relocation technique was used, in order to obtain optimal focal parameters for the best-constrained earthquakes. The results indicate that the seismic activity of the Santorini volcanic center is strongly associated with the tectonic regime of the broader Southern Aegean Sea area as well as with the volcanic processes. The main cluster of the epicenters is located at the Coloumbo Reef, a submarine volcano of the volcanic system of Santorini Islands. A smaller cluster of events is located near the Anydros Islet, aligned in a NE-SW direction, running almost along the main tectonic feature of the area under study, the Santorini-Amorgos Fault Zone. In contrast, the main Santorini Island caldera is characterized by the almost complete absence of seismicity. This contrast is in very good agreement with recent volcanological and marine studies, with the Coloumbo volcanic center showing an intense high-temperature hydrothermal activity, in comparison to the corresponding low-level activity of the Santorini caldera. The high-resolution hypocentral relocations present a clear view of the volcanic submarine structure at the Coloumbo Reef, showing that the main seismic activity is located within a very narrow vertical column, mainly at depths between 6 and 9 km. The focal mechanisms of the best-located events show that the cluster at the Coloumbo Reef is associated with the "Kameni-Coloumbo Fracture Zone", which corresponds to the

  12. Retrospective salt tectonics

    SciTech Connect

    Jackson, M.P.A.

    1996-12-31

    The conceptual breakthroughs in understanding salt tectonics can be recognized by reviewing the history of salt tectonics, which divides naturally into three parts: the pioneering era, the fluid era, and the brittle era. The pioneering era (1856-1933) featured the search for a general hypothesis of salt diapirism, initially dominated by bizarre, erroneous notions of igneous activity, residual islands, in situ crystallization, osmotic pressures, and expansive crystallization. Gradually data from oil exploration constrained speculation. The effects of buoyancy versus orogeny were debated, contact relations were characterized, salt glaciers were discovered, and the concepts of downbuilding and differential loading were proposed as diapiric mechanisms. The fluid era (1933-{approximately}1989) was dominated by the view that salt tectonics resulted from Rayleigh-Taylor instabilities in which a dense fluid overburden having negligible yield strength sinks into a less dense fluid salt layer, displacing it upward. Density contrasts, viscosity contrasts, and dominant wavelengths were emphasized, whereas strength and faulting of the overburden were ignored. During this era, palinspastic reconstructions were attempted; salt upwelling below thin overburdens was recognized; internal structures of mined diapirs were discovered; peripheral sinks, turtle structures, and diapir families were comprehended; flow laws for dry salt were formulated; and contractional belts on divergent margins and allochthonous salt sheets were recognized. The 1970s revealed the basic driving force of salt allochthons, intrasalt minibasins, finite strains in diapirs, the possibility of thermal convection in salt, direct measurement of salt glacial flow stimulated by rainfall, and the internal structure of convecting evaporites and salt glaciers. The 1980`s revealed salt rollers, subtle traps, flow laws for damp salt, salt canopies, and mushroom diapirs.

  13. Interactions between recent tectonic activity and the evolution of mountain relief of the Inner Cottians Alps (Western Alps): preliminary morphotectonic map.

    NASA Astrophysics Data System (ADS)

    Bacenetti, Marco; Morelli, Michele; Cadoppi, Paola; Giardino, Marco; Perotti, Luigi; Perrone, Gianluigi

    2014-05-01

    Possible interactions between recent tectonic activity and the evolution of mountain relief have been investigated at the regional (1:50,000) and local (1:5,000) scale in the Germanasca Valley (Cottian Alps, NW-Italy) through an integrated, multidisciplinary approach combining Structural analysis, Quaternary Geology, Geomorphology and Geomatics. The inner edge of the Cottians Alps and the adjacent Po Plain are among the most densely populated portions of the Piemonte Region (NW-Italy). This area corresponds to the junction between the Alpine and Apennine chains and it is affected by a diffuse low- to moderate- seismicity (Ml<5) and hypocenters at a shallow crustal level (< 20 Km). Available apatite fission track data indicate that this sector reached shallow crustal levels, where brittle deformation mechanisms prevail since Late Oligocene times. Historical earthquakes (e.g. Prarostino's earthquakes, 1808 Ml=5.5; Cumiana's earthquakes, 1980 Ml=4.8) caused both material and social damage in the area. Since faults activity is often associated with characteristic geomorphological features, linear valleys, ridgelines, slope-breaks, steep slopes of uniform aspect, regional anisotropy and tilt of terrain, have been detected in the area. Analysis of digital elevation models, by means of numerical geomorphology, provides a tool to recognize linear features and characterizing the tectonics of an area in a quantitative way. Geomorphology and morphotectonic analyses have been performed using digital orthophotos (AGEA Orthophoto 2009), aerial stereo couples and DEMs (LiDAR5x5 meters, Regione Piemonte 2009). The morphotectonic lineament analysis was conducted using TerraExplorer® Software Systems, Inc. For the field mapping activities, it was used an application called "SRG2" (Support to Geological / Geomorphological Surveys), an extension for ArcPad (ESRI mobile GIS). Into ArcPad, the SRG2 application adds a toolbar made up of several functions for a useful mapping and

  14. Stratigraphy and Stress History Recorded by a Complex Volcano-Tectonic Feature in the Nemesis Tessera Quadrangle, Venus

    NASA Technical Reports Server (NTRS)

    Doggett, T. C.; Grosfils, E. B.

    2002-01-01

    The stress history of a feature, identified as a previously uncataloged dike swarm, at 45N 191E is mapped as clockwise rotation of maximum horizontal compressive stress. It is intermediate between areas associated with compression, mantle upwelling and convection. Additional information is contained in the original extended abstract.

  15. Stratigraphy and Stress History Recorded by a Complex Volcano-Tectonic Feature in the Nemesis Tessera Quadrangle, Venus

    NASA Technical Reports Server (NTRS)

    Doggett, T. C.; Grosfils, E. B.

    2002-01-01

    The stress history of a feature, identified as a previously uncataloged dike swarm, at 45N 191E is mapped as clockwise rotation of maximum horizontal compressive stress. It is intermediate between areas associated with compression, mantle upwelling and convection. Additional information is contained in the original extended abstract.

  16. Incorporation of New and Old Tectonics Concepts Into a Modern Course in Tectonics.

    ERIC Educational Resources Information Center

    Hatcher, Robert D., Jr.

    1983-01-01

    Describes a graduate-level tectonics course which includes the historical basis for modern tectonics concepts and an in-depth review of pros/cons of plate tectonics. Tectonic features discussed include: ocean basins; volcanic arcs; continental margins; continents; orogenic belts; foreland fold and thrust belts; volcanic/plutonic belts of orogens;…

  17. Incorporation of New and Old Tectonics Concepts Into a Modern Course in Tectonics.

    ERIC Educational Resources Information Center

    Hatcher, Robert D., Jr.

    1983-01-01

    Describes a graduate-level tectonics course which includes the historical basis for modern tectonics concepts and an in-depth review of pros/cons of plate tectonics. Tectonic features discussed include: ocean basins; volcanic arcs; continental margins; continents; orogenic belts; foreland fold and thrust belts; volcanic/plutonic belts of orogens;…

  18. Architecture and evolution of an Early Permian carbonate complex on a tectonically active island in east-central California

    USGS Publications Warehouse

    Stevens, Calvin H.; Magginetti, Robert T.; Stone, Paul

    2015-01-01

    The newly named Upland Valley Limestone represents a carbonate complex that developed on and adjacent to a tectonically active island in east-central California during a brief interval of Early Permian (late Artinskian) time. This lithologically unique, relatively thin limestone unit lies within a thick sequence of predominantly siliciclastic rocks and is characterized by its high concentration of crinoidal debris, pronounced lateral changes in thickness and lithofacies, and a largely endemic fusulinid fauna. Most outcrops represent a carbonate platform and debris derived from it and shed downslope, but another group of outcrops represents one or possibly more isolated carbonate buildups that developed offshore from the platform. Tectonic activity in the area occurred before, probably during, and after deposition of this short-lived carbonate complex.

  19. Tectonic Plate Movement.

    ERIC Educational Resources Information Center

    Landalf, Helen

    1998-01-01

    Presents an activity that employs movement to enable students to understand concepts related to plate tectonics. Argues that movement brings topics to life in a concrete way and helps children retain knowledge. (DDR)

  20. Tectonic Plate Movement.

    ERIC Educational Resources Information Center

    Landalf, Helen

    1998-01-01

    Presents an activity that employs movement to enable students to understand concepts related to plate tectonics. Argues that movement brings topics to life in a concrete way and helps children retain knowledge. (DDR)

  1. Seismic hazard assessment of Syria using seismicity, DEM, slope, active tectonic and GIS

    NASA Astrophysics Data System (ADS)

    Ahmad, Raed; Adris, Ahmad; Singh, Ramesh

    2016-07-01

    In the present work, we discuss the use of an integrated remote sensing and Geographical Information System (GIS) techniques for evaluation of seismic hazard areas in Syria. The present study is the first time effort to create seismic hazard map with the help of GIS. In the proposed approach, we have used Aster satellite data, digital elevation data (30 m resolution), earthquake data, and active tectonic maps. Many important factors for evaluation of seismic hazard were identified and corresponding thematic data layers (past earthquake epicenters, active faults, digital elevation model, and slope) were generated. A numerical rating scheme has been developed for spatial data analysis using GIS to identify ranking of parameters to be included in the evaluation of seismic hazard. The resulting earthquake potential map delineates the area into different relative susceptibility classes: high, moderate, low and very low. The potential earthquake map was validated by correlating the obtained different classes with the local probability that produced using conventional analysis of observed earthquakes. Using earthquake data of Syria and the peak ground acceleration (PGA) data is introduced to the model to develop final seismic hazard map based on Gutenberg-Richter (a and b values) parameters and using the concepts of local probability and recurrence time. The application of the proposed technique in Syrian region indicates that this method provides good estimate of seismic hazard map compared to those developed from traditional techniques (Deterministic (DSHA) and probabilistic seismic hazard (PSHA). For the first time we have used numerous parameters using remote sensing and GIS in preparation of seismic hazard map which is found to be very realistic.

  2. Active faulting Vs other surface displacing complex geomorphic phenomena. Case studies from a tectonically active area, Abruzzi Region, central Apennines, Italy

    NASA Astrophysics Data System (ADS)

    Lo Sardo, Lorenzo; Gori, Stefano; Falcucci, Emanuela; Saroli, Michele; Moro, Marco; Galadini, Fabrizio; Lancia, Michele; Fubelli, Giandomenico; Pezzo, Giuseppe

    2016-04-01

    How can be univocally inferred the genesis of a linear surface scarp as the result of an active and capable fault (FAC) in tectonically active regions? Or, conversely, how it is possible to exclude that a scarp is the result of a capable fault activation? Trying to unravel this open questions, we show two ambiguous case studies about the problem of the identification of active and capable faults in a tectonically active area just based on the presence of supposed fault scarps at surface. The selected cases are located in the area comprised between the Middle Aterno Valley Fault (MAVF) and the Campo Imperatore Plain (Abruzzi Region, central Apennines), nearby the epicentral area of the April 6th, 2009 L'Aquila earthquake. In particular, the two case studies analysed are located in a region characterized by a widespread Quaternary faults and by several linear scarps: the case studies of (i) Prata D'Ansidonia area and (ii) Santo Stefano di Sessanio area. To assess the origin and the state of activity of the investigated geomorphic features, we applied a classical geological and geomorphological approach, based on the analysis of the available literature, the interpretation of the aerial photographs, field surveying and classical paleoseismological approach, the latter consisting in digging excavations across the analysed scarps. These analysis were then integrated by morphometrical analyses. As for case (i), we focused on determining the geomorphic "meaning" of linear scarps carved onto fluvial-deltaic conglomerates (dated to the Early Pleistocene; Bertini and Bosi, 1993), up to 3 meters high and up to 1,5 km long, that border a narrow, elongated and flat-bottom depressions, filled by colluvial deposits. These features groove the paleo-landsurface of Valle Daria (Bosi and Bertini, 1970), wide landsurface located between Barisciano and Prata D'Ansidonia. Entwining paleoseismological trenching with geophysical analyses (GPR, ERT and microgravimetrical prospections), it

  3. Active tectonics, paleoseismology and associated methodological challenges posed by the slow moving Alhama de Murcia fault (SE Iberia)

    NASA Astrophysics Data System (ADS)

    Ferrater, Marta; Ortuño, Maria; Masana, Eulàlia; Pallàs, Raimon; Perea, Hector; Baize, Stephane; García-Meléndez, Eduardo; Martínez-Díaz, José J.; Echeverria, Anna; Rockwell, Thomas; Sharp, Warren D.; Arrowsmith, Ramon; Medialdea, Alicia; Rhodes, Edward

    2016-04-01

    The Alhama de Murcia fault (AMF) is a 87 km-long left-lateral slow moving fault and is responsible for the 5.1 Mw 2011 Lorca earthquake. The characterization of the seismic potential of seismogenic strike-slip slow moving faults is necessary but raises huge methodological challenges, as most paleoseismological and active tectonic techniques have been designed on and for fast moving faults. The AMF is used here as a pilot study area to adapt the traditional geomorphological and trenching analyses, especially concerning the precise quantification of offset channels. We: 1) adapted methodologies to slow moving faults, 2) obtained, for the first time, the slip rate of the AMF, and 3) updated its recurrence period and maximum expected magnitude. Morphotectonic studies aim to use the measured tectonic offset of surface channels to calculate seismic parameters. However, these studies lack a standard criterion to score the analysed features. We improved this by differentiating between subjective and objective qualities, and determining up to three objective parameters (lithological changes, associated morphotectonics and shape, and three shape sub-parameters; all ranging from 0 to 1). By applying this methodology to the AMF, we identified and characterized 138 offset features that we mapped on a high-resolution (0.5 × 0.5 m pixel size) Digital Elevation Model (DEM) from a point cloud acquired in 2013 by airborne light detection and ranging (lidar). The identified offsets, together with the ongoing datings, are going to be used to calculate the lateral slip rate of the AMF. In three-dimensional trenches, we measured the offsets of a buried channel by projecting the far-field tendency of the channel onto the fault. This procedure is inspired by the widespread geomorphological procedure and aims to avoid the diffuse deformation in the fault zone associated with slow moving faults. The calculation of the 3D tendency of the channel and its projection onto the fault permitted

  4. Seismic body wave separation in volcano-tectonic activity inferred by the Convolutive Independent Component Analysis

    NASA Astrophysics Data System (ADS)

    Capuano, Paolo; De Lauro, Enza; De Martino, Salvatore; Falanga, Mariarosaria; Petrosino, Simona

    2015-04-01

    One of the main challenge in volcano-seismological literature is to locate and characterize the source of volcano/tectonic seismic activity. This passes through the identification at least of the onset of the main phases, i.e. the body waves. Many efforts have been made to solve the problem of a clear separation of P and S phases both from a theoretical point of view and developing numerical algorithms suitable for specific cases (see, e.g., Küperkoch et al., 2012). Recently, a robust automatic procedure has been implemented for extracting the prominent seismic waveforms from continuously recorded signals and thus allowing for picking the main phases. The intuitive notion of maximum non-gaussianity is achieved adopting techniques which involve higher-order statistics in frequency domain., i.e, the Convolutive Independent Component Analysis (CICA). This technique is successful in the case of the blind source separation of convolutive mixtures. In seismological framework, indeed, seismic signals are thought as the convolution of a source function with path, site and the instrument response. In addition, time-delayed versions of the same source exist, due to multipath propagation typically caused by reverberations from some obstacle. In this work, we focus on the Volcano Tectonic (VT) activity at Campi Flegrei Caldera (Italy) during the 2006 ground uplift (Ciaramella et al., 2011). The activity was characterized approximately by 300 low-magnitude VT earthquakes (Md < 2; for the definition of duration magnitude, see Petrosino et al. 2008). Most of them were concentrated in distinct seismic sequences with hypocenters mainly clustered beneath the Solfatara-Accademia area, at depths ranging between 1 and 4 km b.s.l.. The obtained results show the clear separation of P and S phases: the technique not only allows the identification of the S-P time delay giving the timing of both phases but also provides the independent waveforms of the P and S phases. This is an enormous

  5. Iapetus: Tectonic structure and geologic history

    NASA Technical Reports Server (NTRS)

    Croft, Steven K.

    1991-01-01

    Many papers have been written about the surface of Iapetus, but most of these have discussed either the nature of the strongly contrasting light and dark materials or the cratering record. Little has been said about other geologic features on Iapetus, such as tectonic structures, which would provide constraints on Iapetus' thermal history. Most references have suggested that there is no conclusive evidence for any tectonic activity, even when thermal history studies indicate that there should be. However, a new study of Iapetus' surface involving the use of stereo pairs, an extensive tectonic network has been recognized. A few new observations concerning the craters and dark material were also made. Thus the geology and geologic history of Iapetus can be more fully outlined than before. The tectonic network is shown along with prominent craters and part of the dark material in the geologic/tectonic sketch map. The topology of crater rims and scarps are quite apparent and recognizable in the different image pairs. The heights and slopes of various features given are based on comparison with the depths of craters 50 to 100 km in diameter, which are assumed to have the same depths as craters of similar diameter on Rhea and Titania.

  6. Input of UAV, DTM photo-interpretation and SAR interferometry on active tectonics applied on the Southern Coastal Range (SE Taiwan)

    NASA Astrophysics Data System (ADS)

    Deffontaines, Benoit; Chang, Kuo-Jen; Champenois, Johann; Magalhaes, Samuel; Serries, Gregory

    2016-04-01

    Taiwan is an excellent geomorphic laboratory where both extreme climatic events and high active tectonics compete. Moreover many Earth Sciences and Environmental data bases exist nowadays that help to better constrain both structural geology and active deformations. The latter unfortunately is still poorly known in the Cosatal Range of E.Taiwan in terms of geology due to access difficulties, high relief, paucity of roads, tropical vegetation and high climatic events (typhoons and heavy rainfall) and so on. Indirect methods such as photogrammetric survey using UAV's helps a lot to get high resolution topographic DEM and DTM, better than 10cm in planimetry, that helps a lot to get through careful photo-interpretation, a bird's eye view of the geology. Therefore we were able to much update the famous pre-existing geological maps (Wang and Chen, 1993). Moreover, by combining our high resolution topographic results with those of SAR interferometry (database of Champenois et al, EPSL, 2012), we were able to identify, characterise and quantify the differential active features toward the LOS of the Coastal Range (eastern Taiwan). In order to synthetise and to model the deformation of that famous place, we herein constructed more than 500 parallel projected profiles in order to locate, characterize and quantify the active tectonic features and compare them to the topography and the updated photo-interpreted geology (this work). We then were able to reconstruct the structural geometry of the Coastal Range and the Longitudinal Valley in SE Taiwan. Among our results, we reveal and prove : 1. the whole 2cm differential surrection of the Coastal Range ; 2. the differential displacement between both Central and Coastal Ranges ; 3. we explain the location of the Pinantashi river situated within the Lichi melange that correspond to the maximum surrection of the Coastal Range ; 4. we reveal the different units and their relative displacement within the Coastal Range itself ; 5. we

  7. Glacier Ice Mass Fluctuations and Fault Instability in Tectonically Active Southern Alaska

    NASA Technical Reports Server (NTRS)

    SauberRosenberg, Jeanne M.; Molnia, Bruce F.

    2003-01-01

    Across southern Alaska the northwest directed subduction of the Pacific plate is accompanied by accretion of the Yakutat terrane to continental Alaska. This has led to high tectonic strain rates and dramatic topographic relief of more than 5000 meters within 15 km of the Gulf of Alaska coast. The glaciers of this area are extensive and include large glaciers undergoing wastage (glacier retreat and thinning) and surges. The large glacier ice mass changes perturb the tectonic rate of deformation at a variety of temporal and spatial scales. We estimated surface displacements and stresses associated with ice mass fluctuations and tectonic loading by examining GPS geodetic observations and numerical model predictions. Although the glacial fluctuations perturb the tectonic stress field, especially at shallow depths, the largest contribution to ongoing crustal deformation is horizontal tectonic strain due to plate convergence. Tectonic forces are thus the primary force responsible for major earthquakes. However, for geodetic sites located < 10-20 km from major ice mass fluctuations, the changes of the solid Earth due to ice loading and unloading are an important aspect of interpreting geodetic results. The ice changes associated with Bering Glacier s most recent surge cycle are large enough to cause discernible surface displacements. Additionally, ice mass fluctuations associated with the surge cycle can modify the short-term seismicity rates in a local region. For the thrust faulting environment of the study region a large decrease in ice load may cause an increase in seismic rate in a region close to failure whereas ice loading may inhibit thrust faulting.

  8. Quaternary landscape evolution of tectonically active intermontane basins: the case of the Middle Aterno River Valley (Abruzzo, Central Italy)

    NASA Astrophysics Data System (ADS)

    Falcucci, Emanuela; Gori, Stefano; Della Seta, Marta; Fubelli, Giandomenico; Fredi, Paola

    2014-05-01

    The Middle Aterno River Valley is characterised by different Quaternary tectonic depressions localised along the present course of the Aterno River (Central Apennine) .This valley includes the L'Aquila and Paganica-Castelnuovo-San Demetrio tectonic basins, to the North, the Middle Aterno Valley and the Subequana tectonic basin, to the South. The aim of this contribution is to improve the knowledge about the Quaternary geomorphological and tectonic evolution of this portion of the Apennine chain. A synchronous lacustrine depositional phase is recognized in all these basins and attributed to the Early Pleistocene by Falcucci et al. (2012). At that time, this sector of the chain showed four distinct closed basins, hydrologically separated from each other and from the Sulmona depression. This depression, actually a tectonic basin too, was localized South of the Middle Aterno River Valley and it was drained by an endorheic hydrographic network. The formation of these basins was due to the activity of different fault systems, namely the Upper Aterno River Valley-Paganica system and San Pio delle Camere fault, to the North, and the Middle Aterno River Valley-Subequana Valley fault system to the South. These tectonic structures were responsible for the origin of local depocentres inside the depressions which hosted the lacustrine basins. Ongoing surveys in the uppermost sectors of the Middle Aterno River Valley revealed the presence of sub-horizontal erosional surfaces that are carved onto the carbonate bedrock and suspended several hundreds of metres over the present thalweg. Gently dipping slope breccias referred to the Early Pleistocene rest on these surfaces, thus suggesting the presence of an ancient low-gradient landscape adjusting to the local base level.. Subsequently, this ancient low relief landscape underwent a strong erosional phase during the Middle Pleistocene. This erosional phase is testified by the occurrence of valley entrenchment and of coeval fluvial

  9. Tectonic Geomorphology.

    ERIC Educational Resources Information Center

    Bull, William B.

    1984-01-01

    Summarizes representative quantitative tectonic-geomorphology studies made during the last century, focusing on fault-bounded mountain-front escarpments, marine terraces, and alluvial geomorphic surfaces (considering stream terraces, piedmont fault scarps, and soils chronosequences). Also suggests where tectonic-geomorphology courses may best fit…

  10. Tectonic Geomorphology.

    ERIC Educational Resources Information Center

    Bull, William B.

    1984-01-01

    Summarizes representative quantitative tectonic-geomorphology studies made during the last century, focusing on fault-bounded mountain-front escarpments, marine terraces, and alluvial geomorphic surfaces (considering stream terraces, piedmont fault scarps, and soils chronosequences). Also suggests where tectonic-geomorphology courses may best fit…

  11. Spectral damping scaling factors for shallow crustal earthquakes in active tectonic regions

    USGS Publications Warehouse

    Rezaeian, Sanaz; Bozorgnia, Yousef; Idriss, I.M.; Campbell, Kenneth; Abrahamson, Norman; Silva, Walter

    2012-01-01

    Ground motion prediction equations (GMPEs) for elastic response spectra, including the Next Generation Attenuation (NGA) models, are typically developed at a 5% viscous damping ratio. In reality, however, structural and non-structural systems can have damping ratios other than 5%, depending on various factors such as structural types, construction materials, level of ground motion excitations, among others. This report provides the findings of a comprehensive study to develop a new model for a Damping Scaling Factor (DSF) that can be used to adjust the 5% damped spectral ordinates predicted by a GMPE to spectral ordinates with damping ratios between 0.5 to 30%. Using the updated, 2011 version of the NGA database of ground motions recorded in worldwide shallow crustal earthquakes in active tectonic regions (i.e., the NGA-West2 database), dependencies of the DSF on variables including damping ratio, spectral period, moment magnitude, source-to-site distance, duration, and local site conditions are examined. The strong influence of duration is captured by inclusion of both magnitude and distance in the DSF model. Site conditions are found to have less significant influence on DSF and are not included in the model. The proposed model for DSF provides functional forms for the median value and the logarithmic standard deviation of DSF. This model is heteroscedastic, where the variance is a function of the damping ratio. Damping Scaling Factor models are developed for the “average” horizontal ground motion components, i.e., RotD50 and GMRotI50, as well as the vertical component of ground motion.

  12. 10 Ma of Igneous Activity in the Transmexican Volcanic Belt: Tectonic and Geomagnetic Implications.

    NASA Astrophysics Data System (ADS)

    Ruiz-Martinez, V. C.; Osete, M. L.; Urrutia-Fucugauchi, J.

    2007-05-01

    A total of 51 sites with geochronological control were sampled in the central and western segments of the Transmexican Volcanic Belt (TMVB). Together with other previously published 69 sites from the eastern segment, they span the spatial and temporal activity of the TMVB. Using now the same reference directions and methodologies, they are analyzed in order (i) to determine the possible occurrence and significance (spatially and temporally) of vertical axis crustal block rotations that have been reported in this region; and (ii) to study the geomagnetic Paleo Secular Variation during the last 10 Ma; to check the previously suggested existence of a "Pacific Dipole Window" extending to Mexico. Paleomagnetic results, backed by statistical tests performed according to their geographical distribution (3 structural segments) or according to their ages (Late Miocene, Pliocene or Quaternary), do not support the notion that large vertical axis block rotations (paleomagnetically detectable) occurred in this arc after Late Miocene times. They suggest that the TMVB could be considered paleomagnetically as an unique tectonic domain under a transtensional regime, where its extension component prevails over its left-lateral component. The mean paleomagnetic directions, obtained in the age ranges 10-5 Ma and 5-0 Ma, do not differ from their respective reference directions. In both datasets, VGPs have been selected using quality Fisher's precision parameters and optimum cutoff angles. This results in a circularly symmetrical data distribution with statistically indistinguishable antipodal normal and reverse polarities. VGP dispersions are consistent with those from globally distributed observations at Mexican latitudes for the Miocene and the Plio- Quaternary. An analysis of all the published paleomagnetic data from the TMVB, when combined all together and selected in the same terms, do not support neither the existence of large crustal block rotations nor the persistence of a

  13. Late Quaternary tectonic activity and paleoseismicity of the Eastern Messinia Fault Zone, SW Peloponessus (Messinia, Greece).

    NASA Astrophysics Data System (ADS)

    Valkaniotis, Sotirios; Betzelou, Konstantina; Zygouri, Vassiliki; Koukouvelas, Ioannis; Ganas, Athanassios

    2015-04-01

    The southwestern part of Peloponnesus, Messinia and Laconia, is an area of significant tectonic activity situated near the Hellenic trench. Most of the deformation in this area is accommodated by the Eastern Messinia Fault Zone, bordering the western part of Taygetos Mt range and the west coast of Mani peninsula. The Eastern Messinia Fault Zone (EMFZ) is a complex system of primarily normal faults dipping westwards with a strike of NNW-SSE to N-S direction attaining a total length of more than 100 km from the northern Messinia plain in the north to the southern part of Mani peninsula in the south. The continuity of the EMFZ is disrupted by overlapping faults and relay ramp structures. The central part of the EMFZ, from the town of Oichalia to the city of Kalamata, was investigated by detailed field mapping of fault structures and post-alpine sediment formations together with re-evaluation of historical and modern seismicity. Several fault segments with lengths of 6 to 10 km were mapped, defined and evaluated according to their state of activity and age. Analysis of fault striation measurements along fault planes of the fault zone shows a present regime of WSW-ENE extension, in accordance with focal mechanisms from modern seismicity. Known faults like the Katsareika and Verga faults near the city of Kalamata are interpreted as older-generation faults that are re-activated (e.g. the 1986 Ms 6.0 Kalamata earthquake on Verga Fault) as part of a system of distributed deformation. New fault segments, some of them previously unmapped like the Asprohoma fault to the west of Kalamata, and offshore faults like Kitries and Kourtissa, are being assigned to the EMFZ. Moreover, a paleoseismological trench was excavated in the northern part of Pidima fault segment, one of the most prominent active segments of the central part of the EMFZ, in order to examine the paleoearthquake record of the fault system. A significant number of historical and instrumental earthquakes in the area

  14. Improved Discrimination of Volcanic Complexes, Tectonic Features, and Regolith Properties in Mare Serenitatis from Earth-Based Radar Mapping

    NASA Technical Reports Server (NTRS)

    Campbell, Bruce A.; Hawke, B. Ray; Morgan, Gareth A.; Carter, Lynn M.; Campbell, Donald B.; Nolan, Michael

    2014-01-01

    Radar images at 70 cm wavelength show 4-5 dB variations in backscatter strength within regions of relatively uniform spectral reflectance properties in central and northern Mare Serenitatis, delineating features suggesting lava flow margins, channels, and superposition relationships. These backscatter differences are much less pronounced at 12.6 cm wavelength, consistent with a large component of the 70 cm echo arising from the rough or blocky transition zone between the mare regolith and the intact bedrock. Such deep probing is possible because the ilmenite content, which modulates microwave losses, of central Mare Serenitatis is generally low (2-3% by weight). Modeling of the radar returns from a buried interface shows that an average regolith thickness of 10m could lead to the observed shifts in 70 cm echo power with a change in TiO2 content from 2% to 3%. This thickness is consistent with estimates of regolith depth (10-15m) based on the smallest diameter for which fresh craters have obvious blocky ejecta. The 70 cm backscatter differences provide a view of mare flow-unit boundaries, channels, and lobes unseen by other remote sensing methods. A localized pyroclastic deposit associated with Rima Calippus is identified based on its low radar echo strength. Radar mapping also improves delineation of units for crater age dating and highlights a 250 km long, east-west trending feature in northern Mare Serenitatis that we suggest is a large graben flooded by late-stage mare flows.

  15. Improved Discrimination of Volcanic Complexes, Tectonic Features, and Regolith Properties in Mare Serenitatis from Earth-Based Radar Mapping

    NASA Technical Reports Server (NTRS)

    Campbell, Bruce A.; Hawke, B. Ray; Morgan, Gareth A.; Carter, Lynn M.; Campbell, Donald B.; Nolan, Michael

    2014-01-01

    Radar images at 70 cm wavelength show 4-5 dB variations in backscatter strength within regions of relatively uniform spectral reflectance properties in central and northern Mare Serenitatis, delineating features suggesting lava flow margins, channels, and superposition relationships. These backscatter differences are much less pronounced at 12.6 cm wavelength, consistent with a large component of the 70 cm echo arising from the rough or blocky transition zone between the mare regolith and the intact bedrock. Such deep probing is possible because the ilmenite content, which modulates microwave losses, of central Mare Serenitatis is generally low (2-3% by weight). Modeling of the radar returns from a buried interface shows that an average regolith thickness of 10m could lead to the observed shifts in 70 cm echo power with a change in TiO2 content from 2% to 3%. This thickness is consistent with estimates of regolith depth (10-15m) based on the smallest diameter for which fresh craters have obvious blocky ejecta. The 70 cm backscatter differences provide a view of mare flow-unit boundaries, channels, and lobes unseen by other remote sensing methods. A localized pyroclastic deposit associated with Rima Calippus is identified based on its low radar echo strength. Radar mapping also improves delineation of units for crater age dating and highlights a 250 km long, east-west trending feature in northern Mare Serenitatis that we suggest is a large graben flooded by late-stage mare flows.

  16. A detection method of subrecent to recent tectonic activity in the anticlinal system of the northern Negev, Israel

    SciTech Connect

    Zilberman, E.; Wachs, D. )

    1988-02-01

    Geomorphological and geophysical methods combined with borehole information were employed to search for possible subrecent small-scale vertical movement along the anticlinal fold belt of the central Negev, Israel. Such tectonic deformation might indicate displacement on the buried reverse faults underneath the anticlines. Variations in the thickness of the alluvial fill in the study area, which are in accordance with the fold structures, could be an indication of recent folding activity along the anticlinal system. In order to detect these thickness variations in the alluvial fill, seismic refraction and electrical resistivity measurements were carries out along the valley of Nahal Besor, which crosses the anticlinal belt. The thickness variations of the alluvial fill along the valley were not found to indicate any significant tectonic movement along the anticlines during the Pleistocene. The thickest alluvium was found overlying a karst bedrock, hence karst relief is suggested to be responsible for these variations.

  17. Volcanic and Tectonic Setting of Hydrothermal Activity on the Southern Mid-Atlantic Ridge, 4° - 11°S

    NASA Astrophysics Data System (ADS)

    Melchert, B.; Devey, C. W.; German, C. R.; Haase, K. M.; Koschinsky, A.; Lackschewitz, K.; Yoerger, D. R.

    2006-12-01

    The recurrence rate of volcanism at mid-ocean ridges should drop with spreading rate. Although the southern Mid-Atlantic Ridge, with a spreading full rate of ~3.6 cm/yr, might therefore be expected to show only sporadic magmatic activity, we present information on recently-discovered volcanically, tectonically and hydrothermally active areas south of the equator (at 4°48'S and 9°33'S, see also German et al. 2005; Haase et al. 2005 EOS Trans. AGU 86 (52) Fall Meet. Suppl. Abstr. OS21C-04 & -05). Around the 4°48'S area the median valley floor forms a ~10 km wide, hour-glass shaped, plateau with water depths of around 3000 m. Four closely-spaced vent fields (the high-temperature sites Turtle Pits, Red Lion and Comfortless Cove and the diffuse low-temperature Wideawake site) occur along a flat (total relief 50 m), volcanically and tectonically active 2 km section of this plateau (see German et al. 2005, Haase et al. 2005 op. cit. also Koschinsky et al. this meeting). The Turtle Pits site lies within a small depression associated with a fracture marked by aligned collapse pits. This central depression is surrounded by laminated sheet flows to the north and northwest, whereas jumbled flows are more prevalent to the east. Comfortless Cove is also associated with young volcanics and shows strong tectonic influence on vent location. Red Lion in contrast shows no clear tectonic control - it is characterised by four active chimneys which sit directly on a pillow lava floor. The 9°33'S area is situated on 11 km-thick crust (Bruguier et al. 2003 JGR 108 2093) at 1490 m water depth and is marked by fresh pillow lavas, sheet flows, lava lakes and collapse structures. Low- temperature, diffuse hydrothermal activity is abundant in the area (Haase et al. 2005; Koschinsky et al. 2006 op. cit.) as are larger extinct hydrothermal mounds suggesting more vigourous hydrothermalism in the past. All sites are located east of a large NNW trending escarpment flanking horst and graben

  18. Some aspects of active tectonism in Alaska as seen on ERTS-1

    NASA Technical Reports Server (NTRS)

    Gedney, L. D.; Vanwormer, J. D.

    1973-01-01

    ERTS-1 imagery is proving to be exceptionally useful in delineating structural features in Alaska which have never been recognized on the ground. Previously unmapped features such as seismically active faults and major structural lineaments are especially evident. Among the more significant results of this investigation is the discovery of an active strand of the Denali fault. The new fault has a history of scattered seismicity and was the scene of a magnitude 4.8 earthquake on October 1, 1972. Perhaps of greater significance is the disclosure of a large scale conjugate fracture system north of the Alaska Range. This fracture system appears to result from compressive stress radiating outward from around the outside of the great bend of the Alaska Range at Mt. McKinley.

  19. Plate tectonics conserves angular momentum

    NASA Astrophysics Data System (ADS)

    Bowin, C.

