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Sample records for aleutian islands earthquake

  1. Detection and location of earthquakes in the central Aleutian subduction zone using island and ocean bottom seismograph stations

    SciTech Connect

    Frohlich, C.; Billington, S.; Engdahl, E.R.; Malahoff, A.

    1982-08-10

    A network of eight University of Texas ocean bottom seismographs (OBS) operated for 6 weeks in 1978 about 50 km offshore of Adak Island, Alaska, and nearly islands. In 1979 a similar network of nine instruments was deployed for 7 weeks farther offshore within and up to 100 km seaward of the Aleutian trench. For shallow earthquakes on the outer trench slope, for shallow earthquakes in the thrust zone, and for intermediate-depth events we have analyzed the OBS and island-based network data and evaluated the island network's capabilities for earthquake detection and location and for focal mechanism determination. Our three major conclusions are presented. The first concerns shallow earthquakes on the outer trench slope. In 1979 about 30 earthquakes occurred within the Aleutian trench and up to 60 km seaward of the trench axis. The island network located none of these events and detected P phases for only three of them. Ray tracing shows that the islands lie in a geometric shadow zone for events on the outer trench slope. The best located events are shallower than 20 km and exhibit first motions consistent with normal faulting. Several authors have suggested that these events are caused by bending of the oceanic lithosphere at the outer rise prior to subduction. If so, then the event locations reported here show that the bending stresses exceed the strength of lithosphere only in a narrow zone extending about 10 km landward and 60 km seaward of the trench axis. The second conclusion concerns shallow earthquakes in the thrust zone. Epicenters determined by island stations alone are virtually identical to epicenters determined using data from both island and OBS stations. The third conclusion concerns earthquakes deeper than 70 km. Epicenters determined using island network stations alone lie 10 to 80 km south of those determined using OBS and island stations, with the differences between epicenters depending both on event depth and on the velocity model used.

  2. Late Holocene coastal stratigraphy of Sitkinak Island reveals Aleutian-Alaska megathrust earthquakes and tsunamis southwest of Kodiak Island

    NASA Astrophysics Data System (ADS)

    Nelson, A. R.; Briggs, R. W.; Kemp, A.; Haeussler, P. J.; Engelhart, S. E.; Dura, T.; Angster, S. J.; Bradley, L.

    2012-12-01

    Uncertainty in earthquake and tsunami prehistory of the Aleutian-Alaska megathrust westward of central Kodiak Island limit assessments of southern Alaska's earthquake hazard and forecasts of potentially damaging tsunamis along much of North America's west coast. Sitkinak Island, one of the Trinity Islands off the southwest tip of Kodiak Island, lies at the western end of the rupture zone of the 1964 Mw9.2 earthquake. Plafker reports that a rancher on the north coast of Sitkinak Island observed ~0.6 m of shoreline uplift immediately following the 1964 earthquake, and the island is now subsiding at about 3 mm/yr (PBO GPS). Although a high tsunami in 1788 caused the relocation of the first Russian settlement on southwestern Kodiak Island, the eastern extent of the megathrust rupture accompanying the tsunami is uncertain. Interpretation of GPS observations from the Shumagin Islands, 380 km southwest of Kodiak Island, suggests an entirely to partially creeping megathrust in that region. Here we report the first stratigraphic evidence of tsunami inundation and land-level change during prehistoric earthquakes west of central Kodiak Island. Beneath tidal and freshwater marshes around a lagoon on the south coast of Sitkinak Island, 27 cores and tidal outcrops reveal the deposits of four to six tsunamis in 2200 years and two to four abrupt changes in lithology that may correspond with coseismic uplift and subsidence over the past millennia. A 2- to 45-mm-thick bed of clean to peaty sand in sequences of tidal sediment and freshwater peat, identified in more than one-half the cores as far inland as 1.5 km, was probably deposited by the 1788 tsunami. A 14C age on Scirpus seeds, double 137Cs peaks at 2 cm and 7 cm depths (Chernobyl and 1963?), a consistent decline in 210Pb values, and our assumption of an exponential compaction rate for freshwater peat, point to a late 18th century age for the sand bed. Initial 14C ages suggest that two similar extensive sandy beds, identified

  3. Bayesian probabilities for Mw 9.0+ earthquakes in the Aleutian Islands from a regionally scaled global rate

    NASA Astrophysics Data System (ADS)

    Butler, Rhett; Frazer, L. Neil; Templeton, William J.

    2016-05-01

    We use the global rate of Mw ≥ 9.0 earthquakes, and standard Bayesian procedures, to estimate the probability of such mega events in the Aleutian Islands, where they pose a significant risk to Hawaii. We find that the probability of such an earthquake along the Aleutians island arc is 6.5% to 12% over the next 50 years (50% credibility interval) and that the annualized risk to Hawai'i is about $30 M. Our method (the regionally scaled global rate method or RSGR) is to scale the global rate of Mw 9.0+ events in proportion to the fraction of global subduction (units of area per year) that takes place in the Aleutians. The RSGR method assumes that Mw 9.0+ events are a Poisson process with a rate that is both globally and regionally stationary on the time scale of centuries, and it follows the principle of Burbidge et al. (2008) who used the product of fault length and convergence rate, i.e., the area being subducted per annum, to scale the Poisson rate for the GSS to sections of the Indonesian subduction zone. Before applying RSGR to the Aleutians, we first apply it to five other regions of the global subduction system where its rate predictions can be compared with those from paleotsunami, paleoseismic, and geoarcheology data. To obtain regional rates from paleodata, we give a closed-form solution for the probability density function of the Poisson rate when event count and observation time are both uncertain.

  4. Teleseismic detection in the Aleutian Island Arc

    NASA Astrophysics Data System (ADS)

    Habermann, R. E.

    1983-06-01

    Recently it has become apparent that teleseismic detection has decreased substantially in many regions of the world. The major decrease was related to the closure of the VELA arrays in the United States during the late 1960's. This detection decrease has been recognized in South and Central America, Mexico, the Kuriles, the Caribbean, Tonga, and the New Hebrides. In this paper the effect of the closure of these arrays on the reporting of events in the Aleutian Island Arc is examined. In the Aleutians, the detection history is complicated by the short-term installation of a local network on and near Amchitka Island during the early 1970's. The temporal coincidence of the installation of this network and the closure of the VELA arrays delayed the detection decrease in the central Aleutians until the Amchitka network was closed in early 1973. Reporting in the eastern Aleutians was unaffected by the installation of the Amchitka network. In that region the detection decreased between 1968 and 1970, the time of the closure of the VELA arrays. New techniques have been developed which make it possible to determine the effect of station installation or closure on the reporting in some regions. These techniques rely on plots which show the distribution of an observed seismicity rate change in the magnitude domain. These plots make it possible to recognize probable detection changes and to determine quantitatively magnitude cutoffs which avoid these changes. The magnitude level at which these cutoffs are made is termed the minimum magnitude of homogeneity (mmin h). The reporting of events with mb≤4.6 in the Aleutians decreased substantially during the mid-1970's, so mmin h in this region is 4.7. This is different from the magnitude of completeness (mmin c) which is mb = 5.0±0.1. If one is interested in examining seismicity rates for changes which may be precursors to earthquakes, then awareness of detection-related changes and magnitude cutoffs which avoid these changes

  5. Modeling potential tsunami sources for deposits near Unalaska Island, Aleutian Islands

    NASA Astrophysics Data System (ADS)

    La Selle, S.; Gelfenbaum, G. R.

    2013-12-01

    In regions with little seismic data and short historical records of earthquakes, we can use preserved tsunami deposits and tsunami modeling to infer if, when and where tsunamigenic earthquakes have occurred. The Aleutian-Alaska subduction zone in the region offshore of Unalaska Island is one such region where the historical and paleo-seismicity is poorly understood. This section of the subduction zone is not thought to have ruptured historically in a large earthquake, leading some to designate the region as a seismic gap. By modeling various historical and synthetic earthquake sources, we investigate whether or not tsunamis that left deposits near Unalaska Island were generated by earthquakes rupturing through Unalaska Gap. Preliminary field investigations near the eastern end of Unalaska Island have identified paleotsunami deposits well above sea level, suggesting that multiple tsunamis in the last 5,000 years have flooded low-lying areas over 1 km inland. Other indicators of tsunami inundation, such as a breached cobble beach berm and driftwood logs stranded far inland, were tentatively attributed to the March 9, 1957 tsunami, which had reported runup of 13 to 22 meters on Umnak and Unimak Islands, to the west and east of Unalaska. In order to determine if tsunami inundation could have reached the runup markers observed on Unalaska, we modeled the 1957 tsunami using GeoCLAW, a numerical model that simulates tsunami generation, propagation, and inundation. The published rupture orientation and slip distribution for the MW 8.6, 1957 earthquake (Johnson et al., 1994) was used as the tsunami source, which delineates a 1200 km long rupture zone along the Aleutian trench from Delarof Island to Unimak Island. Model results indicate that runup and inundation from this particular source are too low to account for the runup markers observed in the field, because slip is concentrated in the western half of the rupture zone, far from Unalaska. To ascertain if any realistic

  6. Evidence for shallow megathrust slip across the Unalaska seismic gap during the great 1957 Andreanof Islands earthquake, eastern Aleutian Islands, Alaska

    USGS Publications Warehouse

    Nicolsky, D. J.; Freymueller, J.T.; Witter, R.C.; Suleimani, E. N.; Koehler, R.D.

    2016-01-01

    We reassess the slip distribution of the 1957 Andreanof Islands earthquake in the eastern part of the aftershock zone where published slip models infer little or no slip. Eyewitness reports, tide gauge data, and geological evidence for 9–23 m tsunami runups imply seafloor deformation offshore Unalaska Island in 1957, in contrast with previous studies that labeled the area a seismic gap. Here, we simulate tsunami dynamics for a suite of deformation models that vary in depth and amount of megathrust slip. Tsunami simulations show that a shallow (5–15 km deep) rupture with ~20 m of slip most closely reproduces the 1957 Dutch Harbor marigram and nearby >18 m runup at Sedanka Island marked by stranded drift logs. Models that place slip >20 km predict waves that arrive too soon. Our results imply that shallow slip on the megathrust in 1957 extended east into an area that presently creeps.

  7. Evidence for shallow megathrust slip across the Unalaska seismic gap during the great 1957 Andreanof Islands earthquake, eastern Aleutian Islands, Alaska

    NASA Astrophysics Data System (ADS)

    Nicolsky, D. J.; Freymueller, J. T.; Witter, R. C.; Suleimani, E. N.; Koehler, R. D.

    2016-10-01

    We reassess the slip distribution of the 1957 Andreanof Islands earthquake in the eastern part of the aftershock zone where published slip models infer little or no slip. Eyewitness reports, tide gauge data, and geological evidence for 9-23 m tsunami runups imply seafloor deformation offshore Unalaska Island in 1957, in contrast with previous studies that labeled the area a seismic gap. Here we simulate tsunami dynamics for a suite of deformation models that vary in depth and amount of megathrust slip. Tsunami simulations show that a shallow (5-15 km deep) rupture with 20 m of slip most closely reproduces the 1957 Dutch Harbor marigram and nearby >18 m runup at Sedanka Island marked by stranded drift logs. Slip models >20 km deep predict waves that arrive too soon. Our results imply that shallow slip on the megathrust in 1957 extended east into an area that presently creeps.

  8. Criconematina (nematoda: tylenchida) from the Aleutian Islands

    SciTech Connect

    Bernard, E.C.

    1982-01-01

    A new genus (Cerchnotocriconema) and three new species (C. psephinum, Hemicycliophora anchitkaensis, and Paratylenchus amundseni) are described from Adak and Amchitka Islands in the Aleutian chain. The new genus differs from all other criconematid genera in having irregular, convex sculpturing consisting of small, oval plates on the anterior and posterior regions of each annule, with the mid-annular region minutely punctate or dentate. H. amchitkaensis n. sp. resembles H. sinilis Thorne and H. zuckermani Brzeski, but has only one head annule, instead of two. P. amundseni n. sp., which has a stylet 17 to 19 ..mu..m long, is similar to P. tatea Wu and Townsend and P. labiosus Anderson and Kimpinski, but differs by the presence of males and the possession of conoid-truncate lip region, functional spermatheca, and long male tail (c = 8.5 to 9.5). Seriespinula seymouri Wu (Mehta and Raski), Nothocriconema longulum (Gunhold) De Grisse and Loof, and Macroposthonia xenoplax (Raski) De Grisse and Loof are also reported from the islands.

  9. Seismicity trends and potential for large earthquakes in the Alaska-Aleutian region

    USGS Publications Warehouse

    Bufe, C.G.; Nishenko, S.P.; Varnes, D.J.

    1994-01-01

    The high likelihood of a gap-filling thrust earthquake in the Alaska subduction zone within this decade is indicated by two independent methods: analysis of historic earthquake recurrence data and time-to-failure analysis applied to recent decades of instrumental data. Recent (May 1993) earthquake activity in the Shumagin Islands gap is consistent with previous projections of increases in seismic release, indicating that this segment, along with the Alaska Peninsula segment, is approaching failure. Based on this pattern of accelerating seismic release, we project the occurrence of one or more M???7.3 earthquakes in the Shumagin-Alaska Peninsula region during 1994-1996. Different segments of the Alaska-Aleutian seismic zone behave differently in the decade or two preceding great earthquakes, some showing acceleration of seismic release (type "A" zones), while others show deceleration (type "D" zones). The largest Alaska-Aleutian earthquakes-in 1957, 1964, and 1965-originated in zones that exhibit type D behavior. Type A zones currently showing accelerating release are the Shumagin, Alaska Peninsula, Delarof, and Kommandorski segments. Time-to-failure analysis suggests that the large earthquakes could occur in these latter zones within the next few years. ?? 1994 Birkha??user Verlag.

  10. Earthquake location in island arcs

    USGS Publications Warehouse

    Engdahl, E.R.; Dewey, J.W.; Fujita, K.

    1982-01-01

    A comprehensive data set of selected teleseismic P-wave arrivals and local-network P- and S-wave arrivals from large earthquakes occurring at all depths within a small section of the central Aleutians is used to examine the general problem of earthquake location in island arcs. Reference hypocenters for this special data set are determined for shallow earthquakes from local-network data and for deep earthquakes from combined local and teleseismic data by joint inversion for structure and location. The high-velocity lithospheric slab beneath the central Aleutians may displace hypocenters that are located using spherically symmetric Earth models; the amount of displacement depends on the position of the earthquakes with respect to the slab and on whether local or teleseismic data are used to locate the earthquakes. Hypocenters for trench and intermediate-depth events appear to be minimally biased by the effects of slab structure on rays to teleseismic stations. However, locations of intermediate-depth events based on only local data are systematically displaced southwards, the magnitude of the displacement being proportional to depth. Shallow-focus events along the main thrust zone, although well located using only local-network data, are severely shifted northwards and deeper, with displacements as large as 50 km, by slab effects on teleseismic travel times. Hypocenters determined by a method that utilizes seismic ray tracing through a three-dimensional velocity model of the subduction zone, derived by thermal modeling, are compared to results obtained by the method of joint hypocenter determination (JHD) that formally assumes a laterally homogeneous velocity model over the source region and treats all raypath anomalies as constant station corrections to the travel-time curve. The ray-tracing method has the theoretical advantage that it accounts for variations in travel-time anomalies within a group of events distributed over a sizable region of a dipping, high

  11. 76 FR 3089 - Proposed Information Collection; Comment Request; Alaska Region Bering Sea & Aleutian Islands...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-01-19

    ... Region Bering Sea & Aleutian Islands Crab Permits AGENCY: National Oceanic and Atmospheric Administration... of a currently approved collection. The Crab Rationalization Program allocates Bering Sea and Aleutian Islands (BSAI) crab resources among harvesters, processors, and coastal communities through...

  12. 76 FR 3090 - Proposed Information Collection; Comment Request; Alaska Region; Bering Sea and Aleutian Islands...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-01-19

    ... Region; Bering Sea and Aleutian Islands Crab Arbitration AGENCY: National Oceanic and Atmospheric... extension of a currently approved collection. The Crab Rationalization Program allocates Bering Sea and Aleutian Islands (BSAI) crab resources among harvesters, processors, and coastal communities through...

  13. 78 FR 24362 - Fisheries of the Exclusive Economic Zone Off Alaska; Greenland Turbot in the Aleutian Islands...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-04-25

    ... Economic Zone Off Alaska; Greenland Turbot in the Aleutian Islands Subarea of the Bering Sea and Aleutian Islands Management Area AGENCY: National Marine Fisheries Service (NMFS), National Oceanic and Atmospheric... for Greenland turbot in the Aleutian Islands subarea of the Bering Sea and Aleutian Islands...

  14. Aleutian Pribilof Islands Wind Energy Feasibility Study

    SciTech Connect

    Bruce A. Wright

    2012-03-27

    Under this project, the Aleutian Pribilof Islands Association (APIA) conducted wind feasibility studies for Adak, False Pass, Nikolski, Sand Point and St. George. The DOE funds were also be used to continue APIA's role as project coordinator, to expand the communication network quality between all participants and with other wind interest groups in the state and to provide continued education and training opportunities for regional participants. This DOE project began 09/01/2005. We completed the economic and technical feasibility studies for Adak. These were funded by the Alaska Energy Authority. Both wind and hydro appear to be viable renewable energy options for Adak. In False Pass the wind resource is generally good but the site has high turbulence. This would require special care with turbine selection and operations. False Pass may be more suitable for a tidal project. APIA is funded to complete a False Pass tidal feasibility study in 2012. Nikolski has superb potential for wind power development with Class 7 wind power density, moderate wind shear, bi-directional winds and low turbulence. APIA secured nearly $1M from the United States Department of Agriculture Rural Utilities Service Assistance to Rural Communities with Extremely High Energy Costs to install a 65kW wind turbine. The measured average power density and wind speed at Sand Point measured at 20m (66ft), are 424 W/m2 and 6.7 m/s (14.9 mph) respectively. Two 500kW Vestas turbines were installed and when fully integrated in 2012 are expected to provide a cost effective and clean source of electricity, reduce overall diesel fuel consumption estimated at 130,000 gallons/year and decrease air emissions associated with the consumption of diesel fuel. St. George Island has a Class 7 wind resource, which is superior for wind power development. The current strategy, led by Alaska Energy Authority, is to upgrade the St. George electrical distribution system and power plant. Avian studies in Nikolski and

  15. Earthquakes, plate subduction, and stress reversals in the eastern Aleutian arc

    SciTech Connect

    House, L.S.; Jacob, K.H.

    1983-11-10

    Plate subduction beneath the 1500-km-long segment of the eastern Aleutian arc between Kodiak and Atka islands (154/sup 0/W and 176/sup 0/W longitude) is studied with observations from teleseismic data. The primary data base consists of hypocenters of earthquakes (for the period 1965-1975), carefully selected from the bulletins of the International Seismological Centre, and of 44 new focal mechanism solutions. The principal results of this study are that hypocenters of intermediate-depth earthquakes in the eastern Aleutians appear to define a weakly developed double seismic zone at depths between 70 and 170 km. Additional evidence for a double seismic zone comes from focal mechanisms which generally show downdip-directed P axes for earthquakes in the upper zone and downdip-directed T axes in the lower zone. Major features of the double zone can be explained by thermoelastic stresses in the downgoing plate. The observed predominant downdip stress polarity at intermediate depths in the descending plate reverses along strike of the arc. This stress reverse coincides in map view with a change from a continental to an oceanic arc. The coincidence may result from spatial differences either in the coupling between the plates at shallow depths or in the rheology of the surrounding (oceanic versus continental) mantle. Alternatively, the stress reversel may be related to the time since the last great earthquake. Portions of the eastern Aleutian arc where downdip tension predominates contain one or more seismic gaps that appear to have a high probability for great earthquakes in the next few decades. 7 figures, 2 tables.

  16. Geologic implications of great interplate earthquakes along the Aleutian arc

    SciTech Connect

    Ryan, H.F.; Scholl, D.W.

    1993-12-01

    We present new marine geophysical observations and synthesize previous geologic interpretations of the Aleutian arc to show that the epicenters of these great thrust-type earthquakes coincide with upper plate segments of the arc characterized by a coherent forearc structural fabric. We propose that variations in upper plate structural strength and mobility affect the mechanical properties of the interplate thrust zone and need to be considered in localizing interplate asperities. Forearc tectonic segmentaion associated with the partitioning of strike-slip and thrust motions may exert long-term controls on the rates of seismic moment release.

  17. Vegetation of eastern Unalaska Island, Aleutian Islands, Alaska

    USGS Publications Warehouse

    Talbot, Stephen S.; Schofield, Wilfred B.; Talbot, Sandra L.; Daniëls, Fred J. A.

    2010-01-01

    Plant communities of Unalaska Island in the eastern Aleutian Islands of western Alaska, and their relationship to environmental variables, were studied using a combined Braun-Blanquet and multivariate approach. Seventy relevés represented the range of structural and compositional variation in the matrix of vegetation and landform zonation. Eleven major community types were distinguished within six physiognomic–ecological groups: I. Dry coastal meadows: Honckenya peploides beach meadow, Leymus mollis dune meadow. II. Mesic meadows: Athyrium filix-femina – Aconitum maximum meadow, Athyrium filix-femina – Calamagrostis nutkaensis meadow, Erigeron peregrinus – Thelypteris quelpaertensis meadow. III. Wet snowbed meadow: Carex nigricans snowbed meadow. IV. Heath: Linnaea borealis – Empetrum nigrum heath, Phyllodoce aleutica heath, Vaccinium uliginosum – Thamnolia vermicularis fellfield. V. Mire: Carex pluriflora – Plantago macrocarpa mire. VI. Deciduous shrub thicket: Salix barclayi – Athyrium filix-femina thicket. These were interpreted as a complex gradient primarily influenced by soil moisture, elevation, and pH. Phytogeographical and syntaxonomical analysis of the plant communities indicated that the dry coastal meadows, most of the heaths, and the mire vegetation belonged, respectively, to the widespread classes Honckenyo–Elymetea, Loiseleurio–Vaccinietea, and Scheuchzerio–Caricetea, characterized by their circumpolar and widespread species. Amphi-Beringian species were likely diagnostic of amphi-Beringian syntaxa, many of these yet to be described.

  18. Cranial suture biology of the Aleutian Island inhabitants.

    PubMed

    Cray, James; Mooney, Mark P; Siegel, Michael I

    2011-04-01

    Research on cranial suture biology suggests there is biological and taxonomic information to be garnered from the heritable pattern of suture synostosis. Suture synostosis along with brain growth patterns, diet, and biomechanical forces influence phenotypic variability in cranial vault morphology. This study was designed to determine the pattern of ectocranial suture synostosis in skeletal populations from the Aleutian Islands. We address the hypothesis that ectocranial suture synostosis pattern will differ according to cranial vault shape. Ales Hrdlicka identified two phenotypes in remains excavated from the Aleutian Island. The Paleo-Aleutians, exhibiting a dolichocranic phenotype with little prognathism linked to artifacts distinguished from later inhabitants, Aleutians, who exhibited a brachycranic phenotype with a greater amount of prognathism. A total of 212 crania representing Paleo-Aleuts and Aleutian as defined by Hrdlicka were investigated for suture synostosis pattern following standard methodologies. Comparisons were performed using Guttmann analyses. Results revealed similar suture fusion patterns for the Paleo-Aleut and Aleutian, a strong anterior to posterior pattern of suture fusion for the lateral-anterior suture sites, and a pattern of early termination at the sagittal suture sites for the vault. These patterns were found to differ from that reported in the literature. Because these two populations with distinct cranial shapes exhibit similar patterns of suture synostosis it appears pattern is independent of cranial shape in these populations of Homo sapiens. These findings suggest that suture fusion patterns may be population dependent and that a standardized methodology, using suture fusion to determine age-at-death, may not be applicable to all populations.

  19. Interpretation of broad-band seismograms from central Aleutian earthquakes.

    USGS Publications Warehouse

    Engdahl, E.R.; Kind, R.

    1986-01-01

    Broad-band Graefenberg (GRF) array data from 11 moderate-size shallow-depth earthquakes in the central Aleutians have been used to study the effects of focal depth and structure across the arc on observed waveforms. The theoretical results, primarily phase arrival times, suggest that arc structure is responsible for many of the complicated features seen on vertical-component summation seismograms simulated with different instrument responses from the broad-band array data. Except for one trench event, all the earthquakes studied occurred along the plate interface zone, had similar thrust focal mechanisms, and differed only in depth. As a result, the effects of depth phases on observed GRF waveforms across the arc were found to be systematically related to the increase in focal depth along the shallow-dipping seismic zone. -from Authors

  20. 46 CFR 7.170 - Alaska Peninsula, AK to Aleutian Islands, AK.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 1 2012-10-01 2012-10-01 false Alaska Peninsula, AK to Aleutian Islands, AK. 7.170... BOUNDARY LINES Alaska § 7.170 Alaska Peninsula, AK to Aleutian Islands, AK. (a) A line drawn from the southernmost extremity of Cape Kumlium to the westernmost extremity of Nakchamik Island; thence to...

  1. 46 CFR 7.170 - Alaska Peninsula, AK to Aleutian Islands, AK.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 1 2010-10-01 2010-10-01 false Alaska Peninsula, AK to Aleutian Islands, AK. 7.170... BOUNDARY LINES Alaska § 7.170 Alaska Peninsula, AK to Aleutian Islands, AK. (a) A line drawn from the southernmost extremity of Cape Kumlium to the westernmost extremity of Nakchamik Island; thence to...

  2. 46 CFR 7.170 - Alaska Peninsula, AK to Aleutian Islands, AK.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 1 2011-10-01 2011-10-01 false Alaska Peninsula, AK to Aleutian Islands, AK. 7.170... BOUNDARY LINES Alaska § 7.170 Alaska Peninsula, AK to Aleutian Islands, AK. (a) A line drawn from the southernmost extremity of Cape Kumlium to the westernmost extremity of Nakchamik Island; thence to...

  3. 46 CFR 7.170 - Alaska Peninsula, AK to Aleutian Islands, AK.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 1 2013-10-01 2013-10-01 false Alaska Peninsula, AK to Aleutian Islands, AK. 7.170... BOUNDARY LINES Alaska § 7.170 Alaska Peninsula, AK to Aleutian Islands, AK. (a) A line drawn from the southernmost extremity of Cape Kumlium to the westernmost extremity of Nakchamik Island; thence to...

  4. 46 CFR 7.170 - Alaska Peninsula, AK to Aleutian Islands, AK.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 1 2014-10-01 2014-10-01 false Alaska Peninsula, AK to Aleutian Islands, AK. 7.170... BOUNDARY LINES Alaska § 7.170 Alaska Peninsula, AK to Aleutian Islands, AK. (a) A line drawn from the southernmost extremity of Cape Kumlium to the westernmost extremity of Nakchamik Island; thence to...

  5. 50 CFR Figure 8 to Part 679 - Aleutian Islands Chinook Salmon Savings Area

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 50 Wildlife and Fisheries 13 2013-10-01 2013-10-01 false Aleutian Islands Chinook Salmon Savings Area 8 Figure 8 to Part 679 Wildlife and Fisheries FISHERY CONSERVATION AND MANAGEMENT, NATIONAL... ECONOMIC ZONE OFF ALASKA Pt. 679, Fig. 8 Figure 8 to Part 679—Aleutian Islands Chinook Salmon Savings...

  6. 50 CFR Figure 8 to Part 679 - Aleutian Islands Chinook Salmon Savings Area

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 50 Wildlife and Fisheries 9 2010-10-01 2010-10-01 false Aleutian Islands Chinook Salmon Savings Area 8 Figure 8 to Part 679 Wildlife and Fisheries FISHERY CONSERVATION AND MANAGEMENT, NATIONAL... ECONOMIC ZONE OFF ALASKA Pt. 679, Fig. 8 Figure 8 to Part 679—Aleutian Islands Chinook Salmon Savings...

  7. 50 CFR Figure 8 to Part 679 - Aleutian Islands Chinook Salmon Savings Area

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 50 Wildlife and Fisheries 13 2012-10-01 2012-10-01 false Aleutian Islands Chinook Salmon Savings Area 8 Figure 8 to Part 679 Wildlife and Fisheries FISHERY CONSERVATION AND MANAGEMENT, NATIONAL... ECONOMIC ZONE OFF ALASKA Pt. 679, Fig. 8 Figure 8 to Part 679—Aleutian Islands Chinook Salmon Savings...

  8. 50 CFR Figure 8 to Part 679 - Aleutian Islands Chinook Salmon Savings Area

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 50 Wildlife and Fisheries 11 2011-10-01 2011-10-01 false Aleutian Islands Chinook Salmon Savings Area 8 Figure 8 to Part 679 Wildlife and Fisheries FISHERY CONSERVATION AND MANAGEMENT, NATIONAL... ECONOMIC ZONE OFF ALASKA Pt. 679, Fig. 8 Figure 8 to Part 679—Aleutian Islands Chinook Salmon Savings...

  9. 50 CFR Figure 8 to Part 679 - Aleutian Islands Chinook Salmon Savings Area

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 50 Wildlife and Fisheries 13 2014-10-01 2014-10-01 false Aleutian Islands Chinook Salmon Savings Area 8 Figure 8 to Part 679 Wildlife and Fisheries FISHERY CONSERVATION AND MANAGEMENT, NATIONAL... ECONOMIC ZONE OFF ALASKA Pt. 679, Fig. 8 Figure 8 to Part 679—Aleutian Islands Chinook Salmon Savings...

  10. 50 CFR Table 23 to Part 679 - Aleutian Islands Coral Habitat Protection Areas

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 50 Wildlife and Fisheries 13 2014-10-01 2014-10-01 false Aleutian Islands Coral Habitat Protection Areas 23 Table 23 to Part 679 Wildlife and Fisheries FISHERY CONSERVATION AND MANAGEMENT, NATIONAL... ECONOMIC ZONE OFF ALASKA Pt. 679, Table 23 Table 23 to Part 679—Aleutian Islands Coral Habitat...

  11. 50 CFR Table 23 to Part 679 - Aleutian Islands Coral Habitat Protection Areas

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 50 Wildlife and Fisheries 13 2012-10-01 2012-10-01 false Aleutian Islands Coral Habitat Protection Areas 23 Table 23 to Part 679 Wildlife and Fisheries FISHERY CONSERVATION AND MANAGEMENT, NATIONAL... ECONOMIC ZONE OFF ALASKA Pt. 679, Table 23 Table 23 to Part 679—Aleutian Islands Coral Habitat...

  12. 50 CFR Table 23 to Part 679 - Aleutian Islands Coral Habitat Protection Areas

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 50 Wildlife and Fisheries 9 2010-10-01 2010-10-01 false Aleutian Islands Coral Habitat Protection Areas 23 Table 23 to Part 679 Wildlife and Fisheries FISHERY CONSERVATION AND MANAGEMENT, NATIONAL... ECONOMIC ZONE OFF ALASKA Pt. 679, Table 23 Table 23 to Part 679—Aleutian Islands Coral Habitat...

  13. 50 CFR Table 23 to Part 679 - Aleutian Islands Coral Habitat Protection Areas

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 50 Wildlife and Fisheries 11 2011-10-01 2011-10-01 false Aleutian Islands Coral Habitat Protection Areas 23 Table 23 to Part 679 Wildlife and Fisheries FISHERY CONSERVATION AND MANAGEMENT, NATIONAL... ECONOMIC ZONE OFF ALASKA Pt. 679, Table 23 Table 23 to Part 679—Aleutian Islands Coral Habitat...

  14. Little late Holocene strain accumulation and release on the Aleutian megathrust below the Shumagin Islands, Alaska

    USGS Publications Warehouse

    Witter, Robert C.; Briggs, Richard W.; Engelhart, Simon E.; Gelfenbaum, Guy R.; Koehler, Richard D.; Barnhart, William D.

    2014-01-01

    Can a predominantly creeping segment of a subduction zone generate a great (M > 8) earthquake? Despite Russian accounts of strong shaking and high tsunamis in 1788, geodetic observations above the Aleutian megathrust indicate creeping subduction across the Shumagin Islands segment, a well-known seismic gap. Seeking evidence for prehistoric great earthquakes, we investigated Simeonof Island, the archipelago's easternmost island, and found no evidence for uplifted marine terraces or subsided shorelines. Instead, we found freshwater peat blanketing lowlands, and organic-rich silt and tephra draping higher glacially smoothed bedrock. Basal peat ages place glacier retreat prior to 10.4 ka and imply slowly rising (<0.2 m/ka) relative sea level since ~3.4 ka. Storms rather than tsunamis probably deposited thin, discontinuous deposits in coastal sites. If rupture of the megathrust beneath Simeonof Island produced great earthquakes in the late Holocene, then coseismic uplift or subsidence was too small (≤0.3 m) to perturb the onshore geologic record.

  15. The Aleutian Tsunami of 1946: the Compound Earthquake-Landslide Source and Near-Field Modeling

    NASA Astrophysics Data System (ADS)

    Fryer, G. J.; Yamazaki, Y.; McMurtry, G. M.

    2015-12-01

    The tsunami of April 1, 1946, spread death and destruction throughout the Pacific from the Aleutians to Antarctica, and produced exceptional runup, 42 m, at Scotch Cap on Unimak Island in the near field. López & Okal (2006) showed that the triggering earthquake was at least MW = 8.6, large enough to explain the far-field tsunami but still requiring a landslide or other secondary source to achieve the local runup. No convincing landslide was found until von Huene, et al (2014) merged all available multibeam data and reprocessed a old multichannel line to show that a feature on the Aleutian Terrace they call Lone Knoll (LK) is the displaced block of a translational slide. From 210Pb dating of push cores taken near the summit of LK, we find that a disruption in sedimentation occurred in 1946 at one site, but sedimentation was not disrupted at another site nearby. We infer that the slide block moved coherently at a speed close to the threshold for erosion of the hemipelagic clays. From GLORIA sidescan, Fryer, et al (2004) had earlier tentatively identified LK as a landslide deposit, but if the tsunami crossed the shallow Aleutian Shelf at the long-wave speed, that landslide had to extend up to the shelf edge to satisfy the known 48-min travel time to Scotch Cap. The resulting landslide was enormous, and a multibeam survey later in 2004 showed that it could not exist. The slide imaged by von Huene, et al is far smaller, with a headwall 30 km downslope at a depth of 3 km. The greater distance demands that the tsunami travel much faster across the shelf. The huge runup, however, suggests that wave height was a significant fraction of the water depth (only 80 m), so the tsunami probably crossed the Aleutian Shelf as a bore. From modeling the landslide-generated tsunami with a shock-capturing dispersive code we infer that it did indeed cross the shelf as a bore traveling at roughly twice the long-wave speed. We are still exploring the dependence of the tsunami on slide

  16. A burial cave in the western Aleutian Islands, Alaska.

    PubMed

    West, Dixie; Lefèvre, Christine; Corbett, Debra; Crockford, Susan

    2003-01-01

    During the 1998 field season, the Western Aleutians Archaeological and Paleobiological Project (WAAPP) team located a cave in the Near Islands, Alaska. Near the entrance of the cave, the team identified work areas and sleeping/sitting areas surrounded by cultural debris and animal bones. Human burials were found in the cave interior. In 2000, with permission from The Aleut Corporation, archaeologists revisited the site. Current research suggests three distinct occupations or uses for this cave. Aleuts buried their dead in shallow graves at the rear of the cave circa 1,200 to 800 years ago. Aleuts used the front of the cave as a temporary hunting camp as early as 390 years ago. Finally, Japanese and American military debris and graffiti reveal that the cave was visited during and after World War II. Russian trappers may have also taken shelter there 150 to 200 years ago. This is the first report of Aleut cave burials west of the Delarof Islands in the central Aleutians.

  17. 76 FR 68358 - Fisheries of the Exclusive Economic Zone Off Alaska; Bering Sea and Aleutian Islands Crab...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-11-04

    ... Program, the western Aleutian Islands red king crab and Pribilof Islands red and blue king crab fisheries have failed to open, and the Saint Matthew Island blue king crab fishery has only been open during the... Economic Zone Off Alaska; Bering Sea and Aleutian Islands Crab Rationalization Program AGENCY:...

  18. 76 FR 49423 - Fisheries of the Exclusive Economic Zone Off Alaska; Bering Sea and Aleutian Islands Crab...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-08-10

    ... the CR Program, the western Aleutian Islands red king crab and Pribilof Islands red and blue king crab fisheries have failed to open, and the Saint Matthew Island blue king crab fishery has only been open during... Economic Zone Off Alaska; Bering Sea and Aleutian Islands Crab Rationalization Program AGENCY:...

  19. 75 FR 7403 - Fisheries of the Exclusive Economic Zone Off Alaska; Bering Sea and Aleutian Islands Trawl...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-02-19

    ... Aleutian Islands (BSAI) trawl limited access fisheries, except American Fisheries Act (AFA) vessels using... for vessels participating in the BSAI trawl limited access fishery, except American Fisheries Act...

  20. Paleogene geology and chronology of southwestern Umnak Island, Aleutian Islands, Alaska ( USA).

    USGS Publications Warehouse

    McLean, H.; Hein, J.R.

    1984-01-01

    A slightly deformed marine sedimentary sequence reflecting volcanic arc sedimentation from late Eocene to early Oligocene is intruded by hypabyssal quartz diorite sills and small plutons with apparent ages of about 30 Ma, ie, middle Oligocene. Chemical data from igneous rocks exhibit calc-alkaline and tholeiitic volcanic arc differentiation trends. The fossil ages and radiometric dates from SW Umnak Island are similar to those reported from other central and E Aleutian islands, and indicate uniformity in the chronology and tectonic development of the archipelago during the Paleogene. Paleomagnetic data suggest possible northward movement but remain equivocal and more work is indicated. -after Authors

  1. Hair methylmercury levels of mummies of the Aleutian Islands, Alaska

    SciTech Connect

    Egeland, G.M. Ponce, Rafael Bloom, Nicolas S. Knecht, Rick Loring, Stephen Middaugh, John P.

    2009-04-15

    Ancient human hair specimens can shed light on the extent of pre-historic exposures to methylmercury and provide valuable comparison data with current-day exposures, particularly for Indigenous Peoples who continue to rely upon local traditional food resources. Human hair from ancient Aleutian Island Native remains were tested for total and methylmercury (Hg, MeHg) and were radiocarbon dated. The remains were approximately 500 years old (1450 A.D.). For four adults, the mean and median total hair mercury concentration was 5.8 ppm (SD=0.9). In contrast, MeHg concentrations were lower with a mean of 1.2 ppm (SD=1.8) and a median of 0.54 ppm (0.12-3.86). For the five infants, the mean and median MeHg level was 1.2 ppm (SD=1.8) and 0.20 ppm (0.007-4.61), respectively. Segmental analyses showed variations in MeHg concentrations in 1-cm segments, consistent with fluctuations in naturally occurring exposure to mercury through dietary sources. The levels are comparable to or lower than those found in fish and marine mammal-eating populations today who rely far less on subsistence food than pre-historic humans. The findings are, therefore, compatible with increased anthropogenic release of trace metals during the past several centuries.

  2. Three new species of heteroderoidea (nematoda) from the Aleutian Islands

    SciTech Connect

    Bernard, E.C.

    1981-10-01

    Three new species of Heteroderoidea are described from Adak and Amchitka Islands in the Aleutian chain. Second-stage juveniles of Thecavermiculatus crassicrustata, n. sp., differ from those of T. gracililancea Robbins by having longer stylets (40 to 50 ..mu..m vs 19 to 22 ..mu..m). The female of T. crassicrustata has a longer neck, a more posterior excretory pore, and lacks a posterior protuberance. Meloidodera eurytyla, n. sp., differs from other Meloidodera spp. in that second-stage juveniles have longer stylets (32 to 35 ..mu..m) and much more massive styletknobs, while males have a longitudinally striated basal head annule. Meloidogyne subarctica, n. sp., can be separated from other Meloidogyne spp. by combinations of the following characteristics: perineal pattern with large oval areas in the tail region devoid of striae, arch with few unbroken striae; female excretory pore 1.5 to 2.5 x the stylet length from the anterior end; haploid chromosome number = 18; the spermatheca filled with sperm; stylet length of second-stage juveniles 13.5 to 15.4 ..mu..m.

  3. Molecular genetic status of Aleutian Canada Geese from Buldir and the Semidi Islands, Alaska

    USGS Publications Warehouse

    Pierson, Barbara J.; Pearce, John M.; Talbot, Sandra L.; Shields, Gerald F.; Scribner, Kim T.

    2000-01-01

    We conducted genetic analyses of Aleutian Canada Geese (Branta canadensis leucopareia) from Buldir Island in the western Aleutians and the Semidi Islands in the eastern portion of their breeding range. We compared data from seven microsatellite DNA loci and 143 base pairs of the control region of mitochondrial DNA from the two populations of Aleutian Canada Geese and another small-bodied subspecies, the Cackling Canada Goose (B. c. minima) which nests in western Alaska. The widely separated island-nesting Aleutian geese were genetically more closely related to each other than to mainland-nesting small-bodied geese. The populations of Aleutian geese were genetically differentiated from one another in terms of mitochondrial DNA haplotype and microsatellite allele frequencies, suggesting limited contemporary gene flow and/or major shifts in gene frequency through genetic drift. The degree of population genetic differentiation suggests that Aleutian Canada Goose populations could be considered separate management units. There was some evidence of population bottlenecks, although we found no significant genetic evidence of non-random mating or inbreeding.

  4. 76 FR 49417 - Fisheries of the Exclusive Economic Zone Off Alaska; Bering Sea and Aleutian Islands Management...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-08-10

    ...NMFS proposes regulations that would implement Amendment 93 to the Fishery Management Plan for Groundfish of the Bering Sea and Aleutian Islands Management Area (FMP). This proposed rule would amend the Bering Sea and Aleutian Islands Amendment 80 Program to modify the criteria for forming and participating in a harvesting cooperative. This action is necessary to encourage greater......