    2009-03-01

    A new combined understanding of plate tectonics, Earth internal structure, and the role of impulse in deformation of the Earth's crust is presented. Plate accelerations and decelerations have been revealed by iterative filtering of the quaternion history for the Euler poles that define absolute plate motion history for the past 68 million years, and provide an unprecedented precision for plate angular rotation variations with time at 2-million year intervals. Stage poles represent the angular rotation of a plate's motion between adjacent Euler poles, and from which the maximum velocity vector for a plate can be determined. The consistent maximum velocity variations, in turn, yield consistent estimates of plate accelerations and decelerations. The fact that the Pacific plate was shown to accelerate and decelerate, implied that conservation of plate tectonic angular momentum must be globally conserved, and that is confirmed by the results shown here (total angular momentum ~1.4 E+27 kgm2s-1). Accordingly, if a plate decelerates, other plates must increase their angular momentums to compensate. In addition, the azimuth of the maximum velocity vectors yields clues as to why the "bend" in the Emperor-Hawaiian seamount trend occurred near 46 Myr. This report summarizes processing results for 12 of the 14 major tectonic plates of the Earth (except for the Juan de Fuca and Philippine plates). Plate accelerations support the contention that plate tectonics is a product of torques that most likely are sustained by the sinking of positive density anomalies due to phase changes in subducted gabbroic lithosphere at depth in the upper lower mantle (above 1200 km depth). The tectonic plates are pulled along by the sinking of these positive mass anomalies, rather than moving at near constant velocity on the crests of convection cells driven by rising heat. These results imply that spreading centers are primarily passive reactive features, and fracture zones (and wedge-shaped sites

  20. Synergy of tectonic geomorphology, applied geophysics and remote sensing techniques reveals new data for active extensional tectonism in NW Peloponnese (Greece)

    NASA Astrophysics Data System (ADS)

    Fountoulis, Ioannis; Vassilakis, Emmanuel; Mavroulis, Spyridon; Alexopoulos, John; Dilalos, Spyridon; Erkeki, Athanasia

    2015-05-01

    In tectonically active areas, such as in the northwest Peloponnese of western Greece, geomorphic processes are strongly influenced by active faulting; in many cases such faults cannot be easily identified. In this paper we apply multidisciplinary analysis (morphotectonic indices, neotectonic mapping, geophysical surveys and remote sensing techniques) to map the recently-recognized east-west trending Pineios River normal fault zone with a high degree of accuracy, and to better understand its contribution to the evolution of the ancient region of Elis during Holocene time. Fault activity seems to be related to frequent changes in river flow patterns and to displacements of the nearby shoreline. We argue that fault activity is the main reason for migration of Pineios river mouth as documented for several time periods during historical time. Quantitative constraints on deformation caused by the faulting were applied through the application of the morphotectonic indices proposed in this paper, including drainage network asymmetry and sinuosity, and mountain front sinuosity, all of which indicate that this is a highly active structure. Slip rates calculated to be as high as 0.48 mm/yr for the last 209 ka (based on previously published dating) were verified by applied geophysical methods. The fault surface discontinuity was identified at depth using vertical electrical resistivity measurements and depositional layers of different resistivity were found to be clearly offset. Displacement increases toward the west, reaching an observed maximum of 110 m. The most spectacular landform alteration due to surface deformation is the north-south migration of the river estuary into completely different open sea areas during the late Quaternary, mainly during the Holocene. The sediment transport path has been altered several times due to these changes in river geometry with and the most recent seeming to have occurred almost 2000 years ago. The river estuary migrated to its

  1. Soils and geomorphic evolution of bedrock facets on a tectonically active mountain front, western Sangre de Cristo Mountains, New Mexico

    NASA Astrophysics Data System (ADS)

    Menges, Christopher M.

    1990-09-01

    Soil profiles, colluvial stratigraphy, and detailed hillslope morphology are key elements used for geomorphic interpretations of the form and long-term evolution of triangular facets on a 1200 m high, tectonically active mountain front. The facets are developed on Precambrian gneisses and Tertiary volcanic and plutonic rocks along a complexly segmented, active normal-fault zone in the Rio Grande rift of northern New Mexico. The detailed morphologies of 20- to 350 m high facets are defined by statistical and time-series analyses of 40 field transects that were keyed to observations of colluvium, bedrock, microtopography, and vegetation. The undissected parts of most facets are transport-limited hillslopes mantled with varying thicknesses (0.1 to > 1 m thick) of sand and gravel colluvium between generally sparse (≤10-30%) bedrock outcrops. Facet soils range from (a) thin (≤ 0.2 m) weakly developed soils with cumulic silty A or transitional A/B epipedons above Cox horizons in bedrock or colluvium, to (b) deep (≥0.5-1 m) moderately to strongly developed profiles containing thick cambic (Bw) and/or argillic (Bt) horizons that commonly extend into highly weathered saprolitic bedrock. The presence of strongly weathered profiles and thick colluvium suggests that rates of colluvial transport and hillslope erosion are less than or equal to rates of soil development over at least a large part of the Holocene. The catenary variation of soils and colluvium on selected facet transects indicate that the degree of soil development generally increases and the thickness of colluvium decreases upslope on most facets. This overall pattern is commonly disrupted on large facet hillslopes by irregular secondary soil variations linked to intermediate-scale (20-60 + m long) concave slope elements. These features are interpreted to reflect discontinuous transport and erosion of colluvium down-slope below bedrock outcrops. The degree of weathering in subsurface bedrock commonly

  2. Importance of active tectonics during karst formation. A Middle Eocene to Pleistocene example of the Lina Moutains (Irian Jaya, Indonesia)

    NASA Astrophysics Data System (ADS)

    Thery, J.-M.; Pubellier, M.; Thery, B.; Butterlin, J.; Blondeau, A.; Adams, C. G.

    1999-05-01

    The Lina Moutains show a typical example of karst formation associated to recent and active tectonics. The limestone samples were collected from giant potholes present beneath the heavy rainforest, during speleological expeditions to the Bird's Head of Irian-Jaya. Micropalaeontological data allow us to give a Middle Pleistocene age for the most recent karst formation. A detailed stratigraphy between the Upper Lutetian and the Middle Pleistocene was recorded, with tectonic events during the Oligocene and Pleistocene. The edge of the resurgence layer was also dated. We also conclude the probable existence of a subterraneous network downhill of the karst within the most recent levels of the Kais Limestone formation. We replace this formation within the tectonic evolution of this area between the Eocene and the Middle Pleistocene, in conjunction with the oblique convergence of the Pacific plate carrying volcanic arc fragments and the Australian margin, which resulted in folding, normal faulting associated with local extension, and wrench motion, which are settings capable of creating uplift of the carbonated platform.

  3. The Foreign Language Feature Film and Language Teaching Activities.

    ERIC Educational Resources Information Center

    Chappell, Martin

    1986-01-01

    Analysis of foreign language films, featuring consideration of film sequence, image and film analysis, and literary adaptation, is an effective teaching activity with foreign language students. An example illustrates film analysis activities in a first-year French class. (CB)

  4. The Foreign Language Feature Film and Language Teaching Activities.

    ERIC Educational Resources Information Center

    Chappell, Martin

    1986-01-01

    Analysis of foreign language films, featuring consideration of film sequence, image and film analysis, and literary adaptation, is an effective teaching activity with foreign language students. An example illustrates film analysis activities in a first-year French class. (CB)

  5. Basement Gravity Feature in East-central Nevada and West-central Utah and its Tectonic Implications

    NASA Astrophysics Data System (ADS)

    Ponce, D. A.; Tilden, J. E.

    2006-12-01

    A basement gravity map of east-central Nevada and west-central Utah, derived by removing the effects of Cenozoic deposits, reveals prominent gravity anomalies that reflect lateral density variations in pre-Cenozoic rocks throughout the region. Although some remanent artifacts may be present in the basement gravity map, in general, basement gravity features transcend Basin and Range structures, suggesting that the effects of the Cenozoic deposits were removed reasonably well. In a statewide analysis of basement gravity anomalies in Nevada, Blakely and Jachens (1991) suggest that a basement gravity low that extends across the central part of the state may reflect concealed silicic intrusions within the mid to lower crust. Within east-central Nevada and west-central Utah, this prominent NW-trending basement gravity low transects the region, and poorly correlates to exposed pre-Cenozoic rocks (Stewart and Carlson, 1978; Hintze, 1980). The western margin of the basement gravity low is surprisingly linear and trends about N30°W, a direction similar to that of the northern Nevada rift (e.g., Zoback et al., 1994), a mid- Miocene feature just to the west that may have preferentially followed a pre-existing basement structure (e.g., Ponce and Glen, 2003; 2005). Much of this basement gravity low occurs in a highly extended terrane between two structural troughs - the Butte and the Confusion synclinoriums (e.g., Hose, 1977; Gans and Miller, 1983), composed of downfolded Triassic to Permian rocks. The Butte synclinorium correlates to the western margin of the basement gravity low, whereas, the Confusion synclinorium is just east of the basement gravity low and directly correlates to a basement gravity high over the Confusion Range, Burbank Hills, and Mountain Home Range in west-central Utah (Hintze, 1980). This disconnect between the gravity anomaly polarity of the two synclinoriums may be related to underlying lithologic differences between the two areas such as the presence

  6. GeoBioScience: Red Wood Ants as Bioindicators for Active Tectonic Fault Systems in the West Eifel (Germany)

    PubMed Central

    Berberich, Gabriele; Schreiber, Ulrich

    2013-01-01

    Simple Summary In a 1.140 km² study area of the volcanic West Eifel, approx. 3,000 Red Wood Ant (RWA; Formica rufa-group) mounds had been identified and correlated with tectonically active gas-permeable faults, mostly strike-slip faults. Linear alignment of RWA mounds and soil gas anomalies distinctly indicate the course of these faults, while clusters of mounds indicate crosscut zones of fault systems, which can be correlated with voids caused by crustal block rotation. This demonstrates that RWA are bioindicators for identifying active fault systems and useful where information on the active regime is incomplete or the resolution by technical means is insufficient. Abstract In a 1.140 km² study area of the volcanic West Eifel, a comprehensive investigation established the correlation between red wood ant mound (RWA; Formica rufa-group) sites and active tectonic faults. The current stress field with a NW-SE-trending main stress direction opens pathways for geogenic gases and potential magmas following the same orientation. At the same time, Variscan and Mesozoic fault zones are reactivated. The results showed linear alignments and clusters of approx. 3,000 RWA mounds. While linear mound distribution correlate with strike-slip fault systems documented by quartz and ore veins and fault planes with slickensides, the clusters represent crosscut zones of dominant fault systems. Latter can be correlated with voids caused by crustal block rotation. Gas analyses from soil air, mineral springs and mofettes (CO2, Helium, Radon and H2S) reveal limiting concentrations for the spatial distribution of mounds and colonization. Striking is further the almost complete absence of RWA mounds in the core area of the Quaternary volcanic field. A possible cause can be found in occasionally occurring H2S in the fault systems, which is toxic at miniscule concentrations to the ants. Viewed overall, there is a strong relationship between RWA mounds and active tectonics in the West Eifel

  7. Volcanism & Tectonism

    NASA Image and Video Library

    2011-07-19

    Just as on Earth, volcanism and tectonism are found together on Mars. In this image from NASA 2001 Mars Odyssey spacecraft the ridges and fractures of Claritas Fossae are affecting or perhaps hosting the volcanic flows of Solis Planum.

  8. Tectonic Collapse

    NASA Image and Video Library

    2011-03-16

    The collapse valleys in this portion of the floor of Bernard Crater were likely caused by the formation of Memnonia Fossae, a system of tectonic graben, that passes through the region. This image was captured by NASA Mars Odyssey.

  9. Enceladan Tectonics

    NASA Image and Video Library

    2010-02-23

    This mosaic shows extraordinary details of tectonic deformation in the fractured south polar region of Saturn moon Enceladus, where jets of water ice spray outward to form Saturn E ring. The images were captured by NASA Cassini spacecraft.

  10. Featured Image: Active Cryovolcanism on Europa?

    NASA Astrophysics Data System (ADS)

    Kohler, Susanna

    2017-05-01

    Nighttime thermal image from the Galileo Photopolarimeter-Radiometer, revealing a thermal anomaly around the region where the plumes were observed. [Sparks et al. 2017]This image shows a 1320 900 km, high-resolution Galileo/Voyager USGS map of the surface of Europa, one of Jupiters moons. In March 2014, observations of Europa revealed a plume on its icy surface coming from somewhere within the green ellipse. In February 2016, another plume was observed, this time originating from somewhere within the cyan ellipse. In addition, a nighttime thermal image from the Galileo Photopolarimeter-Radiometer has revealed a thermal anomaly a region of unusually high temperature near the same location. In a recent study led by William Sparks (Space Telescope Science Institute), a team of scientists presents these observations and argues that they provide mounting evidence of active water-vapor venting from ongoing cryovolcanism beneath Europas icy surface. If this is true, then Europas surface is active and provides access to the liquid water at depth boosting the case for Europas potential habitability and certainly making for an interesting target point for future spacecraft exploration of this moon. For more information, check out the paper below!CitationW. B. Sparks et al 2017 ApJL 839 L18. doi:10.3847/2041-8213/aa67f8

  11. The Physics of a Volcanic System: What is the Actual Role Played by Tectonic Setting in Controlling Volcanic Activity?

    NASA Astrophysics Data System (ADS)

    Canon-Tapia, E.

    2005-12-01

    Modern text-books commonly explain volcanic activity as a direct consequence of plate tectonics, overlooking the different scales characteristic of both types of processes. By acknowledging such differences, however, it is possible to envisage a model of a volcanic system that is based in the same principles of hydrostatics established by Blaise Pascal over 300 yrs ago. Such principles allow us to estimate the local conditions required for the occurrence of volcanism at a given location highlighting the importance of the rock strength and the density difference between melt and its surroundings. This model shows that the minimum thickness of the zone of partial melting in the mantle (or seismically defined Low Velocity Zone) that is required to feed volcanic activity might range from 5 to over 100 km, but also that under certain circumstances a rock strength < 200 MPa may suffice to keep magma trapped at depth whereas in other cases a strength > 600 MPa will not suffice to stop magma ascent resulting in volcanic activity at the surface. Consequently, the model of volcanism developed here explains why is that a given LVZ may lead to volcanic activity in some places whereas a completely identical LVZ may not result in volcanic activity in a different location. Consequently, this model provides a general framework that allows us to better understand the actual role played by tectonic setting in controlling volcanism at a planetary scale.

  12. A comprehensive view of Late Quaternary fluvial sediments and stratal architecture in a tectonically active basin: Influence of eustasy, climate, and tectonics on the Bengal Basin and Brahmaputra River system

    NASA Astrophysics Data System (ADS)

    Sincavage, R.; Goodbred, S. L.; Williams, L. A.; Pickering, J.; Wilson, C.; Steckler, M. S.; Seeber, L.; Reitz, M. D.; Hossain, S.; Akhter, S. H.; Mondal, D. R.; Paola, C.

    2013-12-01

    More than 130 closely-spaced (~3-5 km) boreholes have been drilled along five transects in the upper Bengal Basin, providing the first detailed record of the stratigraphic architecture and provenance of the entire Late Quaternary fluviodeltaic sedimentary succession of the Ganges-Brahmaputra-Meghna Delta (GBMD). This effort is part of BanglaPIRE, an interdisciplinary, multi-institutional research effort aimed at unraveling the history and mechanisms of river-tectonic-basin interactions in the GBMD and Bengal basin, around which three tectonic plates converge. Following the Younger-Dryas, the onset of a strong summer monsoon coincident with continued eustatic sea-level rise initiated construction of the modern delta and rapid development of a thick (up to 80 m) succession of fluvial and deltaic sediments. These deposits illustrate several (3-4) avulsions and asymmetric occupations of the Brahmaputra River in the tectonically active Sylhet Basin. We hypothesize that the longer occupation periods (10 3 years) may be classified as major river avulsions driven by autogenic fluvial processes, whereas shorter occupation periods (10 2 years) reflect minor distributive events that may have been initiated by allogenic forcing via floods or earthquakes. Subsidence rates in Sylhet Basin, driven by an active foredeep, are relatively high (~5 mm/yr); however, the Brahmaputra River does not regularly migrate towards this side of the delta. Annual widespread flooding of Sylhet Basin may negate the potential topographic attraction for the system to be steered in this direction. Furthermore, a gentle westward topographic tilt of the active thrust front of the Tripura fold belt appears to have forced lateral steering of the Brahmaputra River and initiated erosion of a bench-cut terrace into an adjacent Pleistocene landform. Tectonic effects over longer timescales (10 3 years) are revealed by the presence of sediment with a unique provenance at the core of regional anticlines, which

  13. Late Pleistocene to Historical Activity of the Hovd Fault (Mongolian Altay) from Tectonic Geomorphology and Paleoseismology

    NASA Astrophysics Data System (ADS)

    Ferry, M. A.; Battogtokh, D.; Ritz, J. F.; Kurtz, R.; Braucher, R.; Klinger, Y.; Ulzibat, M.; Chimed, O.; Demberel, S.

    2015-12-01

    Active tectonics of western Mongolia is dominated by large strike-slip fault systems that produced great historical earthquakes: the Bulnay fault (Mw 8.1 and 8.4 in 1905), the Fu-Yun fault (Mw 8.0 in 1931) and the Bogd fault (Mw 8.1 in 1957). Central to these faults is the Altay Range that accommodates ~4 mm/yr of right-lateral motion. An earthquake of similar magnitude occurred in 1761 and has been attributed to the Hovd fault were seemingly fresh surface rupture was reported in 1985. Here, we study the Ar-Hötöl section of the Hovd fault where surface rupture was described over a length of ~200 km. Detailed mapping of stream gullies from high-resolution Pleiades satellite images show a consistent pattern of right-lateral offsets from a few meters to ~500 m. At Climbing Rock, we surveyed a gully offset by 75 ± 5 m. The associated surface was sampled for 10Be profile which yields an exposure age of 154 ± 20 ka. The resulting minimal right-lateral slip rate ranges 0.4-0.6 mm/yr. However, drainage reconstruction suggests this surface may have recorded as much as 400 ± 20 m of cumulative offset. This implies the Hovd fault may accommodate as much as 2.6 ± 0.4 mm/yr, which would make it the main active fault of the Altay. At a smaller scale, TLS topography documents offsets in the order of 2.5-5 m that likely correspond to the most recent surface-rupturing event with Mw ~8. A value of 2.8-3.0 m is reconstructed from a Uiger grave dated AD 750-840. At Marmot Creek and Small Creek, short drainages flow across the fault and form ponds against the main scarp. Two paleoseimic trenches reveal similar stratigraphy with numerous peat layers that developed over alluvial sands. The fault exhibits near vertical strands affecting pre-ponding units as well as a well-developed peat unit radiocarbon-dated AD 1465-1635. This unit likely corresponds to the ground surface at the time of the last rupture. It is overlain with a sandy pond unit on top of which a second continuous peat

  14. Glaciation in a tectonically active environment: Preliminary observations from the Inylchek and Sary-Dzaz Valleys, Kyrgyz Tian Shan

    NASA Astrophysics Data System (ADS)

    Lifton, N. A.; Beel, C.; Blomdin, R.; Caffee, M. W.; Chen, Y.; Codilean, A.; Goehring, B. M.; Gribenski, N.; Harbor, J.; Hattestrand, C.; Heyman, J.; Ivanov, M.; Kassab, C.; Li, Y.; Petrakov, D.; Rogozhina, I.; Stroeven, A. P.; Usubaliev, R.; Wetzel, H.

    2012-12-01

    the slope. In contrast, the northern slope of this range, draining to the Sary-Dzaz Valley, is characterized by less pronounced relief, yet it exhibits significantly more abundant and pronounced glacial features. Another major left-oblique-slip fault zone, the Nikolaev Line, is thought to intersect the Atbashi-Inylchek fault in the eastern sector of this valley. We are investigating the nature of the asymmetric glacial record on both the north and south faces of this range, with particular interest in the interactions of glaciation and tectonics in the area, and will present preliminary results of our 2012 field investigations.

  15. Active tectonics and drainage evolution in the Tunisian Atlas driven by interaction between crustal shortening and slab pull

    NASA Astrophysics Data System (ADS)

    Camafort, Miquel; Booth-Rea, Guillermo; Pérez-Peña, Jose Vicente; Melki, Fetheddine; Gracia, Eulalia; Azañón, Jose Miguel; Ranero, César R.

    2017-04-01

    Active tectonics in North Africa is fundamentally driven by NW-SE directed slow convergence between the Nubia and Eurasia plates, leading to a region of thrust and strike-slip faulting. In this paper we analyze the morphometric characteristics of the little-studied northern Tunisia sector. The study aimed at identifying previously unknown active tectonic structures, and to further understand the mechanisms that drive the drainage evolution in this region of slow convergence. The interpretation of morphometric data was supported with a field campaign of a selection of structures. The analysis indicates that recent fluvial captures have been the main factor rejuvenating drainage catchments. The Medjerda River, which is the main catchment in northern Tunisia, has increased its drainage area during the Quaternary by capturing adjacent axial valleys to the north and south of its drainage divide. These captures are probably driven by gradual uplift of adjacent axial valleys by reverse/oblique faults or associated folds like El Alia-Teboursouk and Dkhila faults. Our fieldwork found that these faults cut Holocene colluvial fans containing seismites like clastic dikes and sand volcanoes, indicating recent seismogenic faulting. The growth and stabilization of the axial Medjerda River against the natural tendency of transverse drainages might be caused by a combination of dynamic topography and transpressive tectonics. The orientation of the large axial Medjerda drainage that runs from eastern Algeria towards northeastern Tunisia into the Gulf of Tunis, might be the associated to negative buoyancy caused by the underlying Nubia slab at its mouth, together with uplift of the Medjerda headwaters along the South Atlassic dextral transfer zone.

  16. Chemical and Physical Weathering in a Hot-arid, Tectonically Active Alluvial System (Anza-Borrego Desert, CA)

    NASA Astrophysics Data System (ADS)

    Joo, Y. J.; Elwood Madden, M.; Soreghan, G. S.

    2014-12-01

    Climate and tectonics are primary controls on bedrock erosion, and sediment production, transport, and deposition. Additionally, silicate weathering in tectonically active regions is known to play a significant role in global climate owing to the high rates of physical erosion and exposure of unweathered bedrock to chemical weathering, which removes CO2 from the atmosphere. Therefore, the feedback between weathering and climate is key to understanding climate change through Earth history. This study investigates chemical and physical weathering of alluvial sediments in the Anza-Borrego Desert, California, located in the southern part of the San Andreas Fault System. This setting provides an ideal opportunity to study weathering in a hot and arid climate with mean annual temperatures of ~23 °C and mean annual precipitation of ~160 mm in the basin. Samples were collected along a proximal-to-distal transect of an alluvial-fan system sourced exclusively from Cretaceous tonalite of the Peninsular Range. The single bedrock lithology enables exploration of the effects of other variables — climate, transport distance, drainage area, and tectonics— on the physical and chemical properties of the sediments. Although minimal overall (CIA = 56-61), the degree of chemical weathering increases down transect, dominated by plagioclase dissolution. BET surface area of the mud (<63µm) fraction decreases distally, which is consistent with coarsening grain-size. Chemical alteration and BET surface area both increase in a distal region, within the active Elsinore Fault zone. Extensive fracturing here, together with a more-humid Pleistocene climate likely facilitated in-situ bedrock weathering; specifically, dissolution of primary minerals (e.g. plagioclase), preceding the arid alluvial erosion, transport, and deposition in the Holocene. This study further seeks to disentangle the complex record of the climate and tectonic signals imprinted in these sediments.

  17. Glacier ice mass fluctuations and fault instability in tectonically active Southern Alaska

    USGS Publications Warehouse

    Sauber, J.M.; Molnia, B.F.

    2004-01-01

    Across the plate boundary zone in south central Alaska, tectonic strain rates are high in a region that includes large glaciers undergoing wastage (glacier retreat and thinning) and surges. For the coastal region between the Bering and Malaspina Glaciers, the average ice mass thickness changes between 1995 and 2000 range from 1 to 5 m/year. These ice changes caused solid Earth displacements in our study region with predicted values of -10 to 50 mm in the vertical and predicted horizontal displacements of 0-10 mm at variable orientations. Relative to stable North America, observed horizontal rates of tectonic deformation range from 10 to 40 mm/year to the north-northwest and the predicted tectonic uplift rates range from approximately 0 mm/year near the Gulf of Alaska coast to 12 mm/year further inland. The ice mass changes between 1995 and 2000 resulted in discernible changes in the Global Positioning System (GPS) measured station positions of one site (ISLE) located adjacent to the Bagley Ice Valley and at one site, DON, located south of the Bering Glacier terminus. In addition to modifying the surface displacements rates, we evaluated the influence ice changes during the Bering glacier surge cycle had on the background seismic rate. We found an increase in the number of earthquakes (ML???2.5) and seismic rate associated with ice thinning and a decrease in the number of earthquakes and seismic rate associated with ice thickening. These results support the hypothesis that ice mass changes can modulate the background seismic rate. During the last century, wastage of the coastal glaciers in the Icy Bay and Malaspina region indicates thinning of hundreds of meters and in areas of major retreat, maximum losses of ice thickness approaching 1 km. Between the 1899 Yakataga and Yakutat earthquakes (Mw=8.1, 8.1) and prior to the 1979 St. Elias earthquake (M s=7.2), the plate interface below Icy Bay was locked and tectonic strain accumulated. We used estimated ice mass

  18. Seismicity and active tectonics in the Alboran Sea, Western Mediterranean: Constraints from an offshore-onshore seismological network and swath bathymetry data

    NASA Astrophysics Data System (ADS)

    Grevemeyer, Ingo; Gràcia, Eulàlia; Villaseñor, Antonio; Leuchters, Wiebke; Watts, Anthony B.

    2015-12-01

    Seismicity and tectonic structure of the Alboran Sea were derived from a large amphibious seismological network deployed in the offshore basins and onshore in Spain and Morocco, an area where the convergence between the African and Eurasian plates causes distributed deformation. Crustal structure derived from local earthquake data suggests that the Alboran Sea is underlain by thinned continental crust with a mean thickness of about 20 km. During the 5 months of offshore network operation, a total of 229 local earthquakes were located within the Alboran Sea and neighboring areas. Earthquakes were generally crustal events, and in the offshore domain, most of them occurred at crustal levels of 2 to 15 km depth. Earthquakes in the Alboran Sea are poorly related to large-scale tectonic features and form a 20 to 40 km wide NNE-SSW trending belt of seismicity between Adra (Spain) and Al Hoceima (Morocco), supporting the case for a major left-lateral shear zone across the Alboran Sea. Such a shear zone is in accord with high-resolution bathymetric data and seismic reflection imaging, indicating a number of small active fault zones, some of which offset the seafloor, rather than supporting a well-defined discrete plate boundary fault. Moreover, a number of large faults known to be active as evidenced from bathymetry, seismic reflection, and paleoseismic data such as the Yusuf and Carboneras faults were seismically inactive. Earthquakes below the Western Alboran Basin occurred at 70 to 110 km depth and hence reflected intermediate depth seismicity related to subducted lithosphere.

  19. Two-dimensional numerical modeling of tectonic and metamorphic histories at active continental margins

    NASA Astrophysics Data System (ADS)

    Gerya, Taras; Stöckhert, Bernhard

    2006-04-01

    The evolution of an active continental margin is simulated in two dimensions, using a finite difference thermomechanical code with half-staggered grid and marker-in-cell technique. The effect of mechanical properties, changing as a function of P and T, assigned to different crustal layers and mantle materials in the simple starting structure is discussed for a set of numerical models. For each model, representative P T paths are displayed for selected markers. Both the intensity of subduction erosion and the size of the frontal accretionary wedge are strongly dependent on the rheology chosen for the overriding continental crust. Tectonically eroded upper and lower continental crust is carried down to form a broad orogenic wedge, intermingling with detached oceanic crust and sediments from the subducted plate and hydrated mantle material from the overriding plate. A small portion of the continental crust and trench sediments is carried further down into a narrow subduction channel, intermingling with oceanic crust and hydrated mantle material, and to some extent extruded to the rear of the orogenic wedge underplating the overriding continental crust. The exhumation rates for (ultra)high pressure rocks can exceed subduction and burial rates by a factor of 1.5 3, when forced return flow in the hanging wall portion of the self-organizing subduction channel is focused. The simulations suggest that a minimum rate of subduction is required for the formation of a subduction channel, because buoyancy forces may outweigh drag forces for slow subduction. For a weak upper continental crust, simulated by a high pore pressure coefficient in the brittle regime, the orogenic wedge and megascale melange reach a mid- to upper-crustal position within 10 20 Myr (after 400 600 km of subduction). For a strong upper crust, a continental lid persists over the entire time span covered by the simulation. The structural pattern is similar in all cases, with four zones from trench toward arc

  20. Tectonic and Structural Controls of Geothermal Activity in the Great Basin Region, Western USA

    NASA Astrophysics Data System (ADS)

    Faulds, J. E.; Hinz, N.; Kreemer, C. W.

    2012-12-01

    We are conducting a thorough inventory of structural settings of geothermal systems (>400 total) in the extensional to transtensional Great Basin region of the western USA. Most of the geothermal systems in this region are not related to upper crustal magmatism and thus regional tectonic and local structural controls are the most critical factors controlling the locations of the geothermal activity. A system of NW-striking dextral faults known as the Walker Lane accommodates ~20% of the North American-Pacific plate motion in the western Great Basin and is intimately linked to N- to NNE-striking normal fault systems throughout the region. Overall, geothermal systems are concentrated in areas with the highest strain rates within or proximal to the eastern and western margins of the Great Basin, with the high temperature systems clustering in transtensional areas of highest strain rate in the northwestern Great Basin. Enhanced extension in the northwestern Great Basin probably results from the northwestward termination of the Walker Lane and the concomitant transfer of dextral shear into west-northwest directed extension, thus producing a broad transtensional region. The capacity of geothermal power plants also correlates with strain rates, with the largest (hundreds of megawatts) along the Walker Lane or San Andreas fault system, where strain rates range from 10-100 nanostrain/yr to 1,000 nanostrain/yr, respectively. Lesser systems (tens of megawatts) reside in the Basin and Range (outside the Walker Lane), where local strain rates are typically < 10 nanostrain/yr. Of the 250+ geothermal fields catalogued, step-overs or relay ramps in normal fault zones serve as the most favorable setting, hosting ~32% of the systems. Such areas have multiple, overlapping fault strands, increased fracture density, and thus enhanced permeability. Other common settings include a) intersections between normal faults and strike-slip or oblique-slip faults (27%), where multiple minor

  1. Extract the Relational Information of Static Features and Motion Features for Human Activities Recognition in Videos

    PubMed Central

    2016-01-01

    Both static features and motion features have shown promising performance in human activities recognition task. However, the information included in these features is insufficient for complex human activities. In this paper, we propose extracting relational information of static features and motion features for human activities recognition. The videos are represented by a classical Bag-of-Word (BoW) model which is useful in many works. To get a compact and discriminative codebook with small dimension, we employ the divisive algorithm based on KL-divergence to reconstruct the codebook. After that, to further capture strong relational information, we construct a bipartite graph to model the relationship between words of different feature set. Then we use a k-way partition to create a new codebook in which similar words are getting together. With this new codebook, videos can be represented by a new BoW vector with strong relational information. Moreover, we propose a method to compute new clusters from the divisive algorithm's projective function. We test our work on the several datasets and obtain very promising results. PMID:27656199

  2. Precise Landslide Displacement Time Series from Continuous GPS Observations in Tectonically Active and Cold Regions: A Case Study in Alaska

    NASA Astrophysics Data System (ADS)

    Cuddus, Y.; Wang, G.

    2014-12-01

    Over the past 15 years, Global Positioning System (GPS) has been frequently used as a scientific tool to detect potential earth mass movements and to track creeping landslides. In this study, we investigated four-years of continuous GPS data (September 2006-July 2010) recorded at a landslide site in Alaska. This GPS station (AC55) was installed on an un-identified creeping site by the Plate Boundary Observatory (PBO) project, which was funded by the U.S. National Science Foundation. The landslide moves with a steady horizontal velocity of 5.5 cm/year toward NEE, and had a subsidence rate of 2.6 cm/year. There was a considerable correlation between annual snow loading and melting cycles and seasonal variations of the landslide displacements. The seasonal movements vary year to year with an average peak-to-peak amplitude of 1.5 cm and 1.0 cm in horizontal and vertical directions, respectively. This study addresses three challenging issues in applying GPS for landslide monitoring in tectonically active and cold regions. The three challenges include (1) detecting GPS-derived positions that could be contaminated by the snow and ice accumulated on GPS antennas during cold seasons, (2) establishing a precise local reference frame and assessing its accuracy, and (3) excluding local seasonal ground motions from GPS-derived landslide displacements. The methods introduced in this study will be useful for GPS landslide monitoring in other tectonically active and/or cold regions.

  3. GeoBioScience: Red Wood Ants as Bioindicators for Active Tectonic Fault Systems in the West Eifel (Germany).

    PubMed

    Berberich, Gabriele; Schreiber, Ulrich

    2013-05-17

    In a 1.140 km² study area of the volcanic West Eifel, a comprehensive investigation established the correlation between red wood ant mound (RWA; Formica rufa-group) sites and active tectonic faults. The current stress field with a NW-SE-trending main stress direction opens pathways for geogenic gases and potential magmas following the same orientation. At the same time, Variscan and Mesozoic fault zones are reactivated. The results showed linear alignments and clusters of approx. 3,000 RWA mounds. While linear mound distribution correlate with strike-slip fault systems documented by quartz and ore veins and fault planes with slickensides, the clusters represent crosscut zones of dominant fault systems. Latter can be correlated with voids caused by crustal block rotation. Gas analyses from soil air, mineral springs and mofettes (CO₂, Helium, Radon and H₂S) reveal limiting concentrations for the spatial distribution of mounds and colonization. Striking is further the almost complete absence of RWA mounds in the core area of the Quaternary volcanic field. A possible cause can be found in occasionally occurring H₂S in the fault systems, which is toxic at miniscule concentrations to the ants. Viewed overall, there is a strong relationship between RWA mounds and active tectonics in the West Eifel.

  4. Late Pleistocene and Holocene uplift history of Cyprus: implications for active tectonics along the southern margin of the Anatolian microplate

    USGS Publications Warehouse

    Harrison, R.W.; Tsiolakis, E.; Stone, B.D.; Lord, A.; McGeehin, J.P.; Mahan, S.A.; Chirico, P.

    2013-01-01

    The nature of the southern margin of the Anatolian microplate during the Neogene is complex, controversial and fundamental in understanding active plate-margin tectonics and natural hazards in the Eastern Mediterranean region. Our investigation provides new insights into the Late Pleistocene uplift history of Cyprus and the Troodos Ophiolite. We provide isotopic (14C) and radiogenic (luminescence) dates of outcropping marine sediments in eastern Cyprus that identify periods of deposition during marine isotope stages (MIS) 3, 4, 5 and 6. Past sea-levels indicated by these deposits are c. 95±25 m higher in elevation than estimates of worldwide eustatic sea-level. An uplift rate of c. 1.8 mm/year and possibly as much as c. 4.1 mm/year in the past c. 26–40 ka is indicated. Holocene marine deposits also occur at elevations higher than those expected for past SL and suggest uplift rates of c. 1.2–2.1 mm/year. MIS-3 marine deposits that crop out in southern and western Cyprus indicate uniform island-wide uplift. We propose a model of tectonic wedging at a plate-bounding restraining bend as a mechanism for Late Pleistocene to Holocene uplift of Cyprus; uplift is accommodated by deformation and seismicity along the margins of the Troodos Ophiolite and re-activation of its low-angle, basal shear zone.

  5. Stability of active mantle upwelling revealed by net characteristics of plate tectonics.

    PubMed

    Conrad, Clinton P; Steinberger, Bernhard; Torsvik, Trond H

    2013-06-27

    Viscous convection within the mantle is linked to tectonic plate motions and deforms Earth's surface across wide areas. Such close links between surface geology and deep mantle dynamics presumably operated throughout Earth's history, but are difficult to investigate for past times because the history of mantle flow is poorly known. Here we show that the time dependence of global-scale mantle flow can be deduced from the net behaviour of surface plate motions. In particular, we tracked the geographic locations of net convergence and divergence for harmonic degrees 1 and 2 by computing the dipole and quadrupole moments of plate motions from tectonic reconstructions extended back to the early Mesozoic era. For present-day plate motions, we find dipole convergence in eastern Asia and quadrupole divergence in both central Africa and the central Pacific. These orientations are nearly identical to the dipole and quadrupole orientations of underlying mantle flow, which indicates that these 'net characteristics' of plate motions reveal deeper flow patterns. The positions of quadrupole divergence have not moved significantly during the past 250 million years, which suggests long-term stability of mantle upwelling beneath Africa and the Pacific Ocean. These upwelling locations are positioned above two compositionally and seismologically distinct regions of the lowermost mantle, which may organize global mantle flow as they remain stationary over geologic time.

  6. Collision tectonics

    SciTech Connect

    Coward, M.P.; Ries, A.C.

    1985-01-01

    The motions of lithospheric plates have produced most existing mountain ranges, but structures produced as a result of, and following the collision of continental plates need to be distinguished from those produced before by subduction. If subduction is normally only stopped when collision occurs, then most geologically ancient fold belts must be collisional, so it is essential to recognize and understand the effects of the collision process. This book consists of papers that review collision tectonics, covering tectonics, structure, geochemistry, paleomagnetism, metamorphism, and magmatism.

  7. Active Tectonics of Southern Alaska and the Role of the Yakutat Block Constrained by GPS

    NASA Astrophysics Data System (ADS)

    Elliott, J.; Freymueller, J. T.; Larsen, C. F.

    2011-12-01

    GPS data from southern Alaska and the northern Canadian Cordillera have helped redefine the region's tectonic landscape. Instead of a comparatively simple interaction between the Pacific and North American plates, with relative motion accommodated on a single boundary fault, the margin is made up of a number of small blocks and deformation zones with relative motion distributed across a variety of structures. Much of this complexity can be attributed to the Yakutat block, an allochthonous terrane that has been colliding with southern Alaska since the Miocene. We present GPS data from across the region and use it to constrain a tectonic model for the Yakutat block collision and its effects on southern Alaska and eastern Canada. According to our model, the Yakutat block itself moves NNW at a rate of 50 mm/yr. Along its eastern edge, the Yakutat block is fragmenting into small crustal slivers. Part of the strain from the collision is transferred east of the Fairweather - Queen Charlotte fault system, causing the region inboard of the Fairweather fault to undergo a distinct clockwise rotation into the northern Canadian Cordillera. About 5% of the relative motion is transferred even further east, causing small northeasterly motions well into the northern Cordillera. Further north, the GPS data and model results indicate that the current deformation front between the Yakutat block and southern Alaska runs along the western side of the Malaspina Glacier. The majority of the ~37 mm/yr of relative convergence is accommodated along a narrow band of thrust faults concentrated in the southeastern part of the St. Elias orogen. Near the Bering Glacier, the tectonic regime abruptly changes as crustal thrust faults give way to subduction of the Yakutat block beneath the western St. Elias orogen and Prince William Sound. This change aligns with the Gulf of Alaska shear zone, implying that the Pacific plate may be fragmenting in response to the Yakutat collision. From the Bering

  8. Active tectonics in Southern Alaska and the role of the Yakutat block constrained by GPS measurements

    NASA Astrophysics Data System (ADS)

    Elliott, Julie

    2011-12-01

    GPS data from southern Alaska and the northern Canadian Cordillera have helped redefine the region's tectonic landscape. Instead of a comparatively simple interaction between the Pacific and North American plates, with relative motion accommodated on a single boundary fault, the margin is made up of a number of small blocks and deformation zones with relative motion distributed across a variety of structures. Much of this complexity can be attributed to the Yakutat block, an allochthonous terrane that has been colliding with southern Alaska since the Miocene. This thesis presents GPS data from across the region and uses it to constrain a tectonic model for the Yakutat block collision and its effects on southern Alaska and eastern Canada. The Yakutat block itself moves NNW at a rate of 50 mm/yr. Along its eastern edge, the Yakutat block is fragmenting into small crustal slivers. Part of the strain from the collision is transferred east of the Fairweather -- Queen Charlotte fault system, causing the region inboard of the Fairweather fault to undergo a distinct clockwise rotation into the northern Canadian Cordillera. About 5% of the relative motion is transferred even further east, causing small northeasterly motions well into the northern Cordillera. Further north, the GPS data and model results indicate that the current deformation front between the Yakutat block and southern Alaska runs along the western side of the Malaspina Glacier. The majority of the ˜37 mm/yr of relative convergence is accommodated along a narrow band of thrust faults concentrated in the southeastern part of the St. Elias orogen. Near the Bering Glacier, the tectonic regime abruptly changes as crustal thrust faults give way to subduction of the Yakutat block beneath the western St. Elias orogen and Prince William Sound. This change aligns with the Gulf of Alaska shear zone, implying that the Pacific plate is fragmenting in response to the Yakutat collision. The Bering Glacier region is

  9. Anatomy of mass transport deposits in the Dead Sea: sedimentary processes in an active tectonic hypersaline basin

    NASA Astrophysics Data System (ADS)

    Waldmann, Nicolas; Hadzhiivanova, Elitsa; Neugebauer, Ina; Brauer, Achim; Schwab, Markus; Frank, Ute; Dulski, Peter

    2014-05-01

    Continental archives such as interplate endorheic lacustrine sedimentary basins provide an excellent source of data for studying regional climate, seismicity and environmental changes through time. Such is the case for the sediments that were deposited in the Dead Sea basin, a tectonically active pull-apart structure along the Dead Sea fault (DSF). This elongated basin is characterized by steep slopes and a deep and flat basin-floor, which are constantly shaped by seismicity and climate. In this study, we present initial results on the sedimentology and internal structure of mass transport deposits in the Pleistocene Dead Sea. The database used for this study consists of a long core retrieved at ~300 m water depth in the deepest part of the Dead Sea as part of an international scientific effort under the auspice of the ICDP. Micro-facies analysis coupled by elemental scanning (µXRF), granulometry and petrophysical measurements (magnetic susceptibility) have been carried out on selected intervals in order to decipher and identify the source-to-sink processes and controlling mechanisms behind the formation of mass transport deposits. The findings of this study allowed defining and characterizing the mass transport deposits into separate sedimentary facies according to the lake level and limnological conditions. Investigating sediments from the deep Dead Sea basin allowed better understanding and deciphering the depositional processes in relation with the tectonic forces shaping this basin.

  10. Active tectonics evaluation from geomorphic indices for the central and the southern Longmenshan range on the Eastern Tibetan Plateau, China

    NASA Astrophysics Data System (ADS)

    Gao, Mingxing; Zeilinger, Gerold; Xu, Xiwei; Tan, Xibin; Wang, Qingliang; Hao, Ming

    2016-08-01

    We applied the geomorphic indices (hypsometry and stream length gradient) to evaluate the differential uplift of the central and southern Longmenshan, a mountain range characterized by rapid erosion, strong tectonic uplift, and devastating seismic hazards. The results of the geomorphic analysis indicate that the Beichuan-Yingxiu fault and the Shuangshi-Dachuan fault act as major tectonic boundaries separating areas experiencing rapid uplift from slow uplift. The results of the geomorphic analysis also suggest that the Beichuan-Yingxiu fault is the most active fault with the largest relative uplift rates compared to the rest of the faults in the Longmenshan fault system. We compared reflected relative uplift rates based on the hypsometry and stream length gradient indices with geological/geodetic absolute rates. Along-strike and across-strike variations in the hypsometry and stream length gradient correlate with the spatial patterns derived from the apatite fission track exhumation rates, the leveling-derived uplift rate, and coseismic vertical displacements during the 2008 Wenchuan earthquake. These data defined multiple fault relationships in a complex thrust zone and provided geomorphic evidence to evaluate the potential seismic hazards of the southern Longmenshan range.

  11. Active Transportation Safety Features around Schools in Canada

    PubMed Central

    Pinkerton, Bryn; Rosu, Andrei; Janssen, Ian; Pickett, William

    2013-01-01

    The purpose of this study was to describe the presence and quality of active transportation safety features in Canadian school environments that relate to pedestrian and bicycle safety. Variations in these features and associated traffic concerns as perceived by school administrators were examined by geographic status and school type. The study was based on schools that participated in 2009/2010 Health Behaviour in School-aged Children (HBSC) survey. ArcGIS software version 10 and Google Earth were used to assess the presence and quality of ten different active transportation safety features. Findings suggest that there are crosswalks and good sidewalk coverage in the environments surrounding most Canadian schools, but a dearth of bicycle lanes and other traffic calming measures (e.g., speed bumps, traffic chokers). Significant urban/rural inequities exist with a greater prevalence of sidewalk coverage, crosswalks, traffic medians, and speed bumps in urban areas. With the exception of bicycle lanes, the active transportation safety features that were present were generally rated as high quality. Traffic was more of a concern to administrators in urban areas. This study provides novel information about active transportation safety features in Canadian school environments. This information could help guide public health efforts aimed at increasing active transportation levels while simultaneously decreasing active transportation injuries. PMID:24185844

  12. Active transportation safety features around schools in Canada.

    PubMed

    Pinkerton, Bryn; Rosu, Andrei; Janssen, Ian; Pickett, William

    2013-10-31

    The purpose of this study was to describe the presence and quality of active transportation safety features in Canadian school environments that relate to pedestrian and bicycle safety. Variations in these features and associated traffic concerns as perceived by school administrators were examined by geographic status and school type. The study was based on schools that participated in 2009/2010 Health Behaviour in School-aged Children (HBSC) survey. ArcGIS software version 10 and Google Earth were used to assess the presence and quality of ten different active transportation safety features. Findings suggest that there are crosswalks and good sidewalk coverage in the environments surrounding most Canadian schools, but a dearth of bicycle lanes and other traffic calming measures (e.g., speed bumps, traffic chokers). Significant urban/rural inequities exist with a greater prevalence of sidewalk coverage, crosswalks, traffic medians, and speed bumps in urban areas. With the exception of bicycle lanes, the active transportation safety features that were present were generally rated as high quality. Traffic was more of a concern to administrators in urban areas. This study provides novel information about active transportation safety features in Canadian school environments. This information could help guide public health efforts aimed at increasing active transportation levels while simultaneously decreasing active transportation injuries.

  13. International Field Research with Undergraduate Students: Investigating Active Tectonics of the Nicoya Peninsula, Costa Rica

    NASA Astrophysics Data System (ADS)

    Marshall, J. S.; Gardner, T. W.; Protti, M.

    2005-12-01

    Over the past eight years, 18 undergraduate students from 12 U.S. and Costa Rican universities and colleges have participated in field research projects investigating coastal tectonics on the Nicoya Peninsula, Costa Rica. These projects have been organized around two different models: 1) a month-long "field camp" with 10 students and 5 project faculty (Keck Geology Consortium Project, 1998), and 2) several two-week field projects with 1-3 students and one faculty advisor (Cal Poly Pomona University and Trinity University). Under the direction of the authors, each of these projects has been carefully designed to provide a new piece to a larger research puzzle. The Nicoya Peninsula lies along Costa Rica's northern Pacific coast inboard of the Middle America Trench where the Cocos and Caribbean plates converge at 10 cm/yr. In 1950, the peninsula was shaken by a ~M 7.7 subduction earthquake that produced widespread damage and 0.5-1.0 m of coseismic coastal uplift. With a large slip deficit since 1950, the Nicoya Peninsula is viewed as a high-potential seismic gap. Field study of uplifted Quaternary marine terraces along the Nicoya coastline provides undergraduate students with a unique opportunity to examine rapid forearc deformation related to large subduction earthquakes. The field research conducted by each of these students provides the basis for a senior thesis at their home institution. In most cases, the students have focused their individual work on separate, but adjacent field areas. Collectively, each of these projects has generated significant data that contribute toward of an ongoing investigation of fore arc tectonics and subduction cycle earthquakes along the Costa Rican Pacific margin.

  14. Combined Helium and CO2 Isotope Systematics of Turkish Geothermal Systems: Relation to Volcanism and Active Tectonics

    NASA Astrophysics Data System (ADS)

    Gulec, N.; Mutlu, H.; Hilton, D. R.

    2014-12-01

    Helium and CO2 isotope compositions and CO2/3He ratios of Turkish geothermal fluids from various neotectonic provinces suggest genetic relationships with magmatic and tectonic activities. The provinces include western and eastern Anatolia, experiencing extensional and compressional regimes, respectively, and the North Turkish province experiencing strike-slip tectonics associated with the North Anatolian Fault Zone (NAFZ). He-isotope compositions display a range of values from 0.27-1.67 Ra for western Anatolia, 0.85-7.76 Ra for eastern Anatolia, and 0.28-2.19 Ra for NAFZ fluids, with δ13C values between -8.04 and +0.35 ‰, -14.59 and +1.30 ‰ , and -1.92 and +1.52‰ , respectively. CO2/3He ratios lie between 1.66x109-2.35x1013, 2.4x105-3.7x1013and 32x109-26x1013for the fluids of western and eastern Anatolia and the NAFZ, respectively. Combined He-CO2 systematics suggest that degassing and preferential CO2 loss significantly affects some samples resulting in the fractionation of elemental CO2/He ratios.Quantitative assessment of the volatile inventory suggests ~97% and 10% mantle-derived component in the He- and C-inventories, the C-budget being dominated by carbonate contributions in agreement with the composition of basement metamorphics (containing marble) and reservoir lithologies (marble, limestone) in most fields. The highest mantle-He contribution, accompanied by the highest mantle-C, is recorded in eastern Anatolia in the vicinity of the most recently-active Nemrut volcano. Relatively high mantle-He and mantle-C contributions in the Tuzla field of western Anatolia display close spatial association with young, alkaline volcanics. Along the NAFZ, the highest mantle contributions are recorded at the most seismically-active western-central segment. Collectively, these observations suggest the addition of mantle volatiles to crust by young magmatic activities and their transfer to the surface via fault zones of these tectonic provinces.

  15. 10 CFR 960.5-2-11 - Tectonics.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... of active faulting within the geologic setting. (2) Historical earthquakes or past man-induced... design limits. (3) Evidence, based on correlations of earthquakes with tectonic processes and features, (e.g., faults) within the geologic setting, that the magnitude of earthquakes at the site during...

  16. 10 CFR 960.5-2-11 - Tectonics.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... of active faulting within the geologic setting. (2) Historical earthquakes or past man-induced... design limits. (3) Evidence, based on correlations of earthquakes with tectonic processes and features, (e.g., faults) within the geologic setting, that the magnitude of earthquakes at the site during...

  17. 10 CFR 960.5-2-11 - Tectonics.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... of active faulting within the geologic setting. (2) Historical earthquakes or past man-induced... design limits. (3) Evidence, based on correlations of earthquakes with tectonic processes and features, (e.g., faults) within the geologic setting, that the magnitude of earthquakes at the site during...

  18. 10 CFR 960.5-2-11 - Tectonics.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... of active faulting within the geologic setting. (2) Historical earthquakes or past man-induced... design limits. (3) Evidence, based on correlations of earthquakes with tectonic processes and features, (e.g., faults) within the geologic setting, that the magnitude of earthquakes at the site during...

  19. 10 CFR 960.5-2-11 - Tectonics.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... of active faulting within the geologic setting. (2) Historical earthquakes or past man-induced... design limits. (3) Evidence, based on correlations of earthquakes with tectonic processes and features, (e.g., faults) within the geologic setting, that the magnitude of earthquakes at the site during...

  20. Active Pacific North America Plate boundary tectonics as evidenced by seismicity in the oceanic lithosphere offshore Baja California, Mexico

    NASA Astrophysics Data System (ADS)

    Hauksson, Egill; Kanamori, Hiroo; Stock, Joann; Cormier, Marie-Helene; Legg, Mark

    2014-03-01

    Pacific Ocean crust west of southwest North America was formed by Cenozoic seafloor spreading between the large Pacific Plate and smaller microplates. The eastern limit of this seafloor, the continent-ocean boundary, is the fossil trench along which the microplates subducted and were mostly destroyed in Miocene time. The Pacific-North America Plate boundary motion today is concentrated on continental fault systems well to the east, and this region of oceanic crust is generally thought to be within the rigid Pacific Plate. Yet, the 2012 December 14 Mw 6.3 earthquake that occurred about 275 km west of Ensenada, Baja California, Mexico, is evidence for continued tectonism in this oceanic part of the Pacific Plate. The preferred main shock centroid depth of 20 km was located close to the bottom of the seismogenic thickness of the young oceanic lithosphere. The focal mechanism, derived from both teleseismic P-wave inversion and W-phase analysis of the main shock waveforms, and the 12 aftershocks of M ˜3-4 are consistent with normal faulting on northeast striking nodal planes, which align with surface mapped extensional tectonic trends such as volcanic features in the region. Previous Global Positioning System (GPS) measurements on offshore islands in the California Continental Borderland had detected some distributed Pacific and North America relative plate motion strain that could extend into the epicentral region. The release of this lithospheric strain along existing zones of weakness is a more likely cause of this seismicity than current thermal contraction of the oceanic lithosphere or volcanism. The main shock caused weak to moderate ground shaking in the coastal zones of southern California, USA, and Baja California, Mexico, but the tsunami was negligible.

  1. Insights into active tectonics of eastern Taiwan from analyses of geodetic and geologic data

    NASA Astrophysics Data System (ADS)

    Huang, Wen-Jeng; Johnson, Kaj M.; Fukuda, Jun'ichi; Yu, Shui-Beih

    2010-03-01

    About 50 mm/yr of convergence between the Philippine Sea and Eurasian plates is absorbed in eastern Taiwan, and it remains unclear how the convergence is partitioned among active faults. The Longitudinal Valley fault (LVF), the most seismically active fault in eastern Taiwan, creeps at the surface in the south and not in the north; however, it is unclear how much of the fault is locked or creeping at depth. To address these problems, we model Holocene and interseismic deformation of elastic lithospheric blocks moving over a viscoelastic asthenosphere in eastern Taiwan. Through a fully probabilistic scheme, we invert GPS, interferometric synthetic aperture radar, creepmeter, and Holocene marine terrace data for block motions, fault slip rates, and distribution of interseismic creep. The data are explained with four blocks separated by three faults, Central Range fault, LVF, and an offshore fault. The model explains the essential features of interseismic and Holocene deformation. We find that 35-55 mm/yr of slip on the offshore fault is necessary to fit marine terrace uplift rates, which is a larger fraction of the plate convergence than previously recognized. The LVF has a Holocene slip rate of 20-30 mm/yr with approximately equal magnitudes of reverse-slip and left-lateral strike-slip components. Only about half of the surface area of the Longitudinal Valley fault appears to be locked. The southern segment of the LVF creeps at a rate of 5-28 mm/yr down to a depth of 15-20 km, while the northern segment is locked from the surface to a depth of 20 km.

  2. Tectonics and Volcanism of East Africa as Seen Using Remote Sensing Imagery

    NASA Technical Reports Server (NTRS)

    Hutt, Duncan John

    1996-01-01

    The East African Rift is the largest area of active continental geology. The tectonics of this area has been studied with remote sensing data, including AVHRR, Landsat MSS and TM, SPOT, and electronic still camera from Shuttle. Lineation trends have been compared to centers of volcanic and earthquake activity as well as the trends shown on existing geologic maps. Remote sensing data can be used effectively to reveal and analyze significant tectonic features in this area.

  3. A test of the hypothesis that impact-induced fractures are preferred sites for later tectonic activity

    NASA Technical Reports Server (NTRS)

    Solomon, Sean C.; Duxbury, Elizabeth D.

    1987-01-01

    Impact cratering has been an important process in the solar system. The cratering event is generally accompanied by faulting in adjacent terrain. Impact-induced faults are nearly ubiquitous over large areas on the terrestrial planets. The suggestion is made that these fault systems, particularly those associated with the largest impact features are preferred sites for later deformation in response to lithospheric stresses generated by other processes. The evidence is a perceived clustering of orientations of tectonic features either radial or concentric to the crater or basin in question. An opportunity exists to test this suggestion more directly on Earth. The terrestrial continents contain more than 100 known or probable impact craters, with associated geological structures mapped to varying levels of detail. Prime facie evidence for reactivation of crater-induced faults would be the occurrence of earthquakes on these faults in response to the intraplate stress field. Either an alignment of epicenters with mapped fault traces or fault plane solutions indicating slip on a plane approximately coincident with that inferred for a crater-induced fault would be sufficient to demonstrate such an association.

  4. Fault kinematics and active tectonics of the Sabah margin: Insights from the 2015, Mw 6.0, Mt. Kinabalu earthquake

    NASA Astrophysics Data System (ADS)

    Wang, Y.; Wei, S.; Tapponnier, P.; WANG, X.; Lindsey, E.; Sieh, K.

    2016-12-01

    A gravity-driven "Mega-Landslide" model has been evoked to explain the shortening seen offshore Sabah and Brunei in oil-company seismic data. Although this model is considered to account simultaneously for recent folding at the edge of the submarine NW Sabah trough and normal faulting on the Sabah shelf, such a gravity-driven model is not consistent with geodetic data or critical examination of extant structural restorations. The rupture that produced the 2015 Mw6.0 Mt. Kinabalu earthquake is also inconsistent with the gravity-driven model. Our teleseismic analysis shows that the centroid depth of that earthquake's mainshock was 13 to 14 km, and its favored fault-plane solution is a 60° NW-dipping normal fault. Our finite-rupture model exhibits major fault slip between 5 and 15 km depth, in keeping with our InSAR analysis, which shows no appreciable surface deformation. Both the hypocentral depth and the depth of principal slip are far too deep to be explained by gravity-driven failure, as such a model would predict a listric normal fault connecting at a much shallower depth with a very gentle detachment. Our regional mapping of tectonic landforms also suggests the recent rupture is part of a 200-km long system of narrowly distributed active extension in northern Sabah. Taken together, the nature of the 2015 rupture, the belt of active normal faults, and structural consideration indicate that active tectonic shortening plays the leading role in controlling the overall deformation of northern Sabah and that deep-seated, onland normal faulting likely results from an abrupt change in the dip-angle of the collision interface beneath the Sabah accretionary prism.

  5. Martian tectonics: A review

    NASA Technical Reports Server (NTRS)

    Phillips, R. J.

    1987-01-01

    It is concluded that Mars was dominated by vertical tectonism more than any of the other terrestrial planets. The structural imprint of the Tharsis and Elysium provinces extends over half the planet, and despite 15 years of debate over the cause of the elevation, volcanic activity, and tectonic style of Tharsis, no uniform theory of Tharsis evolution has been generally agreed upon. Although several theories have been suggested for the origin of the north-south planetary dichotomy, there is also a lack of a testable, plausible model for that major unknown in Mars' evolution.

  6. Tectonic structure of East Antarctica

    NASA Astrophysics Data System (ADS)

    Leychenkov, German; Grikurov, Garrik; Golynsky, Alexander

    2013-04-01

    First overviews of tectonic structure of the Southern Continent were made by the pioneers of Antarctic earth science investigations almost 100 years ago. Despite rapidly advancing international geological studies under the Antarctic Treaty, the presentations of Antarctic tectonic structure remained largely speculative until the end of the past century when implementation of modern analytical and remote-sensing research technologies enabled compilation of more credible tectonic models of Antarctica. The East Antarctic bedrock consists mainly of the Precambrian crystalline complexes and the Paleozoic-Early Mesozoic platform units. Crystalline Shield is locally complicated by Neoproterozoic aulacogenes and Late Paleozoic to Mesozoic rifts. Shield assemblages reliably recognized in coastal outcrops indicate the predominant occurrence of Archean cratonic nuclei and Mesoproterozoic mobile belts. The undisturbed platform cover strata are exposed in East Antarctica mainly along its boundary with West Antarctica. Tectonic structure of ice-covered regions (more that 99% of the East Antarctic territory) is interpreted using mostly magnetic and bedrock topography data, but other geophysical and geological information (satellite, airborne and over-ice gravity; seismology; active seismics; erratics; detrital zircons dates; etc.) is also important. Archean cratons are geologically documented in western Dronning Maud Land, Enderby Land, Princess Elizabeth Land and in the southern Prince Charles Mts. Their distribution under the ice is marked by a specific magnetic pattern including low-amplitude mosaic and/or high-amplitude long-wavelength anomalies. The most extensive ancient craton being 1000 km across is believed to extend from the southern Prince Charles Mts. to the Gamburtsev Mts. Mesoproterozoic mobile belts are distinguished by elongated high-amplitude magnetic anomalies and are mapped along the costal area as the zone of 250-600 km wide. The Gamburtsev Mts. area is also

  7. Geochemistry, geothermics and relationship to active tectonics of Gujarat and Rajasthan thermal discharges, India

    NASA Astrophysics Data System (ADS)

    Minissale, A.; Chandrasekharam, D.; Vaselli, O.; Magro, G.; Tassi, F.; Pansini, G. L.; Bhramhabut, A.

    2003-09-01

    Most thermal spring discharges of Rajasthan and Gujarat in northwestern India have been sampled and analysed for major and trace elements in both the liquid and associated gas phase, and for 18O/ 16O, D/H (in water), 3He/ 4He and 13C/ 12C in CO 2 (in gas) isotopic ratios. Most thermal springs in Rajasthan are tightly associated to the several regional NE-SW strike-slip faults bordering NE-SW ridges formed by Archaean rocks at the contact with Quaternary alluvial and aeolian sedimentary deposits of the Rajasthan desert. Their Ca-HCO 3 immature character and isotopic composition reveals: (1) meteoric origin, (2) relatively shallow circulation inside the crystalline Archaean formations, (3) very fast rise along faults, and (4) deep storage temperatures of the same order of magnitude as discharging temperatures (50-90°C). Thermal spring discharges in Gujarat are spread over a larger area than in Rajasthan and are associated both with the NNW-SSE fault systems bordering the Cambay basin and the ENE-WSW strike-slip fault systems in the Saurashtra province, west of the Cambay basin. Chemical and isotopic compositions of springs in both areas suggest a meteoric origin of deep thermal waters. They mix with fresh or fossil seawater entering the thermal paths of the spring systems through both the fault systems bordering the Cambay basin, as well as faults and fractures occurring inside the permeable Deccan Basalt Trap in the Saurashtra province. The associated gas phase, at all sampled sites, shows similar features: (1) it is dominated by the presence of atmospheric components (N 2 and Ar), (2) it has high crustal 4He enrichment, (3) it shows crustal 3He/ 4He signature, (4) it has low CO 2 concentration, and (5) the only analysed sample for 13C/ 12C isotopic ratio in CO 2 suggests that CO 2 has a strong, isotopically light organic imprint. All these features and chemical geothermometer estimates of spring waters suggest that any active deep hydrothermal system at the base

  8. Dynamical parameter analysis of continuous seismic signals of Popocatépetl volcano (Central Mexico): A case of tectonic earthquakes influencing volcanic activity

    NASA Astrophysics Data System (ADS)

    Tárraga, Marta; Cruz-Reyna, Servando; Mendoza-Rosas, Ana; Carniel, Roberto; Martínez-Bringas, Alicia; García, Alicia; Ortiz, Ramon

    2012-06-01

    The continuous background seismic activity contains information on the internal state of a volcanic system. Here, we report the influence of major regional tectonic earthquakes (M > 5 in most cases) on such state, reflected as changes in the spectral and dynamical parameters of the volcano continuous seismic data. Although changes do not always occur, analysis of five cases of earthquake-induced variations in the signals recorded at Popocatépetl volcano in central México reveal significant fluctuations following the tectonic earthquakes. External visible volcanic activity, such as small to moderate explosions and ash emissions, were related to those fluctuations. We briefly discuss possible causes of the variations. We conclude that recognition of fluctuations in the dynamical parameters in volcano monitoring seismic signals after tectonic earthquakes, even those located in the far field, hundreds of kilometers away, may provide an additional criterion for eruption forecasting, and for decision making in the definition of volcanic alert levels.

  9. Quaternary migration of active extension revealed by a syn-tectonic alluvial fan shift. A case study in the Northern Apennines of Italy

    NASA Astrophysics Data System (ADS)

    Mirabella, Francesco; Bucci, Francesco; Cardinali, Mauro; Santangelo, Michele; Guzzetti, Fausto

    2016-04-01

    In areas characterized by the progressive migration of active extension through time, shifts in the position of the active depocenter occur. Such shifts through time produces peculiar geomorphological settings that are often characterized by wind gaps, abandoned valleys, streams captures and drainage inversions. These features provide the opportunity to investigate active areas by studying the recent-most geological history of the related nearby basins. We investigate this topic in a tectonically active area in the Northern Apennines of Italy, as indicated by both instrumental and historical seismicity (maximum epicentral intensity I0=VIII) and extension rates in the order of 2.5-2.7 mm/yr. In particular, we study the Montefalco ridge drainage inversion. Here, fluvial sands and imbricated conglomerates deposited in a lower Pleistocene depocenter constituted by an extensional subsiding basin, are presently uplifted more than 200 m above the present day alluvial plain. The Montefalco ridge drainage inversion, at about 400 m a.s.l., separates two valleys, the Gualdo Cattaneo - Bastardo valley to the West (300 m a.s.l.) and the Foligno present-day alluvial plain to the East (200 m a.s.l.). Seismic reflection data show that the maximum thickness of the continental sequence in the Foligno valley is in the order of 500 m. This valley is presently occupied by a 37 km2 alluvial fan produced by the Topino river flowing from NE to SW. To unravel the Quaternary tectonic evolution of the area, we integrate different data sets collected by field mapping, detailed photo-geological data, sediments provenance information, and subsurface data. We interpret the Montefalco ridge as a paleo-Foligno-like alluvial fan representing the evidence of the recent migration of the active extension to the East of around 7 km. Considering an age of deformation of 2.5 My, an extension rate of about 2.8 mm/yr is derived, which corresponds to the present-day geodetic rates. We stress the importance

  10. Ganges-Brahmaputra Delta: Balance of Subsidence, Sea level and Sedimentation in a Tectonically-Active Delta (Invited)

    NASA Astrophysics Data System (ADS)

    Steckler, M. S.; Goodbred, S. L.; Akhter, S. H.; Seeber, L.; Reitz, M. D.; Paola, C.; Nooner, S. L.; DeWolf, S.; Ferguson, E. K.; Gale, J.; Hossain, S.; Howe, M.; Kim, W.; McHugh, C. M.; Mondal, D. R.; Petter, A. L.; Pickering, J.; Sincavage, R.; Williams, L. A.; Wilson, C.; Zumberge, M. A.

    2013-12-01

    Bangladesh is vulnerable to a host of short and long-term natural hazards - widespread seasonal flooding, river erosion and channel avulsions, permanent land loss from sea level rise, natural groundwater arsenic, recurrent cyclones, landslides and huge earthquakes. These hazards derive from active fluvial processes related to the growth of the delta and the tectonics at the India-Burma-Tibet plate junctions. The Ganges and Brahmaputra rivers drain 3/4 of the Himalayas and carry ~1 GT/y of sediment, 6-8% of the total world flux. In Bangladesh, these two great rivers combine with the Meghna River to form the Ganges-Brahmaputra-Meghna Delta (GBMD). The seasonality of the rivers' water and sediment discharge is a major influence causing widespread flooding during the summer monsoon. The mass of the water is so great that it causes 5-6 cm of seasonal elastic deformation of the delta discerned by our GPS data. Over the longer-term, the rivers are also dynamic. Two centuries ago, the Brahmaputra River avulsed westward up to 100 km and has since captured other rivers. The primary mouth of the Ganges has shifted 100s of km eastward from the Hooghly River over the last 400y, finally joining the Brahmaputra in the 19th century. These avulsions are influenced by the tectonics of the delta. On the east side of Bangladesh, the >16 km thick GBMD is being overridden by the Burma Arc where the attempted subduction of such a thick sediment pile has created a huge accretionary prism. The foldbelt is up to 250-km wide and its front is buried beneath the delta. The main Himalayan thrust front is <100 km north, but adjacent to the GBMD is the Shillong Massif, a 300-km long, 2-km high block of uplifted Indian basement that is overthrusting and depressing GBMD sediments to the south. The overthrusting Shillong Massif may represent a forward jump of the Himalayan front to a new plate boundary. This area ruptured in a ~M8 1897 earthquake. Subsidence from the tectonics and differential

  11. Evidence for Tectonic Activity During the Mature Harappan Civilization, 2600-1800 BCE

    NASA Astrophysics Data System (ADS)

    Grijalva, K. A.; Kovach, R. L.; Nur, A. M.

    2006-12-01

    The mature Harappan civilization located in Pakistan and India dates from 2600 to 1800 BCE. By combining seismic data, three-dimensional elastic dislocation modeling, and archaeological findings we examined the role that earthquakes played in the demise of Harappan settlements. The study focuses on three different geographical regions: Gujarat, the Sarasvati-Ghaggar-Hakra River valley, and the Makran coast of Pakistan. In Gujarat, the fluvial system of the Rann of Kachchh has undergone significant changes. The Rann of Kachchh formed as a delta for three rivers, becoming an inland sea during the time of Alexander the Great, and ultimately a salty marsh. These changes were brought about by a combination of sea level changes, the truncation of the three rivers by tectonic uplift and the deepening of the Rann by earthquake induced subsidence. Events analogous to the 1819 Allah Bund earthquake, which dammed the Puran River for seven years, would have significantly altered the water source for downstream settlements. Data from the recent 2001 Bhuj event shows that Harappan settlements would have suffered considerable shaking damage from an analogous historical event. Archaeological studies to date have found direct evidence for of at least one large earthquake at Dholavira in 2200 BCE. A number of the mature Harappan settlements are located along the dry Sarasvati-Ghaggar-Hakra river system. The decline of these sites coincides with the divergence of the Sarasvati-Ghaggar-Hakra system to the Indus and Ganga river systems. A succession of earthquakes, along with a period of aridity, likely led to the disappearance of the Sarasvati-Ghaggar-Hakra system. Although this region has not had any large earthquakes in historic times, there is archaeological evidence of two large events at the Harappan site of Kalibangan, at 2900 and 2700 BCE. Along the Makran coast two settlements, believed to have been Harappan seaports, are now located tens of kilometers inland. Changes in sea

  12. Task 1 quarternary tectonics

    SciTech Connect

    Bell, J.W.

    1994-12-31

    Activities on the task of quarternary tectonics for the Yucca Mountain Site investigations are described. Technical topics include: A preliminary reveiw of Bare Mountain Trench; A preliminary detailed lineament map of the Southwestern part of the proposed repository; A discussion on the 1994 Double Spring Flat, Nevada earthquake; and evidence for temporal clustering.

  13. Upper plate deformation and seismic barrier in front of Nazca subduction zone: The Chololo Fault System and active tectonics along the Coastal Cordillera, southern Peru

    NASA Astrophysics Data System (ADS)

    Audin, Laurence; Lacan, Pierre; Tavera, Hernando; Bondoux, Francis

    2008-11-01

    The South America plate boundary is one of the most active subduction zone. The recent Mw = 8.4 Arequipa 2001 earthquake ruptured the subduction plane toward the south over 400 km and stopped abruptly on the Ilo Peninsula. In this exact region, the subduction seismic crisis induced the reactivation of continental fault systems in the coastal area. We studied the main reactivated fault system that trends perpendicular to the trench by detailed mapping of fault related-geomorphic features. Also, at a longer time scale, a recurrent Quaternary transtensive tectonic activity of the CFS is expressed by offset river gullies and alluvial fans. The presence of such extensional fault systems trending orthogonal to the trench along the Coastal Cordillera in southern Peru is interpreted to reflect a strong coupling between the two plates. In this particular case, stress transfer to the upper plate, at least along the coastal fringe, appears to have induced crustal seismic events that were initiated mainly during and after the 2001 earthquake. The seafloor roughness of the subducting plate is usually thought to be a cause of segmentation along subduction zones. However, after comparing and discussing the role of inherited structures within the upper plate to the subduction zone segmentation in southern Peru, we suggest that the continental structure itself may exert some feedback control on the segmentation of the subduction zone and thus participate to define the rupture pattern of major subduction earthquakes along the southern Peru continental margin.