  5. 76 FR 45219 - Fisheries of the Exclusive Economic Zone Off Alaska; Bering Sea and Aleutian Islands Management...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-07-28

    ...Amendment 93 to the Fishery Management Plan for Groundfish of the Bering Sea and Aleutian Islands Management Area (FMP) would amend the Bering Sea and Aleutian Islands Amendment 80 Program to modify the criteria for forming and participating in a harvesting cooperative. This action is necessary to encourage greater participation in harvesting cooperatives, which enable members to more......

  6. 76 FR 68354 - Fisheries of the Exclusive Economic Zone Off Alaska; Bering Sea and Aleutian Islands Management...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-11-04

    ...NMFS issues regulations implementing Amendment 93 to the Fishery Management Plan for Groundfish of the Bering Sea and Aleutian Islands Management Area (FMP). These regulations amend the Bering Sea and Aleutian Islands Amendment 80 Program to modify the criteria for forming and participating in a harvesting cooperative. This action is necessary to encourage greater participation in harvesting......

  7. 75 FR 50716 - Fisheries of the Exclusive Economic Zone Off Alaska; Bering Sea and Aleutian Islands Crab...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-08-17

    ... Economic Zone Off Alaska; Bering Sea and Aleutian Islands Crab Rationalization Program; Emergency Rule... a processor with West designated IPQ in the West region of the Aleutian Islands. An emergency exists because, due to a recent unforeseen event, no crab processing facility is open in the West region....

  8. 76 FR 5556 - Fisheries of the Exclusive Economic Zone Off Alaska; Allocating Bering Sea and Aleutian Islands...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-02-01

    ... Economic Zone Off Alaska; Allocating Bering Sea and Aleutian Islands King and Tanner Crab Fishery Resources...-designated golden king crab IFQ to be delivered to a processor in the West region of the Aleutian Islands... king crab fishery, while providing for the sustained participation of municipalities in the...

  9. 75 FR 7205 - Fisheries of the Exclusive Economic Zone Off Alaska; Bering Sea and Aleutian Islands Crab...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-02-18

    ... Economic Zone Off Alaska; Bering Sea and Aleutian Islands Crab Rationalization Program; Emergency Rule... with West designated IPQ in the West region of the Aleutian Islands. An emergency exists, because... West region, but due to a recent unforeseen event, no processing facility is open in the West...

  10. 76 FR 44297 - Fisheries of the Exclusive Economic Zone Off Alaska; Allocating Bering Sea and Aleutian Islands...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-07-25

    ... Economic Zone Off Alaska; Allocating Bering Sea and Aleutian Islands King and Tanner Crab Fishery Resources... Fishery Management Plan for Bering Sea/Aleutian Islands King and Tanner Crabs (FMP) and the CR Program to... the amendment is available for public review and comment. The king and Tanner crab fisheries in...

  11. 76 FR 47493 - Fisheries of the Exclusive Economic Zone Off Alaska; Bering Sea and Aleutian Islands King and...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-08-05

    ... Economic Zone Off Alaska; Bering Sea and Aleutian Islands King and Tanner Crabs AGENCY: National Marine... economic zone of the Bering Sea and Aleutian Islands are managed under the FMP. The FMP was prepared by the... ecological conditions warrant doing so. Amendment 39 modifies the existing snow crab rebuilding plan...

  12. 78 FR 59908 - Fisheries of the Exclusive Economic Zone Off Alaska; Bering Sea and Aleutian Islands Management...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-09-30

    ... Economic Zone Off Alaska; Bering Sea and Aleutian Islands Management Area; Amendment 99 AGENCY: National... the Bering Sea and Aleutian Islands Management Area (BSAI FMP) to NMFS for review. If approved... review and comment. NMFS manages the U.S. groundfish fisheries of the Exclusive Economic Zone (EEZ)...

  13. 50 CFR 600.1106 - Longline catcher processor subsector Bering Sea and Aleutian Islands (BSAI) non-pollock...

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... Bering Sea and Aleutian Islands (BSAI) non-pollock groundfish species fee payment and collection system... AND ATMOSPHERIC ADMINISTRATION, DEPARTMENT OF COMMERCE MAGNUSON-STEVENS ACT PROVISIONS Specific... Bering Sea and Aleutian Islands (BSAI) non-pollock groundfish species fee payment and collection...

  14. 76 FR 8700 - Fisheries of the Exclusive Economic Zone Off Alaska; Bering Sea and Aleutian Islands Crab...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-02-15

    ... individual fishing quota (IFQ) and individual processor quota (IPQ) in the Western Aleutian Islands golden...-designated golden king crab IFQ to be delivered to a processor in the West region of the Aleutian Islands... stationary floating crab processors; catcher/processor vessel owner (CPO) QS was assigned to LLP holders...

  15. 76 FR 43658 - Fisheries of the Exclusive Economic Zone Off Alaska; Bering Sea and Aleutian Islands Crab...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-07-21

    ... Alaska; Bering Sea and Aleutian Islands Crab Rationalization Cost Recovery Program AGENCY: National... under the Bering Sea and Aleutian Islands Crab Rationalization Program. This action is intended to provide holders of crab allocations with the fee percentage for the 2011/2012 crab fishing year so...

  16. 50 CFR Figure 6 to Subpart E of... - Alaska Peninsula and Aleutian Islands Rural and Non-Rural Areas

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 50 Wildlife and Fisheries 7 2010-10-01 2010-10-01 false Alaska Peninsula and Aleutian Islands Rural and Non-Rural Areas 6 Figure 6 to Subpart E of Part 300 Wildlife and Fisheries INTERNATIONAL..., Subpt. E, Fig. 6 Figure 6 to Subpart E of Part 300—Alaska Peninsula and Aleutian Islands Rural and...

  17. 50 CFR 600.1105 - Longline catcher processor subsector of the Bering Sea and Aleutian Islands (BSAI) non-pollock...

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... the Bering Sea and Aleutian Islands (BSAI) non-pollock groundfish fishery program. 600.1105 Section... Capacity Reduction Regulations § 600.1105 Longline catcher processor subsector of the Bering Sea and... catcher processor subsector of the Bering Sea and Aleutian Islands (BSAI) non-pollock groundfish...

  18. 50 CFR 600.1105 - Longline catcher processor subsector of the Bering Sea and Aleutian Islands (BSAI) non-pollock...

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... the Bering Sea and Aleutian Islands (BSAI) non-pollock groundfish fishery program. 600.1105 Section... Capacity Reduction Regulations § 600.1105 Longline catcher processor subsector of the Bering Sea and... catcher processor subsector of the Bering Sea and Aleutian Islands (BSAI) non-pollock groundfish...

  19. 50 CFR 600.1105 - Longline catcher processor subsector of the Bering Sea and Aleutian Islands (BSAI) non-pollock...

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... the Bering Sea and Aleutian Islands (BSAI) non-pollock groundfish fishery program. 600.1105 Section... Capacity Reduction Regulations § 600.1105 Longline catcher processor subsector of the Bering Sea and... catcher processor subsector of the Bering Sea and Aleutian Islands (BSAI) non-pollock groundfish...

  20. 50 CFR 600.1105 - Longline catcher processor subsector of the Bering Sea and Aleutian Islands (BSAI) non-pollock...

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... the Bering Sea and Aleutian Islands (BSAI) non-pollock groundfish fishery program. 600.1105 Section... Capacity Reduction Regulations § 600.1105 Longline catcher processor subsector of the Bering Sea and... catcher processor subsector of the Bering Sea and Aleutian Islands (BSAI) non-pollock groundfish...

  1. 76 FR 55276 - Fisheries of the Exclusive Economic Zone Off Alaska; Octopus in the Bering Sea and Aleutian Islands

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-09-07

    ... Economic Zone Off Alaska; Octopus in the Bering Sea and Aleutian Islands AGENCY: National Marine Fisheries...; closure. SUMMARY: NMFS is prohibiting retention of octopus in the Bering Sea and Aleutian Islands (BSAI). This action is necessary because the 2011 total allowable catch of octopus in the BSAI has been...

  2. New Near-Source Tsunami Field Data for the April 1, 1946 Aleutian Earthquake, Alaska

    NASA Astrophysics Data System (ADS)

    Plafker, G.; Synolakis, C. E.; Okal, E. A.

    2001-12-01

    The April 1, 1946 Aleutian earthquake (Ms 7.4; Mw 8.2) stands out among tsunamigenic events because it generated both very high run-up near the earthquake source region and a destructive trans-Pacific tsunami. For this puzzling event, maximum near-field run-up (42 m) is more than 6 times the computed average dip slip on the source fault (Johnson and Satake, 1997). Attempts to model the near-field tsunami have been hampered by an almost total absence of reliable data on wave run-up, direction, and arrival time because the ocean coast in the region was virtually uninhabited, the earthquake and tsunami occurred at night, and there were no nearby recording tide gauges. The lone exception is the Scotch Cap Coast Guard station on the southwestern end of Unimak Island where a reinforced concrete lighthouse and its crew of 5 Coast Guardsmen were obliterated by the tsunami. Survivors at the station, who were in a communications facility on the sea cliff above the lighthouse, report that the wave arrived shortly before low tide at 2:18 A.M., some 48 minutes after the main shock was felt. Previous surveys by Coast Guard personnel indicated a maximum wave run-up elevation of 30-35 m at the station above an unspecified datum. We obtained new data on tsunami distribution along south-facing coasts between Unimak Pass on the west and Sanak Island on the east by measuring the height of driftwood and beach materials that were deposited by the tsunami above the extreme storm tide level. Our data indicate that: 1. The highest measured run-up, which is at the Scotch Cap lighthouse, was 42 m above tide level or about 37 m above present storm tide elevation; 2. Run-up along the rugged coast from Scotch Cap for 12 km NW to Sennett Point is 12.6-18 m and for 30 km east of Scotch Cap to Cape Lutke it is 24-40.6 m; 3. Run-up along the broad lowlands bordering Unimak Bight is 10-15 m and inundation is locally more than 1,000 m; 5. Run-up diminishes to 8 m or less at the SE corner of Unimak

  3. Multi-segment earthquakes and tsunami potential of the Aleutian megathrust

    USGS Publications Warehouse

    Shennan, I.; Bruhn, R.; Plafker, G.

    2009-01-01

    Large to great earthquakes and related tsunamis generated on the Aleutian megathrust produce major hazards for both the area of rupture and heavily populated coastlines around much of the Pacific Ocean. Here we use paleoseismic records preserved in coastal sediments to investigate whether segment boundaries control the largest ruptures or whether in some seismic cycles segments combine to produce earthquakes greater than any observed since instrumented records began. Virtually the entire megathrust has ruptured since AD1900, with four different segments generating earthquakes >M8.0. The largest was the M9.2 great Alaska earthquake of March 1964 that ruptured ???800 km of the eastern segment of the megathrust. The tsunami generated caused fatalities in Alaska and along the coast as far south as California. East of the 1964 zone of deformation, the Yakutat microplate experienced two >M8.0 earthquakes, separated by a week, in September 1899. For the first time, we present evidence that earthquakes ???900 and ???1500 years ago simultaneously ruptured adjacent segments of the Aleutian megathrust and the Yakutat microplate, with a combined area ???15% greater than 1964, giving an earthquake of greater magnitude and increased tsunamigenic potential. ?? 2008 Elsevier Ltd. All rights reserved.

  4. Near-field survey of the 1946 Aleutian tsunami on Unimak and Sanak Islands

    USGS Publications Warehouse

    Okal, E.A.; Plafker, G.; Synolakis, C.E.; Borrero, J.C.

    2003-01-01

    The 1946 Aleutian earthquake stands out among tsunamigenic events because it generated both very high run-up near the earthquake source region and a destructive trans-Pacific tsunami. We obtained new data on the distribution of its tsunami in the near field along south-facing coasts between Unimak Pass on the west and Sanak Island on the east by measuring the height of driftwood and beach materials that were deposited by the tsunami above the extreme storm tide level. Our data indicate that (1) the highest measured run-up, which is at the Scotch Cap lighthouse, was 42 m above tide level or about 37 m above present storm tide elevation; (2) run-up along the rugged coast from Scotch Cap for 12 km northwest to Sennett Point is 12-18 m, and for 30 km east of Scotch Cap to Cape Lutke it is 24-42 m; (3) run-up along the broad lowlands bordering Unimak Bight is 10-20 m, and in-undation is locally more than 2 km; (5) run-up diminishes to 8 m or less at the southeast corner of Unimak Island; (6) no evidence was found for run-up above present storm tides (about 4-5 m above MLLW) on the Ikatan Peninsula or areas along the coast to the west; and (7) run-up above storm tide level in the Sanak Island group is restricted to southwest-facing coasts of Sanak, Long, and Clifford Islands, where it is continuous and locally up to 24 m high. Generation of the tsunami by one or more major earthquake-triggered submarine landslides near the shelf edge south of Unimak Island seems to be the only viable mechanism to account for the data on wave arrival time, run-up heights, and distribution, as well as for unconfirmed anecdotal reports of local postquake increases in water depth and diminished bottom-fisheries productivity. A preliminary hydrodynamic simulation of the local tsunami propagation and run-up using a dipolar model of a possible landslide off Davidson Bank provides an acceptable fit to the characteristics of the distribution of local run-up, with a value at 34 m at the Scotch Cap

  5. History of earthquakes and tsunamis along the eastern Aleutian-Alaska megathrust, with implications for tsunami hazards in the California Continental Borderland

    USGS Publications Warehouse

    Ryan, Holly F.; von Huene, Roland; Wells, Ray E.; Scholl, David W.; Kirby, Stephen; Draut, Amy E.; Dumoulin, J.A.; Dusel-Bacon, C.

    2012-01-01

    During the past several years, devastating tsunamis were generated along subduction zones in Indonesia, Chile, and most recently Japan. Both the Chile and Japan tsunamis traveled across the Pacific Ocean and caused localized damage at several coastal areas in California. The question remains as to whether coastal California, in particular the California Continental Borderland, is vulnerable to more extensive damage from a far-field tsunami sourced along a Pacific subduction zone. Assuming that the coast of California is at risk from a far-field tsunami, its coastline is most exposed to a trans-Pacific tsunami generated along the eastern Aleutian-Alaska subduction zone. We present the background geologic constraints that could control a possible giant (Mw ~9) earthquake sourced along the eastern Aleutian-Alaska megathrust. Previous great earthquakes (Mw ~8) in 1788, 1938, and 1946 ruptured single segments of the eastern Aleutian-Alaska megathrust. However, in order to generate a giant earthquake, it is necessary to rupture through multiple segments of the megathrust. Potential barriers to a throughgoing rupture, such as high-relief fracture zones or ridges, are absent on the subducting Pacific Plate between the Fox and Semidi Islands. Possible asperities (areas on the megathrust that are locked and therefore subject to infrequent but large slip) are identified by patches of high moment release observed in the historical earthquake record, geodetic studies, and the location of forearc basin gravity lows. Global Positioning System (GPS) data indicate that some areas of the eastern Aleutian-Alaska megathrust, such as that beneath Sanak Island, are weakly coupled. We suggest that although these areas will have reduced slip during a giant earthquake, they are not really large enough to form a barrier to rupture. A key aspect in defining an earthquake source for tsunami generation is determining the possibility of significant slip on the updip end of the megathrust near

  6. Avian mortality associated with a volcanic gas seep at Kiska Island, Aleutian Islands, Alaska

    USGS Publications Warehouse

    Bond, Alexander L.; Evans, William C.; Jones, Ian L.

    2012-01-01

    We identified natural pits associated with avian mortality at the base of Kiska Volcano in the western Aleutian Islands, Alaska in 2007. Living, moribund, and dead birds were regularly found at low spots in a canyon between two lava flows during 2001–2006, but the phenomenon was attributed to natural trapping and starvation of fledgling seabirds (mostly Least Auklets, Aethia pusilla) at a colony site with >1 million birds present. However, 302 birds of eight species, including passerines, were found dead at the site during 2007–2010, suggesting additional factors were involved. Most carcasses showed no signs of injury and concentrations of dead birds had accumulated in a few distinctive low pits in the canyon. Gas samples from these locations showed elevated CO2 concentrations in late 2010. Analysis of carcasses indicated no evidence of blunt trauma or internal bleeding. Volcanic gases accumulating at these poorly ventilated sites may have caused the observed mortality, but are temporally variable. Most auklets breeding in the Aleutian Islands do so in recent lava flows that provide breeding habitat; our study documents a cost of this unusual habitat selection.

  7. 75 FR 59687 - Proposed Information Collection; Comment Request; Alaska Region Bering Sea & Aleutian Islands...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-09-28

    ... Region Bering Sea & Aleutian Islands (BSAI) Crab Economic Data Reports AGENCY: National Oceanic and... communities and monitors the ``economic stability for harvesters, processors, and coastal communities.'' The Magnuson-Stevens Act provides specific guidance on the CR Program's mandatory economic data...

  8. 50 CFR 600.1103 - Bering Sea and Aleutian Islands (BSAI) Crab species program.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ....1001, (B) Section 600.1002, (C) Section 600.1003, (D) Section 600.1004, (E) Section 600.1005, (F... 50 Wildlife and Fisheries 12 2013-10-01 2013-10-01 false Bering Sea and Aleutian Islands (BSAI... and section 205 of Pub. L. 107-117, enacted for BSAI crab species. (b) Terms. Unless otherwise...

  9. 76 FR 68161 - Proposed Information Collection; Comment Request; Aleutian Islands Pollock Fishery Requirements

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-11-03

    ... of this law allocates the Aleutian Islands (AI) directed pollock fishery to the Aleut Corporation for... agents for activities necessary for conducting the AI directed pollock fishery. Management provisions for the AI directed pollock fishery include: restrictions on the harvest specifications for the...

  10. 50 CFR 600.1103 - Bering Sea and Aleutian Islands (BSAI) Crab species program.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... Sound blue king crab. NVDC means the U.S. Coast Guard's National Vessel Documentation Center located in...) Crab species program. 600.1103 Section 600.1103 Wildlife and Fisheries FISHERY CONSERVATION AND... Aleutian Islands (BSAI) Crab species program. (a) Purpose. This section's purpose is to implement...

  11. 50 CFR 600.1103 - Bering Sea and Aleutian Islands (BSAI) Crab species program.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... Sound blue king crab. NVDC means the U.S. Coast Guard's National Vessel Documentation Center located in...) Crab species program. 600.1103 Section 600.1103 Wildlife and Fisheries FISHERY CONSERVATION AND... Aleutian Islands (BSAI) Crab species program. (a) Purpose. This section's purpose is to implement...

  12. 77 FR 44172 - Fisheries of the Exclusive Economic Zone Off Alaska; Squid in the Bering Sea and Aleutian Islands...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-07-27

    ... Economic Zone Off Alaska; Squid in the Bering Sea and Aleutian Islands Management Area AGENCY: National... non-specified reserve to the initial total allowable catch of squid in the Bering Sea and Aleutian... 679. The 2012 initial total allowable catch (ITAC) of squid in the BSAI was established as 361...

  13. Condition of groundfish resources of the eastern Bering Sea and Aleutian Islands region in 1982

    SciTech Connect

    Bakkala, R.G.; Low, L.; Ito, D.H.; Narita, R.E.; Ronholt, L.L.

    1983-03-01

    This report contains an assessment of the condition of groundfish and squid in the eastern Bering Sea and Aleutian Islands region through 1982. The assessments are based on species-by-species analyses of the data collected from the commercial fishery and research vessel surveys. Most of the resources in the Bering Sea-Aleutians management region are in good condition, including walleye pollock, Pacific cod, the flatfishes, and Atka mackerel. Pacific cod and yellowfin sole are in excellent condition and at historic high levels of abundance.

  14. Tsunami recurrence in the eastern Alaska-Aleutian arc: A Holocene stratigraphic record from Chirikof Island, Alaska

    USGS Publications Warehouse

    Nelson, Alan R.; Briggs, Richard; Dura, Tina; Engelhart, Simon E.; Gelfenbaum, Guy; Bradley, Lee-Ann; Forman, S.L.; Vane, Christopher H.; Kelley, K.A.

    2015-01-01

    cannot estimate source earthquake locations or magnitudes for most tsunami-deposited beds. We infer that no more than 3 of the 23 possible tsunamis beds at both sites were deposited following upper plate faulting or submarine landslides independent of megathrust earthquakes. If so, the Semidi segment of the Alaska-Aleutian megathrust near Chirikof Island probably sent high tsunamis southward every 180–270 yr for at least the past 3500 yr.                   

  15. InSAR imaging of volcanic deformation over cloud-prone areas - Aleutian islands

    USGS Publications Warehouse

    Lu, Zhong

    2007-01-01

    Interferometric synthetic aperture radar (INSAR) is capable of measuring ground-surface deformation with centimeter-tosubcentimeter precision and spatial resolution of tens-of meters over a relatively large region. With its global coverage and all-weather imaging capability, INSAR is an important technique for measuring ground-surface deformation of volcanoes over cloud-prone and rainy regions such as the Aleutian Islands, where only less than 5 percent of optical imagery is usable due to inclement weather conditions. The spatial distribution of surface deformation data, derived from INSAR images, enables the construction of detailed mechanical models to enhance the study of magmatic processes. This paper reviews the basics of INSAR for volcanic deformation mapping and the INSAR studies of ten Aleutian volcanoes associated with both eruptive and noneruptive activity. These studies demonstrate that all-weather INSAR imaging can improve our understanding of how the Aleutian volcanoes work and enhance our capability to predict future eruptions and associated hazards.

  16. Two new species of the cheilostome bryozoan Cheilopora from the Aleutian Islands.

    PubMed

    Kuklinski, Piotr; Grischenko, Andrei V; Jewett, Stephen C

    2015-05-27

    Two new species of Cheilopora-C. peristomata and C. elfa-are described from the shallow water around Adak and Amchitka of the Andreanof and Rat island groups of the Aleutian Islands. Zooids of both new species have cormidial peristomes, composed by the distal (originating from neighbouring zooid) and proximal lappets. In contrast to previously described species, the strongly elevated peristomial lappets defining the secondary orifice confer the overall shape of an incomplete circle with deep U-shaped proximolateral pseudosinuses. Depending on angle of view, this gives a campanuliform or trifoliate outline to the secondary orifice, by which the new species differ from congeners. Together with previous discoveries from the Aleutians, these two new Cheilopora species are indicative of incomplete knowledge of the marine biodiversity of the region, including the distinctive character of the bryozoan fauna. There is a need for intensification of taxonomic effort along the island arc.

  17. 77 FR 62482 - Fisheries of the Exclusive Economic Zone Off Alaska; Bering Sea and Aleutian Islands Management...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-10-15

    ... Economic Zone Off Alaska; Bering Sea and Aleutian Islands Management Area; Groundfish Retention Standard... (BSAI) management area by removing certain regulatory requirements mandating minimum levels of... Fishery Conservation and Management Act, the fishery management plan, and other applicable law....

  18. 76 FR 35781 - Fisheries of the Exclusive Economic Zone Off Alaska; Bering Sea and Aleutian Islands Crab...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-06-20

    ... necessary to prevent disruption to the Western Aleutian Islands golden king crab fishery, while providing... participants to respond quickly to unforeseen disruptions in processing capacity. From the date an exemption...

  19. SURFACE REMEDIATION IN THE ALEUTIAN ISLANDS: A CASE STUDY OF AMCHITKA ISLAND, ALASKA

    SciTech Connect

    Giblin, M. O.; Stahl, D. C.; Bechtel, J. A.

    2002-02-25

    Amchitka Island, Alaska, was at one time an integral player in the nation's defense program. Located in the North Pacific Ocean in the Aleutian Island archipelago, the island was intermittently inhabited by several key government agencies, including the U.S. Army, the U.S. Atomic Energy Commission (predecessor agency to the U.S. Department of Energy), and the U.S. Navy. Since 1993, the U.S. Department of Energy (DOE) has conducted extensive investigations on Amchitka to determine the nature and extent of contamination resulting from historic nuclear testing. The uninhabited island was the site of three high-yield nuclear tests from 1965 to 1971. These test locations are now part of the DOE's National Nuclear Security Administration Nevada Operations Office's Environmental Management Program. In the summer of 2001, the DOE launched a large-scale remediation effort on Amchitka to perform agreed-upon corrective actions to the surface of the island. Due to the lack of resources available on Amchitka and logistical difficulties with conducting work at such a remote location, the DOE partnered with the Navy and U.S. Army Corps of Engineers (USACE) to share certain specified costs and resources. Attempting to negotiate the partnerships while organizing and implementing the surface remediation on Amchitka proved to be a challenging endeavor. The DOE was faced with unexpected changes in Navy and USACE scope of work, accelerations in schedules, and risks associated with construction costs at such a remote location. Unfavorable weather conditions also proved to be a constant factor, often slowing the progress of work. The Amchitka Island remediation project experience has allowed the DOE to gain valuable insights into how to anticipate and mitigate potential problems associated with future remediation projects. These lessons learned will help the DOE in conducting future work more efficiently, and can also serve as a guide for other agencies performing similar work.

  20. Subduction Controls of Hf and Nd Isotopes in Lavas of the Aleutian Island Arc

    SciTech Connect

    Yogodzinski, Gene; Vervoort, Jeffery; Brown, Shaun Tyler; Gerseny, Megan

    2010-08-29

    The Hf and Nd isotopic compositions of 71 Quaternary lavas collected from locations along the full length of the Aleutian island arc are used to constrain the sources of Aleutian magmas and to provide insight into the geochemical behavior of Nd and Hf and related elements in the Aleutian subduction-magmatic system. Isotopic compositions of Aleutian lavas fall approximately at the center of, and form a trend parallel to, the terrestrial Hf-Nd isotopic array with {var_epsilon}{sub Hf} of +12.0 to +15.5 and {var_epsilon}{sub Nd} of +6.5 to +10.5. Basalts, andesites, and dacites within volcanic centers or in nearby volcanoes generally all have similar isotopic compositions, indicating that there is little measurable effect of crustal or other lithospheric assimilation within the volcanic plumbing systems of Aleutian volcanoes. Hafnium isotopic compositions have a clear pattern of along-arc increase that is continuous from the eastern-most locations near Cold Bay to Piip Seamount in the western-most part of the arc. This pattern is interpreted to reflect a westward decrease in the subducted sediment component present in Aleutian lavas, reflecting progressively lower rates of subduction westward as well as decreasing availability of trench sediment. Binary bulk mixing models (sediment + peridotite) demonstrate that 1-2% of the Hf in Aleutian lavas is derived from subducted sediment, indicating that Hf is mobilized out of the subducted sediment with an efficiency that is similar to that of Sr, Pb and Nd. Low published solubility for Hf and Nd in aqueous subduction fluids lead us to conclude that these elements are mobilized out of the subducted component and transferred to the mantle wedge as bulk sediment or as a silicate melt. Neodymium isotopes also generally increase from east to west, but the pattern is absent in the eastern third of the arc, where the sediment flux is high and increases from east to west, due to the presence of abundant terrigenous sediment in the

  1. August 2008 eruption of Kasatochi volcano, Aleutian Islands, Alaska-resetting an Island Landscape

    USGS Publications Warehouse

    Scott, W.E.; Nye, C.J.; Waythomas, C.F.; Neal, C.A.

    2010-01-01

    Kasatochi Island, the subaerial portion of a small volcano in the western Aleutian volcanic arc, erupted on 7-8 August 2008. Pyroclastic flows and surges swept the island repeatedly and buried most of it and the near-shore zone in decimeters to tens of meters of deposits. Several key seabird rookeries in taluses were rendered useless. The eruption lasted for about 24 hours and included two initial explosive pulses and pauses over a 6-hr period that produced ash-poor eruption clouds, a 10-hr period of continuous ash-rich emissions initiated by an explosive pulse and punctuated by two others, and a final 8-hr period of waning ash emissions. The deposits of the eruption include a basal muddy tephra that probably reflects initial eruptions through the shallow crater lake, a sequence of pumiceous and lithic-rich pyroclastic deposits produced by flow, surge, and fall processes during a period of energetic explosive eruption, and a fine-grained upper mantle of pyroclastic-fall and -surge deposits that probably reflects the waning eruptive stage as lake and ground water again gained access to the erupting magma. An eruption with similar impact on the island's environment had not occurred for at least several centuries. Since the 2008 eruption, the volcano has remained quiet other than emission of volcanic gases. Erosion and deposition are rapidly altering slopes and beaches. ?? 2010 Regents of the University of Colorado.

  2. Abundance, trends and distribution of baleen whales off Western Alaska and the central Aleutian Islands

    NASA Astrophysics Data System (ADS)

    Zerbini, Alexandre N.; Waite, Janice M.; Laake, Jeffrey L.; Wade, Paul R.

    2006-11-01

    Large whales were extensively hunted in coastal waters off Alaska, but current distribution, population sizes and trends are poorly known. Line transect surveys were conducted in coastal waters of the Aleutian Islands and the Alaska Peninsula in the summer of 2001-2003. Abundances of three species were estimated by conventional and multiple covariate distance sampling (MCDS) methods. Time series of abundance estimates were used to derive rates of increase for fin whales ( Balaenoptera physalus) and humpback whales ( Megaptera novaeangliae). Fin whales occurred primarily from the Kenai Peninsula to the Shumagin Islands, but were abundant only near the Semidi Islands and Kodiak. Humpback whales were found from the Kenai Peninsula to Umnak Island and were more abundant near Kodiak, the Shumagin Islands and north of Unimak Pass. Minke whales ( B. acutorostrata) occurred primarily in the Aleutian Islands, with a few sightings south of the Alaska Peninsula and near Kodiak Island. Humpback whales were observed in large numbers in their former whaling grounds. In contrast, high densities of fin whales were not observed around the eastern Aleutian Islands, where whaling occurred. Average abundance estimates (95% CI) for fin, humpback and minke whales were 1652 (1142-2389), 2644 (1899-3680), and 1233 (656-2315), respectively. Annual rates of increase were estimated at 4.8% (95% CI=4.1-5.4%) for fin and 6.6% (5.2-8.6%) for humpback whales. This study provides the first estimate of the rate of increase of fin whales in the North Pacific Ocean. The estimated trends are consistent with those of other recovering baleen whales. There were no sightings of blue or North Pacific right whales, indicating the continued depleted status of these species.

  3. Four new species of Haplosclerida (Porifera, Demospongiae) from the Aleutian Islands, Alaska.

    PubMed

    Lehnert, Helmut; Stone, Robert P

    2013-01-01

    Four new species of Haplosclerida are described from the Aleutian Islands, Alaska: Callyspongia mucosa n.sp., Cladocroce infundibulum n. sp., Cladocroce attu n. sp. and Cladocroce kiska n. sp. The new species are described and compared to congeners of the region. This is the northernmost record of the genus Callyspongia and the first record of the subgenus Callyspongia from the North Pacific Ocean. To accommodate Cladocroce kiska in its genus the definition has to be broadened to allow sigmas.

  4. A new population of Aleutian shield fern (Polystichum aleuticum C. Christens.) on Adak Island, Alaska

    USGS Publications Warehouse

    Talbot, Sandra L.; Talbot, Stephen S.

    2002-01-01

    We report and describe a new population of the endangered Aleutian shield fern (Polystichum aleuticum C. Christens.) discovered on Mount Reed, Adak Island, Alaska. The new population is located at a lower elevation than the other known populations, placing the species' known elevational range between 338 m and 525 m. The discovery of this population is significant because it increases the total number of known populations and individuals for the species.

  5. Geology and geochemistry of the Geyser Bight Geothermal Area, Umnak Island, Aleutian Islands, Alaska

    SciTech Connect

    Nye, C.J. . Geophysical Inst. Alaska Dept. of Natural Resources, Fairbanks, AK . Div. of Geological and Geophysical Surveys); Motyka, R.J. . Div. of Geological and Geophysical Surveys); Turner, D.L. . Geophysical Inst.); Liss, S.A. (Alaska Dept. of Natural Resources, Fairba

    1990-10-01

    The Geyser Bight geothermal area is located on Umnak Island in the central Aleutian Islands. It contains one of the hottest and most extensive areas of thermal springs and fumaroles in Alaska, and is only documented site in Alaska with geysers. The zone of hot springs and fumaroles lies at the head of Geyser Creek, 5 km up a broad, flat, alluvial valley from Geyser Bight. At present central Umnak is remote and undeveloped. This report describes results of a combined program of geologic mapping, K-Ar dating, detailed description of hot springs, petrology and geochemistry of volcanic and plutonic rock units, and chemistry of geothermal fluids. Our mapping documents the presence of plutonic rock much closer to the area of hotsprings and fumaroles than previously known, thus increasing the probability that plutonic rock may host the geothermal system. K-Ar dating of 23 samples provides a time framework for the eruptive history of volcanic rocks as well as a plutonic cooling age.

  6. MERCURY CONCENTRATIONS OF A RESIDENT FRESHWATER FORAGE FISH AT ADAK ISLAND, ALEUTIAN ARCHIPELAGO, ALASKA

    PubMed Central

    Kenney, Leah A.; von Hippel, Frank A.; Willacker, James J.; O’Hara, Todd M.

    2015-01-01

    The Aleutian Archipelago is an isolated arc of over 300 volcanic islands stretching 1,600 km across the interface of the Bering Sea and North Pacific Ocean. Although remote, some Aleutian Islands were heavily impacted by military activities from World War II until recently and were exposed to anthropogenic contaminants, including mercury (Hg). Mercury is also delivered to these islands via global atmospheric transport, prevailing ocean currents, and biotransport by migratory species. Mercury contamination of freshwater ecosystems is poorly understood in this region. Total Hg (THg) concentrations were measured in threespine stickleback fish (Gasterosteus aculeatus) collected from eight lakes at Adak Island, an island in the center of the archipelago with a long military history. Mean THg concentrations for fish whole-body homogenates for all lakes ranged from 0.314 to 0.560 mg/kg dry weight. Stickleback collected from seabird-associated lakes had significantly higher concentrations of THg compared to non-seabird lakes, including all military lakes. The δ13C stable isotope ratios of stickleback collected from seabird lakes suggest an input of marine-derived nutrients and/or marine-derived Hg. PMID:22912068

  7. Mercury concentrations of a resident freshwater forage fish at Adak Island, Aleutian Archipelago, Alaska.

    PubMed

    Kenney, Leah A; von Hippel, Frank A; Willacker, James J; O'Hara, Todd M

    2012-11-01

    The Aleutian Archipelago is an isolated arc of over 300 volcanic islands stretching 1,600 km across the interface of the Bering Sea and North Pacific Ocean. Although remote, some Aleutian Islands were heavily impacted by military activities from World War II until recently and were exposed to anthropogenic contaminants, including mercury (Hg). Mercury is also delivered to these islands via global atmospheric transport, prevailing ocean currents, and biotransport by migratory species. Mercury contamination of freshwater ecosystems is poorly understood in this region. Total Hg (THg) concentrations were measured in threespine stickleback fish (Gasterosteus aculeatus) collected from eight lakes at Adak Island, an island in the center of the archipelago with a long military history. Mean THg concentrations for fish whole-body homogenates for all lakes ranged from 0.314 to 0.560 mg/kg dry weight. Stickleback collected from seabird-associated lakes had significantly higher concentrations of THg compared to non-seabird lakes, including all military lakes. The δ(13)C stable isotope ratios of stickleback collected from seabird lakes suggest an input of marine-derived nutrients and/or marine-derived Hg.

  8. Microbial consortia of gorgonian corals from the Aleutian islands

    USGS Publications Warehouse

    Gray, Michael A.; Stone, R.P.; McLaughlin, M.R.; Kellogg, C.A.

    2011-01-01

    Gorgonians make up the majority of corals in the Aleutian archipelago and provide critical fish habitat in areas of economically important fisheries. The microbial ecology of the deep-sea gorgonian corals Paragorgea arborea, Plumarella superba, and Cryogorgia koolsae was examined with culture-based and 16S rRNA gene-based techniques. Six coral colonies (two per species) were collected. Samples from all corals were cultured, and clone libraries were constructed from P. superba and C. koolsae. Cultured bacteria were dominated by the Gammaproteobacteria, especially Vibrionaceae, with other phyla comprising <6% of the isolates. The clone libraries showed dramatically different bacterial communities between corals of the same species collected at different sites, with no clear pattern of conserved bacterial consortia. Two of the clone libraries (one from each coral species) were dominated by Tenericutes, with Alphaproteobacteria dominating the remaining sequences. The other libraries were more diverse and had a more even distribution of bacterial phyla, showing more similarity between genera than within coral species. Here we report the first microbiological characterization of P. arborea, P. superba, and C. koolsae. FEMS Microbiology Ecology ?? 2011 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. No claim to original US government works.

  9. Dispersal and behavior of pacific halibut hippoglossus stenolepis in the bering sea and Aleutian islands region

    USGS Publications Warehouse

    Seitz, A.C.; Loher, T.; Norcross, Brenda L.; Nielsen, J.L.

    2011-01-01

    Currently, it is assumed that eastern Pacific halibut Hippoglossus stenolepis belong to a single, fully mixed population extending from California through the Bering Sea, in which adult halibut disperse randomly throughout their range during their lifetime. However, we hypothesize that hali but dispersal is more complex than currently assumed and is not spatially random. To test this hypo thesis, we studied the seasonal dispersal and behavior of Pacific halibut in the Bering Sea and Aleutian Islands (BSAI). Pop-up Archival Transmitting tags attached to halibut (82 to 154 cm fork length) during the summer provided no evidence that individuals moved out of the Bering Sea and Aleutian Islands region into the Gulf of Alaska during the mid-winter spawning season, supporting the concept that this region contains a separate spawning group of adult halibut. There was evidence for geographically localized groups of halibut along the Aleutian Island chain, as all of the individuals tagged there displayed residency, with their movements possibly impeded by tidal currents in the passes between islands. Mid-winter aggregation areas of halibut are assumed to be spawning grounds, of which 2 were previously unidentified and extend the species' presumed spawning range ~1000 km west and ~600 km north of the nearest documented spawning area. If there are indeed independent spawning groups of Pacific halibut in the BSAI, their dynamics may vary sufficiently from those of the Gulf of Alaska, so that specifically accounting for their relative segregation and unique dynamics within the larger population model will be necessary for correctly predicting how these components may respond to fishing pressure and changing environmental conditions.?? Inter-Research 2011.

  10. Genetic structure of the Common Eider in the western Aleutian Islands prior to fox eradication

    USGS Publications Warehouse

    Sonsthagen, Sarah A.; Talbot, Sandra L.; Wilson, Robert E.; Petersen, Margaret R.; Williams, Jeffrey C.; Byrd, G. Vernon; McCracken, Kevin G.

    2013-01-01

    Since the late 18th century bird populations residing in the Aleutian Archipelago have been greatly reduced by introduced arctic foxes (Alopex lagopus). We analyzed data from microsatellite, nuclear intron, and mitochondrial (mtDNA) loci to examine the spatial genetic structure, demography, and gene flow among four Aleutian Island populations of the Common Eider (Somateria mollissima) much reduced by introduced foxes. In mtDNA, we found high levels of genetic structure within and between island groups (ΦST = 0.643), but we found no population subdivision in microsatellites or nuclear introns. Differences in genetic structure between the mitochondrial and nuclear genomes are consistent with the Common Eider's breeding and winter biology, as females are highly philopatric and males disperse. Nevertheless, significant differences between islands in the mtDNA of males and marginal significance (P =0.07) in the Z-linked locus Smo 1 suggest that males may also have some level of fidelity to island groups. Severe reduction of populations by the fox, coupled with females' high philopatry, may have left the genetic signature of a bottleneck effect, resulting in the high levels of genetic differentiation observed in mtDNA (ΦST = 0.460–0.807) between islands only 440 km apart. Reestablishment of the Common Eider following the fox's eradication was likely through recruitment from within the islands and bolstered by dispersal from neighboring islands, as suggested by the lack of genetic structure and asymmetry in gene flow between Attu and the other Near Islands.

  11. 50 CFR Table 24 to Part 679 - Except as Noted, Locations in the Aleutian Islands Habitat Conservation Area Open to Nonpelagic...

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 50 Wildlife and Fisheries 13 2014-10-01 2014-10-01 false Except as Noted, Locations in the Aleutian Islands Habitat Conservation Area Open to Nonpelagic Trawl Fishing 24 Table 24 to Part 679... Table 24 to Part 679—Except as Noted, Locations in the Aleutian Islands Habitat Conservation Area...

  12. 50 CFR Table 24 to Part 679 - Except as Noted, Locations in the Aleutian Islands Habitat Conservation Area Open to Nonpelagic...

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 50 Wildlife and Fisheries 13 2013-10-01 2013-10-01 false Except as Noted, Locations in the Aleutian Islands Habitat Conservation Area Open to Nonpelagic Trawl Fishing 24 Table 24 to Part 679... Table 24 to Part 679—Except as Noted, Locations in the Aleutian Islands Habitat Conservation Area...

  13. 50 CFR Table 24 to Part 679 - Except as Noted, Locations in the Aleutian Islands Habitat Conservation Area Open to Nonpelagic...

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 50 Wildlife and Fisheries 9 2010-10-01 2010-10-01 false Except as Noted, Locations in the Aleutian Islands Habitat Conservation Area Open to Nonpelagic Trawl Fishing 24 Table 24 to Part 679 Wildlife and... 24 to Part 679—Except as Noted, Locations in the Aleutian Islands Habitat Conservation Area Open...

  14. 50 CFR Table 24 to Part 679 - Except as Noted, Locations in the Aleutian Islands Habitat Conservation Area Open to Nonpelagic...

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 50 Wildlife and Fisheries 11 2011-10-01 2011-10-01 false Except as Noted, Locations in the Aleutian Islands Habitat Conservation Area Open to Nonpelagic Trawl Fishing 24 Table 24 to Part 679... Table 24 to Part 679—Except as Noted, Locations in the Aleutian Islands Habitat Conservation Area...

  15. 50 CFR Table 24 to Part 679 - Except as Noted, Locations in the Aleutian Islands Habitat Conservation Area Open to Nonpelagic...

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 50 Wildlife and Fisheries 13 2012-10-01 2012-10-01 false Except as Noted, Locations in the Aleutian Islands Habitat Conservation Area Open to Nonpelagic Trawl Fishing 24 Table 24 to Part 679... Table 24 to Part 679—Except as Noted, Locations in the Aleutian Islands Habitat Conservation Area...

  16. An introduced predator alters Aleutian Island plant communities by thwarting nutrient subsidies

    USGS Publications Warehouse

    Maron, J.L.; Estes, J.A.; Croll, D.A.; Danner, E.M.; Elmendorf, S.C.; Buckelew, S.L.

    2006-01-01

    The ramifying effects of top predators on food webs traditionally have been studied within the framework of trophic cascades. Trophic cascades are compelling because they embody powerful indirect effects of predators on primary production. Although less studied, indirect effects of predators may occur via routes that are not exclusively trophic. We quantified how the introduction of foxes onto the Aleutian Islands transformed plant communities by reducing abundant seabird populations, thereby disrupting nutrient subsidies vectored by seabirds from sea to land. We compared soil and plant fertility, plant biomass and community composition, and stable isotopes of nitrogen in soil, plants, and other organisms on nine fox-infested and nine historically fox-free islands across the Aleutians. Additionally, we experimentally augmented nutrients on a fox-infested island to test whether differences in plant productivity and composition between fox-infested and fox-free islands could have arisen from differences in nutrient inputs between island types. Islands with historical fox infestations had soils low in phosphorus and nitrogen and plants low in tissue nitrogen. Soils, plants, slugs, flies, spiders, and bird droppings on these islands had low d15N values indicating that these organisms obtained nitrogen from internally derived sources. In contrast, soils, plants, and higher trophic level organisms on fox-free islands had elevated d15N signatures indicating that they utilized nutrients derived from the marine environment. Furthermore, soil phosphorus (but not nitrogen) and plant tissue nitrogen were higher on fox-free than fox-infested islands. Nutrient subsidized fox-free islands supported lush, high biomass plant communities dominated by graminoids. Fox-infested islands were less graminoid dominated and had higher cover and biomass of low-lying forbs and dwarf shrubs. While d15N profiles of soils and plants and graminoid biomass varied with island size and distance from

  17. Patterns in thermal emissions from the volcanoes of the Aleutian Islands

    NASA Astrophysics Data System (ADS)

    Blackett, M.; Webley, P. W.; Dehn, J.

    2012-12-01

    Using AVHRR data 1993-2011 and the Alaska Volcano Observatory's Okmok II Algorithm, the thermal emissions from all volcanoes in the Aleutian Islands were converted from temperature to power emission and examined for periodicity. The emissions were also summed to quantify the total energy released throughout the period. It was found that in the period April 1997 - January 2004 (37% of the period) the power emission from the volcanoes of the island arc declined sharply to constitute just 5.7% of the total power output for the period (138,311 MW), and this was attributable to just three volcanoes: Veniaminof (1.0%), Cleveland (1.5%) and Shishaldin (3.2%). This period of apparent reduced activity contrasts with the periods both before and after and is unrelated to the number of sensors in orbit at the time. What is also evident from the data set is that in terms of overall power emission over this period, the majority of emitted energy is largely attributable to those volcanoes which erupt with regularity (again, Veniaminof [29.7%], Cleveland [17%] and Shishaldin [11.4%]), as opposed to from the relatively few, large scale events (i.e. Reboubt [5.4%], Okmok [8.3%], Augustine [9.7%]; Pavlov [13.9%] being an exception). Sum power emission from volcanoes in the Aleutian Islands (1993-2011)

  18. Status and distribution of the Kittlitz's Murrelet Brachyramphus brevirostris along the Alaska Peninsula and Kodiak and Aleutian Islands, Alaska

    USGS Publications Warehouse

    Madison, Erica N.; Piatt, John F.; Arimitsu, Mayumi L.; Romano, Marc D.; van Pelt, Thomas I.; Nelson, S. Kim; Williams, Jeffrey C.; DeGange, Anthony R.

    2011-01-01

    The Kittlitz's Murrelet Brachyramphus brevirostris is adapted for life in glacial-marine ecosystems, being concentrated in the belt of glaciated fjords in the northern Gulf of Alaska from Glacier Bay to Cook Inlet. Most of the remaining birds are scattered along coasts of the Alaska Peninsula and Aleutian Islands, where they reside in protected bays and inlets, often in proximity to remnant glaciers or recently deglaciated landscapes. We summarize existing information on Kittlitz's Murrelet in this mainly unglaciated region, extending from Kodiak Island in the east to the Near Islands in the west. From recent surveys, we estimated that ~2400 Kittlitz's Murrelets were found in several large embayments along the Alaska Peninsula, where adjacent ice fields feed silt-laden water into the bays. On Kodiak Island, where only remnants of ice remain today, observations of Kittlitz's Murrelets at sea were uncommon. The species has been observed historically around the entire Kodiak Archipelago, however, and dozens of nest sites were found in recent years. We found Kittlitz's Murrelets at only a few islands in the Aleutian chain, notably those with long complex shorelines, high mountains and remnant glaciers. The largest population (~1600 birds) of Kittlitz's Murrelet outside the Gulf of Alaska was found at Unalaska Island, which also supports the greatest concentration of glacial ice in the Aleutian Islands. Significant populations were found at Atka (~1100 birds), Attu (~800) and Adak (~200) islands. Smaller numbers have been reported from Unimak, Umnak, Amlia, Kanaga, Tanaga, Kiska islands, and Agattu Island, where dozens of nest sites have been located in recent years. Most of those islands have not been thoroughly surveyed, and significant pockets of Kittlitz's Murrelets may yet be discovered. Our estimate of ~6000 Kittlitz's Murrelets along the Alaska Peninsula and Aleutian Islands is also likely to be conservative because of the survey protocols we employed (i.e. early

  19. Inferring relative tsunami magnitudes from inverse and forward sediment transport modeling of tsunami deposits in the Eastern Aleutian Islands.

    NASA Astrophysics Data System (ADS)

    Gelfenbaum, G. R.; La Selle, S.; Witter, R. C.; Jaffe, B. E.; Briggs, R. W.; Koehler, R. D., III; Engelhart, S. E.; Carver, G. A.

    2014-12-01

    Tsunami recurrence intervals can be determined by age dating paleotsunami deposits, but relative tsunami magnitude is more difficult to infer from deposit characteristics alone. Deposit thickness, grain size, and certain sedimentary structures are used to infer hydrodynamic conditions during deposition, which can be used as proxies for tsunami magnitude. Recent field studies in the eastern Alaska-Aleutian subduction zone have identified sequences of tsunami deposits from the 1957 Andreanof Islands earthquake (MW 8.6) and at least five other pre-historic tsunami events from the last 2,400 years. At Stardust Bay on the Pacific Coast of Sedanka Island, a sand-rich deposit attributed to the 1957 tsunami is 1-13 cm thick and is found at elevations up to 18.5 m. Older sand units are 6-50 cm thick and often have rounded gravel at the base of multiple, normally-graded sand beds. At Driftwood Bay on the south side of Umnak Island, about 200 km to the southeast of Stardust Bay, the 1957 deposit is 1 - 5.5 cm thick, underlain by a sequence of peat with up to 8 sandy deposits, some of which exhibit normally-graded beds up to 14 cm thick. Relatively thick deposits that exhibit suspension grading, a type of grading created by sediment falling out of suspension that is often observed in modern tsunami deposits, are typically formed under steady and uniform flow and are therefore good candidates for reconstructing flow conditions using inverse sediment transport models. By applying forward models of sediment transport, we will test how different tsunami waveforms, wave heights, sediment source distributions, roughness, and local slopes affect patterns of deposition. This will help us assess which deposits have characteristics that scale with tsunami wave heights used as initial conditions in the forward model, and are therefore more indicative of relative tsunami magnitude. Here, we attempt to determine if the tsunamis that created the pre-historic deposits found at Stardust and

  20. 77 FR 59852 - Fisheries of the Exclusive Economic Zone Off Alaska; Bering Sea and Aleutian Islands Management...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-10-01

    ...NMFS publishes regulations to implement Amendment 97 to the Fishery Management Plan for Groundfish of the Bering Sea and Aleutian Islands Management Area (FMP). Amendment 97 allows the owner of a trawl catcher/processor vessel authorized to participate in the Amendment 80 catch share program to replace that vessel with a vessel that meets certain requirements. This action establishes the......

  1. 75 FR 21600 - Groundfish Fisheries of the Bering Sea and Aleutian Islands Area and the Gulf of Alaska; King and...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-04-26

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration RIN 0648-XW07 Groundfish Fisheries of the Bering Sea and Aleutian Islands Area and the Gulf of Alaska; King and Tanner Crab Fisheries in the Bering...

  2. 78 FR 13813 - Fisheries of the Exclusive Economic Zone Off Alaska; Bering Sea and Aleutian Islands; 2013 and...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-03-01

    ... Economic Zone Off Alaska; Bering Sea and Aleutian Islands; 2013 and 2014 Harvest Specifications for... criteria set out at Sec. 679.21(e)(1)(i), the 2013 and 2014 PSC limit of red king crab in Zone 1 for trawl...)(ii), the calculated 2013 and 2014 C. bairdi crab PSC limit for trawl gear is 980,000 animals in...

  3. 77 FR 10669 - Fisheries of the Exclusive Economic Zone Off Alaska; Bering Sea and Aleutian Islands; Final 2012...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-02-23

    ... ] levels (OFLs) involves sophisticated statistical analyses of fish populations. The FMP specifies a series... Council is currently considering implementing management measures in the event that Pacific cod is split... Island subarea. This split depends on NMFS developing an age-structured model for the Aleutian...

  4. 75 FR 38430 - Fisheries of the Exclusive Economic Zone Off Alaska; Greenland Turbot in the Aleutian Islands...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-07-02

    ... current available data and finds that the ITAC for Greenland turbot in the Aleutian Islands subarea needs... most recent fisheries data in a timely fashion and would delay the apportionment of the non-specified... and processors. NMFS was unable to publish a notice providing time for public comment because the...

  5. 50 CFR 600.1105 - Longline catcher processor subsector of the Bering Sea and Aleutian Islands (BSAI) non-pollock...

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 50 Wildlife and Fisheries 8 2010-10-01 2010-10-01 false Longline catcher processor subsector of... Capacity Reduction Regulations § 600.1105 Longline catcher processor subsector of the Bering Sea and... catcher processor subsector of the Bering Sea and Aleutian Islands (BSAI) non-pollock groundfish...

  6. 78 FR 28523 - Fisheries of the Exclusive Economic Zone Off Alaska; Bering Sea and Aleutian Islands Crab...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-05-15

    ... the Exclusive Economic Zone Off Alaska; Bering Sea and Aleutian Islands Crab Rationalization Program...://www.regulations.gov or from the Alaska Region Web site at http://alaskafisheries.noaa.gov . The... the NMFS Alaska Region Web site at http://alaskafisheries.noaa.gov . Written comments regarding...

  7. 78 FR 65602 - Fisheries of the Exclusive Economic Zone Off Alaska; Bering Sea and Aleutian Islands Management...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-11-01

    ... National Oceanic and Atmospheric Administration 50 CFR Part 679 RIN 0648-BD03 Fisheries of the Exclusive Economic Zone Off Alaska; Bering Sea and Aleutian Islands Management Area; Amendment 102 AGENCY: National Marine Fisheries Service (NMFS), National Oceanic and Atmospheric Administration (NOAA), Commerce....

  8. Feasibility of Tidal and Ocean Current Energy in False Pass, Aleutian Islands, Alaska final report

    SciTech Connect

    Wright, Bruce Albert

    2014-05-07

    The Aleutian Pribilof Islands Association was awarded a U.S. Department of Energy Tribal Energy Program grant (DE-EE0005624) for the Feasibility of Tidal and Ocean Current Energy in False Pass, Aleutian Islands, Alaska (Project). The goal of the Project was to perform a feasibility study to determine if a tidal energy project would be a viable means to generate electricity and heat to meet long-term fossil fuel use reduction goals, specifically to produce at least 30% of the electrical and heating needs of the tribally-owned buildings in False Pass. The Project Team included the Aleut Region organizations comprised of the Aleutian Pribilof Island Association (APIA), and Aleutian Pribilof Island Community Development Association (APICDA); the University of Alaska Anchorage, ORPC Alaska a wholly-owned subsidiary of Ocean Renewable Power Company (ORPC), City of False Pass, Benthic GeoScience, and the National Renewable Energy Laboratory (NREL). The following Project objectives were completed: collected existing bathymetric, tidal, and ocean current data to develop a basic model of current circulation at False Pass, measured current velocities at two sites for a full lunar cycle to establish the viability of the current resource, collected data on transmission infrastructure, electrical loads, and electrical generation at False Pass, performed economic analysis based on current costs of energy and amount of energy anticipated from and costs associated with the tidal energy project conceptual design and scoped environmental issues. Utilizing circulation modeling, the Project Team identified two target sites with strong potential for robust tidal energy resources in Isanotski Strait and another nearer the City of False Pass. In addition, the Project Team completed a survey of the electrical infrastructure, which identified likely sites of interconnection and clarified required transmission distances from the tidal energy resources. Based on resource and electrical data

  9. Climate program "stone soup": Assessing climate change vulnerabilities in the Aleutian and Bering Sea Islands of Alaska

    NASA Astrophysics Data System (ADS)

    Littell, J. S.; Poe, A.; van Pelt, T.

    2015-12-01

    Climate change is already affecting the Bering Sea and Aleutian Island region of Alaska. Past and present marine research across a broad spectrum of disciplines is shedding light on what sectors of the ecosystem and the human dimension will be most impacted. In a grassroots approach to extend existing research efforts, leveraging recently completed downscaled climate projections for the Bering Sea and Aleutian Islands region, we convened a team of 30 researchers-- with expertise ranging from anthropology to zooplankton to marine mammals-- to assess climate projections in the context of their expertise. This Aleutian-Bering Climate Vulnerability Assessment (ABCVA) began with researchers working in five teams to evaluate the vulnerabilities of key species and ecosystem services relative to projected changes in climate. Each team identified initial vulnerabilities for their focal species or services, and made recommendations for further research and information needs that would help managers and communities better understand the implications of the changing climate in this region. Those draft recommendations were shared during two focused, public sessions held within two hub communities for the Bering and Aleutian region: Unalaska and St. Paul. Qualitative insights about local concerns and observations relative to climate change were collected during these sessions, to be compared to the recommendations being made by the ABCVA team of researchers. Finally, we used a Structured Decision Making process to prioritize the recommendations of participating scientists, and integrate the insights shared during our community sessions. This work brought together residents, stakeholders, scientists, and natural resource managers to collaboratively identify priorities for addressing current and expected future impacts of climate change. Recommendations from this project will be incorporated into future research efforts of the Aleutian and Bering Sea Islands Landscape Conservation

  10. Preliminary volcano-hazard assessment for Akutan Volcano east-central Aleutian Islands, Alaska

    USGS Publications Warehouse

    Waythomas, Christopher F.; Power, John A.; Richter, Donlad H.; McGimsey, Robert G.

    1998-01-01

    Akutan Volcano is a 1100-meter-high stratovolcano on Akutan Island in the east-central Aleutian Islands of southwestern Alaska. The volcano is located about 1238 kilometers southwest of Anchorage and about 56 kilometers east of Dutch Harbor/Unalaska. Eruptive activity has occurred at least 27 times since historical observations were recorded beginning in the late 1700?s. Recent eruptions produced only small amounts of fine volcanic ash that fell primarily on the upper flanks of the volcano. Small amounts of ash fell on the Akutan Harbor area during eruptions in 1911, 1948, 1987, and 1989. Plumes of volcanic ash are the primary hazard associated with eruptions of Akutan Volcano and are a major hazard to all aircraft using the airfield at Dutch Harbor or approaching Akutan Island. Eruptions similar to historical Akutan eruptions should be anticipated in the future. Although unlikely, eruptions larger than those of historical time could generate significant amounts of volcanic ash, fallout, pyroclastic flows, and lahars that would be hazardous to life and property on all sectors of the volcano and other parts of the island, but especially in the major valleys that head on the volcano flanks. During a large eruption an ash cloud could be produced that may be hazardous to aircraft using the airfield at Cold Bay and the airspace downwind from the volcano. In the event of a large eruption, volcanic ash fallout could be relatively thick over parts of Akutan Island and volcanic bombs could strike areas more than 10 kilometers from the volcano.

  11. Gabbroic and Peridotitic Enclaves from the 2008 Kasatochi Eruption, Aleutian Islands, Alaska

    NASA Astrophysics Data System (ADS)

    Kentner, A.; Nadin, E. S.; Izbekov, P. E.; Nye, C. J.; Neill, O. K.

    2012-12-01

    Kasatochi volcano of the Andreanof Islands in the western Aleutian Arc violently erupted over a two day period from August 7-8, 2008. The eruption involved multiple explosive events generating pyroclastic flows, which included abundant mafic and ultramafic enclaves that have since weathered out and accumulated in talus along the coast. These and other mafic enclaves sampled by modern island arc lavas provide insight into subduction magmatism because they emerge from a section of the subduction system that is less likely than shallower zones to be modified by magmatic processes such as mixing, assimilation, or fractionation. We present new whole rock, clinopyroxene, amphibole, plagioclase, and melt compositions from Kasatochi enclaves of the 2008 eruption. The highly crystalline (~40 vol. % phenocryst content), medium-K basaltic andesite host rock contains ~52-55 wt. % SiO2 and 0.6-0.9 wt. % K2O, and is composed of plagioclase, ortho- and clinopyroxene, amphibole, and Ti-magnetite in a microlite-rich groundmass. Upon eruption, this magma sampled two distinct enclave populations: gabbro and peridotite. The gabbro has abundant amphibole (mostly magnesio-hastingsite) and plagioclase with minor clinopyroxene, olivine, and magnetite, while the peridotite is composed of olivine with minor amounts of clinopyroxene and orthopyroxene. There is little textural variation amongst the peridotitic samples collected, but the gabbroic samples vary from layered to massive and cover a range in grain size from fine-grained to pegmatitic. The layered gabbros display centimeter-scale bands of alternating plagioclase- and amphibole-rich layers, with a strong preferential alignment of the amphibole grains. The coarser-grained samples are very friable, with ~10% pore space; disaggregation of these upon host-magma ascent likely formed the amphibole and plagioclase xenocrysts in the andesitic host. Based on the textural and compositional differences, we divide the enclaves into four groups

  12. The 2008 phreatomagmatic eruption of Okmok volcano, Aleutian Islands, Alaska: Chronology, deposits, and landform changes

    USGS Publications Warehouse

    Jessica Larsen,; Neal, Christina; Schaefer, Janet R.; Kaufman, Max; Lu, Zhong

    2015-01-01

    Okmok volcano, Aleutian Islands, Alaska, explosively erupted over a five-week period between July 12 and August 23, 2008. The eruption was predominantly phreatomagmatic, producing fine-grained tephra that covered most of northeastern Umnak Island. The eruption had a maximum Volcanic Explosivity Index (VEI) of 4, with eruption column heights up to 16 km during the opening phase. Several craters and a master tuff cone formed in the caldera as a result of phreatomagmatic explosions and accumulated tephra-fall and surge deposits. Ascending magma continuously interacted with an extensive shallow groundwater table in the caldera, resulting in the phreatomagmatic character of the eruption. Syneruptive explosion and collapse processes enlarged a pre-existing lake, created a second, entirely new lake, and formed new, deep craters. A field of ephemeral collapse pits and collapse escarpments formed where rapid groundwater withdrawal removed material from beneath capping lava flows. This was the first significant phreatomagmatic event in the U.S. since the Ukinrek Maars eruption in 1977.

  13. Role of Subducted Basalt in the Genesis Island Arc Magmas: Evidence from Western Aleutian Seafloor Lavas

    NASA Astrophysics Data System (ADS)

    Yogodzinski, G. M.; Brown, S. T.; Kelemen, P. B.; Vervoort, J. D.; Hoernle, K.; Portnyagin, M.

    2013-12-01

    Western Aleutian seafloor lavas define a highly calc-alkaline series, with Mg numbers (Mg#, Mg/Mg+Fe) greater than 0.65 in dacitic lavas with 2-4% MgO at 63-70% SiO2. These lavas have uniformly radiogenic Hf and Nd and variable, but relatively unradiogenic, Sr and Pb, at the MORB-like end of the spectrum of island-arc lavas. Andesites and dacites have high Sr >1000 ppm, fractionated trace element patterns (Sr/Y=50-350, La/Yb=8-35, Dy/Yb=2-3.5), and low relative abundances of Nb and Ta (La/Ta=100-300), consistent with an enhanced role for residual or cumulate garnet + rutile. MORB-like isotope compositions and high MgO and Mg# relative to silica, rule out an origin for the andesites and dacites by fractional crystallization from basalt, except perhaps, by a process of melt-rock reaction with peridotite. The most fractionated trace element patterns are in western seafloor rhyodacites (69-70% SiO2), which were dredged from volcanic cones built on Bering Sea oceanic lithosphere, where the crust is probably no more than 10 km thick, and so unlikely to produce garnet during crustal melting. We interpret the western seafloor andesites and dacites to have been produced by melting of subducted MORB-like basalt in the eclogite facies, followed by interaction of the resulting high-silica melt with mantle peridotite. This interpretation is consistent with the tectonic setting in the western Aleutians, which is dominated by oblique convergence, capable of producing a relatively hot subducting plate. Western seafloor lavas define an end-member composition with MORB-like isotope compositions and fractionated trace element ratios, which falls at the end of the continuum of compositions for all Aleutian lavas. The end-member character of western seafloor lavas is clearest in plots highlighting their radiogenic Hf, Nd and strong relative depletions in Ta and Yb. The western seafloor lavas also define an end-member composition for Pb isotopes and Ce/Pb (Miller et al., Nature, 1994

  14. Science, policy, and stakeholders: developing a consensus science plan for Amchitka Island, Aleutians, Alaska.

    PubMed

    Burger, Joanna; Gochfeld, Michael; Kosson, David S; Powers, Charles W; Friedlander, Barry; Eichelberger, John; Barnes, David; Duffy, Lawrence K; Jewett, Stephen C; Volz, Conrad D

    2005-05-01

    With the ending of the Cold War, the US Department of Energy is responsible for the remediation of radioactive waste and disposal of land no longer needed for nuclear material production or related national security missions. The task of characterizing the hazards and risks from radionuclides is necessary for assuring the protection of health of humans and the environment. This is a particularly daunting task for those sites that had underground testing of nuclear weapons, where the radioactive contamination is currently inaccessible. Herein we report on the development of a Science Plan to characterize the physical and biological marine environment around Amchitka Island in the Aleutian chain of Alaska, where three underground nuclear tests were conducted (1965-1971). Information on the ecology, geology, and current radionuclide levels in biota, water, and sediment is necessary for evaluating possible current contamination and to serve as a baseline for developing a plan to ensure human and ecosystem health in perpetuity. Other information required includes identifying the location of the salt water/fresh water interface where migration to the ocean might occur in the future and determining groundwater recharge balances, as well as assessing other physical/geological features of Amchitka near the test sites. The Science Plan is needed to address the confusing and conflicting information available to the public about radionuclide risks from underground nuclear blasts in the late 1960s and early 1970s, as well as the potential for volcanic or seismic activity to disrupt shot cavities or accelerate migration of radionuclides into the sea. Developing a Science Plan involved agreement among regulators and other stakeholders, assignment of the task to the Consortium for Risk Evaluation with Stakeholder Participation, and development of a consensus Science Plan that dealt with contentious scientific issues. Involvement of the regulators (State of Alaska), resource

  15. Organochlorine contaminants in fishes from coastal waters west of Amukta Pass, Aleutian Islands, Alaska, USA.

    PubMed

    Miles, A Keith; Ricca, Mark A; Anthony, Robert G; Estes, James A

    2009-08-01

    Organochlorines were examined in liver and stable isotopes in muscle of fishes from the western Aleutian Islands, Alaska, in relation to islands or locations affected by military occupation. Pacific cod (Gadus macrocephalus), Pacific halibut (Hippoglossus stenolepis), and rock greenling (Hexagrammos lagocephalus) were collected from nearshore waters at contemporary (decommissioned) and historical (World War II) military locations, as well as at reference locations. Total (Sigma) polychlorinated biphenyls (PCBs) dominated the suite of organochlorine groups (SigmaDDTs, Sigmachlordane cyclodienes, Sigmaother cyclodienes, and Sigmachlorinated benzenes and cyclohexanes) detected in fishes at all locations, followed by SigmaDDTs and Sigmachlordanes; dichlorodiphenyldichloroethylene (p,p'DDE) composed 52 to 66% of SigmaDDTs by species. Organochlorine concentrations were higher or similar in cod compared to halibut and lowest in greenling; they were among the highest for fishes in Arctic or near Arctic waters. Organochlorine group concentrations varied among species and locations, but SigmaPCB concentrations in all species were consistently higher at military locations than at reference locations. Moreover, all organochlorine group concentrations were higher in halibut from military locations than those from reference locations. A wide range of molecular weight organochlorines was detected at all locations, which implied regional or long-range transport and deposition, as well as local point-source contamination. Furthermore, a preponderance of higher-chlorinated PCB congeners in fishes from contemporary military islands implied recent exposure. Concentrations in all organochlorine groups increased with delta15N enrichment in fishes, and analyses of residual variation provided further evidence of different sources of SigmaPCBs and p,p'DDE among species and locations.

  16. Mercury concentrations in breast feathers of three upper trophic level marine predators from the western Aleutian Islands, Alaska

    USGS Publications Warehouse

    Kaler, Robb S.A.; Kenney, Leah A.; Bond, Alexander L.; Eagles-Smith, Collin A.

    2014-01-01

    Mercury (Hg) is a toxic element distributed globally through atmospheric transport. Agattu Island, located in the western Aleutian Islands, Alaska, has no history of point-sources of Hg contamination. We provide baseline levels of total mercury (THg) concentrations in breast feathers of three birds that breed on the island. Geometric mean THg concentrations in feathers of fork-tailed storm-petrels (Oceanodroma furcata; 6703 ± 1635, ng/g fresh weight [fw]) were higher than all other species, including snowy owl (Bubo scandiacus; 2105 ± 1631, ng/g fw), a raptor with a diet composed largely of storm-petrels at Agattu Island. There were no significant differences in mean THg concentrations of breast feathers among adult Kittlitz’s murrelet (Brachyramphus brevirostris; 1658 ± 1276, ng/g fw) and chicks (1475 ± 671, ng/g fw) and snowy owls. The observed THg concentrations in fork-tailed storm-petrel feathers emphasizes the need for further study of Hg pollution in the western Aleutian Islands.

  17. New species of sponges (Porifera, Demospongiae) from the Aleutian Islands and Gulf of Alaska.

    PubMed

    Lehnert, Helmut; Stone, Robert P

    2015-10-27

    Ten new species of demosponges, assigned to the orders Poecilosclerida, Axinellida and Dictyoceratida, discovered in the Gulf of Alaska and along the Aleutian Island Archipelago are described and compared to relevant congeners. Poecilosclerida include Cornulum globosum n. sp., Megaciella lobata n. sp., M. triangulata n. sp., Artemisina clavata n. sp., A. flabellata n. sp., Coelosphaera (Histodermion) kigushimkada n. sp., Stelodoryx mucosa n. sp. and S. siphofuscus n. sp. Axinellida is represented by Raspailia (Hymeraphiopsis) fruticosa n. sp. and Dictyoceratida is represented by Dysidea kenkriegeri n. sp. The genus Cornulum is modified to allow for smooth tylotes. We report several noteworthy biogeographical observations. We describe only the third species within the subgenus Histodermion and the first from the Indo-Pacific Region. Additionally, the subgenus Hymerhaphiopsis was previously represented by only a single species from Antarctica. We also report the first record of a dictyoceratid species from Alaska. The new collections further highlight the richness of the sponge fauna from the region, particularly for the Poecilosclerida.

  18. Earthquakes; January-February 1977

    USGS Publications Warehouse

    Person, W.J.

    1977-01-01

    There were no major earthquakes (7.0-7.9) during the first 2 months of the year, and no fatalities were reported. Three strong earthquakes occurred- New Guinea, Tadzhik S.S.R, and the Aleutian Islands. The Tadzhik earthquake on January 31 caused considerable damage and possible injuries. The United States experienced a number of earthquakes, but only very minor damage was reported. 

  19. Specification of Tectonic Tsunami Sources Along the Eastern Aleutian Island Arc and Alaska Peninsula for Inundation Mapping and Hazard Assessment

    NASA Astrophysics Data System (ADS)

    Suleimani, E.; Nicolsky, D.; Freymueller, J. T.; Koehler, R.

    2013-12-01

    The Alaska Earthquake Information Center conducts tsunami inundation mapping for coastal communities in Alaska along several segments of the Aleutian Megathrust, each having a unique seismic history and tsunami generation potential. Accurate identification and characterization of potential tsunami sources is a critical component of our project. As demonstrated by the 2011 Tohoku-oki tsunami, correct estimation of the maximum size event for a given segment of the subduction zone is particularly important. In that event, unexpectedly large slip occurred approximately updip of the epicenter of the main shock, based on seafloor GPS and seafloor pressure gage observations, generating a much larger tsunami than anticipated. This emphasizes the importance of the detailed knowledge of the region-specific subduction processes, and using the most up-to-date geophysical data and research models that define the magnitude range of possible future tsunami events. Our study area extends from the eastern half of the 1957 rupture zone to Kodiak Island, covering the 1946 and 1938 rupture areas, the Shumagin gap, and the western part of the 1964 rupture area. We propose a strategy for generating worst-case credible tsunami scenarios for locations that have a short or nonexistent paleoseismic/paleotsunami record, and in some cases lack modern seismic and GPS data. The potential tsunami scenarios are built based on a discretized plate interface model fit to the Slab 1.0 model geometry. We employ estimates of slip deficit along the Aleutian Megathrust from GPS campaign surveys, the Slab 1.0 interface surface, empirical magnitude-slip relationships, and a numerical code that distributes slip among the subfault elements, calculates coseismic deformations and solves the shallow water equations of tsunami propagation and runup. We define hypothetical asperities along the megathrust and in down-dip direction, and perform a set of sensitivity model runs to identify coseismic deformation

  20. Surface wind characteristics of some Aleutian Islands. [for selection of windpowered machine sites

    NASA Technical Reports Server (NTRS)

    Wentink, T., Jr.

    1973-01-01

    The wind power potential of Alaska is assessed in order to determine promising windpower sites for construction of wind machines and for shipment of wind derived energy. Analyses of near surface wind data from promising Aleutian sites accessible by ocean transport indicate probable velocity regimes and also present deficiencies in available data. It is shown that winds for some degree of power generation are available 77 percent of the time in the Aleutians with peak velocities depending on location.

  1. Unexpectedly high diversity of Monoporella (Bryozoa: Cheilostomata) in the Aleutian Islands, Alaska: taxonomy and distribution of six new species.

    PubMed

    Dick, Matthew H

    2008-01-01

    The cheilostome bryozoan genus Monoporella is poorly resolved taxonomically; only four Recent species have been formally described, though several undescribed species have been reported in the literature. The literature indicates no more than five species in the genus occurring in any local region of the world, with one to three species in most regions where the genus has been reported. I examined bryozoans from 52 trawl catches in the western and western-central Aleutian Islands, Alaska, and found specimens of Monoporella in 12 of these samples. Study of these specimens by scanning electron microscopy (SEM) revealed six new species that are described herein: M. flexibila, M. elongata, M. gigantea, M. ellefsoni, M. seastormi, and M. aleutica. Two of the species have erect colony morphologies, a condition not previously reported in Monoporella. The species diversity of Monoporella appears to be greater in the Aleutians than in any other part of the world adequately surveyed. I discuss whether this apparent high diversity is an artifact due to insufficient sampling in the deep shelf zone, and present two hypotheses to explain this high diversity should it prove not to be an artifact: 1) the present high local diversity represents a relict of past high diversity occurring broadly around the North Pacific rim; and 2) a local radiation of Monoporella occurred in the Aleutian archipelago.

  2. Seismicity of the Earth 1900-2010 Aleutian arc and vicinity

    USGS Publications Warehouse

    Benz, Harley M.; Herman, Matthew; Tarr, Arthur C.; Hayes, Gavin P.; Furlong, Kevin P.; Villaseñor, Antonio; Dart, Richard L.; Rhea, Susan

    2011-01-01

    This map shows details of the Aleutian arc not visible in an earlier publication. The Aleutian arc extends about 3,000 km from the Gulf of Alaska to the Kamchatka Peninsula. It marks the region where the Pacific plate subducts into the mantle beneath the North America plate. This subduction is responsible for the generation of the Aleutian Islands and the deep offshore Aleutian Trench. Relative to a fixed North America plate, the Pacific plate is moving northwest at a rate that increases from about 55 mm per year at the arc's eastern edge to 75 mm per year near its western terminus. In the east, the convergence of the plates is nearly perpendicular to the plate boundary. However, because of the boundary's curvature, as one travels westward along the arc, the subduction becomes more and more oblique to the boundary until the relative plate motion becomes parallel to the arc at the Near Islands near its western edge. Subduction zones such as the Aleutian arc are geologically complex and produce numerous earthquakes from multiple sources. Deformation of the overriding North America plate generates shallow crustal earthquakes, whereas slip at the interface of the plates generates interplate earthquakes that extend from near the base of the trench to depths of 40 to 60 km. At greater depths, Aleutian arc earthquakes occur within the subducting Pacific plate and can reach depths of 300 km. Since 1900, six great earthquakes have occurred along the Aleutian Trench, Alaska Peninsula, and Gulf of Alaska: M8.4 1906 Rat Islands; M8.6 1938 Shumagin Islands; M8.6 1946 Unimak Island; M8.6 1957 Andreanof Islands; M9.2 1964 Prince William Sound; and M8.7 1965 Rat Islands. Several relevant tectonic elements (plate boundaries and active volcanoes) provide a context for the seismicity presented on the main map panel. The plate boundaries are most accurate along the axis of the Aleutian Trench and more diffuse or speculative in extreme northeastern Russia. The active volcanoes parallel

  3. New glass sponges (Porifera: Hexactinellida) from deep waters of the central Aleutian Islands, Alaska.

    PubMed

    Reiswig, Henry M; Stone, Robert P

    2013-01-01

    Hexactinellida from deep-water communities of the central Aleutian Islands, Alaska, are described. They were mostly collected by the remotely operated vehicle 'Jason II' from 494–2311 m depths during a 2004 RV 'Roger Revelle' expedition, but one shallow-water species collected with a shrimp trawl from 155 m in the same area is included. The excellent condition of the ROV-collected specimens enabled valuable redescription of some species previously known only from badly damaged specimens. New taxa include one new genus and eight new species in five families. Farreidae consist of two new species, Farrea aleutiana and F. aspondyla. Euretidae consists of only Pinulasma fistulosum n. gen., n. sp. Tretodictyidae include only Tretodictyum amchitkensis n. sp. Euplectellidae consists of only the widespread species Regadrella okinoseana Ijima, reported here over 3,700 km from its closest previously known occurrence. The most diverse family, Rossellidae, consists of Aulosaccus ijimai (Schulze), Aulosaccus schulzei Ijima, Bathydorus sp. (young stage not determinable to species), Caulophacus (Caulophacus) adakensis n. sp., Acanthascus koltuni n. sp., Staurocalyptus psilosus n. sp., Staurocalyptus tylotus n. sp. and Rhabdocalyptus mirabilis Schulze. We present argument for reinstatement of the abolished rossellid subfamily Acanthascinae and return of the subgenera  Staurocalyptus Ijima and Rhabdocalyptus Schulze to their previous generic status. These fauna provides important complexity to the hard substrate communities that likely serve as nursery areas for the young stages of commercially important fish and crab species, refuge from predation for both young and adult stages, and also as a focal source of prey for juvenile and adult stages of those same species.

  4. Stratigraphic framework of Holocene volcaniclastic deposits, Akutan Volcano, east-central Aleutian Islands, Alaska

    USGS Publications Warehouse

    Waythomas, C.F.

    1999-01-01

    Akutan Volcano is one of the most active volcanoes in the Aleutian arc, but until recently little was known about its history and eruptive character. Following a brief but sustained period of intense seismic activity in March 1996, the Alaska Volcano Observatory began investigating the geology of the volcano and evaluating potential volcanic hazards that could affect residents of Akutan Island. During these studies new information was obtained about the Holocene eruptive history of the volcano on the basis of stratigraphic studies of volcaniclastic deposits and radiocarbon dating of associated buried soils and peat. A black, scoria-bearing, lapilli tephra, informally named the 'Akutan tephra,' is up to 2 m thick and is found over most of the island, primarily east of the volcano summit. Six radiocarbon ages on the humic fraction of soil A-horizons beneath the tephra indicate that the Akutan tephra was erupted approximately 1611 years B.P. At several locations the Akutan tephra is within a conformable stratigraphic sequence of pyroclastic-flow and lahar deposits that are all part of the same eruptive sequence. The thickness, widespread distribution, and conformable stratigraphic association with overlying pyroclastic-flow and lahar deposits indicate that the Akutan tephra likely records a major eruption of Akutan Volcano that may have formed the present summit caldera. Noncohesive lahar and pyroclastic-flow deposits that predate the Akutan tephra occur in the major valleys that head on the volcano and are evidence for six to eight earlier Holocene eruptions. These eruptions were strombolian to subplinian events that generated limited amounts of tephra and small pyroclastic flows that extended only a few kilometers from the vent. The pyroclastic flows melted snow and ice on the volcano flanks and formed lahars that traveled several kilometers down broad, formerly glaciated valleys, reaching the coast as thin, watery, hyperconcentrated flows or water floods. Slightly

  5. Phase relations of a high-Mg basalt from the Aleutian Island arc - Implications for primary island arc basalts and high-Al basalts

    NASA Technical Reports Server (NTRS)

    Gust, D. A.; Perfit, M. R.

    1987-01-01

    An experimental investigation of a primitive high-Mg basalt, MK-15, collected from lava flows of the Unalaska Island in the Aleutian Island arc has been conducted in order to study primary and parental island arc basalts and the development of island arc magmas. The results suggest a model in which high-Al basalts are generated by moderate amounts of crystal fractionation from more primitive (high Mg/Mg + Fe, lower Al2O3) basaltic magmas near the arc crust-mantle boundary. Somewhere between 20-30 depth, significant amounts of clinopyroxene and olivine, with lesser amounts of spinel and possibly amphibole, fractionate, forming layer of olivine-clinopyroxenite at the base of the arc crust.

  6. Magnitude 8.1 Earthquake off the Solomon Islands

    NASA Technical Reports Server (NTRS)

    2007-01-01

    On April 1, 2007, a magnitude 8.1 earthquake rattled the Solomon Islands, 2,145 kilometers (1,330 miles) northeast of Brisbane, Australia. Centered less than ten kilometers beneath the Earth's surface, the earthquake displaced enough water in the ocean above to trigger a small tsunami. Though officials were still assessing damage to remote island communities on April 3, Reuters reported that the earthquake and the tsunami killed an estimated 22 people and left as many as 5,409 homeless. The most serious damage occurred on the island of Gizo, northwest of the earthquake epicenter, where the tsunami damaged the hospital, schools, and hundreds of houses, said Reuters. This image, captured by the Landsat-7 satellite, shows the location of the earthquake epicenter in relation to the nearest islands in the Solomon Island group. Gizo is beyond the left edge of the image, but its triangular fringing coral reefs are shown in the upper left corner. Though dense rain forest hides volcanic features from view, the very shape of the islands testifies to the geologic activity of the region. The circular Kolombangara Island is the tip of a dormant volcano, and other circular volcanic peaks are visible in the image. The image also shows that the Solomon Islands run on a northwest-southeast axis parallel to the edge of the Pacific plate, the section of the Earth's crust that carries the Pacific Ocean and its islands. The earthquake occurred along the plate boundary, where the Australia/Woodlark/Solomon Sea plates slide beneath the denser Pacific plate. Friction between the sinking (subducting) plates and the overriding Pacific plate led to the large earthquake on April 1, said the United States Geological Survey (USGS) summary of the earthquake. Large earthquakes are common in the region, though the section of the plate that produced the April 1 earthquake had not caused any quakes of magnitude 7 or larger since the early 20th century, said the USGS.

  7. Volcanoes of the Alaska Peninsula and Aleutian Islands, Alaska: selected photographs

    USGS Publications Warehouse

    Neal, Christina A.; McGimsey, Robert G.

    2002-01-01

    This CD-ROM contains 97 digital images of volcanoes along the Aleutian volcanic arc in Alaska. Perspectives include distant aerial shots, ground views of volcanic products and processes, and dramatic views of eruptions in progress. Each image is stored as a .PCD file in five resolutions. Brief captions, a location map, and glossary are included.

  8. Low frequency earthquakes below southern Vancouver Island

    NASA Astrophysics Data System (ADS)

    Bostock, M. G.; Royer, A. A.; Hearn, E. H.; Peacock, S. M.

    2012-11-01

    The nature and distribution of low frequency earthquakes (LFEs) in subduction zones provide insight into plate boundary deformation downdip of the locked seismogenic zone. We employ network autocorrelation detection to identify LFE families beneath southern Vancouver Island and environs. An initial suite of 5775 LFEs detected in 2004 and 2005 at a select set of 7 stations is grouped into 140 families using waveform cluster analysis. These families are used as templates within an iterative network cross correlation scheme to detect LFEs across different tremor episodes, incorporate new stations, and improve LFE template signal-to-noise ratio. As in southwest Japan, representative LFE locations define a relatively tight, dipping surface several km above the locus of intraslab seismicity, within a prominent, dipping low-velocity zone (LVZ). LFE polarizations for near-vertical source-receiver geometries possess a remarkably uniform dipolar signature indicative of point-source, double-couple excitation. Focal mechanisms determined fromP-wave first motions are characterized by a combination of strike-slip and thrust faulting. We suggest that LFEs and regular intraslab seismicity occur in distinct structural and stress regimes. The LVZ, inferred to represent weak, overpressured, porous and mylonitized metabasalts of oceanic crustal Layer 2, separates LFEs manifesting deformation within a plate boundary shear zone from intraslab earthquakes generated by tensional stresses and dehydration embrittlement within a more competent lower oceanic crustal Layer 3 and underlying mantle.