  14. Evidence and dating of mid-Cretaceous tectonic activity in the San Rafael Swell, Emery County, Utah

    SciTech Connect

    Eaton, J.G. ); Kirkland, J.I. ); Kauffman, E.G. )

    1990-04-01

    Evidence of tectonic activity in the form of recycled conglomerates has been found in middle Cretaceous deposits on the western flank of the San Rafael Swell. These conglomerates, present in the upper part of the Dakota Formation and in the overlying basal Mancos Shale (Tununk Member), are separated by an earliest Turonian unconformity. The conglomerates appear to be derived from the Lower Cretaceous Buckhorn Conglomerate, or similar conglomerates, which were re-exposed by latest Cenomanian uplift. Coarse clastics provided to the nearshore facies of the Dakota Formation by coastal rivers are preserved as a coarsening upward sequence. Continued uplift eventually caused a local marine regression by temporarily inhibiting the initial (latest Cenomanian) transgression of the Greenhorn Sea. In subaerially exposed environments pebbles and cobbles from the Buckhorn were distributed across the coastal floodplain by rivers. These clasts were reworked into a basal lag deposit when renewed transgression of the Greenhorn Sea occurred during the late early Turonian.

  15. How spontaneous brain activity and narcissistic features shape social interaction.

    PubMed

    Scalabrini, Andrea; Huang, Zirui; Mucci, Clara; Perrucci, Mauro Gianni; Ferretti, Antonio; Fossati, Andrea; Romani, Gian Luca; Northoff, Georg; Ebisch, Sjoerd J H

    2017-08-30

    There is an increasing interest in how ongoing spontaneous brain activity and personality provide a predisposition for the processing of environmental demands. It further has been suggested that the brain has an inherent sensitivity to the social environment. Here we tested in healthy volunteers if spontaneous brain activity contributes to a predisposition for social behavior and how this is modulated by narcissistic personality features associated with poor interpersonal functioning. Functional magnetic resonance imaging included a resting state and an experimental paradigm focusing on the anticipation of actively touching an animate (human hand) versus an inanimate target (mannequin hand). The experimental task induced a significant modulation of neural activity in left postcentral gyrus (PostCG), right culmen and, co-varying with narcissistic features, in right anterior insula (AI). Neural activity in anticipation of the animate target significantly correlated with spontaneous activity during the resting state indexed by the Power Law Exponent (PLE) in PostCG and AI. Finally, the correlation between spontaneous and task-induced activity in AI was mediated by narcissistic features. These findings provide novel evidence for a relationship between intrinsic brain activity and social behavior and show how personality could contribute to individual differences in our predisposition to approach the animate world.

  16. Anthropogenic Subsidence Revealed by MTI in an Area of Active Tectonics: Granada Basin

    NASA Astrophysics Data System (ADS)

    Sousa, Joaquim J.

    2010-12-01

    Stanford Method for Persistent Scatterers Multi- Temporal Interferometry (StaMPS-MTI), which combines both the persistent scatterer (PS) and the small baselines (SB) techniques, has been applied to the Otura area, located south of Granada Basin, in the central sector of the Betic Cordillera (southern Spain). The analysis was based on ERS-1/2 and Envisat images, covering the period from 1992 to 2010. The most significant ground motion processes detected in previous studies [1] [2] [3] were confirmed being the subsidence bowl located over the Otura village, with annual velocities along the SAR line-of-sight (LOS) up to 10 mm/yr, the major finding. However, this study differs from its predecessors by the applied methodology and also by the inclusion of an Envisat dataset covering the area to the present. In spite that the region is located in a subsiding sector of the Cordillera, the available data indicate that the tectonic subsidence is extremely lower than the detected rates. Two main causes were identified to explain this unexpected phenomenon: fast infrastructure development taking place in the outskirts of the village (new residential areas) leading to soil compaction; and intensive withdrawal of water from underground originated for the increase of population in the last years.

  17. Progressive failure during the 1596 Keicho earthquakes on the Median Tectonic Line active fault zone, southwest Japan

    NASA Astrophysics Data System (ADS)

    Ikeda, M.; Toda, S.; Nishizaka, N.; Onishi, K.; Suzuki, S.

    2015-12-01

    Rupture patterns of a long fault system are controlled by spatial heterogeneity of fault strength and stress associated with geometrical characteristics and stress perturbation history. Mechanical process for sequential ruptures and multiple simultaneous ruptures, one of the characteristics of a long fault such as the North Anatolian fault, governs the size and frequency of large earthquakes. Here we introduce one of the cases in southwest Japan and explore what controls rupture initiation, sequential ruptures and fault branching on a long fault system. The Median Tectonic Line active fault zone (hereinafter MTL) is the longest and most active fault in Japan. Based on historical accounts, a series of M ≥ 7 earthquakes occurred on at least a 300-km-long portion of the MTL in 1596. On September 1, the first event occurred on the Kawakami fault segment, in Central Shikoku, and the subsequent events occurred further west. Then on September 5, another rupture initiated from the Central to East Shikoku and then propagated toward the Rokko-Awaji fault zone to Kobe, a northern branch of the MTL, instead of the eastern main extent of the MTL. Another rupture eventually extended to near Kyoto. To reproduce this progressive failure, we applied two numerical models: one is a coulomb stress transfer; the other is a slip-tendency analysis under the tectonic stress. We found that Coulomb stress imparted from historical ruptures have triggered the subsequent ruptures nearby. However, stress transfer does not explain beginning of the sequence and rupture directivities. Instead, calculated slip-tendency values show highly variable along the MTL: high and low seismic potential in West and East Shikoku. The initiation point of the 1596 progressive failure locates near the boundary in the slip-tendency values. Furthermore, the slip-tendency on the Rokko-Awaji fault zone is far higher than that of the MTL in Wakayama, which may explain the rupture directivity toward Kobe-Kyoto.

  18. Relationship between the regional tectonic activity and crustal structure in the eastern Tibetan plateau discovered by gravity anomaly

    NASA Astrophysics Data System (ADS)

    Xu, Xiao; Gao, Rui; Guo, Xiaoyu

    2016-04-01

    The eastern Tibetan plateau has been getting more and more attention because it combines active faults, uplifting, and large earthquakes together in a high-population region. Based on the previous researches, the most of Cenozoic tectonic activities were related to the regional structure of the local blocks within the crustal scale. Thus, a better understanding of the crustal structure of the regional tectonic blocks is an important topic for further study. In this paper, we combined the simple Bouguer gravity anomaly with the Moho depths from previous studies to investigate the crustal structure in this area. To highlight the crustal structures, the gravity anomaly caused by the Moho relief has been reduced by forward modeling calculations. A total horizontal derivative (THD) had been applied on the gravity residuals. The results indicated that the crustal gravity residual is compatible with the topography and the geological settings of the regional blocks, including the Sichuan basin, the Chuxiong basin, the Xiaojiang fault, and the Jinhe fault, as well as the Longmenshan fault zone. The THD emphasized the west margin of Yangtze block, i.e., the Longriba fault zone and the Xiaojiang fault cut through the Yangtze block. The checkboard pattern of the gravity residual in the Songpan-Garze fold belt and Chuandian fragment shows that the crust is undergoing a southward and SE-directed extrusion, which is coincident with the flowing direction indicated from the GPS measurements. By integrating the interpretations, the stepwise extensional mechanism of the eastern Tibetan plateau is supported by the southeastward crustal deformation, and the extrusion of Chuandian fragment is achieved by Xianshuihe fault.

  19. Surface Rupture of the 2005 Kashmir, Pakistan, Earthquake and its Active Tectonic Implications

    NASA Astrophysics Data System (ADS)

    Kaneda, H.; Nakata, T.; Tsutsumi, H.; Kondo, H.; Sugito, N.; Awata, Y.; Akhtar, S. S.; Majid, A.; Khattak, W.; Awan, A. A.; Yeats, R. S.

    2006-12-01

    The 8th October 2005 Kashmir earthquake of Mw 7.6 struck the westernmost area of the Indian-Eurasian collision zone, resulting in the worst earthquake disaster ever recorded along the frontal Himalaya. Although none of the historical Himalayan earthquakes is reported to have produced primary surface rupture, our field mapping reveals that the 2005 earthquake accompanied a NW-trending ~70-km-long distinctive surface rupture with maximum and mean vertical separations of ~7 m and ~3 m, respectively. Typical surface expression of faulting is a NE-side-up fault scarp or warp with surface shortening features at its base and tension cracks on its crest. Bulging and back-tilting are also observed on the upthrown side at many places. The surface rupture is subdivided into three geometrical segments separated by small steps. Location of the hypocenter suggests that the rupture was initiated at a deep portion of the northern-central segment boundary and bilaterally propagated to eventually break three segments. Mapped surface rupture trace clearly shows that neither the Himalayan Frontal Thrust (HFT) nor the Main Boundary Thrust (MBT) is responsible for the earthquake, but a geomorphologically-evident active fault within the Sub-Himalaya, the Balakot-Garhi fault, is a causative fault, although a part of the Balakot-Garhi fault appears to coincide with the surface trace of the MBT. Cumulative vertical separation of the most extensively recognized fluvial terrace surface is 7-8 times larger than the 2005 separation, implying occurrence of 7-8 similar earthquakes after the surface abandonment. If this deeply-incised fill surface is related to sediment yield increase due to the last major glaciation around 20 ka, the rupture interval and vertical slip rate of the Balakot-Garhi fault are estimated to be on the order of ~3000 years and ~1 mm/yr, respectively. By using the seismologically determined fault dip of ~30 degrees, horizontal shortening rate across the fault is then

  20. Magma-tectonic interactions in an area of active extension; a review of recent observations, models and interpretations from Iceland

    NASA Astrophysics Data System (ADS)

    Pedersen, Rikke; Sigmundsson, Freysteinn; Drouin, Vincent; Rafn Heimisson, Elías; Parks, Michelle; Dumont, Stéphanie; Árnadóttir, Þóra; Masterlark, Timothy; Ófeigsson, Benedíkt G.; Jónsdóttir, Kristín; Hooper, Andrew

    2016-04-01

    The geological setting of Iceland provides rich opportunities of studying magma-tectonic interactions, as it constitutes Earth's largest part of the mid-oceanic ridge system exposed above sea level. A series of volcanic and seismic zones accommodate the ~2 cm/year spreading between the North-American and Eurasian plates, and the Icelandic hot-spot conveniently provides the means of exposing this oceanic crust-forming setting above sea-level. Both extinct and active plumbing system structures can be studied in Iceland, as the deeply eroded tertiary areas provide views into the structures of extinct volcanic systems, and active processes can be inferred on in the many active volcanic systems. A variety of volcanic and tectonic processes cause the Icelandic crust to deform continuously, and the availability of contemporaneous measurements of crustal deformation and seismicity provide a powerful data set, when trying to obtain insight into the processes working at depth, such as magma migration through the uppermost lithosphere, magma induced host rock deformation and volcanic eruption locations and styles. The inferences geodetic and seismic datasets allow on the active plate spreading processes and subsurface magma movements in Iceland will be reviewed, in particular in relation to the Northern Volcanic Zone (NVZ). There the three phases of a rifting cycle (rifting, post-rifting, inter-rifting) have been observed. The NVZ is an extensional rift segment, bounded to the south by the Icelandic mantle plume, and to the north by the Tjörnes transform zone. The NVZ has typically been divided into five partly overlapping en-echelon fissure swarms, each with a central main volcanic production area. Most recently, additional insight into controlling factors during active rifting has been provided by the Bárðarbunga activity in 2014-2015 that included a major rifting event, the largest effusive eruption in Iceland since 1783, and a gradual caldera collapse. It is evident

  1. Numerical modelling of non-transform discontinuity geometry: Implications for ridge structure, volcano-tectonic fabric development and hydrothermal activity at segment ends

    NASA Astrophysics Data System (ADS)

    Tyler, Stephen; Bull, Jonathan M.; Parson, Lindsay M.; Tuckwell, George W.

    2007-05-01

    Ocean ridge discontinuities partition and offset spreading centres at a range of scales. Large scale discontinuities (10's-100's km) are synonymous with first-order transform faults, which have well defined linear fault zone valleys. In contrast, Non-Transform Discontinuities (NTDs) are diffuse, smaller scale offsets (0 to < 20 km), characterised by central basins or topographic highs. The geometry of NTD offsets can be categorised by the sense of offset, either right-stepping or left-stepping, and by the relative positions of the segment tips. The segment tip configurations include under-lapping, over-lapping or simple across-axis jumps or stepping in the ridge axis. In this study finite difference software is used to model segment geometry at a slow-spreading ridge under a normal tensile-stress within a homogeneous and isotropic medium. Along- and across-axis segment separations were varied incrementally for left- and right-stepping senses. The results show that the ratio of along-axis to across-axis segment tip separation is a dominant control of stress field rotation within an NTD. Features which most clearly show rotation within an NTD include basins and tectonically controlled constructional ridges. The obliquity of these features along with measurements of the surrounding fault fabrics are used as a way of observing and determining stress rotations within NTDs along the Central Indian Ridge (CIR). These rotations were used to obtain segment geometries from models where the central tensor showed an equivalent rotation. The results show that geometry has a profound effect on stress field rotation under which large- and small-scale volcano-tectonic fabrics form. In addition, a shortfall of the predicted model tip relative to interpreted positions, along with morphology and observation of the ridge fabrics at the terminations to some segments, suggests the existence of a zone, broadly analogous to the process zone observed in fracture mechanics, which we call a

  2. Actively controlled multiple-sensor system for feature extraction

    NASA Astrophysics Data System (ADS)

    Daily, Michael J.; Silberberg, Teresa M.

    1991-08-01

    Typical vision systems which attempt to extract features from a visual image of the world for the purposes of object recognition and navigation are limited by the use of a single sensor and no active sensor control capability. To overcome limitations and deficiencies of rigid single sensor systems, more and more researchers are investigating actively controlled, multisensor systems. To address these problems, we have developed a self-calibrating system which uses active multiple sensor control to extract features of moving objects. A key problem in such systems is registering the images, that is, finding correspondences between images from cameras of differing focal lengths, lens characteristics, and positions and orientations. The authors first propose a technique which uses correlation of edge magnitudes for continuously calibrating pan and tilt angles of several different cameras relative to a single camera with a wide angle field of view, which encompasses the views of every other sensor. A simulation of a world of planar surfaces, visual sensors, and a robot platform used to test active control for feature extraction is then described. Motion in the field of view of at least one sensor is used to center the moving object for several sensors, which then extract object features such as color, boundary, and velocity from the appropriate sensors. Results are presented from real cameras and from the simulated world.

  3. Learning Behavior Characterization with Multi-Feature, Hierarchical Activity Sequences

    ERIC Educational Resources Information Center

    Ye, Cheng; Segedy, James R.; Kinnebrew, John S.; Biswas, Gautam

    2015-01-01

    This paper discusses Multi-Feature Hierarchical Sequential Pattern Mining, MFH-SPAM, a novel algorithm that efficiently extracts patterns from students' learning activity sequences. This algorithm extends an existing sequential pattern mining algorithm by dynamically selecting the level of specificity for hierarchically-defined features…

  4. Unconscious Semantic Activation Depends on Feature-Specific Attention Allocation

    ERIC Educational Resources Information Center

    Spruyt, Adriaan; De Houwer, Jan; Everaert, Tom; Hermans, Dirk

    2012-01-01

    We examined whether semantic activation by subliminally presented stimuli is dependent upon the extent to which participants assign attention to specific semantic stimulus features and stimulus dimensions. Participants pronounced visible target words that were preceded by briefly presented, masked prime words. Both affective and non-affective…

  5. Unconscious Semantic Activation Depends on Feature-Specific Attention Allocation

    ERIC Educational Resources Information Center

    Spruyt, Adriaan; De Houwer, Jan; Everaert, Tom; Hermans, Dirk

    2012-01-01

    We examined whether semantic activation by subliminally presented stimuli is dependent upon the extent to which participants assign attention to specific semantic stimulus features and stimulus dimensions. Participants pronounced visible target words that were preceded by briefly presented, masked prime words. Both affective and non-affective…

  6. Masked Primes Activate Feature Representations in Reading Aloud

    ERIC Educational Resources Information Center

    Mousikou, Petroula; Roon, Kevin D.; Rastle, Kathleen

    2015-01-01

    Theories of reading aloud are silent about the role of subphonemic/subsegmental representations in translating print to sound. However, there is empirical evidence suggesting that feature representations are activated in speech production and visual word recognition. In the present study, we sought to determine whether masked primes activate…

  7. Masked Primes Activate Feature Representations in Reading Aloud

    ERIC Educational Resources Information Center

    Mousikou, Petroula; Roon, Kevin D.; Rastle, Kathleen

    2015-01-01

    Theories of reading aloud are silent about the role of subphonemic/subsegmental representations in translating print to sound. However, there is empirical evidence suggesting that feature representations are activated in speech production and visual word recognition. In the present study, we sought to determine whether masked primes activate…

  8. Post 12 Ma tectonic activity of the Subalpine Molasse resolved by combining thermochronology and critical wedge analysis

    NASA Astrophysics Data System (ADS)

    von Hagke, C.; Oncken, O.; Ortner, H.; Cederbom, C.

    2012-04-01

    Thermochronological studies in the Northern Alpine Foreland Basin show that the folded and thrusted part of the basin, the Subalpine Molasse (SM), has been tectonically active during the last 12 Ma (Cederbom, C. E. et al., 2011; von Hagke, C. et al., in review). However, the amount of erosion and timing of thrusting is so far only reported from the Swiss Molasse basin. To test whether this is a local signal and whether climate contributed to this thrusting, we report thermochronological data from a profile south of Lake Constance and analyse the results in the framework of critical taper theory. We selected the Bregenzerach stream as suitable study area because it is one of the few profiles, which provides excellent outcrops in all stratigraphic units of the SM and is located east of the Jura fold and thrust belt, north of the Eastern Alps. We present new apatite (U-Th-Sm)/He (AHe) and apatite fission track (AFT) data. In contrast to the Central Alps, the new data do not show full resetting of the AFT system. This demonstrates that the eastern SM has experienced less erosion than the central SM. The AHe system in contrast, shows complete resetting also in the eastern SM. We observe age-offsets across the same thrusts which have been reactivated in the central SM. This confirms that the SM of the Eastern Alps must have been tectonically active until at least 5 Ma, as is also known from the central SM. This implies reactivation of thrusts, which formed originally in mid to late Miocene times. From critical taper analysis, reactivation of thrusting (assuming constant dip of the basal detachment through time) can only be obtained (1) by an increase of basal detachment strength or (2) a decrease of surface slope. An increase of detachment strength through time is either possible due to jumping of the detachment to another stratigraphic level or a change in pore fluid pressure. A decrease in surface slope is either tectonic- or erosion-controlled. We show that today the

  9. Accurate relocation of seismicity along the North Aegean Trough and its relation to active tectonics

    NASA Astrophysics Data System (ADS)

    Konstantinou, K. I.

    2017-10-01

    The tectonics of northern Aegean are affected by the westward push of Anatolia and the gravitational spreading of the Aegean lithosphere that promote transtensional deformation in the area. This regime is also responsible for the creation of a series of pull-apart basins, collectively known as the North Aegean Trough. This work accurately relocates a total of 2300 earthquakes that were recorded along the North Aegean Trough during 2011-2016 by stations of the Hellenic Unified Seismic Network (HUSN) and strong-motion sensors. Absolute locations for these events were obtained using a nonlinear probabilistic algorithm and utilizing a minimum 1D velocity model with station corrections. The hypocentral depth distribution of these events shows a peak at 8 km diminishing gradually down to 20 km. A systematic overestimation of hypocentral depths is observed in the routine locations provided by the National Observatory of Athens where the majority of events appear to be deeper than 15 km. In order to obtain more accurate relative locations these events were relocated using the double-difference method. A total of 1693 events were finally relocated with horizontal and vertical uncertainties that do not exceed 0.11 km and 0.22 km respectively. Well-defined clusters of seismicity can be observed along the Saros and Sporades basins as well as the Kassandra and Sithonia peninsulas. These clusters either occur along the well-known NE-SW strike-slip faults bounding the basins, or along normal faults whose strike is perpendicular to the regional minimum stress axis. Locking depth along the North Aegean Trough is found to be remarkably stable between 13 and 17 km. This is likely a consequence of simultaneous reduction along the SW direction of heat flow (from 89 to 51 mW/m2) and strain rate (from 600 to 50 nstrain/yr) whose opposite effects are canceled out, precluding any sharp changes in locking depth.

  10. Provenance and sediment-dispersal system in tectonically active rapidly evolving foreland basin, Western Interior

    SciTech Connect

    Khandaker, N.I.; Vondra, C.F.

    1989-03-01

    The Upper Cretaceous Frontier Formation, along the mobile edge of the Western Interior foreland basin, is composed mainly of clastic sediments and was deposited during the initial Late Cretaceous transgressive-regressive phases of the Western Interior seaway across Wyoming. The formation contains many persistent bentonite beds and several sandstone packages in its lower part and a thin, lenticular lithic wacke-polymictic conglomerate association at its upper contact (Torchlight Sandstone Member). Abundant granule to cobble-sized clasts of andesite, granite, chert, and quartzite are set in a poorly sorted sand-to-granule grade volcaniclastic matrix. There is a lithologic continuity of this volcaniclastic unit across the Bighorn Mountains into the Powder River basin. A high-energy distributary complex of sizable areal extent is invoked for the deposition of this linear conglomerate facies. Geochemical investigations of the whole-rock andesite clasts and bentonite allowed more precise definition of character, tectonic setting, and evolutionary stages of sedimentary distributive provinces. Bentonites and andesites are strongly enriched in strontium and barium, but only mildly enriched in heavy rare earth elements and high field-strength elements. These analyzed rocks have trace element characteristics similar in a general way to those of typical orogenic volcanics; they show some significant differences in detail. Composition of volcaniclasts and paleocurrent data indicate a proximal sediment source for the extrabasinal detritus within the Frontier Formation. The possibility of a contribution from a Mesozoic volcanic center in the neighborhood of southwestern Montana is strongly favored. The products of this volcanism constitute an assemblage of deep crustal to mantle( ) derived rocks, and their composition record time-integrated enrichment in light over heavy rare earth elements.

  11. Variations of fluvial tufa sub-environments in a tectonically active basin, Pleistocene Teruel Basin, NE Spain

    NASA Astrophysics Data System (ADS)

    Camuera, Jon; Alonso-Zarza, Ana M.; Rodríguez-Berriguete, Álvaro; Meléndez, Alfonso

    2015-12-01

    The Pleistocene Tortajada fluvial deposit occurs in the eastern active margin of the Teruel Basin. It developed in the early stages of opening of the basin and at present is disconnected to the Alfambra River. The preserved deposits show that the fluvial system consisted in three different sub-environments including: Upper Terraces, Ponds and Cascades. The main facies are framestones of stems, phytoclastic rudstone, framestone of bryophytes, peloidal and filamentous stromatolites, mudstone and detrital (conglomerates and slope-breccias) facies. These facies are arranged in three different sequence types, all of them showing a lower detrital term followed by pond and, in cases, cascade deposits. The microfacies analyses reveal that both biotic and abiotic processes performed an important role in the deposition within the river. Isotopic analyses (δ18O from - 8.58‰ to - 6.70‰ VPDB and δ13C from - 7.44‰ to - 3.97‰ VPDB) are indicative of meteoric water within a hydrologically open system. The carbonate hinterland rocks, together with a semi-arid to sub-humid climate favored carbonate accumulation within the river. Our results point out that the location, morphology and sedimentary sequences of the Tortajada fluvial system had an important tectonic control. The situation of the main and secondary faults controlled the paleomorphology of the river floor. Thus cascades are found in areas of important step faults, whereas the spaces between faults were occupied by fluviatile/lacustrine areas. In addition the development of the different sedimentary sequences was also a reflection of movements of these faults. In short, our study may confirm that tectonism is an important control on tufa development.

  12. Active tectonic deformation of the western Indian plate boundary: A case study from the Chaman Fault System

    NASA Astrophysics Data System (ADS)

    Crupa, Wanda E.; Khan, Shuhab D.; Huang, Jingqiu; Khan, Abdul S.; Kasi, Aimal

    2017-10-01

    Collision of the Eurasian and Indian plates has resulted in two spatially offset subduction zones, the Makran subduction zone to the south and the Himalayan convergent margin to the north. These zones are linked by a system of left-lateral strike-slip faults known as the Chaman Fault System, ∼1200 km, which spans along western Pakistan. Although this is one of the greatest strike-slip faults, yet temporal and spatial variation in displacement has not been adequately defined along this fault system. This study conducted geomorphic and geodetic investigations along the Chaman Fault in a search for evidence of spatial variations in motion. Four study areas were selected over the span of the Chaman Fault: (1) Tarnak-Rud area over the Tarnak-Rud valley, (2) Spinatizha area over the Spinatizha Mountain Range, (3) Nushki area over the Nushki basin, and (4) Kharan area over the northern tip of the Central Makran Mountains. Remote sensing data allowed for in depth mapping of different components and faults within the Kohjak group. Wind and water gap pairs along with offset rivers were identified using high-resolution imagery and digital-elevation models to show displacement for the four study areas. The mountain-front-sinuosity ratio, valley height-to-width-ratio, and the stream-length-gradient index were calculated and used to determine the relative tectonic activity of each area. These geomorphic indices suggest that the Kharan area is the most active and the Tarnak-Rud area is the least active. GPS data were processed into a stable Indian plate reference frame and analyzed. Fault parallel velocity versus fault normal distance yielded a ∼8-10 mm/yr displacement rate along the Chaman Fault just north of the Spinatizha area. InSAR data were also integrated to assess displacement rates along the fault system. Geodetic data support that ultra-slow earthquakes similar to those that strike along other major strike-slip faults, such as the San Andreas Fault System, are

  13. Plate tectonics conserves angular momentum

    NASA Astrophysics Data System (ADS)

    Bowin, C.

    2010-03-01

    velocity on the crests of convection cells driven by rising heat. The magnitude of these sinking mass anomalies is inferred also to be sufficient to overcome basal plate and transform fault frictions. These results imply that spreading centers are primarily passive reactive features, and fracture zones (and wedge-shaped sites of seafloor spreading) are adjustment zones that accommodate strains in the lithosphere. Further, the interlocked pattern of the Australian and Pacific plates the past 42 Million years (with their absolute plate motions near 90° to each other) is taken as strong evidence that large thermally driven "roller" convection cells previously inferred as the driving mechanism in earlier interpretations of continental drift and plate tectonics, have not been active in the Earth's mantle the past 42 Million years, if ever. This report also presents estimates of the changes in location and magnitude of the Earth's axis of total plate tectonic angular momentum for the past 62 million years.

  14. Spiral tectonics

    NASA Astrophysics Data System (ADS)

    Hassan Asadiyan, Mohammad

    2014-05-01

    Spiral Tectonics (ST) is a new window to global tectonics introduced as alternative model for Plate Tectonics (PT). ST based upon Dahw(rolling) and Tahw(spreading) dynamics. Analogues to electric and magnetic components in the electromagnetic theory we could consider Dahw and Tahw as components of geodynamics, when one component increases the other decreases and vice versa. They are changed to each other during geological history. D-component represents continental crust and T-component represents oceanic crust. D and T are two arm of spiral-cell. T-arm 180 degree lags behind D-arm so named Retard-arm with respect to D or Forward-arm. It seems primary cell injected several billions years ago from Earth's center therefore the Earth's core was built up first then mantel and finally the crust was build up. Crust building initiate from Arabia (Mecca). As the universe extended gravitation wave swirled the earth fractaly along cycloid path from big to small scale. In global scale (order-0) ST collect continents in one side and abandoned Pacific Ocean in the other side. Recent researches also show two mantels upwelling in opposite side of the Earth: one under Africa (tectonic pose) and the other under Pacific Ocean (tectonic tail). In higher order (order-1) ST build up Africa in one side and S.America in the other side therefore left Atlantic Ocean meandered in between. In order-n e.g. Khoor Musa and Bandar-Deylam bay are seen meandered easterly in the Iranian part but Khoor Abdullah and Kuwait bay meandered westerly in the Arabian part, they are distributed symmetrically with respect to axis of Persian Gulf(PG), these two are fractal components of easterly Caspian-wing and westerly Black Sea-wing which split up from Anatoly. Caspian Sea and Black Sea make two legs of Y-like structure, this shape completely fitted with GPS-velocity map which start from PG and split up in the Catastrophic Point(Anatoly). We could consider PG as remnants of Ancient Ocean which spent up

  15. Tectonic versus eustatic control on Neogene sedimentation in the Cibao basin of the Dominican Republic: Tectonic dominance near an active plate boundary

    SciTech Connect

    Erikson, J.P. )

    1991-03-01

    Continuous Neogene subsidence, transgression, and brief periods of accelerated subsidence are indicated by the Yaque Group sediments of the Cibao basin of northern Dominican Republic, in which the generally fining-upward sediments are punctuated by two, thick, conglomeratic sequences. Lithologic and paleontologic evidence support continuous subsidence and a tectonic control on sedimentation and is in conflict with an interpretation of one or both of the conglomeratic sequences as being due to a rapid regressive-transgressive cycle and a correlation with a second-order fluctuation (supercycle) on a Vail-type sea-level curve. Subsidence generally outpaced sedimentation, such that water depths almost continuously increased during deposition of all but the uppermost Yaque Group (when the basin shallowed prior to the subaerial exposure), as interpreted from detailed paleontological analyses. The depositional history of the entire {approximately}1 km exposed section and {approximately}5 km subsurface section of the Yaque Group is best explained by a single, continuous, east to west, middle Miocene to earliest Pliocene transgression due to asymmetric basin subsidence. Deposition of the igneous clast-rich conglomerates was probably caused by accelerated basement subsidence at the northern edge of the basin, which oversteepened the depositional slope, led to accelerated transgression of the northern flank of the Central Cordillera, and produced brief pulses of coarse, partially Cordilleran-derived conglomerates. Varying subsidence of the Cibao basin is correlated with episodic uplift and sedimentation in the Cordillera Septentrional.

  16. Tectonic interpretation of the 13 february 2001, mw 6.6, El Salvador Earthquake: New evidences of coseismic surface rupture and paleoseismic activity.

    NASA Astrophysics Data System (ADS)

    Martinez-Diaz, J. J.; Canora, C.; Villamor, P.; Capote, R.; Alvarez-Gomez, J. A.; Berryman, K.; Bejar, M.; Tsige, M.

    2009-04-01

    In February 2001 a major strike slip earthquake stroke the central part of El Salvador causing hundreds of people killed, thousands injured and extensive damage. After this event the scientific effort was mainly focused on the study of the enormous and catastrophic landslides triggered by this event and no evidences of surface faulting were detected. This earthquake was produced by the reactivation of the Ilopango-San Vicente segment of the El Salvador Fault Zone. Recently, a surface rupture displacement on the ground was identified. The analysis of aerial and field photographs taken few hours after the event and the mapping of the conserved ground structures shows a pure strike-slip displacement ranging from 20 to 50 cm, with secondary features indicating dextral shearing. The paleoseismic analysis made through the excavation of six trenches and Radiocarbon dating indicate a minimum slip rate of 2.0 mm/yr and a recurrence of major ruptures (Mw > 6.5) lower than 500 yr. These evidences give interesting local data to increase our understanding about the tectonic behavior and the way how active deformation develops along the northern limit of the forearc sliver related to the Centroamerican subduction area.

  17. An objective method for the assessment of fluid injection-induced seismicity and application to tectonically active regions in central California

    NASA Astrophysics Data System (ADS)

    Goebel, T. H. W.; Hauksson, E.; Aminzadeh, F.; Ampuero, J.-P.

    2015-10-01

    Changes in seismicity rates, whether of tectonic or of induced origin, can readily be identified in regions where background rates are low but are difficult to detect in seismically active regions. We present a novel method to identify likely induced seismicity in tectonically active regions based on short-range spatiotemporal correlations between changes in fluid injection and seismicity rates. The method searches through the entire parameter space of injection rate thresholds and determines the statistical significance of correlated changes in injection and seismicity rates. Applying our method to Kern County, central California, we find that most earthquakes within the region are tectonic; however, fluid injection contributes to seismicity in four different cases. Three of these are connected to earthquake sequences with events above M4. Each of these sequences followed an abrupt increase in monthly injection rates of at least 15,000 m3. The probability that the seismicity sequences and the abrupt changes in injection rates in Kern County coincide by chance is only 4%. The identified earthquake sequences display low Gutenberg-Richter b values of ˜0.6-0.7 and at times systematic migration patterns characteristic for a diffusive process. Our results show that injection-induced pressure perturbations can influence seismic activity at distances of 10 km or more. Triggering of earthquakes at these large distances may be facilitated by complex local geology and faults in tectonically active regions. Our study provides the first comprehensive, statistically robust assessment of likely injection-induced seismicity within a large, tectonically active region.

  18. Active tectonics of the Atacama Basin area, northern Chile: Implications for distribution of convergence across the central Andes

    NASA Astrophysics Data System (ADS)

    Chuang, Yi-Rung; Lin, Yen-Sheng; Shyu, J. Bruce H.

    2013-04-01

    The central Andes in South America is formed as the Nazca plate subducts northeastward beneath the South American plate along the Peru-Chile trench, parallel to the coastline. It has been shown that the convergence rate between the two plates is ~70-80 mm/yr, and about 10-15 mm/yr of the convergence is absorbed in the sub-Andean belt, east of the active volcanic arc. However, the convergence in the forearc region is still not well constrained. In order to understand how much convergence is absorbed in the forearc region, we analyzed the active tectonic characteristics of the Atacama Basin, just west of the active volcanic arc. With the help of various remote sensing datasets such as 30-m and 90-m resolution digital elevation models (DEM) produced from SRTM data, thermal infrared radiometer (TIR) ASTER images, Landsat, and Google Earth images, we identified many N-S trending compressional structures around the Atacama Basin. The active structures are found mainly in the northern and southern part of the basin. The structures in the north deformed many volcanic rocks at the surface, such as ignimbrites and several lava flows. Structures may extend southward to San Pedro de Atacama, the largest town in the Atacama Basin, and produced tectonic scarps inside the town. River terraces also formed in the hanging-wall block of the structures, north of San Pedro. From field surveys, we measured the offset amount of the structures and collected volcanic rocks in order to constrain the age of the deformation. These results enabled us to calculate the long-term deformation rate of the structures. Our results indicate that the long-term slip rate of the structures in the southern part of the basin is quite low, in the order of 10-1 mm/yr. Furthermore, we obtained detailed topographic profiles across the structures. In the south, the profiles were surveyed by using real-time kinematic (RTK) GPS. Together with the attitudes of bedding planes, we constructed the subsurface geometry

  19. Tectonic database and plate tectonic model of the former USSR territory

    SciTech Connect

    Bocharova, N.Yu.; Scotese, C.R.; Pristavakina, E.I.; Zonenshain, L.P. . Center for Russian Geology and Tectonics)

    1993-02-01

    A digital geographic database for the former USSR was compiled using published geologic and geodynamic maps and the unpublished suture map of Lev Zonenshain (1991). The database includes more than 900 tectonic features: strike-slip faults, sutures, thrusts, fossil and active rifts, fossil and active subduction zones, boundaries of the major and minor Precambrian blocks, ophiolites, and various volcanic complexes. The attributes of each structural unit include type of structure, name, age, tectonic setting and geographical coordinates. Paleozoic and Early Mesozoic reconstructions of the former USSR and adjacent regions were constructed using this tectonic database together with paleomagnetic data and the motions of continent over fixed hot spots. Global apparent polar wander paths in European and Siberian coordinates were calculated back to Cambrian time, using the paleomagnetic pole summaries of Van der Voo (1992) and Khramov (1992) and the global plate tectonic model of the Paleomap Project (Scotese and Becker, 1992). Trajectories of intraplate volcanics in South Siberia, Mongolia, Scandinavia and data on the White Mountain plutons and Karoo flood basalts were also taken into account. Using new data, the authors recalculated the stage and finite poles for the rotation of the Siberia and Europe with respect to the hot spot reference frame for the time interval 160 to 450 Ma.