  9. Imaging the transition from Aleutian subduction to Yakutat collision in central Alaska, with local earthquakes and active source data

    USGS Publications Warehouse

    Eberhart-Phillips, D.; Christensen, D.H.; Brocher, T.M.; Hansen, R.; Ruppert, N.A.; Haeussler, P.J.; Abers, G.A.

    2006-01-01

    In southern and central Alaska the subduction and active volcanism of the Aleutian subduction zone give way to a broad plate boundary zone with mountain building and strike-slip faulting, where the Yakutat terrane joins the subducting Pacific plate. The interplay of these tectonic elements can be best understood by considering the entire region in three dimensions. We image three-dimensional seismic velocity using abundant local earthquakes, supplemented by active source data. Crustal low-velocity correlates with basins. The Denali fault zone is a dominant feature with a change in crustal thickness across the fault. A relatively high-velocity subducted slab and a low-velocity mantle wedge are observed, and high Vp/Vs beneath the active volcanic systems, which indicates focusing of partial melt. North of Cook Inlet, the subducted Yakutat slab is characterized by a thick low-velocity, high-Vp/Vs, crust. High-velocity material above the Yakutat slab may represent a residual older slab, which inhibits vertical flow of Yakutat subduction fluids. Alternate lateral flow allows Yakutat subduction fluids to contribute to Cook Inlet volcanism and the Wrangell volcanic field. The apparent northeast edge of the subducted Yakutat slab is southwest of the Wrangell volcanics, which have adakitic composition consistent with melting of this Yakutat slab edge. In the mantle, the Yakutat slab is subducting with the Pacific plate, while at shallower depths the Yakutat slab overthrusts the shallow Pacific plate along the Transition fault. This region of crustal doubling within the shallow slab is associated with extremely strong plate coupling and the primary asperity of the Mw 9.2 great 1964 earthquake. Copyright 2006 by the American Geophysical Union.

  10. Aleutian terranes from Nd isotopes

    NASA Technical Reports Server (NTRS)

    Kay, R. W.; Kay, S. M.; Rubenstone, J. L.

    1986-01-01

    Nd isotope ratios substantiate the identification of oceanic crustal terranes within the continental crustal basement of the Aleutian island arc. The oceanic terranes are exposed in the westernmost Aleutians, but to the east, they are completely buried by isotopically distinct arc-volcanic rocks. Analogous oceanic terranes may be important components of the terrane collages that comprise the continents.

  11. Where was the 1898 Mare Island Earthquake? Insights from the 2014 South Napa Earthquake

    NASA Astrophysics Data System (ADS)

    Hough, S. E.

    2014-12-01

    The 2014 South Napa earthquake provides an opportunity to reconsider the Mare Island earthquake of 31 March 1898, which caused severe damage to buildings at a Navy yard on the island. Revising archival accounts of the 1898 earthquake, I estimate a lower intensity magnitude, 5.8, than the value in the current Uniform California Earthquake Rupture Forecast (UCERF) catalog (6.4). However, I note that intensity magnitude can differ from Mw by upwards of half a unit depending on stress drop, which for a historical earthquake is unknowable. In the aftermath of the 2014 earthquake, there has been speculation that apparently severe effects on Mare Island in 1898 were due to the vulnerability of local structures. No surface rupture has ever been identified from the 1898 event, which is commonly associated with the Hayward-Rodgers Creek fault system, some 10 km west of Mare Island (e.g., Parsons et al., 2003). Reconsideration of detailed archival accounts of the 1898 earthquake, together with a comparison of the intensity distributions for the two earthquakes, points to genuinely severe, likely near-field ground motions on Mare Island. The 2014 earthquake did cause significant damage to older brick buildings on Mare Island, but the level of damage does not match the severity of documented damage in 1898. The high intensity files for the two earthquakes are more over spatially shifted, with the centroid of the 2014 distribution near the town of Napa and that of the 1898 distribution near Mare Island, east of the Hayward-Rodgers Creek system. I conclude that the 1898 Mare Island earthquake was centered on or near Mare Island, possibly involving rupture of one or both strands of the Franklin fault, a low-slip-rate fault sub-parallel to the Rodgers Creek fault to the west and the West Napa fault to the east. I estimate Mw5.8 assuming an average stress drop; data are also consistent with Mw6.4 if stress drop was a factor of ≈3 lower than average for California earthquakes. I

  12. The Aleutian Islands Campaign: The Strengths and Weaknesses of Its Planning Process and Execution

    DTIC Science & Technology

    2014-05-22

    examination reveals how the development of modern doctrine encapsulates these strengths and prevents a repeat of these weaknesses. Regardless of the...comprised of 120 volcanic islands extending west from the southwestern tip of Alaska. The islands stretch for nearly a thousand miles from the Alaska...that overflew the island. Further limiting Japanese success, weather on Umnak quickly grew overcast, thus preventing Japanese discovery of the airfield

  13. 76 FR 11139 - Fisheries of the Exclusive Economic Zone Off Alaska; Bering Sea and Aleutian Islands; Final 2011...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-03-01

    ... development of ABCs and overfishing levels (OFLs) involves sophisticated statistical analyses of fish... require the cooperation of several agencies, including NMFS, the Alaska Department of Fish and Game, and...), Central Aleutian District (CAI), and Western Aleutian District (WAI). \\2\\ The proposed rule split...

  14. Evolution and geochemistry of the Tertiary calc-alkaline plutons in the Adak Island region of the central Aleutian oceanic island arc

    NASA Astrophysics Data System (ADS)

    Kay, Suzanne; Citron, Gary P.; Kay, Robert W.; Jicha, Brian; Tibbetts, Ashley

    2014-05-01

    Calc-alkaline plutons are major crustal building blocks of continental margin mountain belts like the Mesozoic to Tertiary Andes and the Sierra Nevada, but are rare in oceanic island arcs. Some of the most calc-alkaline I-type island arc plutons are in the Central Aleutians with the most extreme signatures, as indicated by FeO/MgO ratios of < ~2 at 48-70% wt. % SiO2, in the ~10 km wide Oligocene Hidden Bay pluton on southern Adak Island and the 10 km wide Miocene Kagalaska pluton to the north on eastern Adak and the adjacent Kagalaska Island. Although small compared to most continental plutons, similarities in intrusive units, mineralogy and chemistry suggest common formation processes. The Aleutian calc-alkaline plutonic rocks mainly differ from continental plutons in having more oceanic like isotopic (87Sr/86Sr = 0.703-0.7033; Epsilon Nd = 9-7.8) and LIL (e.g., higher K/Rb) ratios. The Adak region plutons differ from Tertiary plutons on Unalaska Island further east in being more K-rich and in having a more oxidized and lower-temperature mineralogy. From a regional perspective, the Adak area plutons intrude Eocene/Oligocene Finger Bay Formation mafic volcanic and sedimentary rocks and postdate the small ~38 Ma tholeiitic Finger Bay pluton. The chemistry of these older magmatic rocks is basically similar to that of young Central Aleutian magmatic rocks with boninites and arc tholeiitic magmas seemingly being absent. The formation of the calc-alkaline plutons seems to require a sufficient crustal thickness, fluid concentration and contractional stress such that magma chambers can stabilize significant amounts of pargasitic hornblende. Seismic receiver function analyses (Janiszewski et al., 2013) indicate the modern Adak crust is ~ 37 km thick. Existing and new hornblende, plagioclase and biotite Ar/Ar ages from 16 Hidden Bay pluton and Gannet Lake stock gabbro, porphyritic diorite, diorite, granodiorite, leucogranodiorite and aplite samples range from 34.6 to 30

  15. HLA genes of Aleutian Islanders living between Alaska (USA) and Kamchatka (Russia) suggest a possible southern Siberia origin.

    PubMed

    Moscoso, Juan; Crawford, Michael H; Vicario, Jose L; Zlojutro, Mark; Serrano-Vela, Juan I; Reguera, Raquel; Arnaiz-Villena, Antonio

    2008-02-01

    Aleuts HLA profile has been compared with that of neighboring and worldwide populations. Thirteen thousand one hundred and sixty-four chromosomes have been used for this study. Computer programs have obtained HLA allele frequencies, genetic distances between populations, NJ relatedness dendrograms, correspondence analysis and most frequent HLA extended haplotypes. Aleuts have inhabited Aleutian Islands since about 9000 years BP according to fossil and genetic (mtDNA) records. They are genetically different to Eskimo, Amerindian and Na-Dene speakers according to their HLA profile; this correlates with cultural and anthropological Aleut distinctiveness. No typical Amerindian HLA alleles have been found in a significant frequency. Their HLA relatedness to Saami (or Lapps, northern Scandinavians), Finns and Pomors (North-West Russia) indicates an ancient possible origin from the Baikal Lake Area (southern Siberia) around the present day Buryat peopling area; other origins are not discarded. Aleuts characteristic HLA profile may influence future transplantation programs in the region and be useful to study diseases linked to HLA epidemiology.

  16. The Detection, Characterization and Tracking of Recent Aleutian Island Volcanic Ash Plumes and the Assessment of Their Impact on Aviation

    NASA Technical Reports Server (NTRS)

    Murray, John J.; Hudnall, L. A.; Matus, A.; Krueger, A. J.; Trepte, C. r.

    2010-01-01

    The Aleutian Islands of Alaska are home to a number of major volcanoes which periodically present a significant hazard to aviation. During summer of 2008, the Okmok and Kasatochi volcanoes experienced moderate eruptive events. These were followed a dramatic, major eruption of Mount Redoubt in late March 2009. The Redoubt case is extensively covered in this paper. Volcanic ash and SO2 from each of these eruptions dispersed throughout the atmosphere. This created the potential for major problems for air traffic near the ash dispersions and at significant distances downwind. The NASA Applied Sciences Weather Program implements a wide variety of research projects to develop volcanic ash detection, characterization and tracking applications for NASA Earth Observing System and NOAA GOES and POES satellites. Chemistry applications using NASA AURA satellite Ozone Monitoring System (OMI) retrievals produced SO2 measurements to trace the dispersion of volcanic aerosol. This work was complimented by advanced multi-channel imager applications for the discrimination and height assignment of volcanic ash using NASA MODIS and NOAA GOES and POES imager data. Instruments similar to MODIS and OMI are scheduled for operational deployment on NPOESS. In addition, the NASA Calipso satellite provided highly accurate measurements of aerosol height and dispersion for the calibration and validation of these algorithms and for corroborative research studies. All of this work shortens the lead time for transition to operations and ensures that research satellite data and applications are operationally relevant and utilized quickly after the deployment of operational satellite systems. Introduction

  17. Final Report: Weatherization and Energy Conservation Education and Home Energy and Safety Review in the Aleutian Islands

    SciTech Connect

    Bruce Wright

    2011-08-30

    Aleutian/Pribilof Islands Association, Inc. (APIA) hired three part-time local community members that desire to be Energy Technicians. The energy technicians were trained in methods of weatherization assistance, energy conservation and home safety. They developed a listing of homes in the region that required weatherization, and conducted on-site weatherization and energy conservation education and a home energy and safety reviews in the communities of Akutan, False Pass, King Cove and Nelson Lagoon. Priority was given to these smaller communities as they tend to have the residences most in need of weatherization and energy conservation measures. Local residents were trained to provide all three aspects of the project: weatherization, energy conservation education and a home energy and safety review. If the total energy saved by installing these products is a 25% reduction (electrical and heating, both of which are usually produced by combustion of diesel fuel), and the average Alaska home produces 32,000 pounds of CO2 each year, so we have saved about: 66 homes x 16 tons of CO2 each year x .25 = 264 tons of CO2 each year.

  18. Seismic potential of the Queen Charlotte-Alaska-Aleutian seismic zone

    SciTech Connect

    Nishenko, S.P. ); Jacob, K.H. )

    1990-03-10

    The 5,000 km long Queen Charlotte-Alaska-Aleutian seismic zone is subdivided into 17 unequally sized segments. The 17 segments are chosen to represent areas likely to be ruptured by characteristic earthquakes. This term usually implies repeated breakage of a plate boundary segment by either a large or great earthquake, whose source dimensions remain consistent from cycle to cycle. Formal computations of the conditional probabilities for future large and great earthquakes in the 17 segments of the Queen Charlotte-Alaska-Aleutian seismic zone are based on the following data sets and findings: (1) recurrence intervals from historic and geologic data; (2) direct recurrence time estimates based on rates of relative plate motion and the size or displacement of the most recent characteristic event in each segment; and (3) the application of a lognormal distribution of recurrence times for large and great earthquakes. Results of these computations indicate seven areas that have high (i.e., {ge} 60%) conditional probabilities for the recurrence of either large or great earthquakes within the next 20 years (1988-2008). These areas include Cape St. James, Yakataga, the Shumagin Islands, Unimak Island, and the Fox, Delarof, and Near Islands segments of the Aleutian arc. When a shorter time interval is considered (1988-1998), those segments more likely to rupture in large (M{sub S} 7-7.7) rather than great earthquakes have a high conditional probability. These areas include the Unimak, Fox, and Delarof Islands segments. The largest uncertainties in these forecasts stem from the short historic record (providing a single recurrence time estimate for some segments, or widely varying estimates for others); from the unknown importance of aseismic slip; and from a vague definition of characteristic earthquake size. In fact, characteristic earthquake size may not be a time-invariant quantity.

  19. Earthquakes, November-December 1977

    USGS Publications Warehouse

    Person, W.J.

    1978-01-01

    In the United States, the largest earthquake during this reporting period was a magntidue 6.6 in the Andreanof Islands, which are part of the Aleutian Islands chain, on November 4 that caused some minor damage. Northern California was struck by a magnitude 4.8 earthquake on November 22 causing moderate damage in the Willits area. This was the most damaging quake in the United States during the year. Two major earthquakes of magntidues 7.0 or above to 14 for the year. 

  20. Levels of Polychlorinated Biphenyls (PCBs) and Three Organochlorine Pesticides in Fish from the Aleutian Islands of Alaska

    PubMed Central

    Hardell, Sara; Tilander, Hanna; Welfinger-Smith, Gretchen; Burger, Joanna; Carpenter, David O.

    2010-01-01

    Background Persistent organic pollutants (POPs), including polychlorinated biphenyls (PCBs) and chlorinated pesticides, have been shown to have many adverse human health effects. These contaminants therefore may pose a risk to Alaska Natives that follow a traditional diet high in marine mammals and fish, in which POPs bioaccumulate. Methods and Findings This study examined the levels of PCBs and three pesticides [p, p′-DDE, mirex, and hexachlorobenzene (HCB)] in muscle tissue from nine fish species from several locations around the Aleutian Islands of Alaska. The highest median PCB level was found in rock sole (Lepidopsetta bilineata, 285 ppb, wet weight), while the lowest level was found in rock greenling (Hexagrammos lagocephalus, 104 ppb, wet weight). Lipid adjusted PCB values were also calculated and significant interspecies differences were found. Again, rock sole had the highest level (68,536 ppb, lipid weight). Concerning the PCB congener patterns, the more highly chlorinated congeners were most common as would be expected due to their greater persistence. Among the pesticides, p, p′-DDE generally dominated, and the highest level was found in sockeye salmon (Oncorhynchus nerka, 6.9 ppb, wet weight). The methodology developed by U.S. Environmental Protection Agency (USEPA) was used to calculate risk-based consumption limits for the analyzed fish species. For cancer health endpoints for PCBs, all species would trigger strict advisories of between two and six meals per year, depending upon species. For noncancer effects by PCBs, advisories of between seven and twenty-two meals per year were triggered. None of the pesticides triggered consumption limits. Conclusion The fish analyzed, mainly from Adak, contain significant concentrations of POPs, in particular PCBs, which raises the question whether these fish are safe to eat, particularly for sensitive populations. However when assessing any risk of the traditional diet, one must also consider the many health

  1. Timing of Volcanism on Yunaska Island, Central Aleutian arc, Alaska: an Investigation Applying Multi-temporal Synthetic Aperture Radar

    NASA Astrophysics Data System (ADS)

    Brown, M. E.; Nicolaysen, K. P.; Dehn, J.; Myers, J. D.

    2003-12-01

    The volcanoes of the central Aleutian arc remain largely uninstrumented and unstudied despite numerous eruptions within the last century. Many of these eruptions are not documented and others may not have been observed. Previous synthetic aperture radar (SAR) studies at Westdahl volcano show that radar can be used to relatively date a'a lava flows and to suggest whether some flows are "historic" though not recorded. This is accomplished through comparison of semi-quantitative measurements of surface roughness for young, unvegetated lavas. Because a'a lavas typically become smoother as they weather, they produce less radar backscatter. Thus, lavas that exhibit higher radar backscatter intensities are younger than those with lower backscatter intensities for regions of similar relief and aspect. Located 305 km west of Dutch Harbor, Yunaska has six volcanic centers, of which three have probably been active in the Quaternary. Based on field observations, recent volcanism on Yunaska is associated with the younger of two nested calderas and several smaller vents and cones on the eastern half of the island. Although there is a reported 1937 eruption, it is not clear if this came from fissures north of the caldera or created the intracaldera cinder cone and lava flows. Using a twenty-year composite of SAR data, we establish relative ages for five basaltic andesite lavas from these fissures and from within the young caldera. Clear stratigraphic relationships among three lavas within the caldera provide a check on the accuracy of this technique. The use of SAR to differentiate between young lavas allows us to better document the eruption history of remote volcanoes and to mitigate their hazards.

  2. Forecasters Handbook for the Bering Sea, Aleutian Islands, and Gulf of Alaska

    DTIC Science & Technology

    1993-03-01

    Hawaiian Islands in 1788 to the Pacific Northwest and entered what is now called "Cook’s Inlet," leading to Anchorage. 2.2.2 Topography The Gulf of...Marine Area A Marine Area B Marine Area C 1 Marine Area 0 10 3051 N 𔃺 635 10 4295 ’ N14376 g0 12.5 90 34 90 g. I . 90 𔃼.0 𔃺 .8 NENE ’. 2.’ NE 80 a

  3. Tectonic Setting of the Wooded Island Earthquake Swarm, Eastern Washington

    SciTech Connect

    Blakely, R. J.; Sherrod, B. L.; Weaver, C. S.; Rohay, A. C.; Wells, R. E.

    2012-08-01

    Magnetic anomalies provide insights into the tectonic implications of a swarm of ~1500 shallow (~1 km deep) earthquakes that occurred in 2009 on the Hanford site, Washington. Epicenters were concentrated in a 2 km2 area near Wooded Island in the Columbia River. The largest earthquake (M 3.0) had first motions consistent with slip on a northwest-striking reverse fault. The swarm was accompanied by 35 mm of vertical surface deformation, seen in satellite interferometry (InSAR), interpreted to be caused by ~50 mm of slip on a northwest-striking reverse fault and associated bedding-plane fault in the underlying Columbia River Basalt Group (CRBG). A magnetic anomaly over exposed CRBG at Yakima Ridge 40 km northwest of Wooded Island extends southeastward beyond the ridge to the Columbia River, suggesting that the Yakima Ridge anticline and its associated thrust fault extend southeastward in the subsurface. In map view, the concealed anticline passes through the earthquake swarm and lies parallel to reverse faults determined from first motions and InSAR data. A forward model of the magnetic anomaly near Wooded Island is consistent with uplift of concealed CRBG, with the top surface <200 m below the surface. The earthquake swarm and the thrust and bedding-plane faults modeled from interferometry all fall within the northeastern limb of the faulted anticline. Finally, although fluids may be responsible for triggering the Wooded Island earthquake swarm, the seismic and aseismic deformation are consistent with regional-scale tectonic compression across the concealed Yakima Ridge anticline.

  4. Tectonic setting of the Wooded Island earthquake swarm, eastern Washington

    USGS Publications Warehouse

    Blakely, Richard J.; Sherrod, Brian L.; Weaver, Craig S.; Rohay, Alan C.; Wells, Ray E.

    2012-01-01

    Magnetic anomalies provide insights into the tectonic implications of a swarm of ~1500 shallow (~1 km deep) earthquakes that occurred in 2009 on the Hanford site,Washington. Epicenters were concentrated in a 2 km2 area nearWooded Island in the Columbia River. The largest earthquake (M 3.0) had first motions consistent with slip on a northwest-striking reverse fault. The swarm was accompanied by 35 mm of vertical surface deformation, seen in satellite interferometry (InSAR), interpreted to be caused by ~50 mm of slip on a northwest-striking reverse fault and associated bedding-plane fault in the underlying Columbia River Basalt Group (CRBG). A magnetic anomaly over exposed CRBG at Yakima Ridge 40 km northwest of Wooded Island extends southeastward beyond the ridge to the Columbia River, suggesting that the Yakima Ridge anticline and its associated thrust fault extend southeastward in the subsurface. In map view, the concealed anticline passes through the earthquake swarm and lies parallel to reverse faults determined from first motions and InSAR data. A forward model of the magnetic anomaly near Wooded Island is consistent with uplift of concealed CRBG, with the top surface <200 m below the surface. The earthquake swarm and the thrust and bedding-plane faults modeled from interferometry all fall within the northeastern limb of the faulted anticline. Although fluids may be responsible for triggering the Wooded Island earthquake swarm, the seismic and aseismic deformation are consistent with regional-scale tectonic compression across the concealed Yakima Ridge anticline.

  5. State-of-the-Art for Assessing Earthquake Hazards in the United States. Report 15. Tsunamis, Seiches, and Landslide-Induced Water Waves.

    DTIC Science & Technology

    1979-11-01

    EXCEPT ALEUTIAN ISLANDS) ,LANDSLIDES OR SUBAQUEOUS SLIDES )CAN PRODUCE ZONE 5 ELEVATIONS1 *% (e.g. LITUYA BAY , ALASKA) ALEUTIAN ISLANDS (SAME AS GULF...has been documentedwas generated in 1958 by a landslide that was triggered by an earthquake and slid into Lituya Bay , Alaska. The landslide generated...generated waves in Lituya Bay in 1853, 1874, and 1936 (Miller, 1960). 118. Subaqueous landslides triggered by the 1964 Alaskan tsunami caused widespread

  6. Insights on the 1990 Bohol Tsunamigenic Earthquake, Bohol Island, Philippines

    NASA Astrophysics Data System (ADS)

    Besana, G. M.; Daligdig, J. A.; Abigania, M. T.; Talisic, J. E.; Evangelista, N.

    2004-12-01

    The February 8, 1990 earthquake at Bohol area is one of the few strong earthquakes that have affected central Philippines since the early 1900's. This M6.0 1990 Bohol event nonetheless wrought havoc to at least 16 municipalities, caused numerous casualties, injured about three hundred people, rendered several thousand homeless and evacuated from the coastal areas, and damaged at least P154 million worth of properties. The epicenter of this earthquake was initially placed onshore at 17km east of Tagbilaran City and was attributed to the movement along the Alicia Thrust Fault- a fault trending northeast-southwest. Noticeably, there was no surface rupture and the succeeding aftershocks clustered along a northeast-southwest trend off the eastern shore of Bohol island. In addition, the southeastern part of Bohol island experienced tsunami inundation particularly the municipalities of Jagna, Duero, Guindulman, Garcia Hernandez, and Valencia. In this study, several issues were resolved regarding this seismic event. First, the 1990 Bohol earthquake was generated along an offshore thrust fault based on the reviews of seismicity data from the NEIC. -Post-determined plots of the mainshock and aftershocks indicate offshore event with focal mechanism solutions that imply thrust fault activity. Intensity data likewise indicates that intense ground shaking was mainly felt in the southeastern part of the island. Second, recent field investigations undertaken clearly indicated a widespread tsunami inundation wherein the southeastern shorelines of Bohol likewise experienced a regional retreat in sea level several minutes after the strong ground shaking. Lastly, such tsunamigenic structure could somehow explain the anomalously large waves that impacted Camiguin island, an island more than 50km southeast of Bohol. A reconstruction of true tsunami heights and runup distances was also undertaken based from eyewitness accounts. Future works would involve relocation of aftershocks and

  7. Testing the nutritional-limitation, predator-avoidance, and storm-avoidance hypotheses for restricted sea otter habitat use in the Aleutian Islands, Alaska.

    PubMed

    Stewart, Nathan L; Konar, Brenda; Tinker, M Tim

    2015-03-01

    Sea otters (Enhydra lutris) inhabiting the Aleutian Islands have stabilized at low abundance levels following a decline and currently exhibit restricted habitat-utilization patterns. Possible explanations for restricted habitat use by sea otters can be classified into two fundamentally different processes, bottom-up and top-down forcing. Bottom-up hypotheses argue that changes in the availability or nutritional quality of prey resources have led to the selective use of habitats that support the highest quality prey. In contrast, top-down hypotheses argue that increases in predation pressure from killer whales have led to the selective use of habitats that provide the most effective refuge from killer whale predation. A third hypothesis suggests that current restricted habitat use is based on a need for protection from storms. We tested all three hypotheses for restricted habitat use by comparing currently used and historically used sea otter foraging locations for: (1) prey availability and quality, (2) structural habitat complexity, and (3) exposure to prevailing storms. Our findings suggest that current use is based on physical habitat complexity and not on prey availability, prey quality, or protection from storms, providing further evidence for killer whale predation as a cause for restricted sea otter habitat use in the Aleutian Islands.

  8. Testing the nutritional-limitation, predator-avoidance, and storm-avoidance hypotheses for restricted sea otter habitat use in the Aleutian Islands, Alaska

    USGS Publications Warehouse

    Stewart, Nathan L.; Konar, Brenda; Tinker, M. Tim

    2015-01-01

    Sea otters (Enhydra lutris) inhabiting the Aleutian Islands have stabilized at low abundance levels following a decline and currently exhibit restricted habitat-utilization patterns. Possible explanations for restricted habitat use by sea otters can be classified into two fundamentally different processes, bottom-up and top-down forcing. Bottom-up hypotheses argue that changes in the availability or nutritional quality of prey resources have led to the selective use of habitats that support the highest quality prey. In contrast, top-down hypotheses argue that increases in predation pressure from killer whales have led to the selective use of habitats that provide the most effective refuge from killer whale predation. A third hypothesis suggests that current restricted habitat use is based on a need for protection from storms. We tested all three hypotheses for restricted habitat use by comparing currently used and historically used sea otter foraging locations for: (1) prey availability and quality, (2) structural habitat complexity, and (3) exposure to prevailing storms. Our findings suggest that current use is based on physical habitat complexity and not on prey availability, prey quality, or protection from storms, providing further evidence for killer whale predation as a cause for restricted sea otter habitat use in the Aleutian Islands.

  9. Auklet (Charadriiformes: Alcidae, Aethia spp.) chick meals from the Aleutian Islands, Alaska, have a very low incidence of plastic marine debris.

    PubMed

    Bond, Alexander L; Jones, Ian L; Williams, Jeffrey C; Byrd, G Vernon

    2010-08-01

    The ingestion of plastic marine debris is a chronic problem for some of the world's seabird species, contributing to reduced chick survival, population declines, and deposition of contaminants via absorption in birds' gastrointestinal tract. We analysed the frequency of ingested plastic in chick meals delivered by adults in four species of auklet - Crested (Aethia cristatella), Least (A. pusilla), Parakeet (A. psittacula), and Whiskered (A. pygmaea) - from three breeding colonies in the Aleutian Islands, Alaska, USA over a 14-year period from 1993 to 2006. Among 2541 chick meals, we found plastic in only one - from a Whiskered Auklet on Buldir Island in 1993. While adult Parakeet Auklets have a high frequency of plastic ingestion (over 90%), no chick meals contained plastic. Unlike other seabirds, the planktivorous auklets do not appear to offload plastic to their chicks, and we conclude that auklet chicks are probably at a low risk of contamination from plastic debris.

  10. From birth to death of arc magmatism: The igneous evolution of Komandorsky Islands recorded tectonic changes during 50 Ma of westernmost Aleutian history

    NASA Astrophysics Data System (ADS)

    Höfig, T. W.; Portnyagin, M.; Hoernle, K.; Hauff, F. F.; van den Bogaard, P.; Garbe-Schoenberg, C.

    2013-12-01

    The Komandorsky Islands form the westernmost end of the Aleutian Island Arc. Four igneous complexes, spanning almost 50 Ma of magmatism, have previously been identified (Ivaschenko et al., 1984: Far East Scientific Centre, Vladivostok, 192 pp.). The petrogenesis of this protracted magmatic record and accurate absolute ages of events, however, remain poorly constrained. Our study investigates the relationship between magma composition and tectonic setting. The Komandorsky igneous basement formed in subduction zone setting. It hosts some of the oldest igneous rocks of the entire Aleutian Arc with the onset of magmatism occurring at 47 Ma. This early stage was characterized by classic fluid-dominated arc volcanism, which produced two coeval but likely genetically unrelated magmatic series of tholeiitic mafic and tholeiitic to calc-alkaline felsic rocks. To date, no boninites have been found and therefore arc initiation is different at the Aleutians than at Izu-Bonin-Marianas or the oldest rocks in the Aleutians have yet to be discovered. The prolonged production of the contrasting basalt-rhyolite association on Komandorsky Islands had lasted ~25 Ma and ceased around the Oligocene-Miocene boundary. Concurrently to this long-lasting activity, a gradual transition to a different mode of arc magmatism took place reflected by newly discovered Sr-enriched, HREE-depleted calc-alkaline basaltic andesitic lavas of mid-upper Eocene age spanning a time of at least ~7 Ma. This so-called Transition Series displays a moderate garnet signature marking the increased contribution of a slab-melt component to the magma sources of the Komandorsky Islands. Slab-melt contribution increased with decreasing age leading to strongly adakitic magmatism as early as ~33 Ma (Lower Oligocene), reflected by eruption of high-Sr (up to 2,500 ppm), highly HREE-depleted Adak-type magnesian basaltic andesites and andesites. These remarkable magmas became predominant during the Lower Miocene. They were

  11. Geologic framework of the Aleutian arc, Alaska

    USGS Publications Warehouse

    Vallier, Tracy L.; Scholl, David W.; Fisher, Michael A.; Bruns, Terry R.; Wilson, Frederic H.; von Huene, Roland E.; Stevenson, Andrew J.

    1994-01-01

    The Aleutian arc is the arcuate arrangement of mountain ranges and flanking submerged margins that forms the northern rim of the Pacific Basin from the Kamchatka Peninsula (Russia) eastward more than 3,000 km to Cooke Inlet (Fig. 1). It consists of two very different segments that meet near Unimak Pass: the Aleutian Ridge segment to the west and the Alaska Peninsula-the Kodiak Island segment to the east. The Aleutian Ridge segment is a massive, mostly submerged cordillera that includes both the islands and the submerged pedestal from which they protrude. The Alaska Peninsula-Kodiak Island segment is composed of the Alaska Peninsula, its adjacent islands, and their continental and insular margins. The Bering Sea margin north of the Alaska Peninsula consists mostly of a wide continental shelf, some of which is underlain by rocks correlative with those on the Alaska Peninsula.There is no pre-Eocene record in rocks of the Aleutian Ridge segment, whereas rare fragments of Paleozoic rocks and extensive outcrops of Mesozoic rocks occur on the Alaska Peninsula. Since the late Eocene, and possibly since the early Eocene, the two segments have evolved somewhat similarly. Major plutonic and volcanic episodes, however, are not synchronous. Furthermore, uplift of the Alaska Peninsula-Kodiak Island segment in late Cenozoic time was more extensive than uplift of the Aleutian Ridge segment. It is probable that tectonic regimes along the Aleutian arc varied during the Tertiary in response to such factors as the directions and rates of convergence, to bathymetry and age of the subducting Pacific Plate, and to the volume of sediment in the Aleutian Trench.The Pacific and North American lithospheric plates converge along the inner wall of the Aleutian trench at about 85 to 90 mm/yr. Convergence is nearly at right angles along the Alaska Peninsula, but because of the arcuate shape of the Aleutian Ridge relative to the location of the plates' poles of rotation, the angle of convergence

  12. Seismicity, topography, and free-air gravity of the Aleutian-Alaska subduction zone

    NASA Astrophysics Data System (ADS)

    Wells, R. E.; Blakely, R. J.; Scholl, D. W.; Ryan, H. F.

    2011-12-01

    The Aleutian-Alaska subduction zone, extending 3400 km from the Queen Charlotte Fault to Kamchatka, has been the source of six great megathrust earthquakes in the 20th Century. Four earthquakes have ruptured the 2000-km-long Aleutian segment, where the Cenozoic Aleutian arc overlies the subducting Pacific plate. These include the 1946 M 8.6 earthquake off Unimak Is., the 1957 M 8.6 and 1986 M 8.0 earthquakes off the Andreanoff Is., and the 1965 M 8.7 Rat Is. earthquake. The source regions of these earthquakes inferred from waveform inversions underlie the well-defined Aleutian deep-sea terrace. The deep-sea terrace is about 4 km deep and is underlain by Eocene arc framework rocks, which extend nearly to the trench. It is bounded on its seaward and landward margins by strong topographic and fee-air gravity gradients. The main asperities (areas of largest slip) for the great earthquakes and nearly all of the Aleutian thrust CMT solutions lie beneath the Aleutian terrace, between the maximum gradients. Similar deep-sea terraces are characteristic of non-accretionary convergent margins globally (75% of subduction zones), and, where sampled by drilling (e.g., Japan, Peru, Tonga, Central America), are undergoing sustained subsidence. Sustained subsidence requires removal of arc crust beneath the terrace by basal subduction erosion (BSE). BSE is in part linked to the seismic cycle, as it occurs in the same location as the megathrust earthquakes. Along the eastern 1400 km of the Alaskan subduction zone, the Pacific plate subducts beneath the North American continent. The boundary between the Aleutian segment and the continent is well defined in free-air gravity, and the distinctive deep-sea terrace observed along the Aleutian segment is absent. Instead, the Alaskan margin consists of exhumed, underplated accretionary complexes forming outer arc gravity highs. Superimposed on them are broad topographic highs and lows forming forearc basins (Shumagin, Stevenson) and islands

  13. Mercury, arsenic, cadmium, chromium lead, and selenium in feathers of pigeon guillemots (Cepphus columba) from Prince William Sound and the Aleutian Islands of Alaska.

    PubMed

    Burger, Joanna; Gochfeld, Michael; Sullivan, Kelsey; Irons, David

    2007-11-15

    Arsenic, cadmium, chromium, lead, manganese, mercury and selenium were analyzed in the feathers of pigeon guillemots (Cepphus columba) from breeding colonies in Prince William Sound and in the Aleutian Islands (Amchitka, Kiska) to test the null hypothesis that there were no differences in metal levels as a function of location, gender, or whether the birds were from oiled or unoiled areas in Prince William Sound. Birds from locations with oil from the Exxon Valdez Oil Spill in the environment had higher levels of cadmium and lead than those from unoiled places in Prince William Sound, but otherwise there were no differences in metal levels in feathers. The feathers of pigeon guillemots from Prince William Sound had significantly higher levels of cadmium and manganese, but significantly lower levels of mercury than those from Amchitka or Kiska in the Aleutians. Amchitka had the lowest levels of chromium, and Kiska had the highest levels of selenium. There were few gender-related differences, although females had higher levels of mercury and selenium in their feathers than did males. The levels of most metals are below the known effects levels, except for mercury and selenium, which are high enough to potentially pose a risk to pigeon guillemots and to their predators.

  14. Jabuka island (Central Adriatic Sea) earthquakes of 2003

    NASA Astrophysics Data System (ADS)

    Herak, Davorka; Herak, Marijan; Prelogović, Eduard; Markušić, Snježana; Markulin, Željko

    2005-04-01

    We present analyses of one of the strongest earthquake sequences ever recorded within the Adriatic microplate, which occurred near the Jabuka island in the very centre of the Adriatic Sea. The mainshock (29 March 2003, 17:42, ML=5.5) was preceded by over 150 foreshocks, and followed by many aftershocks, over 4600 of which were recorded on the closest station HVAR (about 90 km to the east). As the epicentre was in the open sea and due to the absence of nearby stations, we were able to confidently locate only 597 events. Hypocentral locations were computed by a grid-search algorithm after seven iterations of refining hypocentres and adjusting station corrections. Epicentres lie in a well-defined area of about 300 km 2, just to the W and NW of the Jabuka island. The vertical cross-sections reveal that hypocentres dip to the NE, closely matching faults from the Jabuka-Andrija fault system, as identified on the available reflection profiles in the area. The fault-plane solution of the main shock based on the first-motion polarity readings agrees well with the CMT solutions and indicates faulting caused by a S-N directed tectonic pressure, on a reverse, dip-slip fault. This is in very good agreement with the seismotectonic framework of the area. These earthquakes are important as they identify the Jabuka-Andrija fault system as an active one, which can significantly influence seismic hazard on the islands in the central Adriatic archipelago and on the Croatian coast between Zadar and Split. Along with several other sequences which occurred in the last two decades, they force us to change our notion of Adria as nearly aseismic, compact and rigid block. In fact, it turns out that recent seismicity of the Central Adriatic Sea is comparable to the seismicity of several well known earthquake-prone areas in the circum-Adriatic region.

  15. 75 FR 69601 - Fisheries of the Exclusive Economic Zone Off Alaska; Pacific Ocean Perch in the Western Aleutian...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-11-15

    ... Zone Off Alaska; Pacific Ocean Perch in the Western Aleutian District of the Bering Sea and Aleutian... for Pacific ocean perch in the Western Aleutian District of the Bering Sea and Aleutian Islands... necessary to prevent exceeding the 2010 allocation of Pacific ocean perch in this area allocated to...

  16. Significance of an Active Volcanic Front in the Far Western Aleutian Arc

    NASA Astrophysics Data System (ADS)

    Yogodzinski, G. M.; Kelemen, P. B.; Hoernle, K.

    2015-12-01

    Discovery of a volcanic front west of Buldir Volcano, the western-most emergent Aleutian volcano, demonstrates that the surface expression of Aleutian volcanism falls below sea level just west of 175.9° E longitude, but is otherwise continuous from mainland Alaska to Kamchatka. The newly discovered sites of western Aleutian seafloor volcanism are the Ingenstrem Depression, a 60 km-long structural depression just west of Buldir, and an unnamed area 300 km further west, referred to as the Western Cones. These locations fall along a volcanic front that stretches from Buldir to Piip Seamount near the Komandorsky Islands. Western Aleutian seafloor volcanic rocks include large quantities of high-silica andesite and dacite, which define a highly calc-alkaline igneous series and carry trace element signatures that are unmistakably subduction-related. This indicates that subducting oceanic lithosphere is present beneath the westernmost Aleutian arc. The rarity of earthquakes below depths of 200 km indicates that the subducting plate is unusually hot. Some seafloor volcanoes are 6-8 km wide at the base, and so are as large as many emergent Aleutian volcanoes. The seafloor volcanoes are submerged in water depths >3000 m because they sit on oceanic lithosphere of the Bering Sea. The volcanic front is thus displaced to the north of the ridge of arc crust that underlies the western Aleutian Islands. This displacement, which developed since approximately 6 Ma when volcanism was last active on the islands, must be a consequence of oblique convergence in a system where the subducting plate and large blocks of arc crust are both moving primarily in an arc-parallel sense. The result is a hot-slab system where low subduction rates probably limit advection of hot mantle to the subarc, and produce a relatively cool and perhaps stagnant mantle wedge. The oceanic setting and highly oblique subduction geometry also severely limit rates of sediment subduction, so the volcanic rocks, which

  17. Alaska Open-file Report 144 Assessment of Thermal Springs Sites Aleutian Arc, Atka Island to Becherof Lake -- Preliminary Results and Evaluation

    SciTech Connect

    Motyka, R.J.; Moorman, M.A.; Liss, S.A.

    1981-12-01

    Twenty of more than 30 thermal spring areas reported to exist in the Aleutian arc extending from Atka Island to Becherof Lake were investigated during July and August, 1980. Thermal activity of three of these sites had diminished substantially or no longer existed. At least seven more sites where thermal-spring activity is probable or certain were not visited because of their remoteness or because of time constraints. The existence of several other reported thermal spring sites could not be verified; these sites are considered questionable. On the basis of geothermometry, subsurface reservoir temperatures in excess of 150 C are estimated for 10 of the thermal spring sites investigated. These sites all occur in or near regions of Recent volcanism. Five of the sites are characterized by fumaroles and steaming ground, indicating the presence of at least a shallow vapor-dominated zone. Two, the Makushin Valley and Glacier Valley thermal areas, occur on the flanks of active Mukushin Volcano located on Unalaska Island, and may be connected to a common source of heat. Gas geothermometry suggests that the reservoir feeding the Kliuchef thermal field, located on the flanks of Kliuchef volcano of northeast Atka Island, may be as high as 239 C.

  18. The 2006-2007 Kuril Islands great earthquake sequence

    USGS Publications Warehouse

    Lay, T.; Kanamori, H.; Ammon, C.J.; Hutko, Alexander R.; Furlong, K.; Rivera, L.