  20. Active tectonics in northern Victoria Land (Antarctica) inferred from the integration of GPS data and geologic setting

    NASA Astrophysics Data System (ADS)

    Dubbini, M.; Cianfarra, P.; Casula, G.; Capra, A.; Salvini, F.

    2010-12-01

    A semipermanent Global Positioning System (GPS) network of 30 vertices known as the Victoria Land Network for Deformation Control (VLNDEF) was set up in the Austral summer of 1998 in northern Victoria Land (NVL), including Terra Nova Bay (TNB), Antarctica. The locations were selected according to the known Cenozoic fault framework, which is characterized by a system of NW-SE regional faults with right-lateral, strike-slip kinematics. The TNB1 permanent GPS station is within the VLNDEF, and following its installation on a bedrock monument in October 1998, it has been recording almost continuously. The GPS network has been surveyed routinely every two summers, using high-quality, dual-frequency GPS receivers. In this study we present the results of a distributed session approach applied to the processing of the GPS data of the VLNDEF. An improved reference frame definition was implemented, including a new Euler pole, to compute the Antarctic intraplate residual velocities. The projection of the residual velocities on the main faults in NVL show present-day activities for some faults, including the Tucker, Leap Year, Lanterman, Aviator, and David faults, with right-lateral strike-slip kinematics and local extensional and compressional components. This active fault pattern divides NVL into eight rigid blocks, each characterized by its relative movements and rigid rotations. These show velocities of up to several millimeters per year, which are comparable to those predicted by plate tectonic theory at active plate margins.

  1. Application of musical timbre discrimination features to active sonar classification

    NASA Astrophysics Data System (ADS)

    Young, Victor W.; Hines, Paul C.; Pecknold, Sean

    2005-04-01

    In musical acoustics significant effort has been devoted to uncovering the physical basis of timbre perception. Most investigations into timbre rely on multidimensional scaling (MDS), in which different musical sounds are arranged as points in multidimensional space. The Euclidean distance between points corresponds to the perceptual distance between sounds and the multidimensional axes are linked to measurable properties of the sounds. MDS has identified numerous temporal and spectral features believed to be important to timbre perception. There is reason to believe that some of these features may have wider application in the disparate field of underwater acoustics, since anecdotal evidence suggests active sonar returns from metallic objects sound different than natural clutter returns when auralized by human operators. This is particularly encouraging since attempts to develop robust automatic classifiers capable of target-clutter discrimination over a wide range of operational conditions have met with limited success. Spectral features relevant to target-clutter discrimination are believed to include click-pitch and envelope irregularity; relevant temporal features are believed to include duration, sub-band attack/decay time, and time separation pitch. Preliminary results from an investigation into the role of these timbre features in target-clutter discrimination will be presented. [Work supported by NSERC and GDC.

  2. Interplay between active and past tectonics in the Hellenic Arc (Greece): Geological and geomorphic evidences from Kythira Island

    NASA Astrophysics Data System (ADS)

    Fernández-Blanco, David; de Gelder, Gino; Delorme, Arthur; Lacassin, Robin; Armijo, Rolando

    2016-04-01

    The Hellenic Arc undergoes the largest convergence velocity and highest seismic activity among Mediterranean subduction systems. The outer-arc high islands of the Hellenic Arc are thus key to understand the mode of deformation of the crust during subduction and the mechanisms behind vertical motions at the front of overriding plates, here and elsewhere. Kythira Island, located between SW Peloponnese and NE Crete, provides an exceptional opportunity to understand the interaction between past and active tectonics in the Hellenic Arc. The recent uplift of the Kythira Island is marked in its landscape as paleosurfaces, marine terraces, abandon valleys and gorges. Together with the sedimentary record of the island and its geologic structures, we attempt to reconstruct its tectonic evolution since the latest Miocene. Here, we present exceptionally detailed geological and geomorphological maps of the Kythira Island based on fieldwork, Pleiades satellite imagery and 2-m resolution DEM, as well as the analyses of marine terraces and river network morphometrics. Pliocene or younger infill sequences rest atop of Palaeocene or older rocks in several marine basins in the island. In the largest marine basin, we found a stratigraphic sequence with a (tilted) continental conglomerate at the base, passing upwards to a disconformal subhorizontal conglomerate, calcarenites and fine sands, and terminating with a marine conglomerate. This marine conglomerate acts as a "cap rock" that marks the topography and shapes the highermost, and most extensive, low-relief surface. Overall, the infill sequence onlaps basement with the exception of the western margin where normal faults partly controlled the deposition of its lower sector. These faults reactivated older Hellenic fold-and-thrust structures, parallel to the subduction trench, and were not active during the maximum marine transgression that led to the deposition of the subhorizontal part of the infill sequence, including the topmost

  3. A tectonic resurfacing model for Venus

    NASA Technical Reports Server (NTRS)

    Solomon, Sean C.

    1993-01-01

    Two remarkable aspects of the population of impact craters on Venus are that craters at all sizes are indistinguishable from a random population and that the vast majority of craters have not been significantly modified by tectonic strain or by volcanic flows external to the crater rim, despite evidence from Magellan images that volcanic and tectonic features are widespread on Venus. One interpretation of these observations is that most of the surface dates from the end of a catastrophic global resurfacing event that ceased about 500 My ago, and that the small fraction of craters volcanically embayed or modified by deformation indicates that volcanic and tectonic activity subsequent to that time has been at much lower levels. An alternative model, in which resurfacing occurs episodically in patches a few hundred kilometers in extent and there is a wider spectrum of surface ages, also appears to be consistent with the characteristics of impact craters on Venus. A number of potential mechanisms for catastrophic resurfacing of Venus have been proposed, ranging from geologically sudden convective destabilization of the global lithosphere to strongly time-dependent heat flux and melt generation in the underlying mantle. In most of these geophysical models, resurfacing occurs implicitly or explicitly by volcanism. We explore the hypothesis that, at least in the geologically recent history of Venus, the primary resurfacing mechanism has been tectonic deformation rather than volcanism. We show how such a hypothesis provides at least as good an explanation of a wide range of observations as do volcanic resurfacing models. Finally, we explore the implications of tectonic resurfacing hypothesis for the controversy over the recent resurfacing history of the planet.

  4. A tectonic resurfacing model for Venus

    NASA Technical Reports Server (NTRS)

    Solomon, Sean C.

    1993-01-01

    Two remarkable aspects of the population of impact craters on Venus are as follows: that craters at all sizes are indistinguishable from a random population; and that the vast majority of craters have not been significantly modified by tectonic strain or by volcanic flows external to the crater rim, despite evidence from Magellan images that volcanic and tectonic features are widespread on Venus. One interpretation of these observations is that most of the surface dates from the end of a catastrophic global resurfacing event that ceased about 500 My ago, and that the small fraction of craters volcanically embayed or modified by deformation indicates that volcanic and tectonic activity subsequent to that time has been at much lower levels. An alternative model, in which resurfacing occurs episodically in patches a few hundred kilometers in extent and there is a wider spectrum of surface ages, also appears to be consistent with the characteristics of impact craters on Venus. A number of potential mechanisms for catastrophic resurfacing of Venus have been proposed ranging from geologically sudden convective destabilization of the global lithosphere to strongly time-dependent heat flux and melt generation in the underlying mantle. In most of these geophysical models, resurfacing occurs implicitly or explicitly by volcanism. We explore here the hypothesis that, at least in the geologically recent history of Venus, the primary resurfacing mechanism has been tectonic deformation rather than volcanism. We show how such a hypothesis provides at least as good an explanation of a wide range of observations as do volcanic resurfacing models. Finally, we explore the implications of the tectonic resurfacing hypothesis for the controversy over the recent resurfacing history of the planet.

  5. Episodic Cenozoic volcanism and tectonism in the Andes of Peru

    USGS Publications Warehouse

    Noble, D.C.; McKee, E.H.; Farrar, E.; Petersen, U.

    1974-01-01

    Radiometric and geologic information indicate a complex history of Cenozoic volcanism and tectonism in the central Andes. K-Ar ages on silicic pyroclastic rocks demonstrate major volcanic activity in central and southern Peru, northern Chile, and adjacent areas during the Early and Middle Miocene, and provide additional evidence for volcanism during the Late Eocene. A provisional outline of tectonic and volcanic events in the Peruvian Andes during the Cenozoic includes: one or more pulses of igneous activity and intense deformation during the Paleocene and Eocene; a period of quiescence, lasting most of Oligocene time; reinception of tectonism and volcanism at the beginning of the Miocene; and a major pulse of deformation in the Middle Miocene accompanied and followed through the Pliocene by intense volcanism and plutonism. Reinception of igneous activity and tectonism at about the Oligocene-Miocene boundary, a feature recognized in other circum-Pacific regions, may reflect an increase in the rate of rotation of the Pacific plate relative to fixed or quasifixed mantle coordinates. Middle Miocene tectonism and latest Tertiary volcanism correlates with and probably is genetically related to the beginning of very rapid spreading at the East Pacific Rise. ?? 1974.

  6. Two primes priming: does feature integration occur before response activation?

    PubMed

    Grainger, Julianne E; Scharnowski, Frank; Schmidt, Thomas; Herzog, Michael H

    2013-07-17

    Responses to a target can be sped up or slowed down by a congruent or incongruent prime, respectively. Even though presentations are rapid, the prime and the target are thought to activate motor responses in strict sequence, with prime activation preceding target activation. In feature fusion, the opposite seems to be the case. For example, a vernier offset to the left is immediately followed by a vernier offset to the right at the same location. The two verniers are not perceived as two elements in sequence but as a single, aligned vernier. Here, we ask the question as to how features are integrated: before or after motor activation? We presented two vernier primes with opposite offset directions preceding a single vernier target. No priming effect occurred when the vernier primes were presented at the same location, indicating that verniers integrate before motor activation. There was also no priming effect when the primes were presented simultaneously at different locations, indicating that there is an integration stage different from the perceptual fusion stage. When the second prime is delayed, it determines priming, even for very long delays. To explain these long integration times, we argue that there is a buffer preceding motor activation.

  7. Role of tectonic and volcanic activity in hydrothermal systems at the southern Mariana Trough: detailed bathymetric characteristics of the hydrothermal sites

    NASA Astrophysics Data System (ADS)

    Yoshikawa, S.; Okino, K.; Asada, M.; Nogi, Y.; Mochizuki, N.; Nakamura, K.

    2012-12-01

    We present the detailed bathymetric characterization of field-scale geological features associated with hydrothermal systems in the southern Mariana Trough near 12°57'N, 143°37'E, using near-bottom swath mapping data collected by the autonomous underwater vehicle (AUV) Urashima during cruise YK09-08 and dive observation data acquired by the submersible Shinkai6500 during cruise YK10-11. In the study area, two of the hydrothermal sites are located on the active backarc spreading axis (the Snail and Yamanaka sites), one is located at the eastern foot of the axial high (the Archean site), and two are located on an off-axis knoll about 5 km from the spreading axis (the Pika and Urashima sites). We examined 1) the nature of' tectonic and volcanic controls on the hydrothermal systems, and 2) the relationship between geomorphological characteristics and hydrothermal activity based on the survey results (Yoshikawa et al., 2012). The two on-axis hydrothermal sites are possibly locally developed on a 4th order spreading segment, in association with diking events (on the basis of comparisons with previously studied cases on the East Pacific Rise). The three off-axis sites (the Archean, Urashima, and Pika sites) appear to represent locations of sustained hydrothermal activity that has created relatively large-scale hydrothermal features compared with those in the on-axis area. The formation of off-axis hydrothermal sites is likely to be closely related to an off-axis magma upwelling system, as evidenced by the absence of fault systems and the undeformed morphology of the mound and knoll. The three off-axis hydrothermal sites are composed mainly of breccia assemblages that probably originated from hydrothermal activity with black smoker venting. These areas are characterized by numerous ridge lines (height, mainly 1-6 m), conical mounds (height: < 100 m, diameter: < 300 m), and bumpy seabed. Most of the ridge lines have formed as a result of collapse of the seafloor. The

  8. Flare-Shaped Acoustic Anomalies in the Water Column Along the Ecuadorian Margin: Relationship with Active Tectonics and Gas Hydrates

    NASA Astrophysics Data System (ADS)

    Michaud, Francois; Proust, Jean-Noël; Dano, Alexandre; Collot, Jean-Yves; Guiyeligou, Grâce Daniella; Hernández Salazar, María José; Ratzov, Gueorgui; Martillo, Carlos; Pouderoux, Hugo; Schenini, Laure; Lebrun, Jean-Frederic; Loayza, Glenda

    2016-10-01

    With hull-mounted multibeam echosounder data, we report for the first time along the active Ecuadorian margin, acoustic signatures of water column fluid emissions and seep-related structures on the seafloor. In total 17 flare-shaped acoustic anomalies were detected from the upper slope (1250 m) to the shelf break (140 m). Nearly half of the flare-shaped acoustic anomalies rise 200-500 m above the seafloor. The base of the flares is generally associated with high-reflectivity backscatter patches contrasting with the neighboring seafloor. We interpret these flares as caused by fluid escape in the water column, most likely gases. High-resolution seismic profiles show that most flares occur close to the surface expression of active faults, deformed areas, slope instabilities or diapiric structures. In two areas tectonic deformation disrupts a Bottom Simulating Reflector (BSR), suggesting that buried frozen gas hydrates are destabilized, thus supplying free gas emissions and related flares. This discovery is important as it opens the way to determine the nature and origin of the emitted fluids and their potential link with the hydrocarbon system of the forearc basins along the Ecuadorian margin.

  9. Active Tectonics in the Central Chilean Andes: 3D Tomography Based on the Aftershock Sequence of the 28 August 2004 Shallow Crustal Earthquake

    NASA Astrophysics Data System (ADS)

    Comte, D.; Farias, M.; Charrier, R.; Gonzalez, A.

    2008-12-01

    Most of the seismological research in the Andes has been mainly oriented to the detection and understanding of the seismicity associated with megathrust earthquakes that characterize the subduction environment that governs the Andean tectonics. However, deployments of temporary networks have allowed the detection of intense crustal seismicity beneath the Chilean forearc-arc region. The temporary seismic network deployed along the Las Leñas and Pangal river valleys (34°25'S), between January and May 2004 permitted to better constrain the abundant shallow intra-continental seismicity previously detected in that region. Although most of the seismicity is randomly distributed in the region, several microearthquakes occur along the trace of the major El Fierro fault-system. This system is well recognized between 33°30' and 35°15'S and is located at or close to the eastern contact between Mesozoic and Cenozoic deposits in the Principal Cordillera and, locally, below active volcanoes, being considered to have participated in the extension and tectonic inversion of a widely extended (>600 km long) Cenozoic basin along the Principal Cordillera. Further south, at 35°S, a Mw=6.5 strike-slip shallow earthquake occurred on August 28, 2004, near of the headwater of the Teno river, close to the Planchon volcano. A 3D detailed Vp and Vs velocities determination was obtained along the 2004 earthquake aftershock area. The aftershocks are distributed along one branch of the El Fierro fault system, with a NNE-SSW direction and depths lower than 15 km. The rupture zone coincides with a sharp contrast in Vp and Vs, also in coincidence with the presence of hydrothermal fluids, gypsum diapers and the volcanic arc, suggesting rheological contrast controlling deformation. At the surface, this zone present an intense contractive deformation produced during the Neogene, which differs from what can be observed in other regions. Present day deformation related to seismicity has no

  10. Active tectonics of the Devils Mountain Fault and related structures, northern Puget Lowland and eastern Strait of Juan de Fuca region, Pacific Northwest

    USGS Publications Warehouse

    Johnson, Samuel Y.; Dadisman, Shawn V.; Mosher, David C.; Blakely, Richard J.; Childs, Jonathan R.

    2001-01-01

    Information from marine high-resolution and conventional seismic-reflection surveys, aeromagnetic mapping, coastal exposures of Pleistocene strata, and lithologic logs of water wells is used to assess the active tectonics of the northern Puget Lowland and eastern Strait of Juan de Fuca region of the Pacific Northwest. These data indicate that the Devils Mountain Fault and the newly recognized Strawberry Point and Utsalady Point faults are active structures and represent potential earthquake sources.

  11. Continental tectonics in the aftermath of plate tectonics

    NASA Technical Reports Server (NTRS)

    Molnar, Peter

    1988-01-01

    It is shown that the basic tenet of plate tectonics, rigid-body movements of large plates of lithosphere, fails to apply to continental interiors. There, buoyant continental crust can detach from the underlying mantle to form mountain ranges and broad zones of diffuse tectonic activity. The role of crustal blocks and of the detachment of crustal fragments in this process is discussed. Future areas of investigation are addressed.

  12. Continental tectonics in the aftermath of plate tectonics

    NASA Technical Reports Server (NTRS)

    Molnar, Peter

    1988-01-01

    It is shown that the basic tenet of plate tectonics, rigid-body movements of large plates of lithosphere, fails to apply to continental interiors. There, buoyant continental crust can detach from the underlying mantle to form mountain ranges and broad zones of diffuse tectonic activity. The role of crustal blocks and of the detachment of crustal fragments in this process is discussed. Future areas of investigation are addressed.

  13. Teaching Plate Tectonic Concepts using GeoMapApp Learning Activities

    NASA Astrophysics Data System (ADS)

    Goodwillie, A. M.; Kluge, S.

    2012-12-01

    GeoMapApp Learning Activities ( http://serc.carleton.edu/geomapapp/collection.html ) can help educators to expose undergraduate students to a range of earth science concepts using high-quality data sets in an easy-to-use map-based interface called GeoMapApp. GeoMapApp Learning Activities require students to interact with and analyse research-quality geoscience data as a means to explore and enhance their understanding of underlying content and concepts. Each activity is freely available through the SERC-Carleton web site and offers step-by-step student instructions and answer sheets. Also provided are annotated educator versions of the worksheets that include teaching tips, additional content and suggestions for further work. The activities can be used "off-the-shelf". Or, since the educator may require flexibility to tailor the activities, the documents are provided in Word format for easy modification. Examples of activities include one on the concept of seafloor spreading that requires students to analyse global seafloor crustal age data to calculate spreading rates in different ocean basins. Another activity has students explore hot spots using radiometric age dating of rocks along the Hawaiian-Emperor seamount chain. A third focusses upon the interactive use of contours and profiles to help students visualise 3-D topography on 2-D computer screens. A fourth activity provides a study of mass wasting as revealed through geomorphological evidence. The step-by-step instructions and guided inquiry approach reduce the need for teacher intervention whilst boosting the time that students can spend on productive exploration and learning. The activities can be used, for example, in a classroom lab with the educator present and as self-paced assignments in an out-of-class setting. GeoMapApp Learning Activities are funded through the NSF GeoEd program and are aimed at students in the introductory undergraduate, community college and high school levels. The activities are

  14. River drainage patterns in the New Zealand Alps primarily controlled by plate tectonic strain

    NASA Astrophysics Data System (ADS)

    Castelltort, Sébastien; Goren, Liran; Willett, Sean D.; Champagnac, Jean-Daniel; Herman, Frédéric; Braun, Jean

    2012-10-01

    River drainage patterns sculpt terrestrial landscapes. Whether these patterns contain fingerprints of past tectonic events is debated. On the one hand, elaborate dendritic river networks always retain an invariant structure, implying that rivers will simply reorganize in response to tectonic perturbations, without long-term trace of the tectonic event. On the other hand, many rivers in active mountain belts seem to be passive features and may record long-term crustal deformation. Here we use numerical simulations, constrained by drainage patterns observed in the Southern Alps of New Zealand, to analyse the response of river basins to distributed plate tectonic strain. We find that both dynamically reorganized and passively deformed rivers coexist in the Southern Alps. Rivers on the western side of the mountain range reorganize and rapidly evolve in response to tectonic deformation. In contrast, rivers on the eastern side resist reorganization and record large-scale plate tectonic influence over timescales of tens of millions of years. We conclude that both types of river drainage pattern in the Southern Alps are primarily controlled by plate tectonic strain, implying that landscape topography can be used to reconstruct the distribution of tectonic strain within zones of continental deformation around the world.

  15. Early Cretaceous stratigraphy, paleontology, and sedimentary tectonics in Paris overthrust foredeep (western Wyoming and southeastern Idaho) compared with Quaternary features of indo-gangetic plain

    SciTech Connect

    Dorr, J.A. Jr.

    1983-08-01

    Fluviatile clastics of the nonmarine, early Cretaceous Gannett and Wayan groups were deposited on wet alluvial megafans and on intervening interfan piedmont slopes which declined eastward into more poorly drained lowlands from a western highland source area uplifted episodically by movements of the Paris overthrust. Lacustrine episodes of deposition intercalated Peterson and Draney limestones with Gannett fluvial clastics. Westward marine transgressions (Skull Creek, Mowry) intercalated mixed lacustrine and brackish facies (Smiths and Cokedale formations) into Wayan fluviatile clastics. Newly discovered fossil vertebrate and invertebrate materials (all fragmentary but identifiable) include: Gannett Group - large reptiles including turtles; Thomas Fork Formation - freshwater gastropods and unionid pelecypods, gastroliths, two types of turtles, large reptilian fragments (dinosaur), and abundant dinosaur eggshell fragments; Wayan Formation - perennially aquatic snails, turtles, unidentifiable large reptiles, two types of crocodilians, an iguanodontid dinosaur (Tenontosaurus), an ankylosaurian dinosaur, a large ornithopod dinosaur, gastroliths, abundant and ubiquitous dinosaur eggshell fragments (numerous types and sizes), and miscellaneous unidentifiable small vertebrate bone fragments. A census of analogous modern reptile reproductive behaviors supports the conclusion that the Wayan, and probably also the Gannett, alluvial fan environments were used as upland breeding grounds by dinosaurs and perhaps other reptiles. Comparison of these Early Cretaceous data with observations on the tectonic setting, sedimentology, and biology of the Quaternary indo-gangetic plain suggests many close analogies between the two sedimentary tectonic settings.

  16. Tectonically driven fluid flow and gold mineralisation in active collisional orogenic belts: comparison between New Zealand and western Himalaya

    NASA Astrophysics Data System (ADS)

    Craw, D.; Koons, P. O.; Horton, T.; Chamberlain, C. P.

    2002-04-01

    Hydrothermal activity and mesothermal-styled gold mineralisation occurs near the main topographic divide of most active or young collisional mountain belts. The Southern Alps of New Zealand is used in this study as a model for the mineralising processes. The collisional tectonics results in a two-sided wedge-shaped orogen into which rock is transported horizontally. Upper crustal rocks pass through the orogen and leave the orogen by erosion, whereas lower crustal rocks are deformed into the mountain roots. High relief drives meteoric water flow to near the brittle-ductile transition. Lower to upper greenschist facies metamorphic reactions, driven by deformation at the crustal decollement and in the root, release water-rich fluids that rise through the orogen. Intimate chemical interaction between fluid and rock results in dissolution and later precipitation of gold, arsenic and sulphur. Fluid flow and mineralisation in the topographic divide region is facilitated by a network of steeply dipping faults and associated rock damage zones where oblique strike-slip faults intersect the thrust faults that strike subparallel to the main mountain range. The Nanga Parbat massif of the western Himalaya is an example of an active collisional zone which hosts hydrothermal activity but no gold mineralisation. The lack of gold mineralisation is due to the following factors: CO 2-dominated rising metamorphic fluid in dehydrated amphibolite-granulite facies metamorphic rocks does not dissolve gold and arsenic; hot (up to 400 °C) meteoric water confined to fractures in the gneiss limits dissolution of gold and arsenic; low density of hot water/dry steam, and low reduced sulphur content of fluid, restrict solubility of gold and arsenic; absence of fracture networks in the core of the massif and the small volumes of circulating fluid limit metal concentration; and lack of reactive rock compositions limits chemically mediated metal deposition.

  17. Features of the Active Evening Plasma Sheet from MMS

    NASA Astrophysics Data System (ADS)

    Moore, T. E.; Chandler, M. O.; Avanov, L. A.; Burch, J. L.; Coffey, V. N.; Ergun, R. E.; Fuselier, S. A.; Gershman, D. J.; Giles, B. L.; Lavraud, B.; MacDonald, E.; Mauk, B.; Mukai, T.; Nakamura, R.; Pollock, C. J.; Russell, C. T.; Saito, Y.; Sauvaud, J. A.; Torbert, R. B.; Yokota, S.

    2015-12-01

    The Magnetospheric Multiscale (MMS) mission, consisting of four identical plasmas and fields observatories, was launched into a 12 RE elliptical equatorial orbit in March 2015 and was in the process of being commissioned through August 2015. During commissioning, the orbit apogee rotated from near midnight through the evening toward the dusk sector and occasionally captured new observations of the plasma sheet, its boundary layers, and the magnetospheric tail lobes. On 22-23 June, an especially active plasma sheet was involved in a major geospace storm that developed a ring current with 200 nT DST. We report on the ion kinetic and flow features of this active plasma sheet, comparing them with familiar observations from earlier missions, as an exercise in validating the MMS observations and assessing their capabilities to provide higher time resolution in multi-point views of thin, fast-moving structures. The observed features include but are not limited to cold lobal wind streams in the lobes, tailward flowing auroral beams and conics, hot earthward field-aligned flows and counter-flows, fast cross-field convection of some flows toward the neutral sheet, and the hot isotropic plasma sheet proper. Relationships between these features, the ionosphere, and the reconnecting magnetotail will be explored and discussed, seeking preliminary conclusions.

  18. A systematic overview of the coincidences of river sinuosity changes and tectonically active structures in the Pannonian Basin

    NASA Astrophysics Data System (ADS)

    Petrovszki, Judit; Székely, Balázs; Timár, Gábor

    2012-12-01

    As tectonic movements change the valley slope (low-gradient reaches of valleys, in sedimentary basins), the alluvial rivers, as sensitive indicators, respond to these changes, by varying their courses to accommodate this forcing. In our study sinuosity values, a commonly used characteristic parameter to detect river pattern changes, were studied for the major rivers in the Pannonian Basin in order to reveal neotectonic influence on their planform shape. Our study area comprises the entire Pannonian Basin (330,000 km2) located in eastern Central-Europe, bounded by the Alps, Carpathians and Dinarides. The studied rivers were mostly in their natural meandering state before the main river regulations of the 19th century. The last quasi-natural, non-regulated river planforms were surveyed somewhat earlier, during the Second Military Survey of the Habsburg Empire. Using the digitized river sections of that survey, the sinuosities of the rivers were calculated with different sample section sizes ranging from 5 km to 80 km. Depending on the bank-full discharge, also a 'most representative' section size is given, which can be connected to the neotectonic activity. In total, the meandering reaches of 28 rivers were studied; their combined length is 7406 km. The places where the river sinuosity changed were compared to the structural lines of the "Atlas of the present-day geodynamics of the Pannonian Basin" (Horváth et al., 2006). 36 junctions along 26 structural lines were identified where the fault lines of this neotectonic map crossed the rivers. Across these points the mean sinuosity changed. Depending on the direction of the relative vertical movements, the sinuosity values increased or decreased. There were some points, where the sinuosity changed in an opposite way. Along these sections, the rivers belong to the range of unorganized meandering or there are lithological margins. Assuming that the rivers indicate on-going faulting accurately, some places were found

  19. Complex Tectonism on Ganymede

    NASA Technical Reports Server (NTRS)

    1997-01-01

    Complex tectonism is evident in these images of Ganymede's surface. 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. The 80 kilometer (50 mile) wide lens-shaped feature in the center of the image is located at 32 degrees latitude and 188 degrees longitude along the border of a region of ancient dark terrain known as Marius Regio, and is near an area of younger bright terrain named Nippur Sulcus. The tectonism that created the structures in the bright terrain nearby has strongly affected the local dark terrain to form unusual structures such as the one shown here. The lens-like appearance of this feature is probably due to shearing of the surface, where areas have slid past each other and also rotated slightly. Note that in several places in these images, especially around the border of the lens-shaped feature, bright ridges appear to turn into dark grooves. Analysis of the geologic structures in areas like this are helping scientists to understand the complex tectonic history of Ganymede.

    North is to the top-left of the image, and the sun illuminates the surface from the southeast. The image covers an area about 63 kilometers (39 miles) by 120 kilometers (75 miles) across at a resolution of 188 meters (627 feet) per picture element. The images were taken on September 6, 1996 at a range of 18,522 kilometers (11,576 miles) by the solid state imaging (CCD) system on NASA's Galileo spacecraft.

    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).

    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.

  20. Complex Tectonism on Ganymede

    NASA Technical Reports Server (NTRS)

    1997-01-01

    Complex tectonism is evident in these images of Ganymede's surface. 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. The 80 kilometer (50 mile) wide lens-shaped feature in the center of the image is located at 32 degrees latitude and 188 degrees longitude along the border of a region of ancient dark terrain known as Marius Regio, and is near an area of younger bright terrain named Nippur Sulcus. The tectonism that created the structures in the bright terrain nearby has strongly affected the local dark terrain to form unusual structures such as the one shown here. The lens-like appearance of this feature is probably due to shearing of the surface, where areas have slid past each other and also rotated slightly. Note that in several places in these images, especially around the border of the lens-shaped feature, bright ridges appear to turn into dark grooves. Analysis of the geologic structures in areas like this are helping scientists to understand the complex tectonic history of Ganymede.

    North is to the top-left of the image, and the sun illuminates the surface from the southeast. The image covers an area about 63 kilometers (39 miles) by 120 kilometers (75 miles) across at a resolution of 188 meters (627 feet) per picture element. The images were taken on September 6, 1996 at a range of 18,522 kilometers (11,576 miles) by the solid state imaging (CCD) system on NASA's Galileo spacecraft.

    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).

    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.

  1. Hot-spot tectonics on Io

    NASA Technical Reports Server (NTRS)

    Mcewen, A. S.

    1985-01-01

    The thesis is that extensional tectonics and low-angle detachment faults probably occur on Io in association with the hot spots. These processes may occur on a much shorter timescale on Ion than on Earth, so that Io could be a natural laboratory for the study of thermotectonics. Furthermore, studies of heat and detachment in crustal extension on Earth and the other terresrial planets (especially Venus and Mars) may provide analogs to processes on Io. The geology of Io is dominated by volcanism and hot spots, most likely the result of tidal heating. Hot spots cover 1 to 2% of Io's surface, radiating at temperatures typically from 200 to 400 K, and occasionally up to 700K. Heat loss from the largest hot spots on Io, such as Loki Patera, is about 300 times the heat loss from Yellowstone, so a tremendous quantity of energy is available for volcanic and tectonic work. Active volcanism on Io results in a resurfacing rate as high as 10 cm per year, yet many structural features are apparent on the surface. Therefore, the tectonics must be highly active.

  2. Damping scaling factors for elastic response spectra for shallow crustal earthquakes in active tectonic regions: "average" horizontal component

    USGS Publications Warehouse

    Rezaeian, Sanaz; Bozorgnia, Yousef; Idriss, I.M.; Abrahamson, Norman; Campbell, Kenneth; Silva, Walter

    2014-01-01

    Ground motion prediction equations (GMPEs) for elastic response spectra are typically developed at a 5% viscous damping ratio. In reality, however, structural and nonstructural systems can have other damping ratios. This paper develops a new model for a damping scaling factor (DSF) that can be used to adjust the 5% damped spectral ordinates predicted by a GMPE for damping ratios between 0.5% to 30%. The model is developed based on empirical data from worldwide shallow crustal earthquakes in active tectonic regions. Dependencies of the DSF on potential predictor variables, such as the damping ratio, spectral period, ground motion duration, moment magnitude, source-to-site distance, and site conditions, are examined. The strong influence of duration is captured by the inclusion of both magnitude and distance in the DSF model. Site conditions show weak influence on the DSF. The proposed damping scaling model provides functional forms for the median and logarithmic standard deviation of DSF, and is developed for both RotD50 and GMRotI50 horizontal components. A follow-up paper develops a DSF model for vertical ground motion.

  3. Evolution of the Late Pleistocene Aspe River (Western Pyrenees, France). Signature of climatic events and active tectonics

    NASA Astrophysics Data System (ADS)

    Nivière, Bertrand; Lacan, Pierre; Regard, Vincent; Delmas, Magali; Calvet, Marc; Huyghe, Damien; Roddaz, Bernard

    2016-03-01

    We make use of the cosmogenic nuclide 10Be exposure to date an alluvial terrace of the Aspe River in the foothills of the northwestern Pyrenees. Initially ascribed to the Rissian glaciation, our dating shows that the terrace was abandoned at 18 ± 2 kyr. In reference to the Late Pleistocene climatic chronology, two kinds of terraces can be distinguished: high-standing fill terraces probably deposited during glacial events and lower cut-in-fill and strath terraces cut during the postglacial river incision. A part of the terrace aggradations could have occurred during the Würmian glacial episodes. Hence, the dated terrace fits in with the prevailing view of incision during climate transitions. Our study also shows that elevation is not a good criterion of terrace correlation, which should be better carried out on the basis of absolute dating. In addition, this dating also suggests a potential Late Pleistocene fault reactivation of the Mail Arrouy thrust in this tectonically active area of the Western Pyrenees.

  4. First results of an INGV project for the integrated analysis of the active tectonics in SW Sicily

    NASA Astrophysics Data System (ADS)

    Mattia, Mario; Giovanni, Barreca; Carla, Bottari; Valentina, Bruno; Pierfrancesco, Burrato; Fabrizio, Cultrera; Luigi, Dardanelli; Sofia, De Gregorio; Luigi, Ferranti; Laura, Guzzetta; Paolo, Madonia; Carmelo, Monaco; Claudia, Pipitone; Fabrizio, Pepe; Francesco, Guglielmino

    2017-04-01

    We present the first results of a project financed by the "Struttura Terremoti" of INGV to study the potential sources of earthquakes in south-western Sicily, including the area hit by the 1968 Belice earthquake sequence and the archaeological area of Selinunte, affected by two earthquakes in historical times. We adopt in this project a multi-disciplinary approach, with the goal of addressing the following points: 1) define the active tectonic framework of south-western Sicily, 2) investigate and characterize on-shore and off-shore faults, potential sources of damaging earthquakes, and 3) evaluate the current deformation rates. To do this, we collected a new set of geodetic (GPS and InSAR) and geochemical data, and performed geological and geomorphological surveys on-land in the area between Mazara, Castelvetrano and Selinunte. We also acquired high-resolution Sparker seismic profiles off-shore Sciacca. Geological and geomorphological surveys have been focused around the 10 km long Castelvetrano-Campobello di Mazara (CCM) lineament, where previous research (Barreca et al., 2014) showed geodetic and geoarchaeological evidence of recent deformation. In particular, a detailed survey of Quaternary coastal forms and deposits was performed, in order to reconstruct the sequence of uplifted paleoshorelines and to search for differential motions between adjacent coastal sectors spanning the CCM. Preliminary observations indicate that the footwall of the CCM hosts a larger number, and a more elevated position of paleo-shorelines suggestive of syntectonic uplift . A grid of about 200 km of high-resolution reflection seismic profiles was recorded along the continental shelf in the offshore of Sciacca. Profiles are mostly oriented in the WNW-ESE direction, with tie lines acquired in ENE-WSW direction. The acoustic source used during seismic prospecting was a 1 kJ Sparker power supply with a multi-tips Sparker array. Preliminary seismic data interpretation indicates that a

  5. Desired features of smartphone applications promoting physical activity.

    PubMed

    Rabin, Carolyn; Bock, Beth

    2011-12-01

    Approximately one-third of adults in the United States are physically inactive. This is a significant public health concern as physical activity (PA) can influence the risk of cardiovascular disease, diabetes, and certain forms of cancer. To minimize these health risks, effective PA interventions must be developed and disseminated to the vast number of individuals who remain sedentary. Smartphone technology presents an exciting opportunity for delivering PA interventions remotely. Although a number of PA applications are currently available for smartphones, these "apps" are not based on established theories of health behavior change and most do not include evidence-based features (e.g., reinforcement and goal setting). Our aim was to collect formative data to develop a smartphone PA app that is empirically and theoretically-based and incorporates user preferences. We recruited 15 sedentary adults to test three currently available PA smartphone apps and provide qualitative and quantitative feedback. Findings indicate that users have a number of specific preferences with regard to PA app features, including that apps provide automatic tracking of PA (e.g., steps taken and calories burned), track progress toward PA goals, and integrate a music feature. Participants also preferred that PA apps be flexible enough to be used with several types of PA, and have well-documented features and user-friendly interfaces (e.g., a one-click main page). When queried by the researcher, most participants endorsed including goal-setting and problem-solving features. These findings provide a blue print for developing a smartphone PA app that incorporates evidence-based components and user preferences.

  6. Episodic activity of a dormant fault in tectonically stable Europe: The Rauw fault (NE Belgium)

    NASA Astrophysics Data System (ADS)

    Verbeeck, Koen; Wouters, Laurent; Vanneste, Kris; Camelbeeck, Thierry; Vandenberghe, Dimitri; Beerten, Koen; Rogiers, Bart; Schiltz, Marco; Burow, Christoph; Mees, Florias; De Grave, Johan; Vandenberghe, Noël

    2017-03-01

    Our knowledge about large earthquakes in stable continental regions comes from studies of faults that generated historical surface rupturing earthquakes or were identified by their recent imprint in the morphology. Here, we evaluate the co-seismic character and movement history of the Rauw fault in Belgium, which lacks geomorphological expression and historical/present seismicity. This 55-km-long normal fault, with known Neogene and possibly Early Pleistocene activity, is the largest offset fault west of the active Roer Valley Graben. Its trace was identified in the shallow subsurface based on high resolution geophysics. All the layers within the Late Pliocene Mol Formation (3.6 to 2.59 Ma) are displaced 7 m vertically, without growth faulting, but deeper deposits show increasing offset. A paleoseismic trench study revealed cryoturbated, but unfaulted, late glacial coversands overlying faulted layers of Mol Formation. In-between those deposits, the fault tip was eroded, along with evidence for individual displacement events. Fragmented clay gouge observed in a micromorphology sample of the main fault evidences co-seismic faulting, as opposed to fault creep. Based on optical and electron spin resonance dating and trench stratigraphy, the 7 m combined displacement is bracketed to have occurred between 2.59 Ma and 45 ka. The regional presence of the Sterksel Formation alluvial terrace deposits, limited to the hanging wall of the Rauw fault, indicates a deflection of the Meuse/Rhine confluence (1.0 to 0.5 Ma) by the fault's activity, suggesting that most of the offset occurred prior to/at this time interval. In the trench, Sterksel Formation is eroded but reworked gravel testifies for its former presence. Hence, the Rauw fault appears as typical of plate interior context, with an episodic seismic activity concentrated between 1.0 and 0.5 Ma or at least between 2.59 Ma to 45 ka, possibly related to activity variations in the adjacent, continuously active Roer Valley

  7. Tectonics of the central Andes

    NASA Technical Reports Server (NTRS)

    Bloom, Arthur L.; Isacks, Bryan L.; Fielding, Eric J.; Fox, Andrew N.; Gubbels, Timothy L.

    1989-01-01

    Acquisition of nearly complete coverage of Thematic Mapper data for the central Andes between about 15 to 34 degrees S has stimulated a comprehensive and unprecedented study of the interaction of tectonics and climate in a young and actively developing major continental mountain belt. The current state of the synoptic mapping of key physiographic, tectonic, and climatic indicators of the dynamics of the mountain/climate system are briefly reviewed.

  8. Regional and global variations in the temporal clustering of tectonic tremor activity

    NASA Astrophysics Data System (ADS)

    Idehara, Koki; Yabe, Suguru; Ide, Satoshi

    2014-12-01

    The temporal distribution of tremor activity exhibits a highly non-Poissonian behavior, and its maximum period of non-Poissonian clustering statistically describes the recurrence interval of major tremor bursts. Here, we examine variations in the temporal clustering properties of tremor activity by assessing their characteristic times, which are determined by the maximum period of the non-Poissonian distribution. By applying a two-point correlation integral to some of the world's major tremor zones, including Shikoku, Kii-Tokai, and Kyushu in Japan; Cascadia, Jalisco, and Guerrero in Mexico; southern Chile; Taiwan; and Manawatu in New Zealand, we reveal local spatial variations in the temporal clustering properties in each tremor zone and show global-scale variations in tremor activity. The spatial variation in local tremor activity is characterized by a gradual transition in the along-dip direction and shorter-wavelength heterogeneities in the along-strike direction, possibly associated with a spatial change in frictional conditions at the plate interface and rheological conditions in the surrounding materials. The characteristic time correlates positively with locally measured median tremor duration, implying an inherent correlation between the moment release rate and the recurrence interval of tremors.

  9. Intermittent Plate Tectonics

    NASA Astrophysics Data System (ADS)

    Silver, P. G.; Behn, M. D.

    2006-12-01

    prevent the ultimate closure of the Pacific basin and thus the cessation of subduction. More noteworthy is where subduction is not initiating. First, there is no evidence for subduction initiation anywhere within the Atlantic basin (excluding the Caribbean and Scotia), despite the mature 100-200 my age of passive-margin oceanic lithosphere. The formation of the Alpine-Himalayan chain represents the cessation of roughly 10,000 km of subduction at about 35-50 ma, Yet, no new subduction zones have initiated south of India or Africa, the two major continents that participated in the collision. These examples illustrate that subduction does not immediately initiate following a continent-continent collision, and may lag by 10s if not 100s of millions of years. The stoppage of plate tectonics, or even a dramatic reduction in subduction flux, would have significant thermal consequences for the mantle. It would effectively mark a temporary switch to "stagnant-lid" tectonics, analogous to that found on Venus, resulting in a significant increase in global mantle potential temperature (30- 100°C per 100 my) and a possibly widespread increase in magmatic activity. Such a hiatus may have occurred in the Mid-Proterozoic (1.1-1.6Ga), an era characterized by the virtual absence of orogenic activity, the longest-lived passive margin (600 My), and the production of enigmatic "anorogenic" granites found over thousands of kilometers in a belt presently stretching from southwestern to northeastern North America.

  10. Seismic source study of the Racha-Dzhava (Georgia) earthquake from aftershocks and broad-band teleseismic body-wave records: An example of active nappe tectonics

    USGS Publications Warehouse

    Fuenzalida, H.; Rivera, L.; Haessler, H.; Legrand, D.; Philip, H.; Dorbath, L.; McCormack, D.; Arefiev, S.; Langer, C.; Cisternas, A.

    1997-01-01

    -S oriented plane. Nappe tectonics has been identified as an important feature in the Caucasus, and the source mechanism is consistent with this observation. A hidden fault is present below the nappe, and no large surface breaks were observed due to the main shock. The epicentral region is characterized by sediments that are trapped between two crystalline basements: the Dzirula Massif, which crops out south of Chiatoura, and the Caucasus Main Range north of Oni. Most, if not all, of the rupture is controlled by the thrusting of overlapping, deformed and folded sediments over the Dzirula Massif. This event is another example of blind active faults, with the distinctive feature that the fault plane dips at a gentle angle. The Racha Range is one of the surface expressions of this blind thrust, and its growth is the consequence and evidence of similar earthquakes in the past.

  11. Tectonics and ice sheet dynamics of West Antarctic margins

    NASA Astrophysics Data System (ADS)

    Gohl, Karsten

    2010-05-01

    An understanding of the glacial history of the Amundsen Sea Embayment (ASE) and Pine Island Bay (PIB) is essential for proposing models on the future development of the West Antarctic Ice Sheet. This requires an understanding of the tectonic history and knowledge of tectonic features such as lineaments, ridges, sills and basins, because basement morphology and inherited erosional features control the flow direction of ice-sheets and the influx of Circum-Polar Deep Water (CDW). This is an attempt to reconstruct the tectonic history with the aim to search for basement features and crustal boundaries which may be correlated to the flow and dynamics of the ice-sheet. The Amundsen Sea Embayment of West Antarctica is in a prominent location for a series of tectonic and magmatic events from Paleozoic to Cenozoic times. Seismic, magnetic and gravity data from the embayment and PIB reveal the crustal thickness and significant tectonic features. NE-SW trending magnetic and gravity anomalies and the thin crust indicate a former rift zone which was active during or in the run-up to the breakup process between Chatham Rise and West Antarctica before or at 90 Ma. NW-SE trending gravity and magnetic anomalies, following a prolongation of Peacock Sound, indicate the extensional southern boundary to the Bellingshausen Plate which was active between 79 and 61 Ma. It is likely that the prominent Pine Island Trough follows a structural boundary between the crustal blocks of Ellsworth Land and Marie Byrd Land. Data are shown from the ASE and PIB which can be interpreted in context with the reconstruction of the ice advance and retreat history in this area. Differences in the behaviour of the ice-sheet are shown to exist for the western and eastern parts of PIB due to basement structures affecting the inflow of CDW.

  12. Vortical Tectonics

    NASA Astrophysics Data System (ADS)

    Mirlin, Eugeny; Mironov, Yury

    2010-05-01

    It is shown that lithospheric plates in their movement on Earth's surface do not undergo typical rotations, as was previously believed, but rather movements of more complicated type, namely vortical (or "whirl"). The specific character of vortical movements is reflective in next various structural-tectonic phenomena at global, regional, and local levels: 1. Propagating of axis of spreading with simultaneous whirling in the appropriate direction, which accompanies the opening of the oceanic basin independently of its size and age. Due to the high instability of rift-genesis and spreading processes, along with main "steam" of rift and spreading there are side "branches" branching off and developing. These are also characterized by vortical type of evolution, and they die out in time; 2. Formation of various scale "embedding" structures - into the smooth and rounded contours of oceanic basins, there are formed by vortical flow, as though a broken, stepped geometry of passive margins is embedded. This is, like segmentation of oceanic bottom, in general, the result of invariable presence of shear component inside a vortex; 3. Formation of tectonic stratification of the oceanic lithosphere, which appears as a consequence of differential rotation of various-scaled volumes of substances in a vortical flow. This causes the vortical differential of the oceanic lithosphere into particular lithospheric layers, which are moving relative to each other along a near-horizontal interface of surfaces; 4. The appearance of tension-compression deformations, cyclically superseding each other in time and space, in a zone of lithospheric accretion at crests of mid-oceanic ridges. The change is caused by the independent rotation of the crust's blocks being moved by vortical flow; here, the gradient of transition from compression to tension increases as the vortical system whirls; 5. Formation of structures of the Earth's crust, caused by the compressive tensions in the region of maximal

  13. Preliminary atlas of active shallow tectonic deformation in the Puget Lowland, Washington

    USGS Publications Warehouse

    Barnett, Elizabeth A.; Haugerud, Ralph A.; Sherrod, Brian L.; Weaver, Craig S.; Pratt, Thomas L.; Blakely, Richard J.

    2010-01-01

    This atlas presents an up-to-date map compilation of the geological and geophysical observations that underpin interpretations of active, surface-deforming faults in the Puget Lowland, Washington. Shallow lowland faults are mapped where observations of deformation from paleoseismic, seismic-reflection, and potential-field investigations converge. Together, results from these studies strengthen the identification and characterization of regional faults and show that as many as a dozen shallow faults have been active during the Holocene. The suite of maps presented in our atlas identifies sites that have evidence of deformation attributed to these shallow faults. For example, the paleoseismic-investigations map shows where coseismic surface rupture and deformation produced geomorphic scarps and deformed shorelines. Other maps compile results of seismic-reflection and potential-field studies that demonstrate evidence of deformation along suspected fault structures in the subsurface. Summary maps show the fault traces derived from, and draped over, the datasets presented in the preceding maps. Overall, the atlas provides map users with a visual overview of the observations and interpretations that support the existence of active, shallow faults beneath the densely populated Puget Lowland.

  14. Age mediation of frontoparietal activation during visual feature search.

    PubMed

    Madden, David J; Parks, Emily L; Davis, Simon W; Diaz, Michele T; Potter, Guy G; Chou, Ying-hui; Chen, Nan-kuei; Cabeza, Roberto

    2014-11-15

    Activation of frontal and parietal brain regions is associated with attentional control during visual search. We used fMRI to characterize age-related differences in frontoparietal activation in a highly efficient feature search task, detection of a shape singleton. On half of the trials, a salient distractor (a color singleton) was present in the display. The hypothesis was that frontoparietal activation mediated the relation between age and attentional capture by the salient distractor. Participants were healthy, community-dwelling individuals, 21 younger adults (19-29 years of age) and 21 older adults (60-87 years of age). Top-down attention, in the form of target predictability, was associated with an improvement in search performance that was comparable for younger and older adults. The increase in search reaction time (RT) associated with the salient distractor (attentional capture), standardized to correct for generalized age-related slowing, was greater for older adults than for younger adults. On trials with a color singleton distractor, search RT increased as a function of increasing activation in frontal regions, for both age groups combined, suggesting increased task difficulty. Mediational analyses disconfirmed the hypothesized model, in which frontal activation mediated the age-related increase in attentional capture, but supported an alternative model in which age was a mediator of the relation between frontal activation and capture.

  15. Active Tectonics of off-Hokuriku, Central Japan, by two ships seismic reflection profiling

    NASA Astrophysics Data System (ADS)

    Kato, Naoko; Sato, Hiroshi; Ishiyama, Tatsuya; Abe, Susumu; Shiraishi, Kazuya

    2015-04-01

    Along the southern to eastern margin of the Sea of Japan, active faults are densely distributed. These submarine active faults produced tsunami disasters, such as 1983 Nihonkai-chubu earthquake (M7.7) and 1993 Hokkaido Nansei-oki earthquake (M7.8). To estimate tsunami hazards, we performed deep seismic reflection profiling to obtain the information of tsunami source faults, off-Hokuriku area in the central part of Honshu, Japan. The survey is carried out as a part of research project named "the integrated research project on seismic and tsunami hazards around the Sea of Japan" funded by MEXT. To obtain long offset data in busy marine activity area, we used two vessels; a gun-ship with 3020 cu. inch air-gun and a cable-ship with a 2-km-long, streamer cable with 156 channels and 480 cu. inch air-gun. Common-midpoint reflection data were acquired using two ships at 4 km offset. The survey area consists of stretched continental crust associated with rifting and opening of the Sea of Japan in early Miocene and is marked by densely distributed syn-rift normal faults. Fault reactivation of normal faults as reverse faults is common. Two phases of fault reactivation are identified from the seismic sections after termination of opening of the Sea of Japan. One is the late Miocene NS trending shortening deformation. This is produced by NS-trending convergence of the Shikoku basin (15 Ma), which belongs to the Philippine Sea plate (PHS) to SW Japan at Nankai trough (Kimura et al., 2005). After the initiation of the subduction of PHS at Nankai trough, the strong shortening deformation is terminated and the fold-and-thrust belt was unconformably covered by sub-horizontal Pliocene sediments. Some horizons of unconformities represent multiple events of shortening driven from the subduction interface. Some normal faults reactivated as active strike-slip and reverse faults in Quaternary. Well observed example is the 2007 Noto peninsula earthquake (M6.8). The 2007 Noto peninsula

  16. Cenozoic Tectonic Activity of the "Passive" North America Margin: Evidence for Cenozoic Activity on Mesozoic or Paleozoic Faults

    NASA Astrophysics Data System (ADS)

    Nedorub, O. I.; Knapp, C. C.

    2012-12-01

    The tectonic history of the Eastern North American Margin (ENAM) incorporates two cycles of continental assembly, multiple pulses of orogeny, rifting, and post-rift geodynamic evolution. This is reflected in the heterogeneous lithosphere of the ENAM which contains fault structures originated in Paleozoic to Mesozoic eras. The South Georgia Rift basin is probably the largest Mesozoic graben within its boundaries that is associated with the breakup of Pangea. It is composed of smaller sub-basins which appear to be bounded by high-angle normal faults, some of which may have been inverted in late Cretaceous and Cenozoic eras. Paleozoic structures may have been reactivated in Cenozoic time as well. The ENAM is characterized by N-NE maximum horizontal compressive stress direction. This maximum compressional stress field is sub-parallel to the strike of the Atlantic Coast province fault systems. Camden, Augusta, Allendale, and Pen Branch faults are four of the many such reactivated faults along the southern part of ENAM. These faults are now buried under the 0-400 m of loosely consolidated Cretaceous and Cenozoic age sediments and thus are either only partially mapped or currently not recognized. Some of the objectives of this study are to map the subsurface expression and geometry of these faults and to investigate the post Cretaceous deformation and possible causes of fault reactivation on a passive margin. This study employs an integrated geophysical approach to investigate the upper 200 m of identified locations of the above mentioned faults. 2-D high-resolution shallow seismic reflection and refraction methods, gravity surveys, GPR, 2-D electrical resistivity and well data are used for analyses and interpretation. Preliminary results suggest that Camden fault shows signs of Cenozoic reactivation through an approximately 30 m offset NW side up mainly along a steeply dipping fault zone in the basal contact of Coastal Plain sediments with the Carolina Piedmont. Drill

  17. Luminescence ages for alluvial-fan deposits in Southern Death Valley: Implications for climate-driven sedimentation along a tectonically active mountain front

    USGS Publications Warehouse

    Sohn, M.F.; Mahan, S.A.; Knott, J.R.; Bowman, D.D.

    2007-01-01

    Controversy exists over whether alluvial-fan sedimentation along tectonically active mountain fronts is driven by climatic changes or tectonics. Knowing the age of sedimentation is the key to understanding the relationship between sedimentation and its cause. Alluvial-fan deposits in Death Valley and throughout the arid southwestern United States have long been the subjects of study, but their ages have generally eluded researchers until recently. Most mapping efforts have recognized at least four major relative-age groupings (Q1 (oldest), Q2, Q3, and Q4 (youngest)), using observed changes in surface soils and morphology, relation to the drainage net, and development of desert pavement. Obtaining numerical age determinations for these morphologic stages has proven challenging. We report the first optically stimulated luminescence (OSL) ages for three of these four stages deposited within alluvial-fans along the tectonically active Black Mountains of Death Valley. Deposits showing distinct, remnant bar and swale topography (Q3b) have OSL ages from 7 to 4 ka., whereas those with moderate to poorly developed desert pavement and located farther above the active channel (Q3a) have OSL ages from 17 to 11 ka. Geomorphically older deposits with well-developed desert pavement (Q2d) have OSL ages ???25 ka. Using this OSL-based chronology, we note that alluvial-fan deposition along this tectonically active mountain front corresponds to both wet-to-dry and dry-to-wet climate changes recorded globally and regionally. These findings underscore the influence of climate change on alluvial fan deposition in arid and semi-arid regions. ?? 2007 Elsevier Ltd and INQUA.

  18. Pleistocene calcrete deposits from southern Spain as indicators of climatic conditions and tectonic activity

    NASA Astrophysics Data System (ADS)

    Herrero, Maria J.; Insua-Arevalo, Juan M.; Garcia-Mayordomo, Julian; Martin-Banda, Raquel

    2014-05-01

    Quaternary calcrete horizons are common weathering products in arid and semi-arid regions of southern Spain. We have analysed a calcrete profile developed within poorly sorted gravels of an alluvial fan. These deposits were sourced from the Carrascoy Range, a fault generated mountain front located in the Internal Zones of the Betic Cordillera (South Spain). During the Pleistocene the climate in southern Spain was dry, either in the form of semi-arid/arid conditions or as seasonal moisture deficits. Alluvial channel incision trends appeared to be disrupted by episodes of alluvial aggradation produced during cold and dry glacial periods. At the top of the aggradational phases, pedogenic processes operated profusely, and, as a result, several calcretes (stage V mature calcrete profiles) were formed. We have analysed one of these calcrete profiles that appears subvertical within the forelimb of a regional fold in relation to the Carrascoy Fault activity. The calcrete consist of a densely cemented hardpan horizon (20 to 40 cm thick) overlain by a thin, 2-cm thick laminar crust. Below the hardpan horizon, carbonate concentrations gradually decrease to clast-coating textures. Calcretes form progressively and a wide range of carbonate phases occur within a single horizon, being the laminar crust the final stage of evolution within a mature pedogenic calcrete deposit, and, therefore, the carbonate within it postdates all the cement phases within the profile. The location of the latest cement phase of the calcrete deposit has been estimated by microscopic observations (to establish their suitability for dating) together with a detailed sedimentological analysis of the calcrete profile in the field. The laminar crust consists of less than 1 mm thick laminae characterized by the alternation of layers of micrite and layers of micrite with ooids, detrital grains and clays indicating environmental conditions in which sedimentation rates were low and episodic. By using radiometric

  19. Geophysical Imaging of Active Tectonics: A Case Study From the Inter Andean Valley, Ecuador

    NASA Astrophysics Data System (ADS)

    Call, C.; Meltzer, A.; Alvardo, A.

    2004-12-01

    The Inter Andean Valley is a Pliocene-Quaternary basin filled with volcanic, lacustrine, fluvial and marine sedimentary deposits. A series of faults sometimes collectively referred to as the Delores-Guayaquil Mega Shear (DGM) traverses the length of the Inter Andean Valley posing a seismic hazard to a number of cities including the capitol, Quito. The DGM is a large right-lateral fault system similar in scale and seismicity to the San Andres Fault system which is understudied, especially in the subsurface. A site characterization study utilizing ground penetrating radar (GPR) and near-surface seismic reflection profiling was conducted in two areas of the Inter Andean Valley where geomorphic evidence suggests active faulting. One area, Nono Valley, exhibits extensional characteristics through basin bounding fault and the second area, Saquisili, has a structure consistent with the geometry of a fault propagation fold. Both areas are covered with thinly layered volcanic ash which is clearly seen in outcrop and the GPR profiles. Saquisili, in addition to the ash layers, has a nonuniform layer of pumice near the surface which was revealed in the drilled holes for the seismic source, which helps to account for the quick attenuation of the higher frequencies. The GPR profiles also image abrupt terminations and offset of horizontal layers, often associated with active faulting. We used a 48 channel multichannel seismograph with 30Hz geophones and a 20ft spacing to collect 24 fold common-midpoint profiles using a Betsy Seis-Gun firing 12 gauge blanks. Preliminary seismic data indicates that the frequency content ranged between 20 and 100 Hz with higher frequencies being systematically filtered out with depth. Seismic velocities range between 740 and 2600 m/s, producing a vertical resolution between 2 and 32.5m to a depth of approximately 900m. The GPR data was collected using a GSSI SIR-2 data accusation system with a 100 MHz antenna. The GPR signal penetrated between 120ns

  20. Young glacially-induced tectonic activity of the Osning Thrust in Central Europe

    NASA Astrophysics Data System (ADS)

    Brandes, C.; Winsemann, J.; Roskosch, J.; Meinsen, J.; Tanner, D.; Frechen, M.; Steffen, H.; Wu, P.

    2012-04-01

    A series of complex metre-scale faults and related fold structures are developed within the Upper Pleistocene alluvial-aeolian complex of the Upper Senne in northern Germany. They are exposed in a pit 1 km away from the Osning Thrust. Growth strata indicate a two-fold evolution of the structures. The faults began as normal faults and were later transformed into reverse faults, which resulted in the formation of small-scale inversion structures with a typical harpoon shape (Brandes et al., in review). OSL ages imply that the sedimentary succession was deposited during the Late Pleniglacial to Late Glacial between 29.3 ± 3.2 ka and 13.1 ± 1.5 ka (Roskosch et al., accept.). We postulate that these structures were caused by activity on the Osning Thrust, during the generation of the forebulge of the Late Pleistocene ice sheet. This led to normal faulting as a consequence of extension in the forebulge area. The OSL ages for the normal fault-related growth strata are in a range of 16-13 ka. Reverse movements occurred later during deglaciation, due to the N-S directed compressional stress field in N Germany. Numerical simulations of the deglaciation seismicity point to seismic events with a thrust mechanism in the study area between 15.5-12.3 ka, although normal faulting is also possible in this time period. In addition various soft-sediment deformation structures occur in the sand pits, including sand blows, clastic dykes and sills, dish-, flame-, and ball and pillow structures. The main driving mechanism for these structures were seismic shock waves. This implies that movement on the Osning Thrust caused earthquakes of a significant magnitude. The soft-sediment deformation varies along strike of the Osning Thrust. In the NW the above-mentioned soft-sediment structures were generated, whereas in a pit 5.5 km to the SE only minor diffuse flower- to antler-like dewatering structures occur. This might indicate that the epicentre of the Late Glacial seismic activity was

  1. Tectonic models for Yucca Mountain, Nevada

    USGS Publications Warehouse

    O'Leary, D. W.

    2006-01-01

    Performance of a high-level nuclear waste repository at Yucca Mountain hinges partly on long-term structural stability of the mountain, its susceptibility to tectonic disruption that includes fault displacement, seismic ground motion, and igneous intrusion. Because of the uncertainty involved with long-term (10,000 yr minimum) prediction of tectonic events (e.g., earthquakes) and the incomplete understanding of the history of strain and its mechanisms in the Yucca Mountain region, a tectonic model is needed. A tectonic model should represent the structural assemblage of the mountain in its tectonic setting and account for that assemblage through a history of deformation in which all of the observed deformation features are linked in time and space. Four major types of tectonic models have been proposed for Yucca Mountain: a caldera model; simple shear (detachment fault) models; pure shear (planar fault) models; and lateral shear models. Most of the models seek to explain local features in the context of well-accepted regional deformation mechanisms. Evaluation of the models in light of site characterization shows that none of them completely accounts for all the known tectonic features of Yucca Mountain or is fully compatible with the deformation history. The Yucca Mountain project does not endorse a preferred tectonic model. However, most experts involved in the probabilistic volcanic hazards analysis and the probabilistic seismic hazards analysis preferred a planar fault type model. ?? 2007 Geological Society of America. All rights reserved.

  2. Active tectonics of the Imperial Valley, southern California: fault damage zones, complex basins and buried faults

    NASA Astrophysics Data System (ADS)

    Persaud, P.; Ma, Y.; Stock, J. M.; Hole, J. A.; Fuis, G. S.; Han, L.

    2016-12-01

    Ongoing oblique slip at the Pacific-North America plate boundary in the Salton Trough produced the Imperial Valley. Deformation in this seismically active area is distributed across a complex network of exposed and buried faults resulting in a largely unmapped seismic hazard beneath the growing population centers of El Centro, Calexico and Mexicali. To better understand the shallow crustal structure in this region and the connectivity of faults and seismicity lineaments, we used data primarily from the Salton Seismic Imaging Project (SSIP) to construct a P-wave velocity profile to 15 km depth, and a 3-D velocity model down to 8 km depth including the Brawley Geothermal area. We obtained detailed images of a complex wedge-shaped basin at the southern end of the San Andreas Fault system. Two deep subbasins (VP <5.65 km/s) are located in the western part of the larger Imperial Valley basin, where seismicity trends and active faults play a significant role in shaping the basin edge. Our 3-D VP model reveals previously unrecognized NE-striking cross faults that are interacting with the dominant NW-striking faults to control deformation. New findings in our profile include localized regions of low VP (thickening of a 5.65-5.85 km/s layer) near faults or seismicity lineaments interpreted as possibly faulting-related. Our 3-D model and basement map reveal velocity highs associated with the geothermal areas in the eastern valley. The improved seismic velocity model from this study, and the identification of important unmapped faults or buried interfaces will help refine the seismic hazard for parts of Imperial County, California.

  3. Saturn's Titan: Surface change, ammonia, and implications for atmospheric and tectonic activity

    USGS Publications Warehouse

    Nelson, R.M.; Kamp, L.W.; Matson, D.L.; Irwin, P.G.J.; Baines, K.H.; Boryta, M.D.; Leader, F.E.; Jaumann, R.; Smythe, W.D.; Sotin, Christophe; Clark, R.N.; Cruikshank, D.P.; Drossart, P.; Pearl, J.C.; Hapke, B.W.; Lunine, J.; Combes, M.; Bellucci, G.; Bibring, J.-P.; Capaccioni, F.; Cerroni, P.; Coradini, A.; Formisano, V.; Filacchione, G.; Langevin, R.Y.; McCord, T.B.; Mennella, V.; Nicholson, P.D.; Sicardy, B.

    2009-01-01

    Titan is known to have a young surface. Here we present evidence from the Cassini Visual and Infrared Mapping Spectrometer that it is currently geologically active. We report that changes in the near-infrared reflectance of a 73,000 km2 area on Titan (latitude 26° S, longitude 78° W) occurred between July 2004 and March of 2006. The reflectance of the area increased by a factor of two between July 2004 and March–April 2005; it then returned to the July 2004 level by November 2005. By late December 2005 the reflectance had surged upward again, establishing a new maximum. Thereafter, it trended downward for the next three months. Detailed spectrophotometric analyses suggest these changes happen at or very near the surface. The spectral differences between the region and its surroundings rule out changes in the distribution of the ices of reasonably expected materials such as H2O, CO2, and CH4 as possible causes. Remarkably, the change is spectrally consistent with the deposition and removal of NH3 frost over a water ice substrate. NH3 has been proposed as a constituent of Titan's interior and has never been reported on the surface. The detection of NH3 frost on the surface might possibly be explained by episodic effusive events occur which bring juvenile ammonia from the interior to the surface. If so, its decomposition would feed nitrogen to the atmosphere now and in the future. The lateral extent of the region exceeds that of active areas on the Earth (Hawaii) or Io (Loki).

  4. Saturn's Titan: Surface change, ammonia, and implications for atmospheric and tectonic activity

    NASA Astrophysics Data System (ADS)

    Nelson, R. M.; Kamp, L. W.; Matson, D. L.; Irwin, P. G. J.; Baines, K. H.; Boryta, M. D.; Leader, F. E.; Jaumann, R.; Smythe, W. D.; Sotin, C.; Clark, R. N.; Cruikshank, D. P.; Drossart, P.; Pearl, J. C.; Hapke, B. W.; Lunine, J.; Combes, M.; Bellucci, G.; Bibring, J.-P.; Capaccioni, F.; Cerroni, P.; Coradini, A.; Formisano, V.; Filacchione, G.; Langevin, R. Y.; McCord, T. B.; Mennella, V.; Nicholson, P. D.; Sicardy, B.

    2009-02-01

    Titan is known to have a young surface. Here we present evidence from the Cassini Visual and Infrared Mapping Spectrometer that it is currently geologically active. We report that changes in the near-infrared reflectance of a 73,000 km 2 area on Titan (latitude 26° S, longitude 78° W) occurred between July 2004 and March of 2006. The reflectance of the area increased by a factor of two between July 2004 and March-April 2005; it then returned to the July 2004 level by November 2005. By late December 2005 the reflectance had surged upward again, establishing a new maximum. Thereafter, it trended downward for the next three months. Detailed spectrophotometric analyses suggest these changes happen at or very near the surface. The spectral differences between the region and its surroundings rule out changes in the distribution of the ices of reasonably expected materials such as H 2O, CO 2, and CH 4 as possible causes. Remarkably, the change is spectrally consistent with the deposition and removal of NH 3 frost over a water ice substrate. NH 3 has been proposed as a constituent of Titan's interior and has never been reported on the surface. The detection of NH 3 frost on the surface might possibly be explained by episodic effusive events occur which bring juvenile ammonia from the interior to the surface. If so, its decomposition would feed nitrogen to the atmosphere now and in the future. The lateral extent of the region exceeds that of active areas on the Earth (Hawaii) or Io (Loki).

  5. Geodetic and geological evidence of active tectonics in south-western Sicily (Italy)

    NASA Astrophysics Data System (ADS)

    Barreca, G.; Bruno, V.; Cocorullo, C.; Cultrera, F.; Ferranti, L.; Guglielmino, F.; Guzzetta, L.; Mattia, M.; Monaco, C.; Pepe, F.

    2014-12-01

    Integrated geological, geodetic and marine geophysical data provide evidence of active deformation in south-western Sicily, in an area spatially coincident with the macroseismic zone of the destructive 1968 Belice earthquake sequence. Even though the sequence represents the strongest seismic event recorded in Western Sicily in historical times, focal solutions provided by different authors are inconclusive on possible faulting mechanism, which ranges from thrusting to transpression, and the seismogenic source is still undefined. Interferometric (DInSAR) observations reveal a differential ground motion on a SW-NE alignment between Campobello di Mazara and Castelvetrano (CCA), located just west of the maximum macroseismic sector. In addition, new GPS campaign-mode data acquired across the CCA alignment documents NW-SE contractional strain accumulation. Morphostructural analysis allowed to associate the alignment detected through geodetic measurements with a topographic offset of Pleistocene marine sediments. The on-land data were complemented by new high-resolution marine geophysical surveys, which indicate recent contraction on the offshore extension of the CCA alignment. The discovery of archaeological remains displaced by a thrust fault associated with the alignment provided the first likely surface evidence of coseismic and/or aseismic deformation related to a seismogenic source in the area. Results of the integrated study supports the contention that oblique thrusting and folding in response to NW-SE oriented contraction is still active. Although we are not able to associate the CCA alignment to the 1968 seismic sequence or to the historical earthquakes that destroyed the ancient Greek city of Selinunte, located on the nearby coastline, our result must be incorporated in the seismic hazard evaluation of this densely populated area of Sicily.

  6. Active shape models with optimised texture features for radiotherapy

    NASA Astrophysics Data System (ADS)

    Cheng, K.; Montgomery, D.; Yang, F.; McLaren, D. B.; McLaughlin, S.; Nailon, W. H.

    2014-03-01

    There is now considerable interest in radiation oncology on the use of shape models of anatomy to improve target delineation and assess anatomical disparity at time of radiotherapy. In this paper a texture based active shape model (ASM) is presented for automatic delineation of the gross tumor volume (GTV), containing the prostate, on computed tomography (CT) images of prostate cancer patients. The model was trained on two-dimensional (2D) contours identified by a radiation oncologist on sequential CT image slices. A three-dimensional (3D) GTV shape was constructed from these and iteratively aligned using Procrustes analysis. To train the model the shape deformation variance was learnt using the Active Shape Model (ASM) approach. In a novel development to this approach a profile feature was selected from pre-computed texture features by minimizing the Mahalanobis distance to obtain the most distinct feature for each landmark. The interior of the GTV was modelled using quantile histograms to initialize the shape model on new cases. From the archive of 42 cases of contoured CT scans, 32 cases were randomly selected for training the model and 10 cases for evaluating performance. The gold standard was defined by the radiation oncologist. The shape model achieved an overall Dice coefficient of 0.81 for all test cases. Performance was found to increase, mean Dice coefficient of 0.87, when the volume size of the new case was similar to the mean shape of the model. With further work the approach has the potential to be used in real-time delineation of target volumes and improve segmentation accuracy.

  7. Regional Tectonic Framework and Human Activities on the North Central Part of The Mexican Volcanic Belt.

    NASA Astrophysics Data System (ADS)

    Nieto-Obregon, J.

    2001-12-01

    Faults and fractures northeasterly oriented dipping NW and SE, with slips mainly normal with a slight left lateral component, affect a suite of rocks of Mesozoic to Pleistocene age, in the area of El Bajio, in the states of Queretaro, Guanajuato, Michoacan, and Aguascalientes. The faults and fractures have affected the infrastructure of the cities and surroundings of Queretaro, Celaya, Salamanca, Irapuato, Silao, Leon and Aguascalientes. In the city of Queretaro, the Tlacote-Balvanera active fault has developed a scarp and its motion may potentially affect life lines of great importance. In Celaya City a N-S trending fault traverses the city and has produced a step wise scarp more than 1.80 m high, damaging houses, streets and life lines. In Salamanca, a fault trending N 60oE, dipping to the SE extends from Cerro Gordo to the SW traversing the city and affecting with a varying degree its infrastructure. Displacements observed within the urban area reach as much as 50 cm. Close to Irapuato City, in a quarry near La Valencianita village, a N 45oE trending fault dipping to the NW affects a lacustrine sequence bearing calcareous horizons. The fault exhibits a throw of 10 m and passes north of the urban area. A similarly oriented fault traverses the city of Irapuato, and near the Traffic Circle of Puente de Guadalupe, changes its strike to the SE and continues to the city limits. In the city of Silao, a fault oriented N 60oE, traverses the city and continues to the SW up to the localities of Venta de Ramales and La Aldea. Important displacements in urban and rural areas reach more than 60 cm. Outside the city of Leon in the junction of the highways to Aguascalientes and Guadalajara a normal fault plane NE oriented and dipping SE shows striations compatible with a normal left lateral motion. Faulting is associated with old buried scarps controlled by pre existing faults, and over exploited aquifers. Some of these faults however are considered potentially active based on

  8. Developing a new synthesis of Arctic Ocean tectonics

    NASA Astrophysics Data System (ADS)

    Coakley, Bernard

    2014-05-01

    Tectonic models for the Mesozoic opening of the Amerasia Basin are dominated by the "windshield wiper" model, first articulated by Sam Carey in 1958. This theory was developed in the context of an expanding earth paradigm for global tectonics. While the expanding earth theory has been rejected, this zombie hypothesis for the development of the Amerasia Basin lingers on. Most models for the development of the Mesozoic Arctic Ocean work from the large scale down, assuming the overall pattern for the tectonic development of the Amerasia Basin is effectively described by a scissors-like opening, a separation of northern Alaska and Siberia from the conjugate margin of northern Canada, rotating apart around a pivot in the Mackenzie Delta. The problem for these models is how to resolve the space problems caused by the ridges that subdivide the basin. The most prominent of these being the Chukchi Borderland, a large block of extended continental crust, which projects out northward into the basin from the continental shelf north of the Bering Strait. A new approach can be based on first understanding the features in the basin and their inter-relationships, then using that knowledge to infer the larger scale basin tectonics, building a tectonic model from local observations. This approach will be discussed in the light of new results from recent studies in the Amerasia Basin and plans for future activities.