    2009-01-01

    The southwestern half of a ???500 km long seismic gap in the central Kuril Island arc subduction zone experienced two great earthquakes with extensive preshock and aftershock sequences in late 2006 to early 2007. The nature of seismic coupling in the gap had been uncertain due to the limited historical record of prior large events and the presence of distinctive upper plate, trench and outer rise structures relative to adjacent regions along the arc that have experienced repeated great interplate earthquakes in the last few centuries. The intraplate region seaward of the seismic gap had several shallow compressional events during the preceding decades (notably an MS 7.2 event on 16 March 1963), leading to speculation that the interplate fault was seismically coupled. This issue was partly resolved by failure of the shallow portion of the interplate megathrust in an MW = 8.3 thrust event on 15 November 2006. This event ruptured ???250 km along the seismic gap, just northeast of the great 1963 Kuril Island (Mw = 8.5) earthquake rupture zone. Within minutes of the thrust event, intense earthquake activity commenced beneath the outer wall of the trench seaward of the interplate rupture, with the larger events having normal-faulting mechanisms. An unusual double band of interplate and intraplate aftershocks developed. On 13 January 2007, an MW = 8.1 extensional earthquake ruptured within the Pacific plate beneath the seaward edge of the Kuril trench. This event is the third largest normal-faulting earthquake seaward of a subduction zone on record, and its rupture zone extended to at least 33 km depth and paralleled most of the length of the 2006 rupture. The 13 January 2007 event produced stronger shaking in Japan than the larger thrust event, as a consequence of higher short-period energy radiation from the source. The great event aftershock sequences were dominated by the expected faulting geometries; thrust faulting for the 2006 rupture zone, and normal faulting for

  19. Analysis of Treasure Island earthquake data using seismic interferometry

    NASA Astrophysics Data System (ADS)

    Mehta, K.; Snieder, R.; Graizer, V.

    2005-12-01

    Seismic interferometry is a powerful tool in extracting the response of ground motion. We show the use of seismic interferometry for analysis of an earthquake recorded by Treasure Island Geotechnical Array near San Francisco, California on 06/26/94. It was a magnitude 4.0 earthquake located at a depth of 6.6 km and distance of 12.6 km from the sensors in borehole. There were six 3-component sensors located at different depths. This problem is similar to the analysis by Snieder and Safak for the Robert A. Millikan Library in Pasadena, California where they deconvolve the recorded wavefield at each of the library floors with the top floor to see the upgoing and the downgoing waves and using that, estimate a shear velocity and a quality factor. They have also shown that for such applications of seismic interferometry, deconvolution of waveforms is superior to correlation. For the Treasure Island data, deconvolving the vertical component of the wavefield for each sensors with the sensor at the surface gives a similar superposition of an upgoing and a downgoing wave. The velocity of these waves agrees well with the compressional wave velocity. We compute the radial and the transverse components. When we window the shear wave arrivals in transverse components at each depth and deconvolve with the one on the surface, the resultant up and down going waves travel with the shear wave velocity. Similar windowing and deconvolution for the radial component also agrees with the shear wave velocity. However, when the radial component is windowed around the compressional waves and deconvolved, the up and the down going waves travel with the shear wave velocity. In the absence of any P to S conversion, the deconvolved waves should be travelling with compressional wave velocity. This suggests that there is a conversion at a depth below the deepest sensor. Receiver functions, defined as the spectral ratio of the radial component with vertical component, can be used to characterize

  20. Unusually large tsunamis frequent a currently creeping part of the Aleutian megathrust

    NASA Astrophysics Data System (ADS)

    Witter, Robert C.; Carver, Gary A.; Briggs, Richard W.; Gelfenbaum, Guy; Koehler, Richard D.; La Selle, SeanPaul; Bender, Adrian M.; Engelhart, Simon E.; Hemphill-Haley, Eileen; Hill, Troy D.

    2016-01-01

    Current models used to assess earthquake and tsunami hazards are inadequate where creep dominates a subduction megathrust. Here we report geological evidence for large tsunamis, occurring on average every 300-340 years, near the source areas of the 1946 and 1957 Aleutian tsunamis. These areas bookend a postulated seismic gap over 200 km long where modern geodetic measurements indicate that the megathrust is currently creeping. At Sedanka Island, evidence for large tsunamis includes six sand sheets that blanket a lowland facing the Pacific Ocean, rise to 15 m above mean sea level, contain marine diatoms, cap terraces, adjoin evidence for scour, and date from the past 1700 years. The youngest sheet and modern drift logs found as far as 800 m inland and >18 m elevation likely record the 1957 tsunami. Previously unrecognized tsunami sources coexist with a presently creeping megathrust along this part of the Aleutian Subduction Zone.

  1. Unusually large tsunamis frequent a currently creeping part of the Aleutian megathrust

    USGS Publications Warehouse

    Witter, Robert C.; Carver, G.A.; Briggs, Richard; Gelfenbaum, Guy R.; Koehler, R.D.; La Selle, SeanPaul M.; Bender, Adrian M.; Engelhart, S.E.; Hemphill-Haley, E.; Hill, Troy D.

    2016-01-01

    Current models used to assess earthquake and tsunami hazards are inadequate where creep dominates a subduction megathrust. Here we report geological evidence for large tsunamis, occurring on average every 300–340 years, near the source areas of the 1946 and 1957 Aleutian tsunamis. These areas bookend a postulated seismic gap over 200 km long where modern geodetic measurements indicate that the megathrust is currently creeping. At Sedanka Island, evidence for large tsunamis includes six sand sheets that blanket a lowland facing the Pacific Ocean, rise to 15 m above mean sea level, contain marine diatoms, cap terraces, adjoin evidence for scour, and date from the past 1700 years. The youngest sheet, and modern drift logs found as far as 800 m inland and >18 m elevation, likely record the 1957 tsunami. Modern creep on the megathrust coexists with previously unrecognized tsunami sources along this part of the Aleutian Subduction Zone.

  2. 75 FR 4491 - Fisheries of the Exclusive Economic Zone Off Alaska; Atka Mackerel in the Bering Sea and Aleutian...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-01-28

    ... Economic Zone Off Alaska; Atka Mackerel in the Bering Sea and Aleutian Islands Management Area AGENCY... mackerel in the Eastern Aleutian District and the Bering Sea subarea of the Bering Sea and Aleutian Islands... necessary to fully use the 2010 A season total allowable catch (TAC) of Atka mackerel in these...

  3. 78 FR 42023 - Fisheries of the Exclusive Economic Zone Off Alaska; Atka Mackerel in the Bering Sea and Aleutian...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-07-15

    ... Economic Zone Off Alaska; Atka Mackerel in the Bering Sea and Aleutian Islands Management Area AGENCY... mackerel in the Central Aleutian district (CAI) of the Bering Sea and Aleutian Islands Management Area... fully use the 2013 total allowable catch (TAC) of Atka mackerel in the CAI by vessels participating...

  4. 75 FR 3873 - Fisheries of the Exclusive Economic Zone Off Alaska; Atka Mackerel in the Bering Sea and Aleutian...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-01-25

    ... Economic Zone Off Alaska; Atka Mackerel in the Bering Sea and Aleutian Islands Management Area AGENCY... mackerel in the Eastern Aleutian District and the Bering Sea subarea of the Bering Sea and Aleutian Islands... necessary to prevent exceeding the 2010 A season total allowable catch (TAC) of Atka mackerel in these...

  5. Evidence for Deep Tectonic Tremor in the Alaska-Aleutian Subduction Zone

    NASA Astrophysics Data System (ADS)

    Brown, J. R.; Prejean, S. G.; Beroza, G. C.; Gomberg, J. S.; Haeussler, P. J.

    2010-12-01

    We search for, characterize, and locate tremor not associated with volcanoes along the Alaska-Aleutian subduction zone using continuous seismic data recorded by the Alaska Volcano Observatory and Alaska Earthquake Information Center from 2005 to the present. Visual inspection of waveform spectra and time series reveal dozens of 10 to 20-minute bursts of tremor throughout the Alaska-Aleutian subduction zone (Peterson, 2009). Using autocorrelation methods, we show that these tremor signals are composed of hundreds of repeating low-frequency earthquakes (LFEs) as has been found in other circum-Pacific subduction zones. We infer deep sources based on phase arrival move-out times of less than 4 seconds across multiple monitoring networks (max. inter-station distances of 50 km), which are designed to monitor individual volcanoes. We find tremor activity is localized in 7 segments: Cook Inlet, Shelikof Strait, Alaska Peninsula, King Cove, Unalaska-Dutch Harbor, Andreanof Islands, and the Rat Islands. Locations along the Cook Inlet, Shelikof Straight and Alaska Peninsula are well constrained due to adequate station coverage. LFE hypocenters in these regions are located on the plate interface and form a sharp edge near the down-dip limit of the 1964 M 9.2 rupture area. Although the geometry, age, thermal structure, frictional and other relevant properties of the Alaska-Aleutian subduction are poorly known, it is likely these characteristics differ along its entire length, and also differ from other subduction zones where tremor has been found. LFE hypocenters in the remaining areas are also located down-dip of the most recent M 8+ megathrust earthquakes, between 60-75 km depth and almost directly under the volcanic arc. Although these locations are less well constrained, our preliminary results suggest LFE/tremor activity marks the down-dip rupture limit for megathrust earthquakes in this subduction zone. Also, we cannot rule out the possibility that our observations could

  6. Beach ridges as paleoseismic indicators of abrupt coastal subsidence during subduction zone earthquakes, and implications for Alaska-Aleutian subduction zone paleoseismology, southeast coast of the Kenai Peninsula, Alaska

    USGS Publications Warehouse

    Kelsey, Harvey M.; Witter, Robert C.; Engelhart, Simon E.; Briggs, Richard; Nelson, Alan R.; Haeussler, Peter J.; Corbett, D. Reide

    2015-01-01

    The Kenai section of the eastern Alaska-Aleutian subduction zone straddles two areas of high slip in the 1964 great Alaska earthquake and is the least studied of the three megathrust segments (Kodiak, Kenai, Prince William Sound) that ruptured in 1964. Investigation of two coastal sites in the eastern part of the Kenai segment, on the southeast coast of the Kenai Peninsula, identified evidence for two subduction zone earthquakes that predate the 1964 earthquake. Both coastal sites provide paleoseismic data through inferred coseismic subsidence of wetlands and associated subsidence-induced erosion of beach ridges. At Verdant Cove, paleo-beach ridges record the paleoseismic history; whereas at Quicksand Cove, buried soils in drowned coastal wetlands are the primary indicators of paleoearthquake occurrence and age. The timing of submergence and death of trees mark the oldest earthquake at Verdant Cove that is consistent with the age of a well documented ∼900-year-ago subduction zone earthquake that ruptured the Prince William Sound segment of the megathrust to the east and the Kodiak segment to the west. Soils buried within the last 400–450 years mark the penultimate earthquake on the southeast coast of the Kenai Peninsula. The penultimate earthquake probably occurred before AD 1840 from its absence in Russian historical accounts. The penultimate subduction zone earthquake on the Kenai segment did not rupture in conjunction with the Prince William Sound to the northeast. Therefore the Kenai segment, which is presently creeping, can rupture independently of the adjacent Prince William Sound segment that is presently locked.

  7. Investigation of the Influence of the Amlia Fracture Zone on the Islands of Four Mountains Region of the Aleutian Arc, AK

    NASA Astrophysics Data System (ADS)

    Nicolaysen, K. P.; Myers, J. D.; Weis, D.

    2013-12-01

    Regional isotopic and trace element investigations of the magmatic source characteristics of the Aleutian arc have attributed regional patterns to variations in the contribution of eclogite through slab melting, to increased proportions of sediment melts, and to variation in the amount of fluid derived by progressive metamorphism of the downgoing slab. Currently the Amlia Fracture Zone (AFZ) is located between the islands of Atka and Seguam and marks a prominent boundary between subduction of large quantities of trench sediments to the east versus sediment impoverished subduction to the west of the AFZ. This boundary is not stationary through time. Instead oblique subduction of the Pacific plate moves the AFZ westward along the arc front, causing sequential subduction beneath the islands of Chuginadak, Yunaska and Seguam circa 5, 2.5 and 1 million years ago, respectively. Lavas from Atka Island, which has not yet received the sediment and fluid spike from the AFZ, act as reference compositions. Comparison of bulk rock trace element ratios and Sr, Nd, Hf, and Pb isotopic compositions for lavas from these islands relative to Atka show that contributions from melted subducted sediment are important in the genesis of Holocene and Pleistocene lavas erupted in the Islands of Four Mountains region of the arc. Sr and Pb isotopic compositions for Yunaska and Chuginadak lavas are as high or higher than Seguam values and trend in the direction of sediment values. La/Nb ratios similarly indicate sediment melting is important for all these lavas. Comparison of values for Holocene relative to Pleistocene values indicate that once sediments are introduced to the magma source, they persist in affecting magma compositions. Comparison of higher Mg# lavas (molar Mg#>50) shows that a group of the oldest sampled lavas on Chuginadak have much lower 208Pb/204Pb, 206Pb/204Pb, and 87Sr/86Sr and higher 143Nd/144Nd, Zr/Y and Zn/Mn relative to all sampled Holocene and Pleistocene lavas from

  8. Earthquake relocation near the Leech River Fault, southern Vancouver Island

    NASA Astrophysics Data System (ADS)

    Li, G.; Liu, Y.; Regalla, C.

    2015-12-01

    The Leech River Fault (LRF), a northeast dipping thrust, extends across the southern tip of Vancouver Island in Southwest British Columbia, where local tectonic regime is dominated by the subduction of the Juan de Fuca plate beneath the North American plate at the present rate of 40-50 mm/year. British Columbia geologic map (Geoscience Map 2009-1A) shows that this area also consists of many crosscutting minor faults in addition to the San Juan Fault north of the LRF. To investigate the seismic evidence of the subsurface structures of these minor faults and of possible hidden active structures in this area, precise earthquake locations are required. In this study, we relocate 941 earthquakes reported by Canadian National Seismograph Network (CNSN) catalog from 2000 to 2015 within a 100km x 55km study area surrounding the LRF. We use HypoDD [Waldhauser, F., 2001] double-difference relocation method by combining P/S phase arrivals provided by the CNSN at 169 stations and waveform data with correlation coefficient values greater than 0.7 at 50 common stations and event separation less than 10km. A total of 900 out of the 931 events satisfy the above relocation criteria. Velocity model used is a 1-D model extracted from the Ramachandran et al. (2005) model. Average relative location errors estimated by the bootstrap method are 546.5m (horizontal) and 1128.6m (in depth). Absolute errors reported by SVD method for individual clusters are ~100m in both dimensions. We select 5 clusters visually according to their epicenters (see figure). Cluster 1 is parallel to the LRF and a thrust FID #60. Clusters 2 and 3 are bounded by two faults: FID #75, a northeast dipping thrust marking the southwestern boundary of the Wrangellia terrane, and FID #2 marking the northern boundary. Clusters 4 and 5, to the northeast and northwest of Victoria respectively, however, do not represent the surface traces of any mapped faults. The depth profile of Cluster 5 depicts a hidden northeast

  9. Large-scale deformation related to the collision of the Aleutian Arc with Kamchatka

    USGS Publications Warehouse

    Gesit, Eric L.; Scholl, David W.

    1994-01-01

    The far western Aleutian Island Arc is actively colliding with Kamchatka. Westward motion of the Aleutian Arc is brought about by the tangential relative motion of the Pacific plate transferred to major, right-lateral shear zones north and south of the arc. Early geologic mapping of Cape Kamchatka (a promontory of Kamchatka along strike with the Aleutian Arc) revealed many similarities to the geology of the Aleutian Islands. Later studies support the notion that Cape Kamchatka is the farthest west Aleutian “island” and that it has been accreted to Kamchatka by the process of arc-continent collision. Deformation associated with the collision onshore Kamchatka includes gravimetrically determined crustal thickening and formation of a narrow thrust belt of intensely deformed rocks directly west of Cape Kamchatka. The trend of the thrust faults is concave toward the collision zone, indicating a radial distribution of maximum horizontal compressive stress. Offshore, major crustal faults trend either oblique to the Kamchatka margin or parallel to major Aleutian shear zones. These offshore faults are complex, accommodating both strike-slip and thrust displacements as documented by focal mechanisms and seismic reflection data. Earthquake activity is much higher in the offshore region within a zone bounded to the north by the northernmost Aleutian shear zone and to the west by an apparent aseismic front. Analysis of focal mechanisms in the region indicate that the present-day arc-continent “contact zone” is located directly east of Cape Kamchatka. In modeling the dynamics of the collision zone using thin viscous sheet theory, the rheological parameters are only partially constrained to values of n (the effective power law exponent) ≥ 3 and Ar(the Argand number) ≤ 30. These values are consistent with a forearc thermal profile of Kamchatka, previously determined from heat flow modeling. The thin viscous sheet modeling also indicates that onshore thrust faulting

  10. Comprehensive study of the seismotectonics of the eastern Aleutian arc and associated volcanic systems. Annual progress report, March 1, 1980-February 28, 1981

    SciTech Connect

    Jacob, K.H.; Davies, J.N.; House, L.

    1981-01-01

    Refined hypocenter locations beneath the Shumagin Islands seismic network of the eastern Aleutian arc, Alaska, provide for the first time conclusive evidence for a double-sheeted dipping seismic (Benioff) zone in this arc. This refined seismicity structure was obtained in the arc section centered on the Shumagin seismic gap. A thorough review of three seismic gaps in the eastern Aleutian arc shows a high potential for great earthquakes within the next one to two decades in the Shumagin and Yakataga seismic gaps, and a less certain potential for a large or great earthquake in the possible Unalaska gap. A tilt reversal was geodetically observed to have occurred in 1978/79 in the forearc region of the Shumagin gap and could indicate the onset of a precursory strain relief episode prior to a great quake. A comparative study of the Pavlof volcano seismicity with that of other recently active volcanoes (i.e., Mt. St. Helens) indicates that island-arc (explosive-type) volcanoes respond to small ambient, periodic stress changes (i.e., tides). Stress drop measurements from earthquakes on the main thrust zone indicate high stress drops within the seismic gap regions of the Aleutian arc and low stress drops outside the gap region.

  11. Modeling connectivity of walleye pollock in the Gulf of Alaska: Are there any linkages to the Bering Sea and Aleutian Islands?

    NASA Astrophysics Data System (ADS)

    Parada, Carolina; Hinckley, Sarah; Horne, John; Mazur, Michael; Hermann, Albert; Curchister, Enrique

    2016-10-01

    We investigated the connectivity of walleye pollock in the Gulf of Alaska (GOA) and linkages to the Bering Sea (BS) and Aleutian Island (AL) regions. We used a spatially-explicit Individual-based model (IBM) coupled to 6 years of a hydrodynamic model that simulates the early life history of walleye pollock in the GOA (eggs to age-0 juveniles). The processes modeled included growth, movement, mortality, feeding and the bioenergetics component for larvae and juveniles. Simulations were set to release particles on the 1st of the month (February to May) in fourteen historical spawning areas in the GOA up to the 1st of September each year. Model results reproduced the link between the Shelikof Strait spawning area and the Shumagin nursery region for March and April spawners, besides other Potential Nursery Areas (PNAs) found in the GOA. A prominent finding of this study was the appearance of the BS as important PNAs for several GOA spawning grounds, which is supported by a consistent flow into the BS through Unimak Pass. The simulations showed the highest density of simulated surviving pollock in the western Bering Sea (WBS) region with the lowest coefficients of variation of the whole domain. Three spawning sectors were defined, which aggregate multiple spawning areas in the eastern (EGOA), central (CGOA) and western Gulf of Alaska (WGOA). A connectivity matrix showed strong retention within the CGOA (25.9%) and EGOA (23.8%), but not in the WGOA (7.2%). Within the GOA, the highest connectivity is observed from EGOA to CGOA (57.8%) followed by the connection from CGOA to WGOA (24.3%). Overall, one of the most prominent connections was from WGOA to WBS (62.8%), followed by a connection from CGOA to WBS (29.2%). In addition, scenarios of shifting spawning locations and nursery sectors of GOA, BS and AL are explored and implications for walleye pollock stock structure hypotheses are discussed.

  12. Hazard communication by the Alaska Volcano Observatory Concerning the 2008 Eruptions of Okmok and Kasatochi Volcanoes, Aleutian Islands, Alaska

    NASA Astrophysics Data System (ADS)

    Adleman, J. N.; Cameron, C. E.; Neal, T. A.; Shipman, J. S.

    2008-12-01

    Augustine volcano in Cook Inlet, Alaska, the number of calls to Ops, emails to the webmaster, and the amount of data served via the AVO website greatly increased during elevated volcanic activity designated by the USGS aviation color code and volcano alert level. Lessons learned include, Ops staffing requirements during periods of high call volume, the need for ash fall hazard information in multiple languages, and the value of real-time observations of remote Aleutian eruptions made by local mariners. An important theme of public inquiries concerned the amount and potential climate impacts of the significant sulfur dioxide gas and ash plumes emitted by Okmok and Kasatochi, including specific questions on the amount of sulfur dioxide discharged during each eruption. The significant plumes produced at the onset of the Okmok and Kasatochi eruptions also had lengthy national and international aviation impacts and yet-to-be resolved hemispherical or possible global, climactic effects.

  13. Aleutian Disease of Mink

    PubMed Central

    Karstad, Lars; Pridham, T. J.

    1962-01-01

    A suspension of tissues from field cases of Aleutian disease was used successfully to reproduce the disease in Aleutian mink. Similarly, suspensions of diseased tissues from the experimentally infected mink were used to transmit the agent of Aleutian disease to both Aleutian mink and standard dark mink. Seitz and millipore filtrates prepared from these tissue suspensions were also infective; a suggestion that the etiologic agent is a virus. Genetic factors and hypersensitivity are discussed as possibly contributing to development of the disease. PMID:17649371

  14. Coccidia of Aleutian Canada geese

    USGS Publications Warehouse

    Greiner, E.C.; Forrester, Donald J.; Carpenter, J.W.; Yparraguirre, D.R.

    1981-01-01

    Fecal samples from 122 captive and 130 free-ranging Aleutian Canada geese (Branta canadensis leucopareia) were examined for oocysts of coccidia. Freeranging geese sampled on the spring staging ground near Crescent City, California were infected with Eimeria hermani, E. truncata, E. magnalabia, E. fulva, E. clarkei and Tyzzeria parvula. Except for E. clarkei, the same species of coccidia were found in geese on their breeding grounds in Alaska. Most of the coccidial infections in captive geese from Amchitka Island, Alaska and Patuxent Wildlife Research Center, Maryland, consisted of Tyzzeria.

  15. Historical Earthquakes and Expected Seismic Damage at Ischia Island, Resurgent Caldera (Southern Italy)

    NASA Astrophysics Data System (ADS)

    Carlino, S.; Cubellis, E.

    2005-05-01

    Information on the seismicity of the Ischia island spans about eight centuries, starting from 1228. This is characterized by the occurence of earthquakes with low energy and high intensity. The most recent earthquake of 1883 caused 2333 deaths and the destruction of the historical and environmental heritage of some areas of the island, specially at Casamicciola town. This event (Imax = XI degree MCS), represents an important date in the prevention of natural disasters, in that it was after this earthquake that the first Seismic Safety Act in Italy was passed. After the 1883 earthquake there was a period of seismic quiescence except for some isolated events felt at beginning of the last century and the very occasional micro-earthquakes recorded in the last 20 years in the northern part of the island. The epicenter of all known earthquakes are on the northern slope of Mt. Epomeo (787 m a. s.l.) resurgent block, while analysis of the effects of earthquakes and the geological structures allows us to evaluate the stress fields that generate the earthquakes. The Mt. Epomeo is a resurgent structure in the central sector of the island, whose uplift is correlated to the caldera resurgence process, for the increase of pressure of shallow magma reservoir. The caldera was formed after a large explosive eruption that deposited the Mt. Epomeo Green Tuff, about 55 ka B.P. The uplift, which started about 30 ka B.P., was of about 900 meters. The resurgent structure is bordered by a system of faults and fractures, with NW-SE, NE-SW and N-S strike and along these faults, in the northern sector, the seismicity has been localized. In a volcanic area, interpretation of the mechanisms of release and propagation of seismic energy is made even more complex as the stress field that acts at a regional level is compounded by that generated from migration of magmatic masses towards the surface, as well as the rheologic properties of the rocks dependent on the high geothermic gradient. Such

  16. Revisiting Notable Earthquakes and Seismic Patterns of the Past Decade in Alaska

    NASA Astrophysics Data System (ADS)

    Ruppert, N. A.; Macpherson, K. A.; Holtkamp, S. G.

    2015-12-01

    Alaska, the most seismically active region of the United States, has produced five earthquakes with magnitudes greater than seven since 2005. The 2007 M7.2 and 2013 M7.0 Andreanof Islands earthquakes were representative of the most common source of significant seismic activity in the region, the Alaska-Aleutian megathrust. The 2013 M7.5 Craig earthquake, a strike-slip event on the Queen-Charlotte fault, occurred along the transform plate boundary in southeast Alaska. The largest earthquake of the past decade, the 2014 M7.9 Little Sitkin event in the western Aleutians, occurred at an intermediate depth and ruptured along a gently dipping fault through nearly the entire thickness of the subducted Pacific plate. Along with these major earthquakes, the Alaska Earthquake Center reported over 250,000 seismic events in the state over the last decade, and its earthquake catalog surpassed 500,000 events in mid-2015. Improvements in monitoring networks and processing techniques allowed an unprecedented glimpse into earthquake patterns in Alaska. Some notable recent earthquake sequences include the 2008 Kasatochi eruption, the 2006-2008 M6+ crustal earthquakes in the central and western Aleutians, the 2010 and 2015 Bering Sea earthquakes, the 2014 Noatak swarm, and the 2014 Minto earthquake sequence. In 2013, the Earthscope USArray project made its way into Alaska. There are now almost 40 new Transportable Array stations in Alaska along with over 20 upgraded sites. This project is changing the earthquake-monitoring scene in Alaska, lowering magnitude of completeness across large, newly instrumented parts of the state.

  17. Earthquakes and related catastrophic events, Island of Hawaii, November 29, 1975; a preliminary report

    USGS Publications Warehouse

    Tilling, Robert I.; Koyanagi, R.Y.; Lipman, P.W.; Lockwood, J.P.; Moore, J.G.; Swanson, D.A.

    1976-01-01

    The largest earthquake in over a century--magnitude 7.2 on the Richter Scale--struck Hawaii the morning of November 29, 1975, at 0448. It was centered about 5 km beneath the Kalapana area on the southeastern coast of the island at 19? 20.1 ' N., long 155? 01.4 ' W.). The earthquake was preceded by numerous foreshocks, the largest of which was a 5.7-magnitude jolt at 0336 the same morning, and was accompanied, or closely followed, by a tsunami seismic sea wave), massive ground movements, hundreds of aftershocks, and a volcanic eruption. The tsunami reached a height of 12.2-14.6 m above sea level on the southeastern coast about 25 km west of the earthquake center, elsewhere generally 8 m or less. The south flank of Kilauea Volcano, which forms the southeastern part of the island, was deformed by dislocations along old and new faults along a 25-km long zone. Downward and seaward fault displacements resulted in widespread subsidence, locally as much as 3.5 m, leaving coconut palms standing in the sea and nearly submerging a small, near-shore island. A brief, small-volume volcanic eruption, triggered by the earthquake and associated ground movements occurred at Kilauea's summit about three-quarters of an hour later. The earthquake, together with the tsunami it generated, locally caused severe property damage in the southeastern part of the island; the tsunami also caused two deaths. Damage from the earthquake and related catastrophic events is estimated by the Hawaii Civil Defense Agency at about $4.1 million. The 1975 Kalapana earthquake and accompanying events represent the latest events in a recurring pattern of behavior for Kilauea. A large earthquake of about the same magnitude, tsunami, subsidence, and eruption occurred at Kilauea in 1868, and a less powerful earthquake and similar related processes are believed to have occurred in 1823. Indeed, the geologic evidence suggests that such events have been repeated many times in Kilauea's past and will continue. The

  18. A great earthquake doublet and seismic stress transfer cycle in the central Kuril islands.

    PubMed

    Ammon, Charles J; Kanamori, Hiroo; Lay, Thorne

    2008-01-31

    Temporal variations of the frictional resistance on subduction-zone plate boundary faults associated with the stick-slip cycle of large interplate earthquakes are thought to modulate the stress regime and earthquake activity within the subducting oceanic plate. Here we report on two great earthquakes that occurred near the Kuril islands, which shed light on this process and demonstrate the enhanced seismic hazard accompanying triggered faulting. On 15 November 2006, an event of moment magnitude 8.3 ruptured the shallow-dipping plate boundary along which the Pacific plate descends beneath the central Kuril arc. The thrust ruptured a seismic gap that previously had uncertain seismogenic potential, although the earlier occurrence of outer-rise compressional events had suggested the presence of frictional resistance. Within minutes of this large underthrusting event, intraplate extensional earthquakes commenced in the outer rise region seaward of the Kuril trench, and on 13 January 2007, an event of moment magnitude 8.1 ruptured a normal fault extending through the upper portion of the Pacific plate, producing one of the largest recorded shallow extensional earthquakes. This energetic earthquake sequence demonstrates the stress transfer process within the subducting lithosphere, and the distinct rupture characteristics of these great earthquakes illuminate differences in seismogenic properties and seismic hazard of such interplate and intraplate faults.

  19. Source process for the 2013 Santa Cruz Islands earthquake

    NASA Astrophysics Data System (ADS)

    Park, Eun Hee; Park, Sun-Cheon; Lee, Jun-Whan

    2015-04-01

    Many places in the world have experienced damage from tsunami. Most tsunamis are induced by large earthquakes that occur under the sea along the trench. Therefore understanding the characteristics of large earthquakes is important to evaluate tsunami hazard as well as earthquake damage. In order to understand the characteristics of large tsunamigenic earthquakes, in this study we analyzed the source process of the 2013 Santa Cruz earthquake (M8.0) on Feb. 6, 2013. According to the U.S. Geological Survey (USGS), 56 earthquakes with magnitudes greater than 5.5 occurred in Jan. 27 - March 8, 2013. Among them, eleven events happened for a week before the mainshock and the maximum magnitude was 6.4. A large aftershock with magnitude of 7.1 occurred immediately after the mainshock, about 10 minutes later. Including this event, the 2013 Santa Cruz event seems to be followed by two large aftershocks of M~7. The length of spatial distribution of aftershocks in 30 days was about 200 km. And this value of the length was used for rough estimation of the fault length during the waveform inversion process. We carried out teleseismic body-wave inversion to obtain the slip distribution of the 2013 earthquake. Teleseismic P waveform data from 19 stations in the epicentral distance between 30° and 90° were used and band-pass filter at 0.005 - 1.0 Hz was applied. And focal depth was assumed to be 28.7 km, according the USGS catalog. And the initial value of source time window was assumed as 120 seconds by the duration of high-frequency energy radiation. According to our inversion results, the fault plane seems the northwesterly striking (strike = 291) and shallowly dipping (dip = 24) fault plane. Large slip area was seen near the hypocenter. Rupture velocity was obtained to be 2.0 km/s. And moment magnitude of 7.9 and maximum dislocation of 1.4 m had the smallest variance between the observed and synthetic waveforms. These values were smaller than the result of previous study. To

  20. Confirmed prediction of the 2 August 2007 MW 6.2 Nevelsk earthquake (Sakhalin Island, Russia)

    NASA Astrophysics Data System (ADS)

    Tikhonov, Ivan N.; Kim, Chun U.

    2010-04-01

    This paper presents the case history of an earthquake prediction, which was prepared by seismologists at the Far East Branch of the Russian Academy of Sciences and submitted to the Russian Ministry of Emergency Situations later on. The prediction, described here briefly, was confirmed with the occurrence of the 2 August 2007 MW 6.2 Nevelsk earthquake. The first symptoms of the large seismic event were recognized as early as 1997, within the so-called "seismic gap of the first kind" (Mogi, 1985). This is the area where large earthquakes are possible but have been absent for at least 100 years, as outlined from historical data along the western coasts of the Sakhalin, Hokkaido and Honshu Islands. The symptoms were related to the incipient "seismic gap of the second kind," where shallow earthquakes with М ≥ 3.0 had disappeared. In December 2005, a long-term prediction of an earthquake with МS = 6.6 ± 0.6 was made when a "seismic gap of the second kind" (Mogi, 1985) became evident since the middle of 2003 in an area of 90 by 60 km. This prediction was to a large extent possible due to the local autonomous digital seismic network set up in 2001 in the southern region of Sakhalin Island. The prediction was accompanied by various anomalous phenomena in advance of the actual predicted event of 2 August 2007 that shocked the city of Nevelsk.

  1. The Differences in Source Dynamics Between Intermediate-Depth and Deep EARTHQUAKES:A Comparative Study Between the 2014 Rat Islands Intermediate-Depth Earthquake and the 2015 Bonin Islands Deep Earthquake

    NASA Astrophysics Data System (ADS)

    Twardzik, C.; Ji, C.

    2015-12-01

    It has been proposed that the mechanisms for intermediate-depth and deep earthquakes might be different. While previous extensive seismological studies suggested that such potential differences do not significantly affect the scaling relationships of earthquake parameters, there has been only a few investigations regarding their dynamic characteristics, especially for fracture energy. In this work, the 2014 Mw7.9 Rat Islands intermediate-depth (105 km) earthquake and the 2015 Mw7.8 Bonin Islands deep (680 km) earthquake are studied from two different perspectives. First, their kinematic rupture models are constrained using teleseismic body waves. Our analysis reveals that the Rat Islands earthquake breaks the entire cold core of the subducting slab defined as the depth of the 650oC isotherm. The inverted stress drop is 4 MPa, compatible to that of intra-plate earthquakes at shallow depths. On the other hand, the kinematic rupture model of the Bonin Islands earthquake, which occurred in a region lacking of seismicity for the past forty years, according to the GCMT catalog, exhibits an energetic rupture within a 35 km by 30 km slip patch and a high stress drop of 24 MPa. It is of interest to note that although complex rupture patterns are allowed to match the observations, the inverted slip distributions of these two earthquakes are simple enough to be approximated as the summation of a few circular/elliptical slip patches. Thus, we investigate subsequently their dynamic rupture models. We use a simple modelling approach in which we assume that the dynamic rupture propagation obeys a slip-weakening friction law, and we describe the distribution of stress and friction on the fault as a set of elliptical patches. We will constrain the three dynamic parameters that are yield stress, background stress prior to the rupture and slip weakening distance, as well as the shape of the elliptical patches directly from teleseismic body waves observations. The study would help us

  2. Seismicity associated with the Sumatra-Andaman Islands earthquake of 26 December 2004

    USGS Publications Warehouse

    Dewey, J.W.; Choy, G.; Presgrave, B.; Sipkin, S.; Tarr, A.C.; Benz, H.; Earle, P.; Wald, D.

    2007-01-01

    The U.S. Geological Survey/National Earthquake Information Center (USGS/ NEIC) had computed origins for 5000 earthquakes in the Sumatra-Andaman Islands region in the first 36 weeks after the Sumatra-Andaman Islands mainshock of 26 December 2004. The cataloging of earthquakes of mb (USGS) 5.1 and larger is essentially complete for the time period except for the first half-day following the 26 December mainshock, a period of about two hours following the Nias earthquake of 28 March 2005, and occasionally during the Andaman Sea swarm of 26-30 January 2005. Moderate and larger (mb ???5.5) aftershocks are absent from most of the deep interplate thrust faults of the segments of the Sumatra-Andaman Islands subduction zone on which the 26 December mainshock occurred, which probably reflects nearly complete release of elastic strain on the seismogenic interplate-thrust during the mainshock. An exceptional thrust-fault source offshore of Banda Aceh may represent a segment of the interplate thrust that was bypassed during the mainshock. The 26 December mainshock triggered a high level of aftershock activity near the axis of the Sunda trench and the leading edge of the overthrust Burma plate. Much near-trench activity is intraplate activity within the subducting plate, but some shallow-focus, near-trench, reverse-fault earthquakes may represent an unusual seismogenic release of interplate compressional stress near the tip of the overriding plate. The interplate-thrust Nias earthquake of 28 March 2005, in contrast to the 26 December aftershock sequence, was followed by many interplate-thrust aftershocks along the length of its inferred rupture zone.

  3. Comparative study of two tsunamigenic earthquakes in the Solomon Islands: 2015 Mw 7.0 normal-fault and 2013 Santa Cruz Mw 8.0 megathrust earthquakes

    NASA Astrophysics Data System (ADS)

    Heidarzadeh, Mohammad; Harada, Tomoya; Satake, Kenji; Ishibe, Takeo; Gusman, Aditya Riadi

    2016-05-01

    The July 2015 Mw 7.0 Solomon Islands tsunamigenic earthquake occurred ~40 km north of the February 2013 Mw 8.0 Santa Cruz earthquake. The proximity of the two epicenters provided unique opportunities for a comparative study of their source mechanisms and tsunami generation. The 2013 earthquake was an interplate event having a thrust focal mechanism at a depth of 30 km while the 2015 event was a normal-fault earthquake occurring at a shallow depth of 10 km in the overriding Pacific Plate. A combined use of tsunami and teleseismic data from the 2015 event revealed the north dipping fault plane and a rupture velocity of 3.6 km/s. Stress transfer analysis revealed that the 2015 earthquake occurred in a region with increased Coulomb stress following the 2013 earthquake. Spectral deconvolution, assuming the 2015 tsunami as empirical Green's function, indicated the source periods of the 2013 Santa Cruz tsunami as 10 and 22 min.

  4. Geologic Survey of the 2 April 2007 Solomon Islands Earthquake and Tsunami

    NASA Astrophysics Data System (ADS)

    Rafiau, W. B.; Jackson, K. L.; Billy, D.; Bonte-Grapentin, M.; Kruger, J.; McAdoo, B. G.; Moore, A. L.; Tiano, B.

    2007-12-01

    The 2 April 2007 magnitude 8.1 Solomon Islands earthquake and tsunami caused extensive damage to coral reefs, coastal erosion, and in some locations, 3 meters of uplift, subsidence, and numerous landslides in the Western and Choiseul Provinces. Extensive damage to the coral reefs ranged from shattered branching corals to 4 meter head corals snapped off their bases and toppled over. The fringing reef on the east coast of Ranongga sustained the greatest degree of damage as it was uplifted 3 m above sea level and remains completely exposed. Sediment samples were collected along transects extended from offshore to onshore environments for larger islands, such as Ghizo, where the tsunami did not pass over the entire island. Smaller islands, such as Nusa Aghana, a transect was conducted from the outer barrier reefs, through the lagoon, across the island, and offshore on the opposing side of the island. Offshore data was collected using a side-scan sonar system that records bathymetry and images coral reef morphology. This data was coupled with snorkeling and SCUBA diving to ground truth the offshore lagoon and reef environments. Sediment samples were collected offshore every 5 m and were documented by underwater photos and GPS coordinates. Offshore to onshore sediment transects reveal that sediment was eroded from seaward facing shorelines, deposited a thin veneer of sediment on islands, and transported the majority of the sediment on coral reefs on the lagoon side of islands, essentially burying coral and lagoonal sediment. Coral reef damaged by the earthquake and tsunami represents a major concern for an already threatened ecosystem. Recovery of the fishing and dive tourism economies rely on the healthy reestablishment of the reef.

  5. Paleo-earthquakes recorded on marine terrace in the Mumaung Island, western Myanmar

    NASA Astrophysics Data System (ADS)

    Shishikura, M.; Okamura, Y.; Fujino, S.; Win, N.; Soe, T. T.; Thura, A.

    2008-12-01

    We found geomorphological evidence of intermittent abrupt sea level changes associated with earthquakes that occurred along the Rakhine coast of western Myanmar, facing the plate-boundary north of the 2004 Sumatra-Andaman earthquake source. Based on air-photo interpretation, we identified Holocene marine terraces divided into at least four (partly six) steps that named L1-4 in descending order along the coast of the Mumaung Island. To measure its height and age, we conducted field survey at 5 sites in the island. The height of each steps are measured to be L1: 15-18m, L2: 12-14 m, L3: 7-10 m and L4: 3-5 m above mean sea level. The lowest terrace, L4, can be correlated to the 1762 Bengal earthquake because samples collected from in-situ uplifted oyster reef and micro atoll are dated to AD1430-1860 by AMS measurement. Amount of uplift of the 1762 event is estimated to 3-5 m in minimum, which is consistent with previous reports of Halsted (1843) and Mallet (1878). Higher terraces are radiocarbon-dated to be L2: AD 680-980 and L3: 150 BC-AD 60. Although reliable sample could not be obtained from the L1 terrace, it is probably correlated with the highest terrace along the coast of Phayonkar Islands, further north of the Mumaung Island, which was dated to 1295-600 BC by Aung et al. (2008). We thus conclude that large earthquake as well as the 1762 event accompanied with uplift of 3-5 m has recurred with interval of about 900 years.

  6. Crustal structure beneath the Japanese Islands inferred from receiver function analysis using similar earthquakes

    NASA Astrophysics Data System (ADS)

    Igarashi, Toshihiro

    2016-04-01

    The stress concentration and strain accumulation process due to inter-plate coupling of the subducting plate should have a large effect on inland shallow earthquakes that occur in the overriding plate. Information on the crustal structure and the crustal thickness is important to understanding their process. In this study, I applied receiver function analysis using similar earthquakes to estimate the crustal velocity structures beneath the Japanese Islands. Because similar earthquakes are caused repeatedly at almost the same place, they are useful for extracting information on spatial distribution and temporal changes of seismic velocity structures beneath the seismic stations. I used telemetric seismographic network data covered the Japanese Islands and moderate-sized similar earthquakes which occurred in the southern Hemisphere with epicentral distances between 30 and 90 degrees for about 26 years from October 1989. Data analysis was performed separately before and after the 2011 Tohoku-Oki earthquake. To identify the spatial distribution of crustal structure, I searched for the best-correlated model between an observed receiver function at each station and synthetic ones by using a grid search method. As results, I clarified the spatial distribution of the crustal velocity structures. The spatial patterns of velocities from the ground surface to 5 km deep are corresponding with basement depth models although the velocities are slower than those of tomography models. They indicate thick sediment layers in several plain and basin areas. The crustal velocity perturbations are consistent with existing tomography models. The active volcanoes correspond low-velocity zones from the upper crust to the crust-mantle transition. A comparison of the crustal structure before and after the 2011 Tohoku-Oki earthquake suggests that the northeastern Japan arc changed to lower velocities in some areas. This kind of velocity changes might be due to other effects such as changes of

  7. Crustal recycling and the aleutian arc

    SciTech Connect

    Kay, R.W.; Kay, S.M. )

    1988-06-01

    Two types of crustal recycling transfer continental crust back into its mantle source. The first of these, upper crustal recycling, involves elements that have been fractionated by the hydrosphere-sediment system, and are subducted as a part of the oceanic crust. The subduction process (S-process) then fractionates these elements, and those not removed at shallow tectonic levels and as excess components of arc magmas are returned to the mantle. Newly determined trace element composition of Pacific oceanic sedimants are variable and mixing is necessary during the S-process, if sediment is to provide excess element in the ratios observed in Aleutian arc magmas. Only a small fraction of the total sediment subducted at the Aleutian trench is required to furnish the excess elements in Aleutian arc magmas. Ba and {sub 10}Be data indicate that this small fraction includes a contribution from the youngest subducted sediment. The second type of recycling, lower crustal recycling, involves crystal cumulates of both arc and oceanic crustal origin, and residues from crustal melting within arc crust. Unlike the silicic sediments, recycled lower crust is mafic to ultramafic in composition. Trace element analyses of xenoliths representing Aleutian arc lower crust are presented. Recycling by delamination of lower crust and attached mantle lithosphere may occur following basalt eclogite phase transformations that are facilitated by terrane suturing events that weld oceanic island arcs to the continents. The relative importance of upper and lower crustal recycling exerts a primary control on continental crustal composition.