  9. Seismicity and active tectonics of the Andes and the origin of the Altiplano

    NASA Technical Reports Server (NTRS)

    Molnar, P.

    1982-01-01

    Large earthquakes and active deformation on the Andes were studied. Earthquakes on the east side of the Andes were generally found to reflect east-west crustal shortening. These earthquakes seem to occur throughout the crust and do not reflect a detachment and low angle thrusting of the sedimentary cover onto the Brazilian shield. Instead they imply deformation of the basement. The rate of shortening is compatible with construction of the Andes by crustal shortening since the late Cretaceous, and the surface geology, at least qualitatively, is considered to reflect this process. Andean margins are considered to be a result of crustal shortening. The crustal shortening in the sub-Andes occurs concurrently with normal faulting at high elevations in parts of the Andes. The normal faulting is associated with the buoyancy of the thick crust. Crustal shortening thickens the crust and work is done against gravity. When the crustal thickness and elevation reach limiting values, the range grows laterally by further thrusting on the margins.

  10. Tectonic map of Indonesia: A progress report

    USGS Publications Warehouse

    Hamilton, Warren Bell

    1970-01-01

    Orogeny, volcanism, and seismicity are now intensely active in Indonesia. Many Dutch tectonists--Brouwer, Umbgrove, van Bemifielen, Smit4Sibinga, Vening Meinesz, Westerveld, and others--recognized that this complex cluster of islands represents an early stage in the evolution of orogenic belts. Not until Indonesia is understood can we comprehend the Alps. This report summarizes some aspects of work to date on the Tectonic Map of Indonesia. The preparation of this map is a joint project of the Geological Survey of Indonesia and the United States Geological Survey, sponsored by the Government of Indonesia and the United States Agency for International Development. The Tectonic Map of Indonesia will be published at a scale of 1:5,000,000. Adjacent regions in other countries will be included to provide a broader context. The map limits presently envisaged are the parallels of 12° N. and 15° S., and the meridians of 91° and 148° E. Tectonic features will be shown in many colors and patterns. Bathymetry is being newly compiled, and will be shown with contours and shades of blue. Figure 1 shows the islands of Indonesia.

  11. Active Tectonics of Western Turkmenistan; Implications for the Onset of South Caspian Subduction

    NASA Astrophysics Data System (ADS)

    Hollingsworth, J.; Jackson, J.; Priestley, K.

    2007-12-01

    The Kopeh Dagh and Balkan mountain ranges of West Turkmenistan are actively deforming as a result of Arabia- Eurasia collision. We combine observations of the geomorphology made from satellite and topographic data, with historical and recent seismicity to identify major active faults, and how they contribute to regional shortening. Between 55--57.5°E, partitioned (north-vergent) thrust and right-lateral strike-slip fault segments, comprising the Ashkabad fault zone, accommodate regional shortening and the westward-extrusion of the NW Kopeh Dagh-South Caspian block, relative to Central Iran and Eurasia. Reconstruction of displaced geology indicates 35~km total right-lateral motion across the Ashkabad fault zone. The Balkan region lies along-strike of the Ashkabad fault zone, west of 55°E. Fault plane solutions indicate shortening is partitioned onto the Balkan thrust and right-lateral Kum-Dagh fault zones. Thrust earthquakes are relatively deep (30--45~km) and lie along a north-dipping plane which extends 40±5~km north beneath the Balkan anticline. Receiver function data from Turkmenbashi and Nebit Dagh indicate these earthquakes occur in the base of the crust, and may therefore be related to bending of the NW Kopeh Dagh-South Caspian lithosphere as it is overthrust by Eurasia. Movement on a north-dipping blind thrust fault is consistent with the broad asymmetric (south-vergent) fold structure of the Balkan range. Recent uplift is also indicated by extensional faults which displace Quaternary geomorphology along the range crest. South of the Balkan range, right-lateral shear occurs across the Kum-Dagh fault zone which is expressed as a series of right-stepping anticlines (affecting Pliocene Red Series and younger sediments), forming important traps for hydrocarbons. An important structural change occurs near 55°E. To the west, Eurasia overthrusts the NW Kopeh Dagh- South Caspian block, while to the east the polarity of thrusting changes and the Kopeh Dagh

  12. Tectonic Activity and Processes Preceding the Formation of the Dead Sea Fault Zone

    NASA Astrophysics Data System (ADS)

    Eppelbaum, L. V.; Pilchin, A. N.

    2007-12-01

    Analysis of geological-geophysical data indicates that at the end of the Proterozoic, blocks of the Arabian Shield (AS) were thrust to the north-west onto the crust of the proto-Mediterranean (PM). This was caused by the pushing of oceanic crust from the south-east forming the Najd faults system (NF). This thrusting took place between 630 and 590 Ma, and is confirmed by the offsets between the Yanbu suture of the AS and Allaqi-Sol Hamid suture of the Nubian Shield (NS), the Bi'r Umq suture of AS and Nakasib suture of NS, and parts of the Yanbu and Nabitah sutures of AS. This caused the separation of AS from NS, and AS from the continental crust to north-east of it with its north-western displacement, resulting in opening of the Persian Gulf. This caused the start of deposition of huge amounts of Vendian-Cambrian evaporites in Saudi Arabia, Oman, Persian Gulf, Zagros, central Iran and other regions. The fact of the formation and preservation of the evaporites, and the common similarities in Vendian-Triassic sedimentary cover of Central Iran, Zagros, Taurus, and Arabian Plate (AP) and common Late Proterozoic-Early Paleozioc magmatic activity, show that these regions did not change their position significantly since then. Results of the DESERT project show that the lowermost part of the crust is present east of the Dead Sea Fault Zone (DSFZ), but it is absent west of it. This could be explained by detachment of the bottom part of the crust west of DSFZ during AP thrusting onto the crust of PM. The lithospheric slice discovered by seismic data between Moho and depth of about 55 km in S. Israel could be a remnant of that crust. During the thrusting, the AP overrode the detached slice. The slice was later remelted during formation of the postorogenic magmatic rocks of 590-530 Ma widespread in Jordan. The formation of three dyke swarms in S. Israel (600-540 Ma), widespread dykes in Sinai (590-530 Ma) and AP (590-530 Ma), as well as high-T-low-P metamorphism between 600

  13. Southeast Papuan crustal tectonics: Imaging extension and buoyancy of an active rift

    NASA Astrophysics Data System (ADS)

    Abers, G. A.; Eilon, Z.; Gaherty, J. B.; Jin, G.; Kim, YH.; Obrebski, M.; Dieck, C.

    2016-02-01

    Southeast Papua hosts the world's youngest ultra-high-pressure (UHP) metamorphic rocks. These rocks are found in an extensional setting in metamorphic core complexes. Competing theories of extensional shear zones or diapiric upwelling have been suggested as driving their exhumation. To test these theories, we analyze the CDPAPUA temporary array of 31 land and 8 seafloor broadband seismographs. Seismicity shows that deformation is being actively accommodated on the core complex bounding faults, offset by transfer structures in a manner consistent with overall north-south extension rather than radial deformation. Rayleigh wave dispersion curves are jointly inverted with receiver functions for crustal velocity structure. They show crustal thinning beneath the core complexes of 30-50% and very low shear velocities at all depths beneath the core complexes. On the rift flanks velocities resemble those of normal continents and increase steadily with depth. There is no evidence for velocity inversions that would indicate that a major density inversion exists to drive crustal diapirs. Also, low-density melt seems minor within the crust. Together with the extension patterns apparent in seismicity, these data favor an extensional origin for the core complexes and limit the role of diapirism as a secondary exhumation mechanism, although deeper mantle diapirs may be undetected. A small number of intermediate-depth earthquakes, up to 120 km deep, are identified for the first time just northeast of the D'Entrecasteaux Islands. They occur at depths similar to those recorded by UHP rocks and similar temperatures, indicating that the modern seismicity occurs at the setting that generates UHP metamorphism.

  14. Seismo-turbidite Sedimentology: Implications for Active Tectonic Margin Stratigraphy and Sediment Facies Patterns

    NASA Astrophysics Data System (ADS)

    Nelson, C. H.; Goldfinger, C.; Gutierrez Pastor, J.; Polonia, A.; Van Daele, M. E.

    2014-12-01

    Earthquakes generate mass transport deposits (MTDs); megaturbidites (MTD overlain by coeval turbidite); multi-pulsed, stacked, and mud homogenite seismo-turbidites; tsunamites; and seiche deposits. The strongest (Mw 9) earthquake shaking signatures appear to create multi-pulsed individual turbidites, where the number and character of multiple coarse-grained pulses for correlative turbidites generally remain constant both upstream and downstream in different channel systems. Multiple turbidite pulses, that correlate with multiple ruptures shown in seismograms of historic earthquakes (e.g. Chile 1960, Sumatra 2004 and Japan 2011), support this hypothesis. The weaker (Mw = or < 8) (e.g. northern California San Andreas) earthquakes generate dominantly upstream simple fining-up (uni-pulsed) turbidites in single tributary canyons and channels; however, downstream stacked turbidites result from synchronously triggered multiple turbidity currents that deposit in channels below confluences of the tributaries. Proven tsunamites, which result from tsunami waves sweeping onshore and shallow water debris into deeper water, are a fine-grained turbidite cap over other seismo-turbidites. In contrast, MTDs and seismo-turbidites result from slope failures. Multiple great earthquakes cause seismic strengthening of slope sediment, which results in minor MTDs in basin floor turbidite system deposits (e.g. maximum run-out distances of MTDs across basin floors along active margins are up to an order of magnitude less than on passive margins). In contrast, the MTDs and turbidites are equally intermixed in turbidite systems of passive margins (e.g. Gulf of Mexico). In confined basin settings, earthquake triggering results in a common facies pattern of coeval megaturbidites in proximal settings, thick stacked turbidites downstream, and ponded muddy homogenite turbidites in basin or sub-basin centers, sometimes with a cap of seiche deposits showing bi-directional flow patterns.

  15. Active tectonics and rheology of slow-moving thrusts in the Tibetan foreland of peninsular India

    NASA Astrophysics Data System (ADS)

    Copley, Alex; Mitra, Supriyo; Sloan, Alastair; Gaonkar, Sharad; Avouac, Jean-Philippe; Hollingsworth, James

    2016-04-01

    Peninsular India is cut by active thrust faults that break in earthquakes in response to the compressive force exerted between India and the Tibetan Plateau. The rate of deformation is low, with 2 +/- 1 mm/yr of shortening being accommodated over the entire N-S extent of the Indian sub-continent. However, the large seismogenic thickness in the region (40-50 km), and the long faults, mean that the rare earthquakes that do occur can have magnitudes up to at least 8. This contribution describes studies of two large Indian earthquakes, and their rheological and hazard implications, using a range of techniques. First, the Mw 7.6 Bhuj (Gujarat) earthquake of 2001 is examined using a combination of seismology, InSAR, and levelling data. A slip model for the earthquake will be presented, which allows the material properties of the fault plane to be examined. Second, a Holocene-age earthquake rupture from central India will be discussed. Geomorphic analysis of the scarps produced by the event suggest a magnitude of 7.6 - 8.4. Both of these earthquakes had unusually large stress-drops, amongst the largest recorded for shallow earthquakes. The information provided by these two events will be combined with calculations for the total compressive force being transmitted through the Indian peninsular in order to suggest that the faults are characterised by a low coefficient of friction (approximately 0.1), and that the stress-drops in the earthquakes are close to complete. In turn, these results imply that the majority of the force being transmitted through the Indian plate is supported by the brittle crust. Finally, the along-strike continuation of the faults will be described, with implications for hazard assessment and material properties throughout India.

  16. Active tectonics of the Seattle fault and central Puget sound, Washington - Implications for earthquake hazards

    USGS Publications Warehouse

    Johnson, S.Y.; Dadisman, S.V.; Childs, J. R.; Stanley, W.D.

    1999-01-01

    We use an extensive network of marine high-resolution and conventional industry seismic-reflection data to constrain the location, shallow structure, and displacement rates of the Seattle fault zone and crosscutting high-angle faults in the Puget Lowland of western Washington. Analysis of seismic profiles extending 50 km across the Puget Lowland from Lake Washington to Hood Canal indicates that the west-trending Seattle fault comprises a broad (4-6 km) zone of three or more south-dipping reverse faults. Quaternary sediment has been folded and faulted along all faults in the zone but is clearly most pronounced along fault A, the northernmost fault, which forms the boundary between the Seattle uplift and Seattle basin. Analysis of growth strata deposited across fault A indicate minimum Quaternary slip rates of about 0.6 mm/yr. Slip rates across the entire zone are estimated to be 0.7-1.1 mm/yr. The Seattle fault is cut into two main segments by an active, north-trending, high-angle, strike-slip fault zone with cumulative dextral displacement of about 2.4 km. Faults in this zone truncate and warp reflections in Tertiary and Quaternary strata and locally coincide with bathymetric lineaments. Cumulative slip rates on these faults may exceed 0.2 mm/yr. Assuming no other crosscutting faults, this north-trending fault zone divides the Seattle fault into 30-40-km-long western and eastern segments. Although this geometry could limit the area ruptured in some Seattle fault earthquakes, a large event ca. A.D. 900 appears to have involved both segments. Regional seismic-hazard assessments must (1) incorporate new information on fault length, geometry, and displacement rates on the Seattle fault, and (2) consider the hazard presented by the previously unrecognized, north-trending fault zone.

  17. Permian to late Cenozoic evolution of northern Patagonia: Main tectonic events, magmatic activity, and depositional trends

    NASA Astrophysics Data System (ADS)

    Uliana, M. A.; Biddle, K. T.

    The late Paleozoic to late Cenozoic evolution of northern Patagonia was influenced significantly by events that occurred while the area was part of the South American sector of Gondwanaland. Late Paleozoic to Middle Triassic subduction along the edge of the supercontinent formed a broad convergent-margin system that is the underpinning of northern Patagonia. Deformation (Gondwanidian orogeny) associated with the subduction is recognized in both the forearc and the convergent backarc areas. Regional extension, accompanied by bimodal volcanism, began in the Late Triassic and led to the formation of a number of north-northwest trending rift basins in Patagonia, which generally followed the Gondwanidian basement grain. Continued extension in the Jurassic and Early Cretaceous led to the opening of the Rocas Verdes marginal basin in southern Chile and, ultimately, to the opening of the South Atlantic Ocean. Once oceanic crust began to form, faulting and volcanism declined in Patagonia. During the late Early Cretaceous to the Late Cretaceous, sags over the rift basins coalesced to form a broad backarc basin behind the volcanic arc to the west. These sags are suggestive of thermally driven subsidence. Subsidence of the evolving Atlantic margin allowed extensive marine transgressions to take place from the east. The stratigraphic record of northern Patagonia reflects these events. The upper Paleozoic to upper Mesozoic sedimentary sequences were deposited in basins directly associated with convergent activity along the margin of Gondwanaland or in rift basins created during its breakup. Even though the Tertiary evolution of Patagonia was dominated by events along the western margin of South America, the patterns of sediment transport, thickness, and general shoreline position were still influenced by the locations of the Mesozoic rifts formed during the breakup of Gondwanaland.

  18. Evidence of active tectonics on a Roman aqueduct system (II-III century A.D.) near Rome, Italy

    NASA Astrophysics Data System (ADS)

    Marra, Fabrizio; Montone, Paola; Pirro, Mario; Boschi, Enzo

    2004-04-01

    In this paper we describe evidence of strong tectonic deformation affecting two aqueducts of Roman age (II-III century A.D.). The channels are located approximately 20 km northeast of Rome along the ancient Via Tiburtina. Brittle and ductile deformation affects these two structures, including extensional joint systems, NE-oriented faults, and horizontal distortion. This deformation is consistent with right-lateral movement on major N-striking faults, and represents the first evidence that tectonic deformation took place in historical times in the vicinity of Rome, with local strike-slip movement superimposed on a regional extensional fault system.

  19. Edaphics, active tectonics and animal movements in the Kenyan Rift - implications for early human evolution and dispersal

    NASA Astrophysics Data System (ADS)

    Kübler, Simon; Owenga, Peter; Rucina, Stephen; King, Geoffrey C. P.

    2014-05-01

    The quality of soils (edaphics) and the associated vegetation strongly controls the health of grazing animals. Until now, this has hardly been appreciated by paleo-anthropologists who only take into account the availability of water and vegetation in landscape reconstruction attempts. A lack of understanding the importance of the edaphics of a region greatly limits interpretations of the relation between our ancestors and animals over the last few million years. If a region lacks vital trace elements then wild grazing and browsing animals will avoid it and go to considerable length and take major risks to seek out better pasture. As a consequence animals must move around the landscape at different times of the year. In complex landscapes, such as tectonically active rifts, hominins can use advanced group behaviour to gain strategic advantage for hunting. Our study in the southern Kenya rift in the Lake Magadi region shows that the edaphics and active rift structures play a key role in present day animal movements as well as the for the location of an early hominin site at Mt. Olorgesailie. We carried out field analysis based on studying the relationship between the geology and soil development as well as the tectonic geomorphology to identify 'good' and 'bad' regions both in terms of edaphics and accessibility for grazing animals. We further sampled different soils that developed on the volcanic bedrock and sediment sources of the region and interviewed the local Maasai shepherds to learn about present-day good and bad grazing sites. At the Olorgesailie site the rift valley floor is covered with flood trachytes; basalts only occur at Mt. Olorgesailie and farther east up the rift flank. The hominin site is located in lacustrine sediments at the southern edge of a playa that extends north and northwest of Mt. Olorgesailie. The lakebeds are now tilted and eroded by motion on two north-south striking faults. The lake was trapped by basalt flows from Mt. Olorgesailie

  20. Active tectonics of North Haji Abad (Hormozgan region) in south of Iran

    NASA Astrophysics Data System (ADS)

    shafiei bafti, amir

    2014-05-01

    Zagros Active Fold -thrust Belt is situated in the northern margin of the Arabian Plat and formed due to shortening, thickening and uplift of tethys sedimentary basin between Arabian and Iranian plates. In this study, the rate of uplift in the northern margin of the Zagros Mountains in southern Iran are examined. The Zagros fault zone in this region is composed of a set faults, including Deragah, Haji Abad, Tezerj and several other faults and also we call these branches from F1 to F8. These segments puts from northwest to the East- Southeast. Based on field surveys and Geological maps, we prepared a structural map from major faults of Zagros fault system for identify faults pattern and estimating of uplift rate movements in Zagros fault. Three methods used to calculation of uplift rate: A: Asymmetry index Accordance with the procedure, in studied area, northeast drainage are longer than of southwest drainage and east minor drainages also longer than the west side drainages, Uplifting in this region is characterized by mentioned asymmetry factor. The amount of this index is AF=71.81. B. Interaction between the faults movements and erosion process We comparison contrast between uplifting movement rates and erosion rates in different parts of studied region by Smf and other indexes. Average amount of Smf=1.1. C. Evaluation of Uplift rate of alluvial terraces was performed by sediment ages and terraces height. We surveyed Quaternary facieses which have ages between 17,000 and 30,000 years old. the rate of uplifting for each fault is follows : Deragah fault and F8 fault between 1.0 to 1.85mm per year and F7, F6, F5, and F4 faults, have a rate Uplifting between 0.6 to 1.0 mm per year and the rate of Uplift for other faults is between 0.04 to 0.06 mm per year. According to our studies, uplift rates in north -east and south-west more than other regions The minimum rate at different stations are about 0.5mm/y to 0.93mm/y and its maximum is 0.88 mm/y to 1.47mm/y.

  1. Active tectonic influence on the evolution of drainage and landscape: Geomorphic signatures from frontal and hinterland areas along the Northwestern Himalaya, India

    NASA Astrophysics Data System (ADS)

    Malik, Javed N.; Mohanty, C.

    2007-03-01

    The Kangra Re-entrant in the NW Himalaya is one of the most seismically active regions, falling into Seismic Zone V along the Himalaya. In 1905 the area experienced one of the great Himalayan earthquakes with magnitude 7.8. The frontal fault system - the Himalayan Frontal Thrust (HFT) associated with the foreland fold - Janauri Anticline, along with other major as well as secondary hinterland thrust faults, provides an ideal site to study the ongoing tectonic activity which has influenced the evolution of drainage and landscape in the region. The present study suggests that the flat-uplifted surface in the central portion of the Janauri Anticline represents the paleo-exit of the Sutlej River. It is suggested that initially when the tectonic activity propagated southward along the HFT the Janauri Anticline grew along two separate fault segments (north and south faults), the gap between these two fault and the related folds allowed the Sutlej River to flow across this area. Later, the radial propagation of the faults towards each other resulted in an interaction of the fault tips, which caused the rapid uplift of the area. Rapid uplift resulted in the disruption and longitudinal deflection of the Sutlej river channel. Fluvial deposits on the flat surface suggest that an earlier fluvial system flowed across this area in the recent past. Geomorphic signatures, like the sharp mountain fronts along the HFT in some places, as well as along various hinterland subordinate faults like the Nalagarh Thrust (NaT), the Barsar Thrust (BaT) and the Jawalamukhi Thrust (JMT); the change in the channel pattern, marked by a tight incised meander of the Beas channel upstream of the JMT indicate active tectonic movements in the area. The prominent V-shaped valleys of the Beas and Sutlej rivers, flowing across the thrust fronts, with Vf values ranging from <1.0-1.5 are also suggestive of ongoing tectonic activity along major and hinterland faults. This suggests that not only is the HFT

  2. Repeated large-magnitude earthquakes in a tectonically active, low-strain continental interior: The northern Tien Shan, Kyrgyzstan

    NASA Astrophysics Data System (ADS)

    Landgraf, A.; Dzhumabaeva, A.; Abdrakhmatov, K. E.; Strecker, M. R.; Macaulay, E. A.; Arrowsmith, Jr.; Sudhaus, H.; Preusser, F.; Rugel, G.; Merchel, S.

    2016-05-01

    The northern Tien Shan of Kyrgyzstan and Kazakhstan has been affected by a series of major earthquakes in the late 19th and early 20th centuries. To assess the significance of such a pulse of strain release in a continental interior, it is important to analyze and quantify strain release over multiple time scales. We have undertaken paleoseismological investigations at two geomorphically distinct sites (Panfilovkoe and Rot Front) near the Kyrgyz capital Bishkek. Although located near the historic epicenters, both sites were not affected by these earthquakes. Trenching was accompanied by dating stratigraphy and offset surfaces using luminescence, radiocarbon, and 10Be terrestrial cosmogenic nuclide methods. At Rot Front, trenching of a small scarp did not reveal evidence for surface rupture during the last 5000 years. The scarp rather resembles an extensive debris-flow lobe. At Panfilovkoe, we estimate a Late Pleistocene minimum slip rate of 0.2 ± 0.1 mm/a, averaged over at least two, probably three earthquake cycles. Dip-slip reverse motion along segmented, moderately steep faults resulted in hanging wall collapse scarps during different events. The most recent earthquake occurred around 3.6 ± 1.3 kyr ago (1σ), with dip-slip offsets between 1.2 and 1.4 m. We calculate a probabilistic paleomagnitude to be between 6.7 and 7.2, which is in agreement with regional data from the Kyrgyz range. The morphotectonic signals in the northern Tien Shan are a prime example of deformation in a tectonically active intracontinental mountain belt and as such can help understand the longer-term coevolution of topography and seismogenic processes in similar structural settings worldwide.

  3. Marine and land active-source seismic investigation of geothermal potential, tectonic structure, and earthquake hazards in Pyramid Lake, Nevada

    NASA Astrophysics Data System (ADS)

    Eisses, A.; Kell, A. M.; Kent, G.; Driscoll, N. W.; Karlin, R. E.; Baskin, R. L.; Louie, J. N.; Smith, K. D.; Pullammanappallil, S.

    2011-12-01

    Preliminary slip rates measured across the East Pyramid Lake fault, or the Lake Range fault, help provide new estimates of extension across the Pyramid Lake basin. Multiple stratigraphic horizons spanning 48 ka were tracked throughout the lake, with layer offsets measured across all significant faults in the basin. A chronstratigraphic framework acquired from four sediment cores allows slip rates of the Lake Range and other faults to be calculated accurately. This region of the northern Walker Lake, strategically placed between the right-lateral strike-slip faults of Honey and Eagle Lakes to the north, and the normal fault bounded basins to the southwest (e.g., Tahoe, Carson), is critical in understanding the underlying structural complexity that is not only necessary for geothermal exploration, but also earthquake hazard assessment due to the proximity of the Reno-Sparks metropolitan area. In addition, our seismic CHIRP imaging with submeter resolution allows the construction of the first fault map of Pyramid Lake. The Lake Range fault can be obviously traced west of Anahoe Island extending north along the east end of the lake in numerous CHIRP lines. Initial drafts of the fault map reveal active transtension through a series of numerous, small, northwest striking, oblique-slip faults in the north end of the lake. A previously field mapped northwest striking fault near Sutcliff can be extended into the west end of Pyramid Lake. This fault map, along with the calculated slip rate of the Lake Range, and potentially multiple other faults, gives a clearer picture into understanding the geothermal potential, tectonic regime and earthquake hazards in the Pyramid Lake basin and the northern Walker Lane. These new results have also been merged with seismicity maps, along with focal mechanisms for the larger events to begin to extend our fault map in depth.

  4. Headache associated with sexual activity: demography, clinical features, and comorbidity.

    PubMed

    Frese, A; Eikermann, A; Frese, K; Schwaag, S; Husstedt, I-W; Evers, S

    2003-09-23

    S: To provide data on the demography, clinical features, and comorbidity of headache associated with sexual activity (HSA). Between 1996 and 2001, 51 patients with the diagnosis of HSA were questioned using a structured interview. The mean age at onset was 39.2 (+/-11.1) years. There was a clear male preponderance (2.9:1). The age at onset had two peaks, with a first peak between the 20th and 24th (n = 13) years of life and a second peak between the 35th and 44th (n = 20) years of life. Eleven patients had HSA type 1 (dull subtype), which gradually increased with increasing sexual excitement. The remaining (n = 40) had HSA type 2 (explosive subtype). The pain was predominantly bilateral (67%), and diffuse or occipital (76%). The quality was nearly equally distributed among dull, throbbing, and stabbing. HSA was not dependent on specific sexual habits and most often occurred during sexual activity with the usual partner (94%) and during masturbation (35%). There was a high comorbidity with migraine (25%), benign exertional headache (29%), and tension-type headache (45%). HSA types 1 and 2 did not significantly differ in demography, clinical features, or comorbidity, except for a higher probability of stopping the attack by breaking off sexual activity in HSA type 1. There were no cases with HSA type 3 (postural subtype). Mean age at onset, a male preponderance, a predominantly bilateral and occipital pain, and a high comorbidity with other primary headaches are in concordance with case reports in the literature. The authors found two peaks for the age at onset, however. There was no clinical evidence proving subtypes 1 and 2 to be distinct disorders. HSA types 1 and 2 may be different manifestations of the same disease rather than distinct entities.

  5. Normal faulting along the western side of the Matese Mountains: Implications for active tectonics in the Central Apennines (Italy)

    NASA Astrophysics Data System (ADS)

    Boncio, Paolo; Dichiarante, Anna Maria; Auciello, Eugenio; Saroli, Michele; Stoppa, Francesco

    2016-01-01

    We provide new field data from geologic mapping and bedrock structural geology along the western side of the Matese Mts in central Italy, a region of high seismicity, strain rates among the highest of the entire Apennines (4-5 mm/yr GPS-determined extension), and poorly constrained active faults. The existing knowledge on the Aquae Iuliae normal fault (AIF) was implemented with geometric and kinematic data that better constrain its total length (16.5 km), the minimum long-term throw rate (0.3-0.4 mm/yr, post-late glacial maximum, LGM), and the segmentation. For the first time, we provide evidence of post-350 ka and possibly late Quaternary activity of the Ailano - Piedimonte Matese normal fault (APMF). The APMF is 18 km long. It is composed of a main 11 km-long segment striking NW-SE and progressively bending to the E-W in its southern part, and a 7 km-long segment striking E-W to ENE-WSW with very poor evidence of recent activity. The available data suggest a possible post-LGM throw rate of the main segment of ≳0.15 mm/yr. There is no evidence of active linkage in the step-over zone between the AIF and APMF (Prata Sannita step-over). An original tectonic model is proposed by comparing structural and geodetic data. The AIF and APMF belong to two major, nearly parallel fault systems. One system runs at the core of the Matese Mts and is formed by the AIF and the faults of the Gallo-Letino-Matese Lake system. The other system runs along the western side of the Matese Mts and is formed by the APMF, linked to the SE with the Piedimonte Matese - Gioia Sannitica fault. The finite extension of the APMF might be transferred to the NW towards the San Pietro Infine fault. The nearly 2-3 mm/yr GPS-determined extension rate is probably partitioned between the two systems, with a ratio that is difficult to establish due to poor GPS coverage. The proposed model, though incomplete (several faults/transfer zones need further investigations), aids in the seismotectonic

  6. Moment tensor inversion of recent local moderate sized Van Earthquakes: seismicity and active tectonics of the Van region : Eastern Turkey

    NASA Astrophysics Data System (ADS)

    Kalafat, D.; Suvarikli, M.; Ogutcu, Z.; Kekovali, K.; Ocal, M. F.; Gunes, Y.; Pinar, A.

    2013-12-01

    strong trust faulting which coincides with the nature of the Van fault. We were currently analysing an archive of over 5000 local events recorded by the KOERI seismic network of over 20 broadband stations between 2010 and 2013 in the whole Van Region. The Van Earthquake initiated and caused an increase in seismic activity of the region. Van Earthquake and its important aftershocks fault mechanism solutions show that the region is under compression and reverse faulting is a result of this regime which is effective on the active compressional tectonics of the region. This study was supported by Bogazici University Research Projects Commission under SRP/BAP project No. 6040.

  7. Non-tectonic exposure Rates along Bedrock Fault Scarps in an active Mountain Belt of the central Apennines

    NASA Astrophysics Data System (ADS)

    Kastelic, Vanja; Burrato, Pierfrancesco; Carafa, Michele M. C.; Basili, Roberto

    2017-04-01

    The central Apennines (Italy) are a mountain chain affected by post-collisional active extension along NW-SE striking normal faults and well-documented regional-scale uplift. Moderate to strong earthquakes along the seismogenically active extensional faults are frequent in this area, thus a good knowledge on the characteristics of the hosting faults is necessary for realistic seismic hazard models. The studied bedrock fault surfaces are generally located at various heights on mountain fronts above the local base level of glacio-fluvial valleys and intermountain fluvio-lacustrine basins and are laterally confined to the extent of related mountain fronts. In order to investigate the exposure of the bedrock fault scarps from under their slope-deposit cover, a process that has often been exclusively attributed to co-seismic earthquake slip and used as proxy for tectonic slip rates and earthquake recurrence estimations, we have set up a measurement experiment along various such structures. In this experiment we measure the relative position of chosen markers on the bedrock surface and the material found directly at the contact with its hanging wall. We present the results of monitoring the contact between the exposed fault surfaces and slope deposits at 23 measurement points on 12 different faults over 3.4 year-long observation period. We detected either downward or upward movements of the slope deposit with respect to the fault surface between consecutive measurements. During the entire observation period all points, except one, registered a net downward movement in the 2.9 - 25.6 mm/yr range, resulting in the progressive exposure of the fault surface. During the monitoring period no major earthquakes occurred in the region, demonstrating the measured exposure process is disconnected from seismic activity. We do however observe a positive correlation between the higher exposure in respect to higher average temperatures. Our results indicate that the fault surface

  8. Steady-state bedrock river response to tectonic and lithologic variations across active folds at the northwest Himalayan front

    NASA Astrophysics Data System (ADS)

    Allen, G. H.; Barnes, J. B.; Kirby, E.; Pavelsky, T. M.

    2011-12-01

    This study examines the response of bedrock channel gradient and width to differences in substrate erodibility and uplift rate along the flanks of active folds in the northwestern Himalaya foreland. Bedrock rivers are a principle driver of topographic evolution in tectonically active landscapes. Several stream power models have been proposed which equate bedrock river incision (E) to a product of channel gradient (S) and upstream drainage area (A) such that, E=KSmAn, where K, m, and n are constants which depend on dominant erosional processes. These models account for changes in channel width (W, a key influence on river incision) by assuming width scales predictably with upstream drainage area such that, W=kwAb, where kw and b are empirical constants. This relationship is often not valid in areas with varying lithology because channel morphology depends in part on the underlying rock strength. Furthermore, the degree to which steady-state channels respond to changes in substrate erodibility has yet to be well tested. In this study, we explicitly account for channel width variations using new quantitative methods to more accurately constrain river incision potential and its relationship to changes in bedrock erodibility and uplift rate in an active steady-state landscape. We focus on the Chandigarh and Mohand anticlines, two active fault-bend folds in the Siwalik Hills in northwestern India. We use digital topography and high resolution (5 m) satellite images to measure channel widths and gradients over ~100 channels draining both flanks resulting in >100,000 width measurements. We then normalize channel widths and slopes to upstream drainage area yielding two sensitive channel morphometrics: normalized width index (kwn) and normalized steepness index (ksn). Our observations show that both kwn and ksn vary systematically with changes in uplift rate and lithology. For example, at locations where channels cross into an erosionally resistant bedrock lithology, mean

  9. Cenozoic tectonic reorganizations of the Death Valley region, southeast California and southwest Nevada

    USGS Publications Warehouse

    Fridrich, Christopher J.; Thompson, Ren A.

    2011-01-01

    The Death Valley region, of southeast California and southwest Nevada, is distinct relative to adjacent regions in its structural style and resulting topography, as well as in the timing of basin-range extension. Cenozoic basin-fill strata, ranging in age from greater than or equal to 40 to approximately 2 million years are common within mountain-range uplifts in this region. The tectonic fragmentation and local uplift of these abandoned basin-fills indicate a multistage history of basin-range tectonism. Additionally, the oldest of these strata record an earlier, pre-basin-range interval of weak extension that formed broad shallow basins that trapped sediments, without forming basin-range topography. The Cenozoic basin-fill strata record distinct stratigraphic breaks that regionally cluster into tight age ranges, constrained by well-dated interbedded volcanic units. Many of these stratigraphic breaks are long recognized formation boundaries. Most are angular unconformities that coincide with abrupt changes in depositional environment. Deposits that bound these unconformities indicate they are weakly diachronous; they span about 1 to 2 million years and generally decrease in age to the west within individual basins and regionally, across basin boundaries. Across these unconformities, major changes are found in the distribution and provenance of basin-fill strata, and in patterns of internal facies. These features indicate rapid, regionally coordinated changes in strain patterns defined by major active basin-bounding faults, coincident with step-wise migrations of the belt of active basin-range tectonism. The regionally correlative unconformities thus record short intervals of radical tectonic change, here termed "tectonic reorganizations." The intervening, longer (about 3- to 5-million-year) interval of gradual, monotonic evolution in the locus and style of tectonism are called "tectonic stages." The belt of active tectonism in the Death Valley region has abruptly

  10. A tectonic geomorphological classification of the walls of Valles Marineris

    NASA Technical Reports Server (NTRS)

    Spencer, J. R.