  8. 76 FR 33171 - Fisheries of the Exclusive Economic Zone Off Alaska; Alaska Plaice in the Bering Sea and Aleutian...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-06-08

    ... Economic Zone Off Alaska; Alaska Plaice in the Bering Sea and Aleutian Islands Management Area AGENCY... Bering Sea and Aleutian Islands management area (BSAI). This action is necessary to prevent exceeding the 2011 Alaska plaice total allowable catch (TAC) specified for the BSAI. DATES: Effective 1200...

  9. 76 FR 33172 - Fisheries of the Exclusive Economic Zone Off Alaska; Alaska Plaice in the Bering Sea and Aleutian...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-06-08

    ... Economic Zone Off Alaska; Alaska Plaice in the Bering Sea and Aleutian Islands Management Area AGENCY... of the non-specified reserve to the initial total allowable catch of Alaska plaice in the Bering Sea and Aleutian Islands management area (BSAI). This action is necessary to allow the fisheries...

  10. Handbook for Central Aleutian Site: The Aleuts of the Eighteenth Century, Social Studies Unit, Book IV.

    ERIC Educational Resources Information Center

    Partnow, Patricia H.

    Artifacts and animal remains found at the Central Aleutian Site are described. The site consists of a house pit and a midden, or refuse pile. The house and artifacts, used in the mid-1700s, were abandoned about the time the Russians first came to the Aleutian Islands. The following information is given for the different types of artifacts:…

  11. Damage to coastal villages due to the 1992 Flores Island earthquake tsunami

    NASA Astrophysics Data System (ADS)

    Tsuji, Yoshinobu; Matsutomi, Hideo; Imamura, Fumihiko; Takeo, Minoru; Kawata, Yoshiaki; Matsuyama, Masafumi; Takahashi, Tomoyuki; Sunarjo; Harjadi, Prih

    1995-09-01

    A field survey of the 1992 Flores Island earthquake tsunami was conducted during December 29, 1992 to January 5, 1993 along the north coast of the eastern part of Flores Island. We visited over 40 villages, measured tsunami heights, and interviewed the inhabitants. It was clarified that the first wave attacked the coast within five minutes at most of the surveyed villages. The crust was uplifted west of the Cape of Batumanuk, and subsided east of it. In the residential area of Wuring, which is located on a sand spit with ground height of 2 meters, most wooden houses built on stilts collapsed and 87 people were killed even though the tsunami height reached only 3.2 meters. In the two villages on Babi Island, the tsunami swept away all wooden houses and killed 263 of 1,093 inhabitants. Tsunami height at Riang-Kroko village on the northeastern end of Flores Island reached 26.2 meters and 137 of the 406 inhabitants were killed by the tsumani. Evidence of landslides was detected at a few points on the coast of Hading Bay, and the huge tsunami was probably formed by earthquake-induced landslides. The relationship between tsunami height and mortality was checked for seven villages. The efficiencies of trees arranged in front of coastal villages, and coral reefs in dissipating the tsunami energy are discussed.

  12. The Great 2006 and 2007 Kuril Earthquakes, Forearc Segmentation and Seismic Activity of the Central Kuril Islands Region

    NASA Astrophysics Data System (ADS)

    Baranov, B. V.; Ivashchenko, A. I.; Dozorova, K. A.

    2015-12-01

    We present a structural study of the Central Kuril Islands forearc region, where the great megathrust tsunamigenic earthquake ( M w 8.3) occurred on November 15, 2006. Based on new bathymetry and seismic profiles obtained during two research cruises of R/V Akademik Lavrentiev in 2005 and 2006, ten crustal segments with along-arc length ranging from 30 to 100 km, separated by NS- and NW-trending transcurrent faults were identified within the forearc region. The transcurrent faults may serve as barriers impeding stress transfer between the neighboring segments, so that stress accumulated within separate forearc segments is usually released by earthquakes of moderate-to-strong magnitudes. However, the great November 15, 2006 earthquake ruptured seven of the crustal segments probably following a 226-year gap since the last great earthquake in 1780. The geographic extent of earthquake rupture zones, aftershock areas and earthquake clusters correlate well with forearc crustal segments identified using the geophysical data. Based on segmented structure of the Central Kuril Islands forearc region, we consider and discuss three scenarios of a great earthquake occurrence within this area. Although the margin is segmented, we suggest that a rupture could occupy the entire seismic gap with a total length of about 500 km. In such a case, the earthquake magnitude M w might exceed 8.5, and such an event might generate tsunami waves significantly exceeding in height to those produced by the great 2006-2007 Kuril earthquakes.

  13. Earthquakes

    MedlinePlus

    An earthquake happens when two blocks of the earth suddenly slip past one another. Earthquakes strike suddenly, violently, and without warning at any time of the day or night. If an earthquake occurs in a populated area, it may cause ...

  14. Earthquakes

    MedlinePlus

    ... Thunderstorms & Lightning Tornadoes Tsunamis Volcanoes Wildfires Main Content Earthquakes Earthquakes are sudden rolling or shaking events caused ... at any time of the year. Before An Earthquake Look around places where you spend time. Identify ...

  15. Potential geologic hazards of North Aleutian shelf, Bristol Bay, Alaska

    SciTech Connect

    Molnia, B.F.; Schwab, W.C.

    1985-02-01

    Federal OSC lease sale 92, North Aleutian shelf, Alaska, is scheduled for April 1985. The area, located in the southeastern Bering Sea, has 3 basins with sedimentary thicknesses in excess of 4 km. Six geologic conditions that could cause problems during petroleum development are: (1) seismicity, (2) recent faulting, (3) gas-charged sediment, (4) bed forms and active sediment transport, (5) scours, and (6) volcanism. Since 1953, the region has a history of at least 10 shallow earthquakes, including a 1971 back-arc event with a Richter magnitude of 5.2. The largest event impacting the entire region, a Richter magnitude 8.7 earthquake, occurred in 1938. Normal faults are located along the southern edge of the St. George basin, and on the northeastern edge of the Amak basin. Many exhibit increased offset with depth, surficial sags, and small surficial cracks. Surprising was the absence of any evidence of sea-floor sediment instability. Sonar bright spots, and possible, near-surface gas-charged sediment occur west of Amak Island and north of Unimak Island. An area of megaripples and dunes covers more than 1500 km/sup 2/. Bed forms have spacings of 20-50 m and heights of 1-3 m. Observations suggest that coarse sand may be actively transported. Thousands of scours, many linear and parallel, some greater than 800 m long, 250 m wide, and incised up to 5 m, were identified. Pavlof, an Alaskan Peninsula active volcano, located 45 km northeast of Cold Bay, has a continuous history of steam release and occasional eruption. Lahars, nuee ardentes are unknown. None of the geologic conditions identified precludes petroleum development or production. The potential impact of these factors must, however, be included in planning for future petroleum activities.

  16. The isolated 678-km deep 30 May 2015 MW 7.9 Ogasawara (Bonin) Islands earthquake

    NASA Astrophysics Data System (ADS)

    Ye, L.; Lay, T.; Zhan, Z.; Kanamori, H.; Hao, J.

    2015-12-01

    Deep-focus earthquakes, located 300 to 700 km below the Earth's surface within sinking slabs of relatively cold oceanic lithosphere, are mysterious phenomena. Seismic radiation from deep events is essentially indistinguishable from that for shallow stick-slip frictional-sliding earthquakes, but the confining pressure and temperature are so high for deep-focus events that a distinct process is likely needed to account for their abrupt energy release. The largest recorded deep-focus earthquake (MW 7.9) in the Izu-Bonin slab struck on 30 May 2015 beneath the Ogasawara (Bonin) Islands, isolated from prior seismicity by over 100 km in depth, and followed by only 2 small aftershocks. Globally, this is the deepest (678 km) major (MW > 7) earthquake in the seismological record. Seismicity indicates along-strike contortion of the Izu-Bonin slab, with horizontal flattening near a depth of 550 km in the Izu region and progressive steepening to near-vertical toward the south above the location of the 2015 event. Analyses of a large global data set of P, SH and pP seismic phases using short-period back-projection, subevent directivity, and broadband finite-fault inversion indicate that the mainshock ruptured a shallowly-dipping fault plane with patchy slip that spread over a distance of ~40 km with variable expansion rate (~5 km/s down-dip initially, ~3 km/s up-dip later). During the 17 s rupture duration the radiated energy was ~3.3 x 1016 J and the stress drop was ~38 MPa. The radiation efficiency is moderate (0.34), intermediate to that of the 1994 Bolivia and 2013 Sea of Okhotsk MW 8.3 earthquakes, indicating a continuum of processes. The isolated occurrence of the event suggests that localized stress concentration associated with the pronounced deformation of the Izu-Bonin slab likely played a role in generating this major earthquake.

  17. Impacts of earthquake on atoll in Nansha Islands, South China Sea

    NASA Astrophysics Data System (ADS)

    Guo, Lei; Zhan, Wenhuan; Xiong, Lijia; Chen, Wujin; Yao, Yantao; Li, Jian

    2016-04-01

    Coral reef is a kind of rock soil masses. It is a special marine geotechnical medium, which are made up of the reef coral debris undergo very long geological age. Atoll is the predominant type of coral reefs in South China Sea. In recent years, there are more and more construction projects on the reef flat in Nansha Islands, South China Sea. Therefore, it is very important to estimate the stability of coral reefs, especially the atolls. According to the geological structure characters of atoll in Nansha Islands, a model of reef body is presented in this paper to study the influence of earthquake. Meanwhile, Geostudio, which is a popular geotechnical engineering simulation software, is used to stimulate the stress and deformation situation of reef body under different six kinds of earthquake intensity. The factor of safety can be calculated by the limit equilibrium method. And the possible scenario of earthquake-induced landslides and sliding scale can be defined through the Newmark sliding block method. The stress distribution and deformation behavior are studied. The main relations between atoll and earthquake are analyzed as follows: (1) the safety factor of reef slope exceeds 1.993 under self-gravity state; (2) It may cause slope's instability and bring slumping when the safety factor is less than one. The factor of safety decreases with increased earthquake intensity and it may fluctuate around a particular value when earthquake intensity continues to increase; (3) The smaller shallow landslide as new developed part of the reef is subject to collapse under earthquake action and the bigger slope of reef is more stable. The results show that it is feasible to evaluate the stability of coral reef by using geotechnical engineering simulation method, which can help to provide some information for construction on coral reefs in South China Sea. In the meantime,the authers wish to thank the National Natural Science Foundation of China (NO.41376063)and the National

  18. Improving three dimensional velocity model for Puerto Rico - Virgin Islands for rapid earthquake re-locations

    NASA Astrophysics Data System (ADS)

    Huerfano, V. A.; Lopez, A. M.; Castillo, L.; Baez-Sanchez, G.; Soto-Cordero, L.; Lin, G.; Zhang, Q.

    2010-12-01

    Puerto Rico and the Virgin Islands (PRVI) block lie on the northeastern boundary of the Caribbean plate, where active transpressional tectonics result in the deformation of the boundaries of this block. Every year hundreds of earthquakes occur within and around PRVI region and at least four destructive earthquakes after 1700 are documented in the historical records. The mission of the Puerto Rico Seismic Network (PRSN), Department of Geology of the University of Puerto Rico in Mayagüez is to detect, analyze, disseminate earthquake/tsunami messages and investigate the seismicity in the PR/VI. Currently the PRSN operates 30 seismic stations and receive real time stream from over 75 station installed around the Caribbean. 25 years worth of data recorded by the PRSN has been quality checked and compiled to constrain a new velocity structure using the tomographic package TomoDD. Currently at PRSN, the velocity structure to perform real-time determination of hypocenters consists of a 1-D model. Therefore, this ambitious tomographic study seek to produce a more comprehensive velocity model to be implemented at the PRSN for the daily earthquake locations. Results from this study are a collaborative effort between the University of Miami and the University of Puerto Rico - Mayaguez.

  19. Modern salt-marsh and tidal-flat foraminifera from Sitkinak and Simeonof Islands, southwestern Alaska

    USGS Publications Warehouse

    Kemp, Andrew C.; Engelhart, Simon E.; Culver, Stephen J.; Nelson, Alan R.; Briggs, Richard W.; Haeussler, Peter J.

    2013-01-01

    We describe the modern distribution of salt-marsh and tidal-flat foraminifera from Sitkinak Island (Trinity Islands) and Simeonof Island (Shumagin Islands), Alaska, to begin development of a dataset for later use in reconstructing relative sea-level changes caused by great earthquakes along the Alaska-Aleutian subduction zone. Dead foraminifera were enumerated from a total of 58 surface-sediment samples collected along three intertidal transects around a coastal lagoon on Sitkinak Island and two intertidal transects on Simeonof Island. Two distinctive assemblages of salt-marsh foraminifera were recognized on Sitkinak Island. Miliammina fusca dominated low-marsh settings and Balticammina pseudomacrescens dominated the high marsh. These two species make up >98% of individuals. On Simeonof Island, 93% of individuals in high-marsh settings above mean high water were B. pseudomacrescens. The tidal flat on Simeonof Island was dominated by Cibicides lobatulus (60% of individuals), but the lower limit of this species is subtidal and was not sampled. These results indicate that uplift or subsidence caused by repeated earthquakes along the Alaska-Aleutian subduction zone could be reconstructed in coastal sediments using alternating assemblages of near monospecific B. pseudomacrescens and low-marsh or tidal-flat foraminifera.

  20. The 7.2 magnitude earthquake, November 1975, Island of Hawaii

    USGS Publications Warehouse

    1976-01-01

    It was centered about 5 km beneath the Kalapana area on the southeastern coast of Hawaii, the largest island of the Hawaiian chain (Fig. 1) and was preceded by numerous foreshocks. The event was accompanied, or followed shortly, by a tsunami, large-scale ground movemtns, hundreds of aftershocks, an eruption in the summit caldera of Kilauea Volcano. The earthquake and the tsunami it generated produced about 4.1 million dollars in property damage, and the tsumani caused two deaths. Although we have some preliminary findings about the cause and effects of the earthquake, detailed scientific investigations will take many more months to complete. This article is condensed from a recent preliminary report (Tillings an others 1976)

  1. Earthquakes.

    ERIC Educational Resources Information Center

    Walter, Edward J.

    1977-01-01

    Presents an analysis of the causes of earthquakes. Topics discussed include (1) geological and seismological factors that determine the effect of a particular earthquake on a given structure; (2) description of some large earthquakes such as the San Francisco quake; and (3) prediction of earthquakes. (HM)

  2. Earthquakes.

    ERIC Educational Resources Information Center

    Pakiser, Louis C.

    One of a series of general interest publications on science topics, the booklet provides those interested in earthquakes with an introduction to the subject. Following a section presenting an historical look at the world's major earthquakes, the booklet discusses earthquake-prone geographic areas, the nature and workings of earthquakes, earthquake…

  3. Tsunami Runup in the Middle Kuril Islands from the Great Earthquake of 15 Nov 2006

    NASA Astrophysics Data System (ADS)

    Bourgeois, J.; Pinegina, T.; Razhegaeva, N.; Kaistrenko, V.; Levin, B.; Macinnes, B.; Kravchunovskaya, E.

    2007-12-01

    Two expeditions to the middle Kuril Islands [IMGG FED RAS, NSF Kurils Biocomplexity Project] in the summer of 2007 yielded tsunami runup and inundation measurements from the 15 Nov 2006 Mw 8.3 subduction-zone earthquake, and possibly from the 13 Jan 2007 Mw 8.1 earthquake seaward of the subduction zone. Both earthquakes produced measurable tsunamis in the far field, the 13 Jan tsunami significantly smaller; the 15 Nov tsunami did some damage in the harbor of Crescent City, CA. Ours are the first near-source measurements because no one lives in the middle Kurils. Moreover, because KBP visited many of the same sites in summer of 2006, we have numerous before-and-after comparisons, including quantified erosion. We measured 120 profiles and made more than 300 runup measurements. We found dramatic tsunami effects of erosion and deposition, with widespread runup of 8-12 m, up to about 20 m, between and including Simushir and Matua islands. In most cases, we measured runup with a transit and surveying rod, producing a topographic profile from sea level to the slope above runup indicators; in some cases, we used a hand level and tape. Runup/inundation criteria were generally subhorizontal lines of floatable debris, typically wood, plastic, glass floats, and styrofoam. Single occurrences, e.g., of a plastic bottle were not considered adequate. Corroborative evidence, not used independently, included limits of consistently oriented stems of tall grasses and flowers, limit of sand and gravel deposits above turf and dead vegetation, and elevation of fresh erosion of turf from slopes landward of the beach plain. Currently we are compiling, correcting and vetting our measurements, which will be submitted to online databases. Topographic profiles obviously had an effect on the data, with short, steep profiles generating high runup and short inundation; most beach-ridge profiles had longer inundation and shorter runup. However, at Ainu Bay on Matua Island, we found as much as 18

  4. Evolution of stickleback in 50 years on earthquake-uplifted islands

    PubMed Central

    Lescak, Emily A.; Bassham, Susan L.; Catchen, Julian; Gelmond, Ofer; Sherbick, Mary L.; von Hippel, Frank A.

    2015-01-01

    How rapidly can animal populations in the wild evolve when faced with sudden environmental shifts? Uplift during the 1964 Great Alaska Earthquake abruptly created freshwater ponds on multiple islands in Prince William Sound and the Gulf of Alaska. In the short time since the earthquake, the phenotypes of resident freshwater threespine stickleback fish on at least three of these islands have changed dramatically from their oceanic ancestors. To test the hypothesis that these freshwater populations were derived from oceanic ancestors only 50 y ago, we generated over 130,000 single-nucleotide polymorphism genotypes from more than 1,000 individuals using restriction site-associated DNA sequencing (RAD-seq). Population genomic analyses of these data support the hypothesis of recent and repeated, independent colonization of freshwater habitats by oceanic ancestors. We find evidence of recurrent gene flow between oceanic and freshwater ecotypes where they co-occur. Our data implicate natural selection in phenotypic diversification and support the hypothesis that the metapopulation organization of this species helps maintain a large pool of genetic variation that can be redeployed rapidly when oceanic stickleback colonize freshwater environments. We find that the freshwater populations, despite population genetic analyses clearly supporting their young age, have diverged phenotypically from oceanic ancestors to nearly the same extent as populations that were likely founded thousands of years ago. Our results support the intriguing hypothesis that most stickleback evolution in fresh water occurs within the first few decades after invasion of a novel environment. PMID:26668399

  5. Earthquakes

    ERIC Educational Resources Information Center

    Roper, Paul J.; Roper, Jere Gerard

    1974-01-01

    Describes the causes and effects of earthquakes, defines the meaning of magnitude (measured on the Richter Magnitude Scale) and intensity (measured on a modified Mercalli Intensity Scale) and discusses earthquake prediction and control. (JR)

  6. Earthquakes

    MedlinePlus

    ... and Cleanup Workers Hurricanes PSAs ASL Videos: Hurricanes Landslides & Mudslides Lightning Lightning Safety Tips First Aid Recommendations ... Disasters & Severe Weather Earthquakes Extreme Heat Floods Hurricanes Landslides Tornadoes Tsunamis Volcanoes Wildfires Winter Weather Earthquakes Language: ...

  7. Integrated Seismicity Model to Detect Pairs of Possible Interdependent Earthquakes and Its Application to Aftershocks of the 2011 Tohoku-Oki Earthquake and Sequence of the 2014 Kermadec and Rat Islands Earthquakes

    NASA Astrophysics Data System (ADS)

    Miyazawa, M.; Tamura, R.

    2015-12-01

    We introduce an integrated seismicity model to stochastically evaluate the time intervals of consecutive earthquakes at global scales, making it possible to detect a pair of earthquakes that are remotely located and possibly related to each other. The model includes seismicity in non-overlapping areas and comprehensively explains the seismicity on the basis of point process models, which include the stationary Poisson model, the aftershock decay model following Omori-Utsu's law, and/or the epidemic-type aftershock sequence (ETAS) model. By use of this model, we examine the possibility of remote triggering of the 2011 M6.4 eastern Shizuoka earthquake in the vicinity of Mt. Fuji that occurred 4 days after the Mw9.0 Tohoku-Oki earthquake and 4 minutes after the M6.2 off-Fukushima earthquake that located about 400 km away, and that of the 2014 Mw7.9 Rat Islands earthquake that occurred within one hour after the Mw6.7 Kermadec earthquake that located about 9,000 km away and followed two large (Mw6.9, 6.5) earthquakes in the region. Both target earthquakes occurred during the passage of surface waves propagating from the previous large events. We estimated probability that the time interval is shorter than that between consecutive events and obtained dynamic stress changes on the faults. The results indicate that the M6.4 eastern Shizuoka event may be rather triggered by the static stress changes from the Tohoku-Oki earthquake and that the Mw7.9 Rat Islands event may have been remotely triggered by the Kermadec events possibly via cyclic fatigue.

  8. Geophysical Investigation of the Wooded Island earthquake swarm, Hanford Site, Washington (Invited)

    NASA Astrophysics Data System (ADS)

    Blakely, R. J.; Weaver, C. S.; Wells, R. E.; Sherrod, B. L.; Rohay, A.; Wicks, C. W.

    2010-12-01

    Magnetic anomalies provide insights into possible tectonic causes of a swarm of over ~1500 shallow (<2 km deep) microearthquakes that occurred in 2009 on the Hanford Site, Washington. The swarm was concentrated in a 2 km2 area at Wooded Island in the Columbia River, about 16 km northeast of the Rattlesnake Mountain fault and 17 km south of the Gable Mountain fault. The largest earthquake was MW 3.0 and had first motion consistent with slip on a northwest-striking reverse fault. The swarm was accompanied by 35 mm of surface deformation observable in satellite interferometry, interpreted to be caused by ~50 mm of slip on a shallow, west-northwest-striking reverse fault and associated bedding-plane fault in underlying Columbia River Basalt Group (CRBG) [Wicks et al., in press]. A linear magnetic anomaly over the Yakima Ridge anticline 40 km northwest of Wooded Island extends southeastward beyond exposed CRBG, suggesting that anticlinal structures also extend southeastward in the subsurface. This interpretation is consistent with the depth to the top of CRBG as determined from closely spaced boreholes in this area [Thorne et al., 2006], which also define a subsurface ridge extending southeastward from Yakima Ridge, coincident with the magnetic anomaly, to about longitude 119°26'W. The CRBG ridge seen in borehole data does not obviously continue east of this longitude, but the magnetic anomaly continues discontinuously all the way to the Columbia River and beyond. The source of the anomaly is entirely concealed by Quaternary sediments, but subtle hints of surface uplift are seen in 7.5-minute topographic maps and in a discontinuous pattern of late Pleistocene Missoula flood deposits exposed through younger dune sands. The positive magnetic anomaly passes through the southern part of the Wooded Island earthquake swarm, where it strikes parallel to subtle patterns in the distribution of epicenters and is coincident with a northeast-side-up reverse fault interpreted from

  9. 75 FR 792 - Fisheries of the Economic Exclusive Zone Off Alaska; Pacific Cod in the Bering Sea and Aleutian...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-01-06

    ... Exclusive Zone Off Alaska; Pacific Cod in the Bering Sea and Aleutian Islands AGENCY: National Marine...: Temporary rule; modification of a closure. SUMMARY: NMFS is opening directed fishing for Pacific cod by catcher Pacific cod by catcher/processors using hook-and-line gear in the Bering Sea and Aleutian...

  10. 76 FR 59924 - Fisheries of the Exclusive Economic Zone Off Alaska; Sharks in the Bering Sea and Aleutian...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-09-28

    ... Economic Zone Off Alaska; Sharks in the Bering Sea and Aleutian Islands Management Area AGENCY: National...: Temporary rule; closure. SUMMARY: NMFS is prohibiting retention of sharks in the Bering Sea and Aleutian... sharks in the BSAI has been reached. DATES: Effective 1200 hrs, Alaska local time (A.l.t.), September...

  11. 78 FR 57097 - Fisheries of the Exclusive Economic Zone Off Alaska; Sharks in the Bering Sea and Aleutian...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-09-17

    ... Economic Zone Off Alaska; Sharks in the Bering Sea and Aleutian Islands Management Area AGENCY: National...: Temporary rule; closure. SUMMARY: NMFS is prohibiting retention of sharks in the Bering Sea and Aleutian... sharks in the BSAI has been reached. DATES: Effective 1200 hrs, Alaska local time (A.l.t.), September...

  12. Volcanic Tsunami Generation in the Aleutian Arc of Alaska

    NASA Astrophysics Data System (ADS)

    Waythomas, C. F.; Watts, P.

    2003-12-01

    , geological evidence of tsunamis, such as tsunami deposits on land, should be found in the area around Augustine Island. Paradoxically, unequivocal evidence for tsunami inundation has been found. Augustine Volcano is the most historically active volcano in the Cook Inlet region and a future tsunami from the volcano would have devastating consequences to villages, towns, oil-production facilities, and the fishing industry, especially if it occurred at high tide (the tidal range in this area is about 5 m). Numerical simulation experiments of tsunami generation, propagation and inundation using a subaerial debris avalanche source at Augustine volcano indicate only modest wave generation because of the shallow water surrounding the volcano (maximum water depth about 25 m). Lahar flows produced during eruptions at snow and ice clad volcanoes in the Aleutian arc also deliver copious amounts of sediment to the sea. These flows only rarely transform to subaqueous debris flows that may become tsunamigenic. However, the accumulation of loose, unconsolidated sediment on the continental shelf may lead to subaqueous debris flows and landslides if these deposits become mobilized by large earthquakes. Tsunamis produced by this mechanism could potentially reach coastlines all along the Pacific Rim. Finally, recent work in the western Aleutian Islands indicates that many of the island volcanoes in this area have experienced large-scale flank collapse. Because these volcanoes are surrounded by deep water, the tsunami hazard associated with a future sector collapse could be significant.

  13. Diverse deformation patterns of Aleutian volcanoes from InSAR

    USGS Publications Warehouse

    Lu, Zhiming; Dzurisin, D.; Wicks, C.; Power, J.

    2008-01-01

    Interferometric synthetic aperture radar (InSAR) is capable of measuring ground-surface deformation with centimeter-to-subcentimeter precision at a spatial resolution of tens of meters over an area of hundreds to thousands of square kilometers. With its global coverage and all-weather imaging capability, InSAR has become an increasingly important measurement technique for constraining magma dynamics of volcanoes over remote regions such as the Aleutian Islands. The spatial pattern of surface deformation data derived from InSAR images enables the construction of detailed mechanical models to enhance the study of magmatic processes. This paper summarizes the diverse deformation patterns of the Aleutian volcanoes observed with InSAR and demonstrates that deformation patterns and associated magma supply mechanisms in the Aleutians are diverse and vary between volcanoes. These findings provide a basis for improved models and better understanding of magmatic plumbing systems.

  14. Fault Segmentation and Earthquake Generation in the Transition from Strike-slip to Subduction Plate Motion, Saint Elias Orogen, Alaska and Yukon (Invited)

    NASA Astrophysics Data System (ADS)

    Bruhn, R. L.; Shennan, I.; Pavlis, T. L.

    2010-12-01

    The structural transition from strike-slip motion along the Fairweather transform fault to subduction on the Aleutian megathrust occurs within the collision zone between the Yakutat microplate and southern Alaska. The collision is marked by belts of thrust and strike-slip faulting both within the microplate and along its margins, forming a complex fault network that mechanically interacts with rupturing of the Aleutian megathrust on one hand, and the Fairweather transform fault on the other. For example, stress released by M8+ earthquakes within the central and eastern parts of the Yakutat microplate in 1899 may have constrained the 1964 rupture on the Aleutian megathrust to the western part of the microplate. However, megathrust earthquakes circa 900 BP and 1500 BP may have ruptured farther east than in 1964, generating earthquakes of significantly greater magnitude and tsunami potential. Structurally, the thrust-faulting earthquake of Sept. 10, 1899 occurred on faults that are loaded primarily by the Fairweather transform, but the earlier event of Sept. 4 is more closely linked to the Aleutian megathrust. Large reverse faults that rise off of the megathrust are superimposed on older structures within the microplate; creating complex duplex and wedge fault geometries beneath the mountains onshore that link to simpler fault propagation folds offshore. These lateral variations in fault network style correlate with 1) permanent uplift of the coast at ≈ 1 cm/yr in the Yakataga region of the microplate, 2) an abrupt change in structural style and orientation across the Kayak Island - Bering Glacier deformation zone, and 3) the seaward limit of ruptures in the 1899 earthquakes which occurred beneath the mountains onshore. Future goals include refining locations of earthquake source faults and determining the recurrence history of earthquakes within the Yakutat microplate. The history of rupturing within the microplate offshore is of particular interest given the

  15. Preliminary analysis of the earthquake (MW 8.1) and tsunami of April 1, 2007, in the Solomon Islands, southwestern Pacific Ocean

    USGS Publications Warehouse

    Fisher, Michael A.; Geist, Eric L.; Sliter, Ray; Wong, Florence L.; Reiss, Carol; Mann, Dennis M.

    2007-01-01

    On April 1, 2007, a destructive earthquake (Mw 8.1) and tsunami struck the central Solomon Islands arc in the southwestern Pacific Ocean. The earthquake had a thrust-fault focal mechanism and occurred at shallow depth (between 15 km and 25 km) beneath the island arc. The combined effects of the earthquake and tsunami caused dozens of fatalities and thousands remain without shelter. We present a preliminary analysis of the Mw-8.1 earthquake and resulting tsunami. Multichannel seismic-reflection data collected during 1984 show the geologic structure of the arc's frontal prism within the earthquake's rupture zone. Modeling tsunami-wave propagation indicates that some of the islands are so close to the earthquake epicenter that they were hard hit by tsunami waves as soon as 5 min. after shaking began, allowing people scant time to react.

  16. Impact of the earthquake and tsunami of December 26, 2004, on the groundwater regime at Neill Island (south Andaman).

    PubMed

    Singh, V S

    2008-10-01

    The aquifer and groundwater regime has been affected by the earthquake and tsunami of December 26, 2004, particularly on the islands and coastal regions of India. The groundwater regime on many islands of Andaman and Nicobar islands, which is the only source of fresh water on the islands, has been found to be deteriorated. Detailed hydrogeological studies have been carried out at one of the tiny islands of Andaman, namely Neill Island, and results have been compared with prior observations. It has been found that the shell limestone aquifer at a few places has developed cracks due to the earthquake and these openings have allowed quick movement of seawater into the aquifer resulting into deterioration of groundwater quality. In the places where the aquifer is at sea level, the tsunami waves have caused seawater ingress. Most parts of the island which have hard mudstone as a base and where the aquifer lies much above sea level, did not show any change in groundwater regime.

  17. Surface faults on Montague Island associated with the 1964 Alaska earthquake: Chapter G in The Alaska earthquake, March 27, 1964: regional effects

    USGS Publications Warehouse

    Plafter, George

    1967-01-01

    Two reverse faults on southwestern Montague Island in Prince William Sound were reactivated during the earthquake of March 27, 1964. New fault scarps, fissures, cracks, and flexures appeared in bedrock and unconsolidated surficial deposits along or near the fault traces. Average strike of the faults is between N. 37° E. and N. 47° E.; they dip northwest at angles ranging from 50° to 85°. The dominant motion was dip slip; the blocks northwest of the reactivated faults were relatively upthrown, and both blocks were upthrown relative to sea level. No other earthquake faults have been found on land. The Patton Bay fault on land is a complex system of en echelon strands marked by a series of spectacular landslides along the scarp and (or) by a zone of fissures and flexures on the upthrown block that locally is as much as 3,000 feet wide. The fault can be traced on land for 22 miles, and it has been mapped on the sea floor to the southwest of Montague Island an additional 17 miles. The maximum measured vertical component of slip is 20 to 23 feet and the maximum indicated dip slip is about 26 feet. A left-lateral strike-slip component of less than 2 feet occurs near the southern end of the fault on land where its strike changes from northeast to north. Indirect evidence from the seismic sea waves and aftershocks associated with the earthquake, and from the distribution of submarine scarps, suggests that the faulting on and near Montague Island occurred at the northeastern end of a reactivated submarine fault system that may extend discontinuously for more than 300 miles from Montague Island to the area offshore of the southeast coast of Kodiak Island. The Hanning Bay fault is a minor rupture only 4 miles long that is marked by an exceptionally well defined almost continuous scarp. The maximum measured vertical component of slip is 16⅓ feet near the midpoint, and the indicated dip slip is about 20 feet. There is a maximum left-lateral strike-slip component of one

  18. Intraslab rupture triggering megathrust rupture coseismically in the 17 December 2016 Solomon Islands Mw 7.9 earthquake

    NASA Astrophysics Data System (ADS)

    Lay, Thorne; Ye, Lingling; Ammon, Charles J.; Kanamori, Hiroo

    2017-02-01

    The 17 December 2016 Solomon Islands earthquake (Mw 7.9) initiated 103 km deep in the subducting Solomon Sea slab near the junction of the Solomon Islands and New Britain trenches. Most aftershocks are located near the Solomon Islands plate boundary megathrust west of Bougainville, where previous large interplate thrust faulting earthquakes occurred in 1995 (Mw 7.7) and 1971 (Mw 8.0). Teleseismic body wave modeling and aftershock relocations indicate that the initial 30 s of the 2016 rupture occurred over depths of 90 to 120 km on an intraslab fault dipping 30° to the southwest, almost perpendicular to the dipping slab interface. The next 50 s of rupture took place at depths of 32 to 47 km in the deeper (Domain C) portion of the overlying megathrust fault dipping 35° to the northeast. High susceptibility to triggering in the region accounts for this compound rupture of two separate fault planes.

  19. Damages in American Samoa due to the 29 September 2009 Samoa Islands Region Earthquake Tsunami

    NASA Astrophysics Data System (ADS)

    Okumura, Y.; Takahashi, T.; Suzuki, S.

    2009-12-01

    A large earthquake of Mw 8.0 occurred in Samoa Islands Region in the early morning on 29 September 2009 (local time). A Large Tsunami generated by the earthquake hit Samoa, American Samoa, Tonga. Total 192 people were died or missing in these three countries (22 October 2009). The authors surveyed in Tutuila Island, American Samoa from 6 to 8 in October 2009 with the aim to find out damages in the disaster. In American Samoa, death and missing toll was 35. The main findings are as follows; first, human damages were little for tsunami run-up height of about 4 to 6 meters and tsunami arrival time of about 20 minutes. We can suppose that residents evacuated quickly after feeling shaking or something. Secondly, houses were severely damaged in some low elevation coastal villages such as Amanave, Leone, Pago Pago, Tula and so on. Third, a power plant and an airport, which are important infrastructures in relief and recovery phase, were also severely damaged. Inundation depth at the power plant was 2.31 meters. A blackout in the daytime lasted when we surveyed. On the other hand, the airport could use already at that time. But it was closed on the first day in the disaster because of a lot of disaster debris on the runway carried by tsunami. Inundation depth at the airport fence was measured in 0.7 to 0.8 meters. Other countries in the south-western Pacific region may have power plants or airports with similar risk, so it should be assessed against future tsunami disasters. Inundated thermal power plant in Pago Pago Debris on runway in Tafuna Airport (Provided by Mr. Chris Soti, DPA)

  20. Identifying potential habitat for the endangered Aleutian shield fern using topographical characteristics

    USGS Publications Warehouse

    Duarte, Adam; Wolcott, Daniel M.; Chow, T. Edwin

    2012-01-01

    The Aleutian shield fern Polystichum aleuticum is endemic to the Aleutian archipelago of Alaska and is listed as endangered pursuant to the U.S. Endangered Species Act. Despite numerous efforts to discover new populations of this species, only four known populations are documented to date, and information is needed to prioritize locations for future surveys. Therefore, we incorporated topographical habitat characteristics (elevation, slope, aspect, distance from coastline, and anthropogenic footprint) found at known Aleutian shield fern locations into a Geographical Information System (GIS) model to create a habitat suitability map for the entirety of the Andreaonof Islands. A total of 18 islands contained 489.26 km2 of highly suitable and moderately suitable habitat when weighting each factor equally. This study reports a habitat suitability map for the endangered Aleutian shield fern using topographical characteristics, which can be used to assist current and future recovery efforts for the species.

  1. Properties of GPS noise at Japan islands before and after Tohoku mega-earthquake.

    PubMed

    Lyubushin, Alexey; Yakovlev, Pavel

    2014-01-01

    The field of 3-components GPS signals is analyzed for the network of 1203 stations at the Japanese islands from January 30 up to March 26, 2011. This time interval includes just over 40 days of observation before the Tohoku mega-earthquake on March 11, 2011 (M = 9.0) and nearly 16 days of observation following this event. The signals from each station are three-component time series with time step 30 minutes. We study the statistical properties of the random fluctuations of GPS signals before and after the seismic catastrophe after transition to increments. The values of wavelet-based spectral index for GPS noise components for each station were estimated separately for pieces of records before and after seismic event. The maps of the noise spectral index are constructed as the values for grid size of 50 × 50 nodes covering the region under study, based on information from 10 stations closest to each node. These maps clearly extract the region of future seismic catastrophe by relatively high noise spectral index. The using of principal components method distinguished this spatial anomaly more explicitly. These results support the hypothesis that statistical properties of random fluctuations of geophysical fields carry important information about earthquake preparation.

  2. Massive edifice failure at Aleutian arc volcanoes

    USGS Publications Warehouse

    Coombs, M.L.; White, S.M.; Scholl, D. W.

    2007-01-01

    Along the 450-km-long stretch of the Aleutian volcanic arc from Great Sitkin to Kiska Islands, edifice failure and submarine debris-avalanche deposition have occurred at seven of ten Quaternary volcanic centers. Reconnaissance geologic studies have identified subaerial evidence for large-scale prehistoric collapse events at five of the centers (Great Sitkin, Kanaga, Tanaga, Gareloi, and Segula). Side-scan sonar data collected in the 1980s by GLORIA surveys reveal a hummocky seafloor fabric north of several islands, notably Great Sitkin, Kanaga, Bobrof, Gareloi, Segula, and Kiska, suggestive of landslide debris. Simrad EM300 multibeam sonar data, acquired in 2005, show that these areas consist of discrete large blocks strewn across the seafloor, supporting the landslide interpretation from the GLORIA data. A debris-avalanche deposit north of Kiska Island (177.6?? E, 52.1?? N) was fully mapped by EM300 multibeam revealing a hummocky surface that extends 40??km from the north flank of the volcano and covers an area of ??? 380??km2. A 24-channel seismic reflection profile across the longitudinal axis of the deposit reveals a several hundred-meter-thick chaotic unit that appears to have incised into well-bedded sediment, with only a few tens of meters of surface relief. Edifice failures include thin-skinned, narrow, Stromboli-style collapse as well as Bezymianny-style collapse accompanied by an explosive eruption, but many of the events appear to have been deep-seated, removing much of an edifice and depositing huge amounts of debris on the sea floor. Based on the absence of large pyroclastic sheets on the islands, this latter type of collapse was not accompanied by large eruptions, and may have been driven by gravity failure instead of magmatic injection. Young volcanoes in the central and western portions of the arc (177?? E to 175?? W) are located atop the northern edge of the ??? 4000-m-high Aleutian ridge. The position of the Quaternary stratocones relative to the

  3. Vulnerability of Eastern Caribbean Islands Economies to Large Earthquakes: The Trinidad and Tobago Case Study

    NASA Astrophysics Data System (ADS)

    Lynch, L.

    2015-12-01

    The economies of most of the Anglo-phone Eastern Caribbean islands have tripled to quadrupled in size since independence from England. There has also been commensurate growth in human and physical development as indicated by macro-economic indices such as Human Development Index and Fixed Capital Formation. A significant proportion of the accumulated wealth is invested in buildings and infrastructure which are highly susceptible to strong ground motion since the region is located along an active plate boundary. In the case of Trinidad and Tobago, Fixed Capital Formation accumulation since 1980 is almost US200 billion dollars. Recent studies have indicated that this twin island state is at significant risk from several seismic sources, both on land and offshore. To effectively mitigate the risk it is necessary to prescribe long-term measures such as the development and implementation of building code and standards, structural retrofitting, land use planning, preparedness planning and risk transfer mechanisms. The record has shown that Trinidad and Tobago has been been slow in the prescribing such measures which has consequently compounded it vulnerability to large earthquakes. This assessment reveals that the losses from a large (magnitude 7+) on land or an extreme (magnitude 8+) event could result in losses of up to US28B and that current risk transfer measures will only cater for less than ten percent of such losses.

  4. Reconnaissance engineering geology of the Metlakatla area, Annette Island, Alaska, with emphasis on evaluation of earthquakes and other geologic hazards

    USGS Publications Warehouse

    Yehle, Lynn A.

    1977-01-01

    A program to study the engineering geology of most larger Alaska coastal communities and to evaluate their earthquake and other geologic hazards was started following the 1964 Alaska earthquake; this report about the Metlakatla area, Annette Island, is a product of that program. Field-study methods were of a reconnaissance nature, and thus the interpretations in the report are tentative. Landscape of the Metlakatla Peninsula, on which the city of Metlakatla is located, is characterized by a muskeg-covered terrane of very low relief. In contrast, most of the rest of Annette Island is composed of mountainous terrane with steep valleys and numerous lakes. During the Pleistocene Epoch the Metlakatla area was presumably covered by ice several times; glaciers smoothed the present Metlakatla Peninsula and deeply eroded valleys on the rest. of Annette Island. The last major deglaciation was completed probably before 10,000 years ago. Rebound of the earth's crust, believed to be related to glacial melting, has caused land emergence at Metlakatla of at least 50 ft (15 m) and probably more than 200 ft (61 m) relative to present sea level. Bedrock in the Metlakatla area is composed chiefly of hard metamorphic rocks: greenschist and greenstone with minor hornfels and schist. Strike and dip of beds are generally variable and minor offsets are common. Bedrock is of late Paleozoic to early Mesozoic age. Six types of surficial geologic materials of Quaternary age were recognized: firm diamicton, emerged shore, modern shore and delta, and alluvial deposits, very soft muskeg and other organic deposits, and firm to soft artificial fill. A combination map unit is composed of bedrock or diamicton. Geologic structure in southeastern Alaska is complex because, since at least early Paleozoic time, there have been several cycles of tectonic deformation that affected different parts of the region. Southeastern Alaska is transected by numerous faults and possible faults that attest to major

  5. Earthquake!

    ERIC Educational Resources Information Center

    Hernandez, Hildo

    2000-01-01

    Examines the types of damage experienced by California State University at Northridge during the 1994 earthquake and what lessons were learned in handling this emergency are discussed. The problem of loose asbestos is addressed. (GR)

  6. Earthquakes

    USGS Publications Warehouse

    Shedlock, Kaye M.; Pakiser, Louis Charles

    1998-01-01

    One of the most frightening and destructive phenomena of nature is a severe earthquake and its terrible aftereffects. An earthquake is a sudden movement of the Earth, caused by the abrupt release of strain that has accumulated over a long time. For hundreds of millions of years, the forces of plate tectonics have shaped the Earth as the huge plates that form the Earth's surface slowly move over, under, and past each other. Sometimes the movement is gradual. At other times, the plates are locked together, unable to release the accumulating energy. When the accumulated energy grows strong enough, the plates break free. If the earthquake occurs in a populated area, it may cause many deaths and injuries and extensive property damage. Today we are challenging the assumption that earthquakes must present an uncontrollable and unpredictable hazard to life and property. Scientists have begun to estimate the locations and likelihoods of future damaging earthquakes. Sites of greatest hazard are being identified, and definite progress is being made in designing structures that will withstand the effects of earthquakes.

  7. Magnitudes and moment-duration scaling of low-frequency earthquakes beneath southern Vancouver Island

    NASA Astrophysics Data System (ADS)

    Bostock, M. G.; Thomas, A. M.; Savard, G.; Chuang, L.; Rubin, A. M.

    2015-09-01

    We employ 130 low-frequency earthquake (LFE) templates representing tremor sources on the plate boundary below southern Vancouver Island to examine LFE magnitudes. Each template is assembled from hundreds to thousands of individual LFEs, representing over 269,000 independent detections from major episodic-tremor-and-slip (ETS) events between 2003 and 2013. Template displacement waveforms for direct P and S waves at near epicentral distances are remarkably simple at many stations, approaching the zero-phase, single pulse expected for a point dislocation source in a homogeneous medium. High spatiotemporal precision of template match-filtered detections facilitates precise alignment of individual LFE detections and analysis of waveforms. Upon correction for 1-D geometrical spreading, attenuation, free surface magnification and radiation pattern, we solve a large, sparse linear system for 3-D path corrections and LFE magnitudes for all detections corresponding to a single-ETS template. The spatiotemporal distribution of magnitudes indicates that typically half the total moment release occurs within the first 12-24 h of LFE activity during an ETS episode when tidal sensitivity is low. The remainder is released in bursts over several days, particularly as spatially extensive rapid tremor reversals (RTRs), during which tidal sensitivity is high. RTRs are characterized by large-magnitude LFEs and are most strongly expressed in the updip portions of the ETS transition zone and less organized at downdip levels. LFE magnitude-frequency relations are better described by power law than exponential distributions although they exhibit very high b values ≥˜5. We examine LFE moment-duration scaling by generating templates using detections for limiting magnitude ranges (MW<1.5, MW≥2.0). LFE duration displays a weaker dependence upon moment than expected for self-similarity, suggesting that LFE asperities are limited in fault dimension and that moment variation is dominated by

  8. ICESat Observations of Topographic Change in the Northern Segment of the 2004 Sumatra-Andaman Islands Earthquake Rupture Zone

    NASA Technical Reports Server (NTRS)

    Harding, David; Sauber, J.; Luthcke, S.; Carabajal, C.; Muller, J

    2005-01-01

    The Andaman Islands are located 120 km east of the Sunda trench in the northern quarter of the 1300 km long rupture zone of the 2004 Sumatra-Andaman Islands earthquake inferred from the distribution of aftershocks. Initial field reports indicate that several meters of uplift and up to a meter of submergence occurred on the western and eastern shorelines of the Andaman Islands, respectively, associated with the earthquake (Bilham, 2005). Satellite images also document uplift of western shoreline coral reef platforms above sea level. Body-wave (Ji, 2005; Yamamaka, 2005) and tide-gauge (Ortiz, 2005) slip inversions only resolve coseismic slip in the southern one-third to one-half of the rupture zone. The amount of coseismic slip in the Andaman Islands region is poorly constrained by these inversions. The Ice, Cloud, and land Elevation Satellite (ICESat), a part of the NASA Earth Observing System, is being used to document the spatial pattern of Andaman Islands vertical displacements in order to constrain models of slip distribution in the northern part of the rupture zone. ICESat carries the Geoscience Laser Altimeter System (GLAS) that obtains elevation measurements from 80 m diameter footprints spaced 175 m apart along profiles. For surfaces of low slope, single-footprint absolute elevation and horizontal accuracies of 10 cm and 6 m (1 sigma), respectively, referenced to the ITRF 2002 TOPEX/Poseidon ellipsoid are being obtained. Laser pulse backscatter waveforms enable separation of ground topography and overlying vegetation cover. During each 33-day observing period ICESat acquires three profiles crossing the Andaman Islands. A NNE-SSW oriented track consists of 1600 laser footprints along the western side of North, Middle, and South Andaman Islands and 240 laser footprints across the center of Great Andaman Island. Two NNW-SSE tracks consist of 440 footprints across Middle Andaman Island and 25 footprints across the west side of Sentinel Island. Cloud

  9. Spatial distributions of earthquake-induced landslides and hillslope preconditioning in the northwest South Island, New Zealand

    NASA Astrophysics Data System (ADS)

    Parker, R. N.; Hancox, G. T.; Petley, D. N.; Massey, C. I.; Densmore, A. L.; Rosser, N. J.

    2015-10-01

    Current models to explain regional-scale landslide events are not able to account for the possible effects of the legacy of previous earthquakes, which have triggered landslides in the past and are known to drive damage accumulation in brittle hillslope materials. This paper tests the hypothesis that spatial distributions of earthquake-induced landslides are determined by both the conditions at the time of the triggering earthquake (time-independent factors) and the legacy of past events (time-dependent factors). To explore this, we undertake an analysis of failures triggered by the 1929 Buller and 1968 Inangahua earthquakes, in the northwest South Island of New Zealand. The spatial extents of landslides triggered by these events were in part coincident. Spatial distributions of earthquake-triggered landslides are determined by a combination of earthquake and local characteristics, which influence the dynamic response of hillslopes. To identify the influence of a legacy from past events, we first use logistic regression to control for the effects of time-independent variables. Through this analysis we find that seismic ground motion, hillslope gradient, lithology, and the effects of topographic amplification caused by ridge- and slope-scale topography exhibit a consistent influence on the spatial distribution of landslides in both earthquakes. We then assess whether variability unexplained by these variables may be attributed to the legacy of past events. Our results suggest that hillslopes in regions that experienced strong ground motions in 1929 were more likely to fail in 1968 than would be expected on the basis of time-independent factors alone. This effect is consistent with our hypothesis that unfailed hillslopes in the 1929 earthquake were weakened by damage accumulated during this earthquake and its associated aftershock sequence, which influenced the behaviour of the landscape in the 1968 earthquake. While our results are tentative, they suggest that the

  10. A Study of Low-Frequency Earthquake Magnitudes in Northern Vancouver Island

    NASA Astrophysics Data System (ADS)

    Chuang, L. Y.; Bostock, M. G.

    2015-12-01

    Tectonic tremor and low frequency earthquakes (LFE) have been extensively studied in recent years in northern Washington and southern Vancouver Island (VI). However, far less attention has been directed to northern VI where the behavior of tremor and LFEs is less well documented. We investigate LFE properties in this latter region by assembling templates using data from the POLARIS-NVI and Sea-JADE experiments. The POLARIS-NVI experiment comprised 27 broadband seismometers arranged along two mutually perpendicular arms with an aperture of ~60 km centered near station WOS (lat. 50.16, lon. -126.57). It recorded two ETS events in June 2006 and May 2007, each with duration less than a week. For these two episodes, we constructed 68 independent, high signal to noise ratio LFE templates representing spatially distinct asperities on the plate boundary in NVI, along with a catalogue of more than 30 thousand detections. A second data set is being prepared for the complementary 2014 Sea-JADE data set. The precisely located LFE templates represent simple direct P-waves and S-waves at many stations thereby enabling magnitude estimation of individual detections. After correcting for radiation pattern, 1-D geometrical spreading, attenuation and free-surface magnification, we solve a large, sparse linear system for 3-D path corrections and LFE magnitudes for all detections corresponding to a single LFE template. LFE magnitudes range up to 2.54, and like southern VI are characterized by high b-values (b~8). In addition, we will quantify LFE moment-duration scaling and compare with southern Vancouver Island where LFE moments appear to be controlled by slip, largely independent of fault area.

  11. Seasonal and distributional patterns of seabirds along the Aleutian Archipelago

    USGS Publications Warehouse

    Renner, M.; Hunt, G.L.; Piatt, J.F.; Byrd, G.V.

    2008-01-01

    The Aleutian Archipelago is of global importance to seabirds during the northern summer, but little is known about seabird use of these waters during winter. We compare summer and winter abundances of seabirds around 3 islands: Buldir in the western, Kasatochi in the central, and Aiktak in the eastern Aleutians. The density of combined seabird biomass in nearshore marine waters was higher in summer than in winter at Buldir and Kasatochi, but was higher in winter at Aiktak, despite the departure of abundant migratory species. Comparing foraging guilds, we found that only piscivores increased at the western and central sites in winter, whereas at the eastern site several planktivorous species increased as well. The only planktivore remaining in winter at the central and western sites in densities comparable to summer densities was whiskered auklet Aethia pygmaea. Crested auklet Aethia cristatella and thick-billed murre Uria lomvia showed the greatest proportional winter increase at the eastern site. The seasonal patterns of the seabird communities suggest a winter breakdown of the copepod-based food web in the central and western parts of the archipelago, and a system that remains rich in euphausiids in the eastern Aleutians. We suggest that in winter crested auklets take the trophic role that short-tailed shearwaters Puffinus tenuirostris occupy during summer. We hypothesize that advection of euphausiids in the Aleutian North Slope Current is important for supporting the high biomass of planktivores that occupy the Unimak Pass region on a year-round basis. ?? Inter-Research 2008.

  12. Tohoku-Oki Earthquake Tsunami Runup and Inundation Data for Sites Around the Island of Hawaiʻi

    USGS Publications Warehouse

    Trusdell, Frank A.; Chadderton, Amy; Hinchliffe, Graham; Hara, Andrew; Patenge, Brent; Weber, Tom

    2012-01-01

    At 0546 U.t.c. March 11, 2011, a Mw 9.0 ("great") earthquake occurred near the northeast coast of Honshu Island, Japan, generating a large tsunami that devastated the east coast of Japan and impacted many far-flung coastal sites around the Pacific Basin. After the earthquake, the Pacific Tsunami Warning Center issued a tsunami alert for the State of Hawaii, followed by a tsunami-warning notice from the local State Civil Defense on March 10, 2011 (Japan is 19 hours ahead of Hawaii). After the waves passed the islands, U.S. Geological Survey (USGS) scientists from the Hawaiian Volcano Observatory (HVO) measured inundation (maximum inland distance of flooding), runup (elevation at maximum extent of inundation) and took photographs in coastal areas around the Island of Hawaiʻi. Although the damage in West Hawaiʻi is well documented, HVO's mapping revealed that East Hawaiʻi coastlines were also impacted by the tsunami. The intent of this report is to provide runup and inundation data for sites around the Island of Hawaiʻi.

  13. Uplift and subsidence reveal a nonpersistent megathrust rupture boundary (Sitkinak Island, Alaska)

    USGS Publications Warehouse

    Briggs, Richard W.; Engelhart, Simon E.; Nelson, Alan R.; Dura, Tina; Kemp, Andrew C.; Haeussler, Peter J.; Corbett, D. Reide; Angster, Stephen J.; Bradley, Lee-Ann

    2014-01-01

    We report stratigraphic evidence of land-level change and tsunami inundation along the Alaska-Aleutian megathrust during prehistoric and historical earthquakes west of Kodiak Island. On Sitkinak Island, cores and tidal outcrops fringing a lagoon reveal five sharp lithologic contacts that record coseismic land-level change. Radiocarbon dates, 137Cs profiles, CT scans, and microfossil assemblages are consistent with rapid uplift ca. 290-0, 520-300, and 1050-790 cal yr BP, and subsidence in AD 1964 and ca. 640-510 cal yr BP. Radiocarbon, 137Cs, and 210Pb ages bracketing a sand bed traced 1.5 km inland and evidence for sudden uplift are consistent with Russian accounts of an earthquake and tsunami in AD 1788. The mixed uplift and subsidence record suggests that Sitkinak Island sits above a non-persistent boundary near the southwestern limit of the AD 1964 Mw 9.2 megathrust rupture.

  14. Polycyclic aromatic hydrocarbon exposure in Steller's eiders (Polysticta stelleri) and harlequin ducks (Histronicus histronicus) in the Eastern Aleutian Islands, Alaska, USA

    USGS Publications Warehouse

    Miles, A.K.; Flint, P.L.; Trust, K.A.; Ricca, M.A.; Spring, S.E.; Arrieta, D.E.; Hollmen, T.; Wilson, B.W.

    2007-01-01

    Seaducks may be affected by harmful levels of polycyclic aromatic hydrocarbons (PAHs) at seaports near the Arctic. As an indicator of exposure to PAHs, we measured hepatic enzyme 7-ethoxyresorufin-O-deethylase activity (EROD) to determine cytochrome P4501A induction in Steller's eiders (Polysticta stelleri) and Harlequin ducks (Histronicus histronicus) from Unalaska, Popof, and Unga Islands (AK, USA) in 2002 and 2003. We measured PAHs and organic contaminants in seaduck prey samples and polychlorinated biphenyl congeners in seaduck blood plasma to determine any relationship to EROD. Using Akaike's information criterion, species and site differences best explained EROD patterns: Activity was higher in Harlequin ducks than in Steller's eiders and higher at industrial than at nonindustrial sites. Site-specific concentrations of PAHs in blue mussels ([Mytilus trossilus] seaduck prey; PAH concentrations higher at Dutch Harbor, Unalaska, than at other sites) also was important in defining EROD patterns. Organochlorine compounds rarely were detected in prey samples. No relationship was found between polychlorinated biphenyl congeners in avian blood and EROD, which further supported inferences derived from Akaike's information criterion. Congeners were highest in seaducks from a nonindustrial or reference site, contrary to PAH patterns. To assist in interpreting the field study, 15 captive Steller's eiders were dosed with a PAH known to induce cytochrome P4501A. Dosed, captive Steller's eiders had definitive induction, but results indicated that wild Steller's eiders were exposed to PAHs or other inducing compounds at levels greater than those used in laboratory studies. Concentrations of PAHs in blue mussels at or near Dutch Harbor (∼1,180–5,980 ng/g) approached those found at highly contaminated sites (∼4,100–7,500 ng/g).

  15. Earthquakes

    EPA Pesticide Factsheets

    Information on this page will help you understand environmental dangers related to earthquakes, what you can do to prepare and recover. It will also help you recognize possible environmental hazards and learn what you can do to protect you and your family

  16. Environmental contaminants in bald eagle eggs from the Aleutian archipelago.

    PubMed

    Anthony, Robert G; Miles, A Keith; Ricca, Mark A; Estes, James A

    2007-09-01

    We collected 136 fresh and unhatched eggs from bald eagle (Haliaeetus leucocephalus) nests and assessed productivity on eight islands in the Aleutian archipelago, 2000 to 2002. Egg contents were analyzed for a broad spectrum of organochlorine (OC) contaminants, mercury (Hg), and stable isotopes of carbon (delta13C) and nitrogen (delta15N). Concentrations of polychlorinated biphenyls (SigmaPCBs), p,p'-dichlorodiphenyldichloroethylene (DDE), and Hg in bald eagle eggs were elevated throughout the archipelago, but the patterns of distribution differed among the various contaminants. Total PCBs were highest in areas of past military activities on Adak and Amchitka Islands, indicating local point sources of these compounds. Concentrations of DDE and Hg were higher on Amchitka Island, which was subjected to much military activity during World War II and the middle of the 20th century. Concentrations of SigmaPCBs also were elevated on islands with little history of military activity (e.g., Amlia, Tanaga, Buldir), suggesting non-point sources of PCBs in addition to point sources. Concentrations of DDE and Hg were highest in eagle eggs from the most western Aleutian Islands (e.g., Buldir, Kiska) and decreased eastward along the Aleutian chain. This east-to-west increase suggested a Eurasian source of contamination, possibly through global transport and atmospheric distillation and/or from migratory seabirds. Eggshell thickness and productivity of bald eagles were normal and indicative of healthy populations because concentrations of most contaminants were below threshold levels for effects on reproduction. Contrary to our predictions, contaminant concentrations were not correlated with stable isotopes of carbon (delta13C) or nitrogen (delta15N) in eggs. These latter findings indicate that contaminant concentrations were influenced more by point sources and geographic location than trophic status of eagles among the different islands.

  17. Environmental contaminants in bald eagle eggs from the Aleutian archipelago

    USGS Publications Warehouse

    Anthony, R.G.; Miles, A.K.; Ricca, M.A.; Estes, J.A.

    2007-01-01

    We collected 136 fresh and unhatched eggs from bald eagle (Haliaeetus leucocephalus) nests and assessed productivity on eight islands in the Aleutian archipelago, 2000 to 2002. Egg contents were analyzed for a broad spectrum of organochlorine (OC) contaminants, mercury (Hg), and stable isotopes of carbon (??13C) and nitrogen (??15N). Concentrations of polychlorinated biphenyls (??PCBs), p,p???- dichlorodiphenyldichloroethylene (DDE), and Hg in bald eagle eggs were elevated throughout the archipelago, but the patterns of distribution differed among the various contaminants. Total PCBs were highest in areas of past military activities on Adak and Amchitka Islands, indicating local point sources of these compounds. Concentrations of DDE and Hg were higher on Amchitka Island, which was subjected to much military activity during World War II and the middle of the 20th century. Concentrations of ??PCBs also were elevated on islands with little history of military activity (e.g., Amlia, Tanaga, Buldir), suggesting non-point sources of PCBs in addition to point sources. Concentrations of DDE and Hg were highest in eagle eggs from the most western Aleutian Islands (e.g., Buldir, Kiska) and decreased eastward along the Aleutian chain. This east-to-west increase suggested a Eurasian source of contamination, possibly through global transport and atmospheric distillation and/or from migratory seabirds. Eggshell thickness and productivity of bald eagles were normal and indicative of healthy populations because concentrations of most contaminants were below threshold levels for effects on reproduction. Contrary to our predictions, contaminant concentrations were not correlated with stable isotopes of carbon (??13C) or nitrogen (??15N) in eggs. These latter findings indicate that contaminant concentrations were influenced more by point sources and geographic location than trophic status of eagles among the different islands. ?? 2007 SETAC.

  18. Fault plane modelling of the 2003 August 14 Lefkada Island (Greece) earthquake based on the analysis of ENVISAT SAR interferograms

    NASA Astrophysics Data System (ADS)

    Ilieva, M.; Briole, P.; Ganas, A.; Dimitrov, D.; Elias, P.; Mouratidis, A.; Charara, R.

    2016-12-01

    On 2003 August 14, a Mw = 6.2 earthquake occurred offshore the Lefkada Island in the eastern Ionian Sea, one of the most seismically active areas in Europe. The earthquake caused extended damages in the island, and a number of ground failures, especially along the north-western coast. Seven ascending ENVISAT/ASAR images are used to process six co-seismic interferograms. The ROI-PAC package is used for interferogram generation with the SRTM DEM applied in a two-pass method. The formation of the co-seismic pairs is limited due to the existence of one pre-seismic image only. Dense vegetation is covering the island, which is an obstacle in getting good coherence, since C-band images are used. Nevertheless, ground deformation, of > 56 mm (two fringes) in the line of sight of the satellite, is detected in all six co-seismic interferograms. By inversion of the data from the observed fringes, a best fitting model of the activated fault is calculated assuming a dislocation in an elastic half space. The inferred fault is a pure dextral strike-slip fault, dipping 59 ± 5° eastward, 16 ± 2 km long and 10 ± 2 km wide. It is located north of the fault of the Mw = 6.5 2015 November 17 earthquake, and a 10-15 km gap remains between the two faults. The 2003 fault does not reach the surface and its upper edge is at a depth of 3.5 ± 1 km. No evidence is found of slip south of the Lefkada Island as suggested by some seismological studies.

  19. Magnitudes and Moment-Duration Scaling of Low-Frequency Earthquakes Beneath Southern Vancouver Island

    NASA Astrophysics Data System (ADS)

    Bostock, M. G.; Thomas, A.; Rubin, A. M.; Savard, G.; Chuang, L. Y.

    2015-12-01

    We employ 130 low-frequency-earthquake (LFE) templates representing tremor sources on the plate boundary below southern Vancouver Island to examine LFE magnitudes. Each template is assembled from 100's to 1000's of individual LFEs, representing over 300,000 independent detections from major episodic-tremor-and- slip (ETS) events between 2003 and 2013. Template displacement waveforms for direct P- and S-waves at near epicentral distances are remarkably simple at many stations, approaching the zero-phase, single pulse expected for a point dislocation source in a homogeneous medium. High spatio-temporal precision of template match-filtered detections facilitates precise alignment of individual LFE detections and analysis of waveforms. Upon correction for 1-D geometrical spreading, attenuation, free-surface magnification and radiation pattern, we solve a large, sparse linear system for 3-D path corrections and LFE magnitudes for all detections corresponding to a single ETS template. The spatio-temporal distribution of magnitudes indicates that typically half the total moment release occurs within the first 12-24 hours of LFE activity during an ETS episode when tidal sensitity is low. The remainder is released in bursts over several days, particularly as spatially extensive RTRs, during which tidal sensitivity is high. RTR's are characterized by large magnitude LFEs, and are most strongly expressed in the updip portions of the ETS transition zone and less organized at downdip levels. LFE magnitude-frequency relations are better described by power-law than exponential distributions although they exhibit very high b-values ≥ 6. We examine LFE moment-duration scaling by generating templates using detections for limiting magnitude ranges MW<1.5, MW≥ 2.0. LFE duration displays a weaker dependence upon moment than expected for self-similarity, suggesting that LFE asperities are limited in dimension and that moment variation is dominated by slip. This behaviour implies

  20. A Large Refined Catalog of Earthquake Relocations and Focal Mechanisms for the Entire Island of Hawaii and Their Seismotectonic Implications

    NASA Astrophysics Data System (ADS)

    Lin, G.; Okubo, P.

    2015-12-01

    We present a refined catalog of earthquake locations and focal mechanisms for the Island of Hawaii, focusing on Mauna Loa and Kilauea volcanoes. The location catalog is based on first-arrival times and waveform data of both compressional and shear waves from over 181,000 events on and near the Island of Hawaii between 1986 and 2009 recorded by the seismic stations at the Hawaiian Volcano Observatory. We relocate all the earthquakes by applying ray-tracing through an existing three-dimensional velocity model, similar event cluster analysis and a differential-time relocation method. The resulting location catalog represents an extension of previous relocation studies, covering a longer time period and consisting of more events with well-constrained absolute locations. The focal mechanisms are obtained based on the compressional-wave first motion polarities by applying the HASH program to the waveform cross-correlation relocated earthquakes. Overall, the good-quality focal solutions are dominated by normal faulting in our study area, especially in the active Kaoiki and Hilea seismic zones. Kilauea caldera is characterized by a mixture of approximately equal numbers of normal, strike-slip, and reverse faults, whereas focal mechanisms in its south flank are predominantly reverse. Our results are essential for mapping the seismic strain and stress field and for understanding the seismo-volcano-tectonic relationships within the magmatic systems.

  1. Geological and biological heterogeneity of the Aleutian margin (1965-4822 m)

    NASA Astrophysics Data System (ADS)

    Rathburn, A. E.; Levin, L. A.; Tryon, M.; Gieskes, J. M.; Martin, J. B.; Pérez, M. E.; Fodrie, F. J.; Neira, C.; Fryer, G. J.; Mendoza, G.; McMillan, P. A.; Kluesner, J.; Adamic, J.; Ziebis, W.

    2009-01-01

    Geological, biological and biogeochemical characterization of the previously unexplored margin off Unimak Island, Alaska between 1965 and 4822 m water depth was conducted to examine: (1) the geological processes that shaped the margin, (2) the linkages between depth, geomorphology and environmental disturbance in structuring benthic communities of varying size classes and (3) the existence, composition and nutritional sources of methane seep biota on this margin. The study area was mapped and sampled using multibeam sonar, a remotely operated vehicle (ROV) and a towed camera system. Our results provide the first characterization of the Aleutian margin mid and lower slope benthic communities (microbiota, foraminifera, macrofauna and megafauna), recognizing diverse habitats in a variety of settings. Our investigations also revealed that the geologic feature known as the “Ugamak Slide” is not a slide at all, and could not have resulted from a large 1946 earthquake. However, sediment disturbance appears to be a pervasive feature of this margin. We speculate that the deep-sea occurrence of high densities of Elphidium, typically a shallow-water foraminiferan, results from the influence of sediment redeposition from shallower habitats. Strong representation of cumacean, amphipod and tanaid crustaceans among the Unimak macrofauna may also reflect sediment instability. Although some faunal abundances decline with depth, habitat heterogeneity and disturbance generated by canyons and methane seepage appear to influence abundances of biota in ways that supercede any clear depth gradient in organic matter input. Measures of sediment organic matter and pigment content as well as C and N isotopic signatures were highly heterogeneous, although the availability of organic matter and the abundance of microorganisms in the upper sediment (1-5 cm) were positively correlated. We report the first methane seep on the Aleutian slope in the Unimak region (3263-3285 m), comprised of

  2. Tsunami hazards to U.S. coasts from giant earthquakes in Alaska

    USGS Publications Warehouse

    Ryan, Holly F.; von Huene, Roland; Scholl, Dave; Kirby, Stephen

    2012-01-01

    In the aftermath of Japan's devastating 11 March 2011Mw 9.0 Tohoku earthquake and tsunami, scientists are considering whether and how a similar tsunami could be generated along the Alaskan-Aleutian subduction zone (AASZ). A tsunami triggered by an earthquake along the AASZ would cross the Pacific Ocean and cause extensive damage along highly populated U.S. coasts, with ports being particularly vulnerable. For example, a tsunami in 1946 generated by a Mw 8.6 earthquake near Unimak Pass, Alaska (Figure 1a), caused significant damage along the U.S. West Coast, took 150 lives in Hawaii, and inundated shorelines of South Pacific islands and Antarctica [Fryer et al., 2004; Lopez and Okal, 2006]. The 1946 tsunami occurred before modern broadband seismometers were in place, and the mechanisms that created it remain poorly understood.

  3. Tsunami hazards to U.S. coasts from giant earthquakes in Alaska

    NASA Astrophysics Data System (ADS)

    Ryan, Holly; von Huene, Roland; Scholl, Dave; Kirby, Steve

    2012-05-01

    In the aftermath of Japan's devastating 11 March 2011Mw 9.0 Tohoku earthquake and tsunami, scientists are considering whether and how a similar tsunami could be generated along the Alaskan-Aleutian subduction zone (AASZ). A tsunami triggered by an earthquake along the AASZ would cross the Pacific Ocean and cause extensive damage along highly populated U.S. coasts, with ports being particularly vulnerable. For example, a tsunami in 1946 generated by a Mw 8.6 earthquake near Unimak Pass, Alaska (Figure 1a), caused signifcant damage along the U.S. West Coast, took 150 lives in Hawaii, and inundated shorelines of South Pacific islands and Antarctica [Fryer et al., 2004; Lopez and Okal, 2006]. The 1946 tsunami occurred before modern broadband seismometers were in place, and the mechanisms that created it remain poorly understood.

  4. Continuous uplift near the seaward edge of the Prince William Sound megathrust: Middleton Island, Alaska

    USGS Publications Warehouse

    Savage, James C.; Plafker, George; Svarc, Jerry L.; Lisowski, Michael

    2014-01-01

    Middleton Island, located at the seaward edge of the continental shelf 50 km from the base of the inner wall of the Aleutian Trench, affords an opportunity to make land-based measurements of uplift near the toe of the Prince William Sound megathrust, site of the 1964, M = 9.2, Alaska earthquake. Leveling surveys (1973–1993) on Middleton Island indicate roughly uniform tilting (~1 µrad/a down to the northwest) of the island, and GPS surveys (1993–2012) show an uplift rate of 14 mm/a of the island relative to fixed North America. The data are consistent with a combined (coseismic and postseismic) uplift (in meters) due to the 1964 earthquake as a function of time τ (years after the earthquake) u(τ) = (3.5 + 1.21 log10 [1 + 1.67 τ]) H(τ) where 3.5 is the coseismic uplift and H(τ) is 0 for τ < 0 and 1 otherwise. The current uplift on Middleton Island is attributed to continuous slip on a fault splaying off from the megathrust, and the long-term uplift is the superposition of the effects of past earthquakes, each earthquake being similar to the 1964 event. Then, the predicted uplift at time t due to a sequence of earthquakes at times tiwould be . From studies of strandlines associated with the uplifted terraces on Middleton Island, Plafker et al. (1992) estimated the occurrence times of the last six earthquakes and measured the present-day elevations of those strandlines. The predicted uplift is in rough agreement with those measurements. About half of the predicted uplift is due to postseismic relaxation from previous earthquakes.

  5. Seismic tomography of Basse-Terre volcanic island, Guadeloupe, Lesser Antilles, using earthquake travel times and noise correlations

    NASA Astrophysics Data System (ADS)

    Barnoud, Anne; Coutant, Olivier; Bouligand, Claire; Massin, Frédérick; Stehly, Laurent

    2015-04-01

    We image the volcanic island of Basse-Terre, Guadeloupe, Lesser Antilles, using both earthquake travel times and noise correlations. (1) A new earthquake catalog was recently compiled for the Lesser Antilles by the CDSA/OVSG/IPGP (Massin et al., EGU General Assembly 2014) and allows us to perform classical travel time tomography to obtain smooth 3D body wave velocity models. The geometrical configuration of the volcanic arc controls the resolution of the model in our zone of interest. (2) Surface wave tomography using noise correlations was successfully applied to volcanoes (Brenguier et al., Geophys. Res. Lett. 2007). We use seismic noise recorded at 16 broad-band stations and 9 short-period stations from Basse-Terre over a period of six years (2007-2012). For each station pair, we extract a dispersion curve from the noise correlation to get surface wave velocity models. The inversion of the dispersion curves produces a 3D S-wave velocity model of the island. The spatial distribution of seismic stations accross the island is highly heterogeneous, leading to higher resolution near the dome of the Soufrière of Guadeloupe volcano. Resulting velocity models are compared with densities obtained by 3D inversion of gravimetric data (Barnoud et al., AGU Fall Meeting 2013). Further work should include simultaneous inversion of seismic and gravimetric datasets to overcome resolution limitations.

  6. Aleutian basin oceanic crust

    USGS Publications Warehouse

    Christeson, Gail L.; Barth, Ginger A.

    2015-01-01

    We present two-dimensional P-wave velocity structure along two wide-angle ocean bottom seismometer profiles from the Aleutian basin in the Bering Sea. The basement here is commonly considered to be trapped oceanic crust, yet there is a change in orientation of magnetic lineations and gravity features within the basin that might reflect later processes. Line 1 extends ∼225 km from southwest to northeast, while Line 2 extends ∼225 km from northwest to southeast and crosses the observed change in magnetic lineation orientation. Velocities of the sediment layer increase from 2.0 km/s at the seafloor to 3.0–3.4 km/s just above basement, crustal velocities increase from 5.1–5.6 km/s at the top of basement to 7.0–7.1 km/s at the base of the crust, and upper mantle velocities are 8.1–8.2 km/s. Average sediment thickness is 3.8–3.9 km for both profiles. Crustal thickness varies from 6.2 to 9.6 km, with average thickness of 7.2 km on Line 1 and 8.8 km on Line 2. There is no clear change in crustal structure associated with a change in orientation of magnetic lineations and gravity features. The velocity structure is consistent with that of normal or thickened oceanic crust. The observed increase in crustal thickness from west to east is interpreted as reflecting an increase in melt supply during crustal formation.

  7. The 1964 Great Alaska Earthquake and tsunamis: a modern perspective and enduring legacies

    USGS Publications Warehouse

    Brocher, Thomas M.; Filson, John R.; Fuis, Gary S.; Haeussler, Peter J.; Holzer, Thomas L.; Plafker, George; Blair, J. Luke

    2014-01-01

    The magnitude 9.2 Great Alaska Earthquake that struck south-central Alaska at 5:36 p.m. on Friday, March 27, 1964, is the largest recorded earthquake in U.S. history and the second-largest earthquake recorded with modern instruments. The earthquake was felt throughout most of mainland Alaska, as far west as Dutch Harbor in the Aleutian Islands some 480 miles away, and at Seattle, Washington, more than 1,200 miles to the southeast of the fault rupture, where the Space Needle swayed perceptibly. The earthquake caused rivers, lakes, and other waterways to slosh as far away as the coasts of Texas and Louisiana. Water-level recorders in 47 states—the entire Nation except for Connecticut, Delaware, and Rhode Island— registered the earthquake. It was so large that it caused the entire Earth to ring like a bell: vibrations that were among the first of their kind ever recorded by modern instruments. The Great Alaska Earthquake spawned thousands of lesser aftershocks and hundreds of damaging landslides, submarine slumps, and other ground failures. Alaska’s largest city, Anchorage, located west of the fault rupture, sustained heavy property damage. Tsunamis produced by the earthquake resulted in deaths and damage as far away as Oregon and California. Altogether the earthquake and subsequent tsunamis caused 129 fatalities and an estimated $2.3 billion in property losses (in 2013 dollars). Most of the population of Alaska and its major transportation routes, ports, and infrastructure lie near the eastern segment of the Aleutian Trench that ruptured in the 1964 earthquake. Although the Great Alaska Earthquake was tragic because of the loss of life and property, it provided a wealth of data about subductionzone earthquakes and the hazards they pose. The leap in scientific understanding that followed the 1964 earthquake has led to major breakthroughs in earth science research worldwide over the past half century. This fact sheet commemorates Great Alaska Earthquake and

  8. Effects of the earthquake of March 27, 1964, on the communities of Kodiak and nearby islands: Chapter F in The Alaska earthquake, March 27, 1964: effects on communities

    USGS Publications Warehouse

    Kachadoorian, Reuben; Plafker, George

    1967-01-01

    The great earthquake (Richter magnitude of 8.4–8.5) that struck south-central Alaska at 5:36 p.m., Alaska standard time, on March 27, 1964 (03:36, March 28, Greenwich mean time), was felt in every community on Kodiak Island and the nearby islands. It was the most severe earthquake to strike this part of Alaska in modern time, and took the lives of 18 persons in the area by drowning; this includes two in Kodiak and three at Kaguyak. Property damage and loss of income to the communities is estimated at more than $45 million. The largest community, Kodiak, had the greatest loss from the earthquake. Damage was caused chiefly by 5.6 feet of tectonic subsidence and a train of 10 seismic sea waves that inundated the low-lying areas of the town. The seismic sea waves destroyed all but one of the docking facilities and more than 215 structures; many other structures were severely damaged. The waves struck the town during the evening hours of March 27 and early morning hours of March 28. They moved from the southwest and northeast: and reached their maximum height of 20–30 feet above mean lower low water at Shahafka Cove between 11:00 and 11:45 p.m., March 27. The violently destructive seismic sea waves not only severely damaged homes, shops, and naval-station structures but also temporarily crippled the fishing industry in Kodiak by destroying the processing plants and most of the fishing vessels. The waves scoured out 10 feet of sediments in the channel between Kodiak Island and Near Island and exposed bedrock. This bedrock presented a major post-earthquake construction problem because no sediments remained into which piles could be driven for foundations of waterfront facilities. Because of tectonic subsidence, high tides now flood Mission and Potatopatch Lakes which, before the earthquake, had not been subject to tidal action. The subsidence also accelerated erosion of the unconsolidated sediments along the shoreline in the city of Kodiak. Seismic shaking lasted 4

  9. Sequence of deep-focus earthquakes beneath the Bonin Islands identified by the NIED nationwide dense seismic networks Hi-net and F-net

    NASA Astrophysics Data System (ADS)

    Takemura, Shunsuke; Saito, Tatsuhiko; Shiomi, Katsuhiko

    2017-03-01

    An M 6.8 ( Mw 6.5) deep-focus earthquake occurred beneath the Bonin Islands at 21:18 (JST) on June 23, 2015. Observed high-frequency (>1 Hz) seismograms across Japan, which contain several sets of P- and S-wave arrivals for the 10 min after the origin time, indicate that moderate-to-large earthquakes occurred sequentially around Japan. Snapshots of the seismic energy propagation illustrate that after one deep-focus earthquake occurred beneath the Sea of Japan, two deep-focus earthquakes occurred sequentially after the first ( Mw 6.5) event beneath the Bonin Islands in the next 4 min. The United States Geological Survey catalog includes three Bonin deep-focus earthquakes with similar hypocenter locations, but their estimated magnitudes are inconsistent with seismograms from across Japan. The maximum-amplitude patterns of the latter two earthquakes were similar to that of the first Bonin earthquake, which indicates similar locations and mechanisms. Furthermore, based on the ratios of the S-wave amplitudes to that of the first event, the magnitudes of the latter events are estimated as M 6.5 ± 0.02 and M 5.8 ± 0.02, respectively. Three magnitude-6-class earthquakes occurred sequentially within 4 min in the Pacific slab at 480 km depth, where complex heterogeneities exist within the slab.[Figure not available: see fulltext.

  10. Coseismic deformation, field observations and seismic fault of the 17 November 2015 M = 6.5, Lefkada Island, Greece earthquake

    NASA Astrophysics Data System (ADS)

    Ganas, Athanassios; Elias, Panagiotis; Bozionelos, George; Papathanassiou, George; Avallone, Antonio; Papastergios, Asterios; Valkaniotis, Sotirios; Parcharidis, Issaak; Briole, Pierre

    2016-09-01

    On November 17, 2015 07:10:07 UTC a strong, shallow Mw6.5 earthquake, occurred on the island of Lefkada along a strike-slip fault with right-lateral sense of slip. The event triggered widespread environmental effects at the south and western part of the island while, the intensity and severity of these earthquake-induced deformations is substantially decreased towards the eastern part of the island. Relocation of seismicity and inversion of geophysical (GPS, InSAR) data indicate that the seismic fault runs parallel to the west coast of Lefkada, along the Aegean - Apulia plate boundary. The fault plane strikes N20 ± 5°E and dips to east with an angle of about 70 ± 5°. Coseismic deformation was measured in the order of tens of centimeters of horizontal motion by continuous GPS stations of NOANET (the NOA GPS network) and by InSAR (Sentinel 1 A image pairs). A coseismic uniform-slip model was produced from inversion of InSAR data and permanent GPS stations. The earthquake measured Mw = 6.5 using both the geodetic moment produced by the slip model, as well as the PGD relation of Melgar et al. (2015, GRL). In the field we observed no significant vertical motion of the shoreline or surface expression of faulting, this is consistent with the predictions of the model. The interferograms show a large decorrelation area that extends almost along all the western coast of Lefkada. This area correlates well with the mapped landslides. The 2003-2015 pattern of seismicity in the Ionian Sea region indicates the existence of a 15-km seismic gap offshore NW Cephalonia.

  11. Late Holocene earthquakes on the Toe Jam Hill fault, Seattle fault zone, Bainbridge Island, Washington

    USGS Publications Warehouse

    Nelson, A.R.; Johnson, S.Y.; Kelsey, H.M.; Wells, R.E.; Sherrod, B.L.; Pezzopane, S.K.; Bradley, L.-A.; Koehler, R. D.; Bucknam, R.C.

    2003-01-01

    Five trenches across a Holocene fault scarp yield the first radiocarbon-measured earthquake recurrence intervals for a crustal fault in western Washington. The scarp, the first to be revealed by laser imagery, marks the Toe Jam Hill fault, a north-dipping backthrust to the Seattle fault. Folded and faulted strata, liquefaction features, and forest soil A horizons buried by hanging-wall-collapse colluvium record three, or possibly four, earthquakes between 2500 and 1000 yr ago. The most recent earthquake is probably the 1050-1020 cal. (calibrated) yr B.P. (A.D. 900-930) earthquake that raised marine terraces and triggered a tsunami in Puget Sound. Vertical deformation estimated from stratigraphic and surface offsets at trench sites suggests late Holocene earthquake magnitudes near M7, corresponding to surface ruptures >36 km long. Deformation features recording poorly understood latest Pleistocene earthquakes suggest that they were smaller than late Holocene earthquakes. Postglacial earthquake recurrence intervals based on 97 radiocarbon ages, most on detrital charcoal, range from ???12,000 yr to as little as a century or less; corresponding fault-slip rates are 0.2 mm/yr for the past 16,000 yr and 2 mm/yr for the past 2500 yr. Because the Toe Jam Hill fault is a backthrust to the Seattle fault, it may not have ruptured during every earthquake on the Seattle fault. But the earthquake history of the Toe Jam Hill fault is at least a partial proxy for the history of the rest of the Seattle fault zone.