    1984-01-01

    Viking 1 imagery of the Coprates NW quadrangle was used in an attempt to develop a geomorphic classification scheme for the canyon walls of Valles Marineris analogous to that devised to evaluate the relative tectonic activity of terrestrial mountain fronts. The four classes of walls established are described and mapped. Regions where a class cannot be assigned owing to the presence of intra canyon sediments, landslides, or landslide debris; and apparent fault scarps that occur on the canyon floor rather than at the wall base are also shown. The most striking feature is the concentration of active tectonic features within lus Chasma, and to a lesser extent in Tithonium Chasma, as well as along the north walls of Coprates and East Candor.

  11. The Palu Koro Shear Zone, a 1000-kilometer-long zone of Middle Miocene Tectonic activity in Sulawesi and Eastern Borneo

    SciTech Connect

    Scardina, A.D. ); Haan, E.A. ); Maher, K.A. )

    1994-07-01

    The middle Miocene was a period of major tectonic activity for Sulawesi and eastern Borneo. Previous workers have documented the effects of the collision of the Sula and Buton microplates on Sulawesi, the uplift of Borneo, and overthrusting onshore and offshore Sabah. These tectonic events are thought to be related to motion along a regional shear zone that extends 1000 km from the southeastern limb of Sulawesi to the offshore of northern Sabah. Rangin (1989) originally suggested that the collision of the Sula microcontinent was responsible for the compression that lead to the overthrusting onshore Sabah. Here the authors present additional evidence of the long-range effects of this collision and its control on the basin development and formation of hydrocarbon-bearing structures.

  12. Soft sediment deformation structures in a lacustrine sedimentary succession induced by volcano-tectonic activities: An example from the Cretaceous Beolgeumri Formation, Wido Volcanics, Korea

    NASA Astrophysics Data System (ADS)

    Ko, Kyoungtae; Kim, Sung Won; Lee, Hong-Jin; Hwang, In Gul; Kim, Bok Chul; Kee, Won-Seo; Kim, Young-Seog; Gihm, Yong Sik

    2017-08-01

    The Cretaceous Beolgeumri Formation is composed of laminated mudstones intercalated with sandstones, chert, and a bed of lapilli tuff that were deposited in a lacustrine environment at the terminal part of a regional strike-slip fault systems on the southwestern Korean Peninsula. The Beolgeumri Formation contains various types of soft sediment deformation (SSD) structures that are characterized by a wide extent (< 4 km), lateral continuity (< 200 m), and vertical repetition. The SSD structures can be classified into six categories based on their morphological features and deformation styles: 1) fold structures, 2) load structures, 3) water-escape structures, 4) rip-down structures, 5) boudin structures, and 6) synsedimentary fault structures. Field examination of SSD structures together with an analysis of the sedimentological records of the Beolgeumri Formation indicate that the SSD structures formed largely by liquefaction and/or fluidization triggered by ground shaking during earthquakes. To constrain the timing of the development of SSD structures in the Beolgeumri Formation, we conducted sensitive high-resolution ion microprobe (SHRIMP) U-Pb zircon age dating of block sized lithic clasts bearing volcaniclastic deposits that conformably underlie (the Mangryeongbong Tuff) and overlie (the Ttandallae Tuff) the Beolgeumri Formation. The Mangryeongbong and Ttandallae Tuffs have ages of 86.63 ± 0.83 Ma and 87.24 ± 0.36 Ma, respectively, indicating that the Beolgeumri Formation was deposited during a short interval between major volcanic eruptions. The large lithic clasts of volcaniclastic deposits suggest that the Beolgeumri Formation was deposited adjacent to an active volcanic edifice(s). Syndepositional magmatic activities are suggested by the occurrence of a lapilli tuff bed in the Beolgeumri Formation and an igneous intrusion (intermediate sill) that is crosscut by a sand dike, as well as the similar age results of the underlying and overlying volcaniclastic

  13. Stress and tectonics on Mars

    NASA Technical Reports Server (NTRS)

    Banerdt, W. B.; Golombek, Matthew P.; Tanaka, Kenneth L.

    1992-01-01

    Deformation of the Martian lithosphere and the various theoretical formulations used to model its behavior on local, regional, and global scales are studied. An overview of the various classes of tectonic features found on Mars is presented. The tectonic record on Mars, which provides the basic framework for interpreting theoretical thermomechanical models in terms of major tectonic events and provinces is summarized. The thickness of the elastic lithosphere is estimated using its response to local surface loads, and significant spatial variability is found, with values ranging from 20 to 300 km. A comparison of the major radial graben systems with theoretical stress models shows that more than one mechanism of lithospheric deformation is required to produce its enormous extent.

  14. Tectonics of the Easter plate

    NASA Technical Reports Server (NTRS)

    Engeln, J. F.; Stein, S.

    1984-01-01

    A new model for the Easter plate is presented in which rift propagation has resulted in the formation of a rigid plate between the propagating and dying ridges. The distribution of earthquakes, eleven new focal mechanisms, and existing bathymetric and magnetic data are used to describe the tectonics of this area. Both the Easter-Nazca and Easter-Pacific Euler poles are sufficiently close to the Easter plate to cause rapid changes in rates and directions of motion along the boundaries. The east and west boundaries are propagating and dying ridges; the southwest boundary is a slow-spreading ridge and the northern boundary is a complex zone of convergent and transform motion. The Easter plate may reflect the tectonics of rift propagation on a large scale, where rigid plate tectonics requires boundary reorientation. Simple schematic models to illustrate the general features and processes which occur at plates resulting from large-scale rift propagation are used.

  15. Sedimentation close to the active Medlicott Wadia Thrust (Western Himalaya): How to estimate climatic base level changes and tectonics

    NASA Astrophysics Data System (ADS)

    Vignon, V.; Mugnier, J.-L.; Vassallo, R.; Srivastava, P.; Malik, M. A.; Jayangondaperumal, R.; Jouanne, F.; Buoncristiani, J. F.; Carcaillet, J.; Replumaz, A.; Jomard, H.

    2017-05-01

    The Medlicott-Wadia Thrust (MWT) is one of the major active out-of-sequence thrusts in the Himalaya. Studies on Quaternary terraces in its vicinity have been performed using sedimentological, geomorphic and geochronological methods. We focus on the Riasi zone, south of the Pir Panjal range, in the Jammu and Kashmir region of India. The sedimentary units of Quaternary landforms have been mapped as a function of their location with respect to the thrust faults, their relative chronology, and their lithology. Three aggrading sedimentary units, five thin units above strath surfaces at the footwall of the fault system, and seven thin units above strath surfaces at its hangingwall are identified. The terraces have been dated by combining Optically Stimulated Luminescence (OSL) on fine-grained deposits and cosmogenic-nuclide dating (10Be) on sandstone pebbles sampled along depth profiles throughout the alluvial units. Three major allostratigraphic units were defined with upper surface ages estimated at 4, 15, and 36 ± 3 ka; the two older allostratigraphic units are encased terraces at the hangingwall but superposed sedimentary units at the footwall. They are related to phases of elevation of the river level (respectively 30 and 60 m) at 36-38 and 14-15 ka and to a phase of extensive lateral incision before 4 ka. These units present vertical offsets induced by the MWT of 50, 190, and 375 m, respectively. By taking the aggradation/incision rates at the footwall of the MWT into account, we found that the uplift of the hangingwall remains uniform since 36 ka, with a value of 10 mm/yr. Therefore, the aggradation/incision events observed in the Riasi area cannot be ascribed to variations in the tectonic rates and are most likely driven by climatic fluctuations. The high uplift rate is possibly local and related to the Chenab recess, which affects the Himalayan frontal structure. Our results indicate that the MWT is an active growth fault, and one of the main emergences of the

  16. Seismic structure of the western U.S. mantle and its relation to regional tectonic and magmatic activity

    NASA Astrophysics Data System (ADS)

    Schmandt, Brandon

    Vigorous convective activity in the western U.S. mantle has long been inferred from the region's widespread intra-plate crustal deformation, volcanism, and high elevations, but the specific form of convective activity and the degree and nature of lithospheric involvement have been strongly debated. I design a seismic travel-time tomography method and implement it with seismic data from the EarthScope Transportable Array and complementary arrays to constrain three-dimensional seismic structure beneath the western U.S. Tomographic images of variations in compressional velocity, shear velocity, and the ratio of shear to compressional velocity in the western U.S. mantle to a depth of 1000 km are produced. Using these results I investigate mantle physical properties, Cenozoic subduction history, and the influence of small-scale lithospheric convection on regional tectonic and magmatic activity, with particular focus on southern California and the Pacific Northwest. This dissertation includes previously published co-authored material. Chapter II presents a travel-time tomography method I designed and first implemented with data from southern California and the surrounding southwestern U.S. The resulting images provide a new level of constraint on upper mantle seismic anomalies beneath the Transverse Ranges, southern Great Valley, Salton Trough, and southwestern Nevada volcanic field. Chapter III presents tomographic images of the western U.S. mantle, identifies upper mantle volumes where partial melt is probable, and discusses implications of the apparently widespread occurrence of gravitational instabilities of continental lithsophere and the complex geometry and buoyancy of subducted ocean lithosphere imaged beneath the western U.S. In Chapter IV, tomography images are used in conjunction with geologic constraints on major transitions in crustal deformation and magmatism to construct a model for Pacific Northwest evolution since the Cretaceous. Accretion in the Pacific

  17. Active tectonics of the onshore Hengchun accretionary prism using UAV high resolution topography and ALOS PS-InSAR time series (Southern Taiwan)

    NASA Astrophysics Data System (ADS)

    Deffontaines, Benoit; Chang, Kuo-Jen; Champenois, Johann; Lin, Kuan-Chuan; Hu, Jyr-Ching; Fruneau, Benedicte

    2017-04-01

    Geometry, characterization and quantification of active faults are major concern in Taiwan, especially following the Chichi earthquake of september 21st, 1999. Among the targets that still remain poorly kown in terms of active tectonics, is the Hengchun peninsula (Southern Taiwan). From the geodynamic point of view, the latter corresponds to the outcropping top of the Manila accretionary prism of the Manila subduction zone that runs from Luzon (N. Philippines) to South Taiwan. In order to settle the Hengchun structural sketch map, we needed to up-date the CPC and CGS pre-existing geological maps using GIS mapping and photo-interpretation of both UAV's acquisition : 1). the very high precision (<50cm) and resolution (<10cm) Digital Terrain Model and the 2). the georeferenced aerial photograph mosaic of the studied area. Moreover, the superimposition of the resulting structural sketch map with ALOS-1 multi-temporal SAR Interferometry results (PS and SBAS) helps to give motions, characterisation and quantification of the displacements along LOS during the monitoring time-series (2007-11). We focus herein both on the global tectonic behaviour of the Hengchun peninsula (uplifted left part and eastward tilted plateau) as well as the geometry, the characterization and the quantification of the Hengchun (active highly dipping left-lateral transpressive strike-slip fault), Kenting and Manchou (low active dipping thrusts) and FengGang active faults (active highly dipping right-lateral transpressive thrust ramp). Finaly, as the Hengchun ridge face one of the last major earthquake of Taiwan (Hengchun EQ, december the 26th, 2006, depth: 44km, ML=7.0), it is needed to much better constrain the active Hengchun peninsula structures and tectonics in order to prevent major destructions in the near future.

  18. The Geological, Geomorphological Features and Kinematic Analysis of Active Faults Controlling Kemalpaşa Basin, Southwestern Part of Gediz Graben, Western Anatolia

    NASA Astrophysics Data System (ADS)

    Tepe, Çiǧdem; Sözbilir, Hasan

    2016-04-01

    The purpose of this study is to discuss the geological and geomorphological features of active faults controlling Kemalpaşa Basin. The study consists of basin-bounding faults expressions, kinematic and geomorphic analysis. Kemalpaşa Basin, which is approximately ENE trending and asymmetric graben is located in the southern part of Gediz Graben. Menderes Massif and Bornova Complex comprise the basement rocks of basin. Kızılca Formation, Sütçüler Formation and Alluvium uncomformably overlie the basement rocks. Kemalpaşa Basin which is one of the Quaternary basin in the Western Anatolia Extensional Province was developed at the structural border of the Spildaǧı Fault Zone in the north and the Kemalpaşa Fault in the south. Both the north and south margin-bounding faults of Kemalpaşa Basin are oblique-slip normal faults. According to the results of kinematic analysis, Kemalpaşa Basin has been formed under a NE-GW trending extensional tectonic regime. The variation in the relative degree of tectonic activity in Kemalpaşa Basin and its surroundings were interpreted a detailed geomorphic study of the fault-generated mountain fronts and drainage pattern of the both sides. To identify the impacts of active faults controlling the north and south margins of Kemalpaşa Basin on the geomorphological evolution, the geomorphic indices such as drainage basin geometries, triangular facets, axial river profiles have been determined and the degree of tectonic activity in the both sides of Kemalpaşa Basin has been numerically defined using morphometric indexes such as asymmetry factor (AF), hypsometric curve and integral (HI), valley floor width-to-height ratio (Vf) and mountain front sinuosity (Smf). In morphometric analysis, the both sides of the basin were investigated separating into two segments as the west and east. The values of HI (0,28-0,60), Vf (0,27-0,60) and Smf (1,3) calculated for the western part of the north margin compared with the values of HI (0

  19. Martian plate tectonics

    NASA Astrophysics Data System (ADS)

    Sleep, N. H.

    1994-03-01

    The northern lowlands of Mars have been produced by plate tectonics. Preexisting old thick highland crust was subducted, while seafloor spreading produced thin lowland crust during late Noachian and Early Hesperian time. In the preferred reconstruction, a breakup margin extended north of Cimmeria Terra between Daedalia Planum and Isidis Planitia where the highland-lowland transition is relatively simple. South dipping subduction occured beneath Arabia Terra and east dipping subduction beneath Tharsis Montes and Tempe Terra. Lineations associated with Gordii Dorsum are attributed to ridge-parallel structures, while Phelegra Montes and Scandia Colles are interpreted as transfer-parallel structures or ridge-fault-fault triple junction tracks. Other than for these few features, there is little topographic roughness in the lowlands. Seafloor spreading, if it occurred, must have been relatively rapid. Quantitative estimates of spreading rate are obtained by considering the physics of seafloor spreading in the lower (approx. 0.4 g) gravity of Mars, the absence of vertical scarps from age differences across fracture zones, and the smooth axial topography. Crustal thickness at a given potential temperature in the mantle source region scales inversely with gravity. Thus, the velocity of the rough-smooth transition for axial topography also scales inversely with gravity. Plate reorganizations where young crust becomes difficult to subduct are another constraint on spreading age. Plate tectonics, if it occurred, dominated the thermal and stress history of the planet. A geochemical implication is that the lower gravity of Mars allows deeper hydrothermal circulation through cracks and hence more hydration of oceanic crust so that more water is easily subducted than on the Earth. Age and structural relationships from photogeology as well as median wavelength gravity anomalies across the now dead breakup and subduction margins are the data most likely to test and modify hypotheses

  20. Unified model of tectonics and heat transport in a frigid Enceladus.

    PubMed

    Gioia, Gustavo; Chakraborty, Pinaki; Marshak, Stephen; Kieffer, Susan W

    2007-08-21

    Recent data from the Cassini spacecraft have revealed that Enceladus, the 500-km-diameter moon of Saturn, has a southern hemisphere with a distinct arrangement of tectonic features, intense heat flux, and geyser-like plumes. How did the tectonic features form? How is the heat transported from depth? To address these questions, we formulate a simple model that couples the mechanics and thermodynamics of Enceladus and gives a unified explanation of the salient tectonic features, the plumes, and the transport of heat from a source at a depth of tens of kilometers to the surface. Our findings imply that tiny, icy moons can develop complex surficial geomorphologies, high heat fluxes, and geyser-like activity even if they do not have hot, liquid, and/or convecting interiors.

  1. Unified model of tectonics and heat transport in a frigid Enceladus

    PubMed Central

    Gioia, Gustavo; Chakraborty, Pinaki; Marshak, Stephen; Kieffer, Susan W.

    2007-01-01

    Recent data from the Cassini spacecraft have revealed that Enceladus, the 500-km-diameter moon of Saturn, has a southern hemisphere with a distinct arrangement of tectonic features, intense heat flux, and geyser-like plumes. How did the tectonic features form? How is the heat transported from depth? To address these questions, we formulate a simple model that couples the mechanics and thermodynamics of Enceladus and gives a unified explanation of the salient tectonic features, the plumes, and the transport of heat from a source at a depth of tens of kilometers to the surface. Our findings imply that tiny, icy moons can develop complex surficial geomorphologies, high heat fluxes, and geyser-like activity even if they do not have hot, liquid, and/or convecting interiors. PMID:17699628

  2. Temporal and spatial complexity in post-glacial sedimentation on the tectonically active, Poverty Bay continental margin of New Zealand

    NASA Astrophysics Data System (ADS)

    Orpin, Alan R.; Alexander, Clark; Carter, Lionel; Kuehl, Steve; Walsh, J. P.

    2006-11-01

    On the eastern Raukumara Ranges of the New Zealand East Coast, active tectonics, vigorous weather systems, and human colonisation have combined to cause widespread erosion of the mudstone- and sandstone-dominated hinterland. The Waipaoa River sedimentary dispersal system is an example that has responded to environmental change, and is now New Zealand's second largest river in terms of suspended sediment discharge. This paper presents new sediment accumulation rates for the continental shelf and slope that span century to post-glacial time scales. These data are derived from radiochemical tracer, palynological, tephrostratigraphic, and seismic methods. We hypothesise on the temporal and spatial complexity of post-glacial sedimentation across the margin and identify the broad extent of sediment dispersal from the Waipaoa system. The ˜15 km 3 Poverty Bay mid-shelf basin lies adjacent to the mouth of the Waipaoa River, reaching a maximum thickness of ˜45 m. A post-glacial mud lobe of an additional ˜3 km 3 extends through the Poverty Gap and out onto the uppermost slope, attaining 40 m thickness in a structurally controlled sub-basin. Here, an offset in the last-glacial erosion surface indicates that deposition was sympathetic with fault activity and the creation of accommodation space, implying that sedimentation was not supply limited. Contrary to classical shelf sedimentation models, the highest modern accumulation rate of 1 cm y -1 occurs on the outer-shelf sediment lobe, approximately ˜2 times the rate recorded at the mid-shelf basin depocentre, and ˜10 times faster than the excess 210Pb rates estimated from the slope. Pollen records from slope cores fingerprint Polynesian then European settlement, and broaden the spatial extent of post-settlement sedimentation initially documented from the Poverty Bay mid-shelf. Changes in sub-millennial sedimentation infer a 2-3-times increase in post-settlement accumulation on the shelf but a smaller 1-2 times increase on

  3. The Mw 5.4 Reggio Emilia 1996 earthquake: active compressional tectonics in the Po Plain, Italy

    NASA Astrophysics Data System (ADS)

    Selvaggi, G.; Ferulano, F.; Di Bona, M.; Frepoli, A.; Azzara, R.; Basili, A.; Chiarabba, C.; Ciaccio, M. G.; Di Luccio, F.; Lucente, F. P.; Margheriti, L.; Nostro, C.

    2001-01-01

    We have analysed the seismic sequence that occurred in October 1996 near the town of Reggio Emilia on the southern edge of the Po Plain. The onset of the sequence was marked by a 5.4 moment magnitude main shock, located at 15km depth. The main-shock focal mechanism is a reverse solution with a strike-slip component and the scalar moment is 1.46×1017Nm. We used broad-band digital recordings from a borehole station, located at about 70km from the epicentre, for a spectral analysis in order to estimate attenuation and source parameters for the main shock. In addition, the empirical Green's function method has been applied to evaluate the source time function in terms of both moment rate and stress rate. We infer an asperity-like rupture process for the main shock, as suggested by the short duration of the stress release with respect to the overall duration of the moment rate function. This analysis also allows us to estimate the average dynamic stress drop of the main shock (600bar). We analysed the digital recordings of the temporary local seismic network deployed after the main shock and of a permanent local network maintained by the Italian Petroleum Agency (AGIP). During 15days of field experiments, we recorded more than 800 aftershocks, which delineate a 9km long, NE-elongated distribution, confined between 12 and 15km depth, suggesting that the basement is involved in the deformation processes. 102 focal mechanism of aftershocks have been computed from P-wave polarities, showing mainly pure reverse solutions. We calculate the principal stress axes from a selected population of earthquakes providing a constraint on the stress regime of this part of the Po Plain. The focal mechanisms are consistent with a N-S subhorizontal σ1. All the seismological data we have analysed confirm that this region is undergoing active compressional tectonics, as already inferred from recent earthquakes, geomorphological data and other stress indicators. Moreover, the elongation of

  4. Tectonic Framework of the Kachchh Rift Basin

    NASA Astrophysics Data System (ADS)

    Talwani, P.; Gangopadhyay, A. K.

    2001-05-01

    Evaluation of available geological data has allowed us to determine the tectonic framework of the Kachchh rift basin (KRB), the host to the 1819 Kachchh (MW 7.8), 1956 Anjar ( M 6.0) and the recent January 26, 2001 Bhachau (MW 7.6) earthquakes. The ~ 500 km x 200 km east-west trending KRB was formed during the Mesozoic following the break-up of Gondwanaland. It is bounded to the north and south by the Nagar Parkar and Kathiawar faults which separate it from the Precambrian granitic rocks of the Indian craton. The eastern border is the Radanpur-Barmer arch (defined by an elongate belt of gravity highs) which separates it from the early Cretaceous Cambay rift basin. KRB extends ~ 150 km offshore to its western boundary, the continental shelf. Following India's collision with Eurasia, starting ~ 50 MY ago, there was a stress reversal, from an extensional to the (currently N-S) compressional regime. Various geological observations attest to continuous tectonic activity within the KRB. Mesozoic sediments were uplifted and folded and then intruded by Deccan trap basalt flows in late Cretaceous. Other evidence of continuous tectonic activity include seismically induced soft sediment deformation features in the Upper Jurassic Katrol formation on the Kachchh Mainland and in the Holocene sequences in the Great Rann. Pleistocene faulting in the fluvial sequence along the Mahi River (in the bordering Cambay rift) and minor uplift during late Quaternary at Nal Sarovar, prehistoric and historic seismicity associated with surface deformation further attest to ongoing tectonic activity. KRB has responded to N-S compressional stress regime by the formation of east-west trending folds associated with Allah Bund, Kachchh Mainland, Banni, Vigodi, Katrol Hills and Wagad faults. The Allah Bund, Katrol Hill and Kachchh Mainland faults were associated with the 1819, 1956 and 2001 earthquakes. Northeast trending Median High, Bhuj fault and Rajkot-Lathi lineament cut across the east

  5. Modeling place field activity with hierarchical slow feature analysis.

    PubMed

    Schönfeld, Fabian; Wiskott, Laurenz

    2015-01-01

    What are the computational laws of hippocampal activity? In this paper we argue for the slowness principle as a fundamental processing paradigm behind hippocampal place cell firing. We present six different studies from the experimental literature, performed with real-life rats, that we replicated in computer simulations. Each of the chosen studies allows rodents to develop stable place fields and then examines a distinct property of the established spatial encoding: adaptation to cue relocation and removal; directional dependent firing in the linear track and open field; and morphing and scaling the environment itself. Simulations are based on a hierarchical Slow Feature Analysis (SFA) network topped by a principal component analysis (ICA) output layer. The slowness principle is shown to account for the main findings of the presented experimental studies. The SFA network generates its responses using raw visual input only, which adds to its biological plausibility but requires experiments performed in light conditions. Future iterations of the model will thus have to incorporate additional information, such as path integration and grid cell activity, in order to be able to also replicate studies that take place during darkness.

  6. Modeling place field activity with hierarchical slow feature analysis

    PubMed Central

    Schönfeld, Fabian; Wiskott, Laurenz

    2015-01-01

    What are the computational laws of hippocampal activity? In this paper we argue for the slowness principle as a fundamental processing paradigm behind hippocampal place cell firing. We present six different studies from the experimental literature, performed with real-life rats, that we replicated in computer simulations. Each of the chosen studies allows rodents to develop stable place fields and then examines a distinct property of the established spatial encoding: adaptation to cue relocation and removal; directional dependent firing in the linear track and open field; and morphing and scaling the environment itself. Simulations are based on a hierarchical Slow Feature Analysis (SFA) network topped by a principal component analysis (ICA) output layer. The slowness principle is shown to account for the main findings of the presented experimental studies. The SFA network generates its responses using raw visual input only, which adds to its biological plausibility but requires experiments performed in light conditions. Future iterations of the model will thus have to incorporate additional information, such as path integration and grid cell activity, in order to be able to also replicate studies that take place during darkness. PMID:26052279

  7. PAH features within few hundred parsecs of active galactic nuclei

    NASA Astrophysics Data System (ADS)

    Jensen, J. J.; Hönig, S. F.; Rakshit, S.; Alonso-Herrero, A.; Asmus, D.; Gandhi, P.; Kishimoto, M.; Smette, A.; Tristram, K. R. W.

    2017-09-01

    Spectral features from polycyclic aromatic hydrocarbon (PAH) molecules observed in the mid-infrared (mid-IR) range are typically used to infer the amount of recent and ongoing star formation on kiloparsec scales around active galactic nuclei (AGN) where more traditional methods fail. This method assumes that the observed PAH features are excited predominantly by star formation. With current ground-based telescopes and the upcoming James Webb Space Telescope, much smaller spatial scales can be probed and we aim at testing if this assumption still holds in the range of few tens to few hundreds of parsecs. For that, we spatially map the emitted 11.3 μm PAH surface flux as a function of distance from 0.4-4 arcsec from the centre in 28 nearby AGN using ground-based high-angular-resolution mid-IR spectroscopy. We detect and extract the 11.3 μm PAH feature in 13 AGN. The fluxes within each aperture are scaled to a luminosity-normalized distance from the nucleus to be able to compare intrinsic spatial scales of AGN radiation spanning about two orders of magnitude in luminosity. For this, we establish an empirical relation between the absorption-corrected X-ray luminosity and the sublimation radius in these sources. Once normalized, the radial profiles of the emitted PAH surface flux show similar radial slopes, with a power-law index of approximately -1.1, and similar absolute values, consistent within a factor of a few of each other as expected from the uncertainty in the intrinsic scale estimate. We interpret this as evidence that the profiles are caused by a common compact central physical process, either the AGN itself or circumnuclear star formation linked in strength to the AGN power. A photoionization-based model of an AGN exciting dense clouds in its environment can reproduce the observed radial slope and confirms that the AGN radiation field is strong enough to explain the observed PAH surface fluxes within ∼10-500 pc of the nucleus. Our results advice caution

  8. The damages of Ksiaz Castle architecture in relation to new informations on the structure and indications of recent tectonic activity in Świebodzice Depression

    NASA Astrophysics Data System (ADS)

    Kasza, Damian; Kaczorowski, Marek; Zdunek, Ryszard; Wronowski, Roman

    2017-04-01

    First informations about the aspects of recent tectonic activity in Książ area (Świebodzice Depression) come from indications of horizontal pendulums (HP), launched in 1974 in Książ. Over 40-years long series of observation have provided informations about the periods when it came to a sudden change of WP's measuring azimuths. This phenomenon has been interpreted as the result of tilting of rock blocks on which HPs are installed. Recent tectonic activity was confirmed by water-tube tiltmeters (WT) which have recorded episodically appeared events of tiltings of foundation and vertical movements. The consequences of strike-slip movements in Książ area are reflected both in the structure of the Świebodzice Basin (e.g. displacements of geological formations, deformations of the geometry of the Pełcznica River valley) as well as damages of architectural elements of the Książ Castle, where the underground Geodynamic Laboratory of Space Research Centre of Polish Academy of Sciences is located (GL SRC PAS). Tectonic phenomena recorded by both types of tiltmeters (HP and WT) are observed in forms of tilting of foundation and vertical movements. The cause of these effects are horizontal strike-slip movements on the surface of discontinuities (faults) in the Książ massif. From the mechanical point of view faults are the nodes of distribution for these movements. Because of the faults orientation in relation to the main direction of tectonic displacement GL's measuring instruments show transformation of the horizontal component of the movement to vertical movements and tiltings of foundation. Geological and geodetic works carried out in the Książ area allowed for identification and measurement of faults visible in underground corridors of GL. Analysis of the direction parameters of identified surface of discontinuities allowed to build a model of the structure of Książ massif. Created model contains 12 interpreted main zones of dislocation. Determined routes

  9. Quarternary tectonics, Task 1

    SciTech Connect

    Bell, J.W.

    1993-09-30

    Activities conducted for the evaluation of the geology and seismotectonics stability of Yucca Mountain as a potential site for the underground disposal of high-level radioactive wastes continued. Tasks concerned with quaternary tectonics include: scheduling of photography of Little Skull Mountain area; the collection and dating of rock varnish samples from the 1932 Cedar Mountain earthquake area for carbon 14 AMS and cation-ratio analysis; collection of samples for thermoluminescence dating from the 1932 Cedar Mountain earthquake area; mapping of the northern area of Crater Flat; and surveying of the May 17, 1993 Eureka the Valley earthquake area.

  10. Tectonic ancestry of central Montana and its influence on inversion tectonics

    SciTech Connect

    Woodward, L.A.

    1996-06-01

    Inversion tectonics, where structurally low areas become structurally high, has profound implications for hydrocarbon exploration. Effective exploration depends on understanding structures, timing, and controls on tectonic inversion. In central Montana tectonic inversion occurred three times in Phanerozoic time and reflects Precambrian tectonic trends. Westerly striking, steep foliation in Archean crystalline rocks defines the tectonic grain in basement exposures. The Helena embayment of the Middle Proterozoic Belt Basin formed an east-trending aulacogen extending into the craton in central Montana. Westerly trending fault-blocks of probable Late Proterozoic age formed within the embayment. The trough was tectonically inverted in the Devonian, but was depressed in the Carboniferous, accumulating major thicknesses of Madison Group and Big Snowy Group strata. Tectonic inversion again occurred with rise of the {open_quotes}Belt island{close_quotes} in the Jurassic. The trough was reactivated with a thick accumulation of lower Lower Cretaceous strata. Laramide (Late Cretaceous-early Tertiary) deformation resulted in tectonic inversion with rise of the Little Belt, Big Snowy, and related uplifts. Reactivation with reverse and strike-slip movement occurred on synsedimentary Proterozoic westerly trending normal faults that bounded the Helena embayment. Subsidence was probably related to crustal extension, whereas tectonic inversion and rise is inferred to be caused by crustal shortening. West-northwesterly trending en echelon folds that cross central Montana suggest major left shift. The Precambrian structural framework and fabric of the region thus appear to have had major influence on tectonic features that were multiply reactivated in Phanerozoic time.

  11. Seismicity at Uturuncu Volcano, Bolivia: Volcano-Tectonic Earthquake Swarms Triggered by the 2010 Maule, Chile Earthquake and Non-Triggered Background Activity

    NASA Astrophysics Data System (ADS)

    Christensen, D. H.; Chartrand, Z. A.; Jay, J.; Pritchard, M. E.; West, M. E.; McNutt, S. R.

    2010-12-01

    We find that the 270 ky dormant Uturuncu Volcano in SW Bolivia exhibits relatively high rates of shallow, volcano-tectonic seismicity that is dominated by swarm-like activity. We also document that the 27 February 2010 Mw 8.8 Maule, Chile earthquake triggered an exceptionally high rate of seismicity in the seconds to days following the main event. Although dormant, Uturuncu is currently being studied due to its large-scale deformation rate of 1-2 cm/yr uplift as revealed by InSAR. As part of the NASA-funded Andivolc project to investigate seismicity of volcanoes in the central Andes, a seismic network of 15 stations (9 Mark Products L22 short period and 6 Guralp CMG40T intermediate period sensors) with an average spacing of about 10 km was installed at Uturuncu from April 2009 to April 2010. Volcano-tectonic earthquakes occur at an average rate of about 3-4 per day, and swarms of 5-60 events within a span of minutes to hours occur a few times per month. Most of these earthquakes are located close to the summit at depths near and above sea level. The largest swarm occurred on 28 September 2009 and consisted of 60 locatable events over a time span of 28 hours. The locations of volcano-tectonic earthquakes at Uturuncu are oriented in a NW-SE trend, which matches the dominant orientation of regional faults and suggests a relationship between the fault system at Uturuncu and the regional tectonics of the area; a NW-SE trending fault beneath Uturuncu may serve to localize stresses that are accumulating over the broad area of uplift. Based on automated locations, the maximum local magnitude of these events is approximately M = 4 and the average magnitude is approximately M = 2. An initial estimate of the b-value is about b = 1.2. The Mw 8.8 Maule earthquake on 27 February 2010 triggered hundreds of local volcano-tectonic events at Uturuncu. High-pass filtering of the long period surface waves reveals that the first triggered events occurred with the onset of the Rayleigh

  12. Decadal to millennial deformation in the Pamir - Tian Shan collision zone, NW China and surface expression of active tectonics

    NASA Astrophysics Data System (ADS)

    Bufe, A.; Bookhagen, B.; Burbank, D. W.; Bekaert, D. P.; Hussain, E.

    2013-12-01

    The collision between the Pamir and the Tian Shan is a type example of intracontinental collision. GPS studies show that in Northwest China, at the junction between the Tarim basin, the Pamir and the Tian Shan, 7-9 mm/y of north-south shortening are presently accommodated across the boundary between the two orogens. Here, the deformation has mostly stepped out from the high mountain front into the foreland and has formed a complex array of compressional structures. We compare rates of decadal deformation in the area with 104- to 106-year estimates and investigate the extent to which stream profiles and topography reflect the active tectonics in this setting. A dataset of decadal deformation rates around the Tarim-Tian Shan-Pamir junction in Northwest China is obtained from Interferometric Synthetic Aperture Radar (InSAR) time-series analysis. We use the StaMPS/MTI package to combine small-baseline and persistent-scatterer techniques and obtain results that show no significant residual topographic phase correlation. Our data show that deformation has stepped away from the high mountain front and is concentrated on a few structures in the foreland of the Pamir and Tian Shan. Line-of-sight deformation of up to 2-4 mm/y on the Pamir Frontal Thrust (PFT) and the Kashi detachment anticline are observed. No significant displacement of the Main Pamir Thrust can be detected. Within error, the modern deformation rates agree with previously published millennial to million-year estimates along the PFT. However, decadal deformation rates deviate from million-year shortening and rock-uplift rates of anticlines in the foreland of the Tian Shan. It remains unclear whether the discrepancy arises from a recent change to a new persistent uplift rate, or merely from short timescale fluctuation of uplift rate, for example within an earthquake cycle. In an additional step, we extract stream profiles and normalized steepness index (ksn) values for rivers with drainage areas larger than 9

  13. The nature of magmatism at Palinpinon geothermal field, Negros Island, Philippines: implications for geothermal activity and regional tectonics

    NASA Astrophysics Data System (ADS)

    Rae, Andrew J.; Cooke, David R.; Phillips, David; Zaide-Delfin, Maribel

    2004-01-01

    The Palinpinon geothermal field, Negros Island, Philippines is a high-temperature, liquid-dominated geothermal system in an active island-arc volcanic setting. This paper presents a regional context for the Palinpinon geology, discusses the petrogenetic evolution of magmatism in the district and assesses the genetic relationships between intrusion and geothermal circulation. The oldest rock formation, the Lower Puhagan Volcanic Formation (Middle Miocene), is part of a volcanic sequence that is traceable throughout the Visayas region and is related to subduction of the Sulu Sea oceanic basin in a southeasterly direction beneath the Sulu arc. Late Miocene to Early Pliocene times mark a period of regional subsidence and marine sedimentation. A thick sequence of calcareous sediments (Okoy Formation) was deposited during this period. Magmatism in Early Pliocene to Recent times coincided with commencement