  12. Reconstructing Tsunami Deposits in the Eastern Aleutians Using Forward and Inverse Sediment Transport Models

    NASA Astrophysics Data System (ADS)

    La Selle, S.; Gelfenbaum, G. R.; Jaffe, B. E.; Witter, R. C.

    2015-12-01

    Tsunami deposits on coastal plains are commonly observed to gradually thin inland and contain upward fining sand units. These characteristics help validate the assumptions (steady and uniform onshore flow and sediment settling from suspension) that are employed by inverse sediment transport models, which predict flow speed from thickness and grain size data. On Sedanka Island in the eastern Aleutian Islands, a sequence of 6 tsunami deposits from the last 1700 years have been described that extend across an 800 m strandplain and reach elevations up to 15 m. The youngest deposit is attributed to the 1957 Andreanof Island earthquake (Mw 8.6) and is 1-13 cm thick. The older deposits are thicker (6-50 cm) and all of the layers contain upward fining sand units. Although the total volume of sediment varies among deposits, they all thicken landward, toward the back of the valley. We developed a Delft3D forward tsunami sediment transport model to better understand the conditions that resulted in this spatial pattern of deposit thickening. Results from a profile model suggest that sediment eroded from the beach and berm is transported to the back of the valley during uprush. Significant deposition does not occur until the initial wave reflects off the steep topography at the back of the valley and the local flow velocity drops, with the highest rate of deposition occurring during slow return flow as sediment settles out of the water column. A 3D model will be used to determine if the funnel-shape of the valley produces convergences that can explain the observed deposit thickening, and to see if a majority of the deposition still occurs during return flow. Finally, we will use flow depths from the forward model to constrain a TSUSEDMOD inverse model and see if it can reproduce the observed deposit grading and modeled flow velocities. If so, the inverse model may be applied to deposits in other locations where similar hydrodynamic conditions are suspected occur.

  13. Aleutian Ancorinidae (Porifera, Astrophorida): Description of three new species from the genera Stelletta and Ancorina.

    PubMed

    Lehnert, Helmut; Stone, Robert P

    2014-06-30

    Two new species of the genus Stelletta and one new species of Ancorina are described from the Aleutian Islands of Alaska and compared to congeners of the region. This is the first record of the genus Ancorina in the North Pacific Ocean. Stelletta ovalae Tanita 1965 is also reported for the first time from the Bering Sea and Alaska. 

  14. Coseismic deformation and slip model of the 17 November 2015 M=6.5 earthquake, Lefkada Island, Greece

    NASA Astrophysics Data System (ADS)

    Ganas, Athanassios; Melgar, Diego; Briole, Pierre; Geng, Jianghui; Papathanassiou, George; Bozionelos, George; Avallone, Antonio; Valkaniotis, Sotirios; Mendonidis, Evangelos; Argyrakis, Panagiotis; Moshou, Alexandra; Elias, Panagiotis

    2016-04-01

    On November 17, 2015 a strong, shallow earthquake, Mw 6.5, occurred on the island of Lefkada along a strike-slip fault with right-lateral sense of slip. The event triggered widespread environmental effects that were mainly reported at the south and western part of the island while moving towards the eastern part, the intensity and severity of these earthquake-induced deformations were decreased. Coseismic deformation was measured in the order of tens of centimeters of horizontal motion by continuous GPS stations of NOANET (the NOA GPS network) and by InSAR (Sentinel 1A image pairs). Released interferograms from various groups show a large decorrelation area that extends almost along all the western coast of Lefkada, observation which provides strong support of landsliding. We also found extensive landslides during field work and no surface ruptures. A coseismic slip model was produced from the ascending InSAR, which it's cleaner than the GPS only and both data sets have ~90% variance reduction. The fault dips to the east-southeast at an angle of 65-70 degrees.

  15. Seismicity controlled by resistivity structure: the 2016 Kumamoto earthquakes, Kyushu Island, Japan

    NASA Astrophysics Data System (ADS)

    Aizawa, Koki; Asaue, Hisafumi; Koike, Katsuaki; Takakura, Shinichi; Utsugi, Mitsuru; Inoue, Hiroyuki; Yoshimura, Ryokei; Yamazaki, Ken'ichi; Komatsu, Shintaro; Uyeshima, Makoto; Koyama, Takao; Kanda, Wataru; Shiotani, Taro; Matsushima, Nobuo; Hata, Maki; Yoshinaga, Tohru; Uchida, Kazunari; Tsukashima, Yuko; Shito, Azusa; Fujita, Shiori; Wakabayashi, Asuma; Tsukamoto, Kaori; Matsushima, Takeshi; Miyazaki, Masahiro; Kondo, Kentaro; Takashima, Kanade; Hashimoto, Takeshi; Tamura, Makoto; Matsumoto, Satoshi; Yamashita, Yusuke; Nakamoto, Manami; Shimizu, Hiroshi

    2017-01-01

    The M JMA 7.3 Kumamoto earthquake that occurred at 1:25 JST on April 16, 2016, not only triggered aftershocks in the vicinity of the epicenter, but also triggered earthquakes that were 50-100 km away from the epicenter of the main shock. The active seismicity can be divided into three regions: (1) the vicinity of the main faults, (2) the northern region of Aso volcano (50 km northeast of the mainshock epicenter), and (3) the regions around three volcanoes, Yufu, Tsurumi, and Garan (100 km northeast of the mainshock epicenter). Notably, the zones between these regions are distinctively seismically inactive. The electric resistivity structure estimated from one-dimensional analysis of the 247 broadband (0.005-3000 s) magnetotelluric and telluric observation sites clearly shows that the earthquakes occurred in resistive regions adjacent to conductive zones or resistive-conductive transition zones. In contrast, seismicity is quite low in electrically conductive zones, which are interpreted as regions of connected fluids. We suggest that the series of the earthquakes was induced by a local accumulated stress and/or fluid supply from conductive zones. Because the relationship between the earthquakes and the resistivity structure is consistent with previous studies, seismic hazard assessment generally can be improved by taking into account the resistivity structure. Following on from the 2016 Kumamoto earthquake series, we suggest that there are two zones that have a relatively high potential of earthquake generation along the western extension of the MTL. [Figure not available: see fulltext.

  16. Comparison of Tsunami height Distributions of the 1960 and the 2010 Chilean Earthquakes on the Coasts of the Japanese Islands

    NASA Astrophysics Data System (ADS)

    Tsuji, Y.; Takahashi, T.; Imai, K.

    2010-12-01

    The tsunami of the Chilean Earthquake (Mw8.8) of February 27, 2010 was detected also on the coasts of the Japanese Islands about 23 hours after the occurrence of the main shock. It caused no human damage. There was slight house damage manly in Miyagi prefecture, south part of Sanriku coast; six and fifty one houses were flooded above and below the floor, respectively. It caused remarkable fishery loss of 75 Million US$ mainly due to breaking of cultivation rafts. The tsunami of the 1960 Chilean Earthquake(Mw9.5) also hit the Japanese coasts more severely. It caused more immense damage than the 2010 tsunami; 142 people were killed, 1,581 houses were entirely destroyed, and 1,256 houses were swept away. Most of damage occurred in the districts of Sanriku coast, where inundation heights exceeded six meters at several points. We made field survey along the Japanese coast, visited offices of fishermen’s cooperatives at over 300 fishery ports, gathered eyewitnesses counts, and obtained information of the inundation limit, arrival time, and building and fishery damage. On the basis of the information of inundation, we measured tsunami heights. We obtained data of tsunami height at more than two hundred points (Tsuji et al., 2010). The distributions of the two tsunamis of the 1960 and the 2010 Chilean earthquakes on the coasts along the Japanese Islands are shown as Fig. 1. The maximum height of 2.2 meters was recorded at Kesennuma City, Miyagi Prefecture. The heights of the 2010 tsunami were generally one third of those of the 1960 tsunami. An eminent peak appears at Sanriku coast commonly for both tsunamis. In addition smaller peaks also appear commonly at the coasts of the east part of Hokkaido, near the top of Boso peninsula, near the top of Izu Peninsula, the east coast of Kii Peninsula, Tokushima prefecture, eastern part of Shikoku, and near the Cape Ashizuri in western part of Shikoku. Fig. 1 Trace height distributions of the tsunamis of the 1960(red) and the 2010

  17. Triggered aseismic slip adjacent to the 6 February 2013 Mw 8.0 Santa Cruz Islands megathrust earthquake

    NASA Astrophysics Data System (ADS)

    Hayes, Gavin P.; Furlong, Kevin P.; Benz, Harley M.; Herman, Matthew W.

    2014-02-01

    Aseismic or slow slip events have been observed in many subduction zones, but whether they affect the occurrence of earthquakes or result from stress changes caused by nearby events is unclear. In an area lacking direct geodetic observations, inferences can be made from seismological studies of co-seismic slip, associated stress changes and the spatiotemporal nature of aftershocks. These observations indicate that the February 2013 Mw 8.0 Santa Cruz Islands earthquake may have triggered slow or aseismic slip on an adjacent section of the subduction thrust over the following hours to days. This aseismic event was equivalent to Mw 7.6, significantly larger than any earthquakes in the aftershock sequence. The aseismic slip was situated within the seismogenic portion of the subduction interface, and must have occurred to the south of the main seismic slip and most aftershocks in order to promote right-lateral faulting in the upper plate, the dominant deformation style of the aftershock sequence. This plate boundary segment can support either stable sliding (aseismic) or stick-slip (seismic) deformation in response to different driving conditions. The complete lack of aftershocks on the thrust interface implies this pair of megathrust slip episodes (seismic and aseismic) released a substantial portion of the stored strain on the northernmost section of the Vanuatu subduction zone.

  18. Japan unified hIgh-resolution relocated catalog for earthquakes (JUICE): Crustal seismicity beneath the Japanese Islands

    NASA Astrophysics Data System (ADS)

    Yano, Tomoko E.; Takeda, Tetsuya; Matsubara, Makoto; Shiomi, Katsuhiko

    2017-04-01

    We have generated a high-resolution catalog called the ;Japan Unified hIgh-resolution relocated Catalog for Earthquakes; (JUICE), which can be used to evaluate the geometry and seismogenic depth of active faults in Japan. We relocated > 1.1 million hypocenters from the NIED Hi-net catalog for events which occurred between January 2001 and December 2012, to a depth of 40 km. We apply a relative hypocenter determination method to the data in each grid square, in which entire Japan is divided into 1257 grid squares to parallelize the relocation procedure. We used a double-difference method, incorporating cross-correlating differential times as well as catalog differential times. This allows us to resolve, in detail, a seismicity distribution for the entire Japanese Islands. We estimated location uncertainty by a statistical resampling method, using Jackknife samples, and show that the uncertainty can be within 0.37 km in the horizontal and 0.85 km in the vertical direction with a 90% confidence interval for areas with good station coverage. Our seismogenic depth estimate agrees with the lower limit of the hypocenter distribution for a recent earthquake on the Kamishiro fault (2014, Mj 6.7), which suggests that the new catalog should be useful for estimating the size of future earthquakes for inland active faults.

  19. Triggered aseismic slip adjacent to the 6 February 2013 Mw 8.0 Santa Cruz Islands megathrust earthquake

    USGS Publications Warehouse

    Hayes, Gavin P.; Furlong, Kevin P.; Benz, Harley M.; Herman, Matthew W.

    2014-01-01

    Aseismic or slow slip events have been observed in many subduction zones, but whether they affect the occurrence of earthquakes or result from stress changes caused by nearby events is unclear. In an area lacking direct geodetic observations, inferences can be made from seismological studies of co-seismic slip, associated stress changes and the spatiotemporal nature of aftershocks. These observations indicate that the February 2013 Mw 8.0 Santa Cruz Islands earthquake may have triggered slow or aseismic slip on an adjacent section of the subduction thrust over the following hours to days. This aseismic event was equivalent to Mw 7.6, significantly larger than any earthquakes in the aftershock sequence. The aseismic slip was situated within the seismogenic portion of the subduction interface, and must have occurred to the south of the main seismic slip and most aftershocks in order to promote right-lateral faulting in the upper plate, the dominant deformation style of the aftershock sequence. This plate boundary segment can support either stable sliding (aseismic) or stick-slip (seismic) deformation in response to different driving conditions. The complete lack of aftershocks on the thrust interface implies this pair of megathrust slip episodes (seismic and aseismic) released a substantial portion of the stored strain on the northernmost section of the Vanuatu subduction zone.

  20. Did the November 17, 2009 Queen Charlotte Island (QCI) earthquake fill a predicted seismic gap?

    NASA Astrophysics Data System (ADS)

    Vasudevan, K.; Eaton, D. W.; Iverson, A.

    2010-12-01

    Seismicity in the Queen Charlotte Fault (QCF) zone occurs along the transform boundary between the Pacific and North American lithospheric plates and is the region where the largest recorded earthquake in Canada (Ms = 8.1) occurred, on August 22, 1949. Right-lateral relative motion across the QCF, in conjunction with minor convergence, has been suggested to play a role in the source characteristics of earthquakes in this region. A segment of the QCF between the inferred rupture zone of the 1949 earthquake and that of a magnitude 7.4 earthquake in 1970 has been identified as seismic gap that, if fully ruptured, is capable of producing a M ~ 7 earthquake. On November 17, 2009 a Mw 6.6 earthquake occurred within this seismicity gap and was well recorded by regional seismograph stations in Canada and the U.S., including three recently installed temporary broadband seismograph stations in northern Alberta. The distribution of aftershocks from the 2009 earthquake, as well as maps of calculated Coulomb stresses from the previous events, are compatible with the seismic gap hypothesis. In addition, we have computed a seismic moment tensor for this event by least-squares waveform fitting, primarily surface waves, which shows a predominantly strike-slip focal mechanism. Our integrated results of source parameters and Coulomb failure stress changes provide the first direct confirmation that the 2009 event occurred within the predicted seismic gap between the 1949 and 1970 earthquakes. This evidence is important for hazard assessment in this region where offshore oil and gas drilling has been proposed.

  1. Source Mechanism of May 30, 2015 Bonin Islands, Japan Deep Earthquake (Mw7.8) Estimated by Broadband Waveform Modeling

    NASA Astrophysics Data System (ADS)

    Tsuboi, S.; Nakamura, T.; Miyoshi, T.

    2015-12-01

    May 30, 2015 Bonin Islands, Japan earthquake (Mw 7.8, depth 679.9km GCMT) was one of the deepest earthquakes ever recorded. We apply the waveform inversion technique (Kikuchi & Kanamori, 1991) to obtain slip distribution in the source fault of this earthquake in the same manner as our previous work (Nakamura et al., 2010). We use 60 broadband seismograms of IRIS GSN seismic stations with epicentral distance between 30 and 90 degrees. The broadband original data are integrated into ground displacement and band-pass filtered in the frequency band 0.002-1 Hz. We use the velocity structure model IASP91 to calculate the wavefield near source and stations. We assume that the fault is squared with the length 50 km. We obtain source rupture model for both nodal planes with high dip angle (74 degree) and low dip angle (26 degree) and compare the synthetic seismograms with the observations to determine which source rupture model would explain the observations better. We calculate broadband synthetic seismograms with these source propagation models using the spectral-element method (Komatitsch & Tromp, 2001). We use new Earth Simulator system in JAMSTEC to compute synthetic seismograms using the spectral-element method. The simulations are performed on 7,776 processors, which require 1,944 nodes of the Earth Simulator. On this number of nodes, a simulation of 50 minutes of wave propagation accurate at periods of 3.8 seconds and longer requires about 5 hours of CPU time. Comparisons of the synthetic waveforms with the observation at teleseismic stations show that the arrival time of pP wave calculated for depth 679km matches well with the observation, which demonstrates that the earthquake really happened below the 660 km discontinuity. In our present forward simulations, the source rupture model with the low-angle fault dipping is likely to better explain the observations.

  2. Stratigraphic evidence for earthquakes and tsunamis on the west coast of South Andaman Island, India during the past 1000 years

    NASA Astrophysics Data System (ADS)

    Malik, Javed N.; Banerjee, Chiranjib; Khan, Afzal; Johnson, Frango C.; Shishikura, Masanobu.; Satake, Kenji.; Singhvi, Ashok K.

    2015-10-01

    Stratigraphic records from west coast of South Andaman Island revealed evidence of three historical earthquakes and associated transoceanic tsunamis during past 1000 yrs, in addition to the Mw 9.3 tsunamigenic earthquake of 26 December, 2004. Our finding suggests that along with Sumatran arc segment the Andaman-Arakan segment is also capable of generating mega-subduction zone earthquakes and transoceanic tsunamis. To study the near sub-surface stratigraphic succession we excavated shallow trenches and obtained geoslices from two sites around Collinpur (sites 1 and 2). The exposed succession comprised 11 lithounits (Unit a - youngest and k - oldest) of alternating sequence of coarser units overlain by peaty soils and some of these are indicative of deposition during paleo-tsunami events. Event I that predated AD 800, and is marked by a 35-40 cm thick deposit of fine gravel to coarse sands along with broken shell fragments (Unit k). Event II dated around AD 660-800, is represented by 20-25 cm thick coarse sand and broken shell fragments (Unit i). Based on stratigraphic evidences of land-level changes, this event is attributed to a near source rupture along Andaman-Arakan segment, accompanied by a transoceanic tsunami. Event III, occurred around AD 1120-1300, is marked by a 50 cm thick sand deposit (Unit g). The 2004 tsunami resulted in deposition of 15 cm thick medium to coarse sand at the same location. We infer that the 2004 tsunami and Event III resulted in different styles of sedimentation at the same site. Four events at Collinpur along with the record of a subsidence event of AD 1679 from the east coast of Andaman, close-to, Port Blair (Malik et al., 2011), suggest that mega-subduction zone earthquakes and associated tsunamis recur at an interval of 300-500 years at variable locations along the Sumatra-Andaman subduction zone.

  3. Influence of the Amlia fracture zone on the evolution of the Aleutian Terrace forearc basin, central Aleutian subduction zone

    USGS Publications Warehouse

    Ryan, Holly F.; Draut, Amy E.; Keranen, Katie M.; Scholl, David W.

    2012-01-01

    During Pliocene to Quaternary time, the central Aleutian forearc basin evolved in response to a combination of tectonic and climatic factors. Initially, along-trench transport of sediment and accretion of a frontal prism created the accommodation space to allow forearc basin deposition. Transport of sufficient sediment to overtop the bathymetrically high Amlia fracture zone and reach the central Aleutian arc began with glaciation of continental Alaska in the Pliocene. As the obliquely subducting Amlia fracture zone swept along the central Aleutian arc, it further affected the structural evolution of the forearc basins. The subduction of the Amlia fracture zone resulted in basin inversion and loss of accommodation space east of the migrating fracture zone. Conversely, west of Amlia fracture zone, accommodation space increased arcward of a large outer-arc high that formed, in part, by a thickening of arc basement. This difference in deformation is interpreted to be the result of a variation in interplate coupling across the Amlia fracture zone that was facilitated by increasing subduction obliquity, a change in orientation of the subducting Amlia fracture zone, and late Quaternary intensification of glaciation. The change in coupling is manifested by a possible tear in the subducting slab along the Amlia fracture zone. Differences in coupling across the Amlia fracture zone have important implications for the location of maximum slip during future great earthquakes. In addition, shaking during a great earthquake could trigger large mass failures of the summit platform, as evidenced by the presence of thick mass transport deposits of primarily Quaternary age that are found in the forearc basin west of the Amlia fracture zone.

  4. April 16, 2015 Crete Island Earthquake (Mw=5.9) Series and its Seismotectonic Significance, Southern Aegean Sea

    NASA Astrophysics Data System (ADS)

    Yalçın, Hilal; Kürçer, Akın; Gülen, Levent

    2016-04-01

    The active deformation of the southern Aegean Sea is a result of the northward motion of the African and Arabian Plates with respect to the Eurasian Plate in the Eastern Mediterranean Region. The Hellenic subduction zone plays a key role in the active tectonics of the region. On 16 April, 2015, a moderate earthquake occurred on the eastern part of Hellenic arc (south of Crete island), with a moment magnitude of Mw=5.9. A series of aftershocks were occurred within four months following the mainshock, which have magnitudes varying from Mw = 3.4 to 5.4. Source parameters of the 16 April 2015 earthquake have been modeled in order to reveal the regional stress tensor and the tectonic style of the region. In this study, the source parameters of the main shock and 36 aftershocks that have magnitudes M≥3.4 have been determined and modeled by seismic moment tensor waveform inversion method developed by Sokos and Zahradnik (2006) algorithm using the near-field and regional waveforms. The depth of earthquakes are varied from 2 to 61 km. Stress tensor can describe reliably principle stress axes (σ1, σ2, σ3), their relative size and stress field variations. Stress tensor inversions have been carried out using the Micheal method (1984, 1987). In this study, 16 April 2015 Crete Earthquake mainshock (Mw=5.9), a total of 36 earthquake moment tensor solutions that belong to the Crete earthquake sequence and 24 earthquake moment tensor solutions of previous main shocks in the region have been compiled and used in the stress inversion calculation. Orientations of σ1, σ2 and σ3 were computed and the principal directions are projected onto a lower hemisphere Wulff net. The best fit was attained for Phi = 0.38+/-0.13609 and indicated that the stress regime revealed strike-slip faulting with reverse component and for the azimuth and plunge pair of (-161.6°, 21.7°) for σ1, (-11.1°, 65.4°) for σ2 and (103.8°, 10.9°) for σ3. At the final step of the study, Gutenberg and

  5. Erosion and deposition on a beach raised by the 1964 earthquake, Montague Island, Alaska: Chapter H in The Alaska earthquake, March 27, 1964: regional effects

    USGS Publications Warehouse

    Kirkby, M.J.; Kirkby, Anne V.

    1969-01-01

    During the 1964 Alaska earthquake, tectonic deformation uplifted the southern end of Montague Island as much as 33 feet or more. The uplifted shoreline is rapidly being modified by subaerial and marine processes. The new raised beach is formed in bedrock, sand, gravel, and deltaic bay-head deposits, and the effect of each erosional process was measured in each material. Fieldwork was concentrated in two areas—MacLeod Harbor on the northwest side and Patton Bay on the southeast side of Montague Island. In the unconsolidated deltaic deposits of MacLeod Harbor, 97 percent of the erosion up to June 1965, 15 months after the earthquake, was fluvial, 2.2 percent was by rainwash, and only 0.8 percent was marine; 52 percent of the total available raised beach material had already been removed. The volume removed by stream erosion was proportional to low-flow discharge raised to the power of 0.75 to 0.95, and this volume increased as the bed material became finer. Stream response to the relative fall in base level was very rapid, most of the downcutting in unconsolidated materials occurring within 48 hours of the uplift for streams with low flows greater than 10 cubic feet per second. Since then, erosion by these streams has been predominantly lateral. Streams with lower discharges, in unconsolidated materials, still had knickpoints after 15 months. No response to uplift could be detected in stream courses above the former preearthquake sea level. Where the raised beach is in bedrock, it is being destroyed principally by marine action but at such a low rate that no appreciable erosion of bedrock was found 15 months after the earthquake. A dated rock platform raised earlier has eroded at a mean rate of 0.49 foot per year. In this area the factor limiting the rate of erosion was rock resistance rather than the transporting capacity of the waves. The break in slope between the top of the raised beach and the former seacliff is being obliterated by debris which is

  6. Subducting plate geology in three great earthquake ruptures of the western Alaska margin, Kodiak to Unimak

    USGS Publications Warehouse

    von Huene, Roland; Miller, John J.; Weinrebe, Wilhelm

    2012-01-01

    Three destructive earthquakes along the Alaska subduction zone sourced transoceanic tsunamis during the past 70 years. Since it is reasoned that past rupture areas might again source tsunamis in the future, we studied potential asperities and barriers in the subduction zone by examining Quaternary Gulf of Alaska plate history, geophysical data, and morphology. We relate the aftershock areas to subducting lower plate relief and dissimilar materials in the seismogenic zone in the 1964 Kodiak and adjacent 1938 Semidi Islands earthquake segments. In the 1946 Unimak earthquake segment, the exposed lower plate seafloor lacks major relief that might organize great earthquake rupture. However, the upper plate contains a deep transverse-trending basin and basement ridges associated with the Eocene continental Alaska convergent margin transition to the Aleutian island arc. These upper plate features are sufficiently large to have affected rupture propagation. In addition, massive slope failure in the Unimak area may explain the local 42-m-high 1946 tsunami runup. Although Quaternary geologic and tectonic processes included accretion to form a frontal prism, the study of seismic images, samples, and continental slope physiography shows a previous history of tectonic erosion. Implied asperities and barriers in the seismogenic zone could organize future great earthquake rupture.

  7. Tectonics earthquake distribution pattern analysis based focal mechanisms (Case study Sulawesi Island, 1993–2012)

    SciTech Connect

    Ismullah M, Muh. Fawzy; Lantu,; Aswad, Sabrianto; Massinai, Muh. Altin

    2015-04-24

    Indonesia is the meeting zone between three world main plates: Eurasian Plate, Pacific Plate, and Indo – Australia Plate. Therefore, Indonesia has a high seismicity degree. Sulawesi is one of whose high seismicity level. The earthquake centre lies in fault zone so the earthquake data gives tectonic visualization in a certain place. This research purpose is to identify Sulawesi tectonic model by using earthquake data from 1993 to 2012. Data used in this research is the earthquake data which consist of: the origin time, the epicenter coordinate, the depth, the magnitude and the fault parameter (strike, dip and slip). The result of research shows that there are a lot of active structures as a reason of the earthquake in Sulawesi. The active structures are Walannae Fault, Lawanopo Fault, Matano Fault, Palu – Koro Fault, Batui Fault and Moluccas Sea Double Subduction. The focal mechanism also shows that Walannae Fault, Batui Fault and Moluccas Sea Double Subduction are kind of reverse fault. While Lawanopo Fault, Matano Fault and Palu – Koro Fault are kind of strike slip fault.

  8. InSAR measurement of surface deformation at the Hanford Reservation associated with the 2009 Wooded Island earthquake swarm (Invited)

    NASA Astrophysics Data System (ADS)

    Wicks, C. W.; Gomberg, J. S.; Weaver, C. S.

    2009-12-01

    Earthquake swarms are frequent in much of eastern Washington. Earthquakes in these swarms typically are in the range of magnitude 1 to 3 and are often shallow with depths of a few kilometers. The most recent swarm of small earthquakes occurred from January 2009 through July 2009 and was located near Wooded Island 15 km north of Richland, Washington on the southeastern corner of the Hanford Reservation. The swarm location is along the eastern edge of the Yakima Fold and Thrust Belt, where swarm activity appears to be common. The Wooded Island swarm location is about 10 km northeast of the northwest-striking Rattlesnake Mountain fault and about 10 km south of the Gable Mountain fault that strikes west-northwest. Both of these mapped faults are associated with major thrusts that deform the Columbia River basalts, but the relation between these faults and the current swarm location is unknown. Although there have been at least two other swarms near Wooded Island in the last 30 years, the current swarm is of particular interest because we are able to map the surface deformation associated with the swarm with multi-temporal InSAR images from the European Space Agency’s ENVISAT satellite. We find two clear “pods” of deformation in interferograms generated from the satellite data, coincident with the distribution of the swarm hypocenters. We measure about 35 mm of peak surface deformation in the satellite line-of-sight direction. The deformation became resolvable in interferograms after the end of February 2009, when seismicity rates were highest. Preliminary modeling of the deformation is consistent with two small (about two km long) reverse faults each striking west-northwest with nearly 50 mm of slip. The geodetically estimated slip exceeds the seismic slip significantly, suggesting that the swarm was driven by aseismic creep. One of the modeled faults is well constrained to be shallow, about 200 m deep, and both faults occur within the underlying ~3 km thick

  9. The isolated ˜680 km deep 30 May 2015 MW 7.9 Ogasawara (Bonin) Islands earthquake

    NASA Astrophysics Data System (ADS)

    Ye, Lingling; Lay, Thorne; Zhan, Zhongwen; Kanamori, Hiroo; Hao, Jin-Lai

    2016-01-01

    Deep-focus earthquakes, located in very high-pressure conditions 300 to 700 km below the Earth's surface within sinking slabs of relatively cold oceanic lithosphere, are mysterious phenomena. The largest recorded deep-focus earthquake (MW 7.9) in the Izu-Bonin slab struck on 30 May 2015 beneath the Ogasawara (Bonin) Islands, isolated from prior seismicity by over 100 km in depth, and followed by only a few small aftershocks. Globally, this is the deepest (680 km centroid depth) event with MW ≥ 7.8 in the seismological record. Seismicity indicates along-strike contortion of the Izu-Bonin slab, with horizontal flattening near a depth of 550 km in the Izu region and rapid steepening to near-vertical toward the south above the location of the 2015 event. This event was exceptionally well-recorded by seismic stations around the world, allowing detailed constraints to be placed on the source process. Analyses of a large global data set of P, SH and pP seismic phases using short-period back-projection, subevent directivity, and broadband finite-fault inversion indicate that the mainshock ruptured a shallowly-dipping fault plane with patchy slip that spread over a distance of ∼40 km with a multi-stage expansion rate (∼ 5 + km /s down-dip initially, ∼3 km/s up-dip later). During the 17 s total rupture duration the radiated energy was ∼ 3.3 ×1016 J and the stress drop was ∼38 MPa. The radiation efficiency is moderate (0.34), intermediate to that of the 1994 Bolivia and 2013 Sea of Okhotsk MW 8.3 deep earthquakes, indicating that source processes of very large deep earthquakes sample a wide range of behavior from dissipative, more viscous failure to very brittle failure. The isolated occurrence of the event, much deeper than the apparently thermally-bounded distribution of Bonin-slab seismicity above 600 km depth, suggests that localized stress concentration associated with the pronounced deformation of the Izu-Bonin slab and proximity to the 660-km phase

  10. Transverse tectonic boundaries near Kodiak Island, Alaska.

    USGS Publications Warehouse

    Fisher, M.A.; Bruns, T.R.; Von Huene, R.

    1981-01-01

    Transverse tectonic boundaries exist at the NE and SW ends of the Kodiak islands, so that the Aleutian arc-trench system is longitudinally segmented in this area. Evidence for the transverse boundaries includes alignments of such geologic features as offset volcanic lineations, terminations of structural trends, and boundaries of discrete zones of earthquake aftershock sequences. The boundaries appear to be broad zones of disruption that began to form during the late Miocene or Pliocene. Although oceanic fracture zones and seamount chains intersect the continental margin near the boundaries, subduction of these features probably did not cause the tectonic boundaries. The fracture zones and seamount chains have swept northeastward along the margin, at least since the late Pliocene, because of the direction of convergence of the Pacific and N American plates. -Authors

  11. Tremor and plate coupling in the eastern Aleutians

    NASA Astrophysics Data System (ADS)

    Wech, A.; Freymueller, J. T.

    2013-12-01

    Tectonic tremor has been observed in numerous places along the 2500 km of the Alaska subduction zone. Though not as evidently ubiquitous as in other subduction zones, some tremor activity coincided with a large slow slip event on the mainland that occurred between 1998 and 2001 [Peterson and Christensen, 2009], and there are reports of several instances of tremor along the Aleutian arc [Peterson et al., 2011; Brown et al., 2013]. However, because these studies have focused on the characterization of manually detected tremors, the full extent of where, when and how much tremor activity occurs along the margin remains unknown, along with its role in subduction. Here we perform a systematic search for tectonic tremor activity along the margin. Starting in the eastern Aleutian Islands, a 'sweet spot' known for persistent tectonic tremor (ambient and triggered), we apply an automated method to detect and locate tremor and find a nearly daily occurrence of short-duration (<20 min) ambient tremor. In 18 months of data, we find the tremor to concentrate in 3 distinct zones of activity, occurring where the plate is 50-70 km deep. Constraints on tremor depths and along-dip locations are inhibited by the linear Aleutian station geometry, but epicenters lie trenchward of the islands and are resolved well enough to be distinguished from volcanic activity. We compare these results with geodetic observations. Time histories of each of the tremor patches show nearly daily activity in the region with an along strike change in tremor rate coincident with a change in updip coupling inferred from GPS. To the southwest, downdip of where the plate is locked, the total tremor activity is half that of the northeast-most patch where the plate is unlocked updip. We suggest that this updip transition in plate coupling is controlling the tremor behavior downdip, and that the most active tremor patch is experiencing more activity because of the additional loading from above.

  12. Geologic effects of the March 1964 earthquake and associated seismic sea waves on Kodiak and nearby islands, Alaska: Chapter D in The Alaska earthquake, March 27, 1964: regional effects

    USGS Publications Warehouse

    Plafker, George; Kachadoorian, Reuben

    1966-01-01

    Kodiak Island and the nearby islands constitute a mountainous landmass with an aggregate area of 4,900 square miles that lies at the western border of the Gulf of Alaska and from 20 to 40 miles off the Alaskan mainland. Igneous and metamorphic rocks underlie most of the area except for a narrow belt of moderately to poorly indurated rocks bordering the Gulf of Alaska coast and local accumulations of unconsolidated alluvial and marine deposits along the streams and coast. The area is relatively undeveloped and is sparsely inhabited. About 4,800 of the 5,700 permanent residents in the area live in the city of Kodiak or at the Kodiak Naval Station. The great earthquake, which occurred on March 27, 1964, at 5:36 p.m. Alaska standard time (March 28,1964, 0336 Greenwich mean time), and had a Richter magnitude of 8.4-8.5, was the most severe earthquake felt on Kodiak Island and its nearby islands in modern times. Although the epicenter lies in Prince William Sound 250 miles northeast of Kodiak—the principal city of the area—the areal distribution of the thousands of aftershocks that followed it, the local tectonic deformation, and the estimated source area of the subsequent seismic sea wave, all suggest that the Kodiak group of islands lay immediately adjacent to, and northwest of, the focal region from which the elastic seismic energy was radiated. The duration of strong ground motion in the area was estimated at 2½ minutes. Locally, the tremors were preceded by sounds audible to the human ear and were reportedly accompanied in several places by visible ground waves. Intensity and felt duration of the shocks during the main earthquake and aftershock sequence varied markedly within the area and were strongly influenced by the local geologic environment. Estimated Mercalli intensities in most areas underlain by unconsolidated Quaternary deposits ranged from VIII to as high as IX. In contrast, intensities in areas of upper Tertiary rock ranged from VII to VIII, and in

  13. Using Inundation and Sediment Transport Modeling To Characterize Earthquake Source Parameters from Tsunami Deposits

    NASA Astrophysics Data System (ADS)

    Gelfenbaum, G. R.; La Selle, S.; Witter, R. C.; Sugawara, D.; Jaffe, B. E.

    2015-12-01

    Inferring the relative magnitude of tsunamis generated during earthquakes based on the characteristics of sandy coastal deposits is a challenging problem. Using a hydrodynamic and sediment transport model, we explore whether the volume of sandy tsunami deposits can be used to infer tsunami magnitude and seafloor deformation. For large subduction zone earthquakes specifically, we are testing the hypothesis that onshore tsunami deposit volume is correlated with nearshore tsunami wave height and coseismic slip. First, we test this hypothesis using onshore tsunami deposit volume data and offshore slip for the 2011 Tohoku earthquake and tsunami. This test considers tsunami deposit volume and offshore slip as they vary alongshore across a wide range of sediment sources, offshore and onshore slopes, and boundary roughness conditions. Preliminary analysis suggests that a strong correlation exists between onshore tsunami deposit volume and adjacent offshore coseismic slip, so long as ample sediment were available along the coast to be eroded. Second, we apply a Delft3D tsunami inundation and sediment transport model to Stardust Bay in the U.S. Aleutian Islands, where 6 tsunamis in the last ~1700 years deposited marine sand across a coastal plain as much as 800 m inland and up to ~15 m above mean sea level. The youngest sand sheet, probably deposited by a tsunami generated during the 1957 Andreanof Islands earthquake (Mw 8.6), has the smallest sediment volume. Several older deposits have larger volumes. Models show that ≥10 m of slip on the Aleutian subduction megathrust offshore of Stardust Bay could produce the onshore sediment volume measured for the 1957 deposit. Older tsunami deposits of greater volume require up to 14 m of megathrust slip. Model sensitivity studies show that onshore sediment volume is most sensitive to megathrust slip and less sensitive to other unknowns such as width of fault rupture and roughness of inundated terrain

  14. Implications for stress changes along the Motagua fault and other nearby faults using GPS and seismic constraints on the M=7.3 2009 Swan Islands earthquake

    NASA Astrophysics Data System (ADS)

    Graham, S. E.; Rodriguez, M.; Rogers, R. D.; Strauch, W.; Hernandez, D.; Demets, C.

    2010-12-01

    The May 28, 2009 M=7.3 Swan Islands earthquake off the north coast of Honduras caused significant damage in the northern part of the country, including seven deaths. This event, the largest in the region for several decades, ruptured the offshore continuation of the Motagua-Polochic fault system, whose 1976 earthquake (located several hundred kilometers to the southwest of the 2009 epicenter) caused more than 23,000 deaths in Central America and left homeless 20% of Guatemala’s population. We use elastic half-space modeling of coseismic offsets measured at 39 GPS stations in Honduras, El Salvador, and Guatemala to better understand the slip source of the recent Swan Islands earthquake. Measured offsets range from .32 meters at a campaign site near the Motagua fault in northern Honduras to 4 millimeters at five continuous sites in El Salvador. Coulomb stress calculations based on the estimated distribution of coseismic slip will be presented and compared to earthquake focal mechanisms and aftershock locations determined from a portable seismic network that was installed in northern Honduras after the main shock. Implications of the Swan Islands rupture for the seismically hazardous Motagua-Polochic fault system will be described.

  15. GPS and seismic constraints on the M = 7.3 2009 Swan Islands earthquake: implications for stress changes along the Motagua fault and other nearby faults

    NASA Astrophysics Data System (ADS)

    Graham, Shannon E.; DeMets, Charles; DeShon, Heather R.; Rogers, Robert; Maradiaga, Manuel Rodriguez; Strauch, Wilfried; Wiese, Klaus; Hernandez, Douglas

    2012-09-01

    We use measurements at 35 GPS stations in northern Central America and 25 seismometers at teleseismic distances to estimate the distribution of slip, source time function and Coulomb stress changes of the Mw = 7.3 2009 May 28, Swan Islands fault earthquake. This event, the largest in the region for several decades, ruptured the offshore continuation of the seismically hazardous Motagua fault of Guatemala, the site of the destructive Ms = 7.5 earthquake in 1976. Measured GPS offsets range from 308 millimetres at a campaign site in northern Honduras to 6 millimetres at five continuous sites in El Salvador. Separate inversions of geodetic and seismic data both indicate that up to ˜1 m of coseismic slip occurred along a ˜250-km-long rupture zone between the island of Roatan and the eastern limit of the 1976 M = 7.5 Motagua fault earthquake in Guatemala. Evidence for slip ˜250 km west of the epicentre is corroborated independently by aftershocks recorded by a local seismic network and by the high concentration of damage to structures in areas of northern Honduras adjacent to the western limit of the rupture zone. Coulomb stresses determined from the coseismic slip distribution resolve a maximum of 1 bar of stress transferred to the seismically hazardous Motagua fault and further indicate unclamping of normal faults along the northern shore of Honduras, where two M > 5 normal-faulting earthquakes and numerous small earthquakes were triggered by the main shock.

  16. Inter-plate aseismic slip on the subducting plate boundaries estimated from repeating earthquakes

    NASA Astrophysics Data System (ADS)

    Igarashi, T.

    2015-12-01

    Sequences of repeating earthquakes are caused by repeating slips of small patches surrounded by aseismic slip areas at plate boundary zones. Recently, they have been detected in many regions. In this study, I detected repeating earthquakes which occurred in Japan and the world by using seismograms observed in the Japanese seismic network, and investigated the space-time characteristics of inter-plate aseismic slip on the subducting plate boundaries. To extract repeating earthquakes, I calculate cross-correlation coefficients of band-pass filtering seismograms at each station following Igarashi [2010]. I used two data-set based on USGS catalog for about 25 years from May 1990 and JMA catalog for about 13 years from January 2002. As a result, I found many sequences of repeating earthquakes in the subducting plate boundaries of the Andaman-Sumatra-Java and Japan-Kuril-Kamchatka-Aleutian subduction zones. By applying the scaling relations among a seismic moment, recurrence interval and slip proposed by Nadeau and Johnson [1998], they indicate the space-time changes of inter-plate aseismic slips. Pairs of repeating earthquakes with the longest time interval occurred in the Solomon Islands area and the recurrence interval was about 18.5 years. The estimated slip-rate is about 46 mm/year, which correspond to about half of the relative plate motion in this area. Several sequences with fast slip-rates correspond to the post-seismic slips after the 2004 Sumatra-Andaman earthquake (M9.0), the 2006 Kuril earthquake (M8.3), the 2007 southern Sumatra earthquake (M8.5), and the 2011 Tohoku-oki earthquake (M9.0). The database of global repeating earthquakes enables the comparison of the inter-plate aseismic slips of various plate boundary zones of the world. I believe that I am likely to detect more sequences by extending analysis periods in the area where they were not found in this analysis.

  17. Earthquake evidence for along-arc extension in the Mariana Islands

    NASA Astrophysics Data System (ADS)

    Heeszel, David S.; Wiens, Douglas A.; Shore, Patrick J.; Shiobara, Hajime; Sugioka, Hiroko

    2008-12-01

    Analysis of data from a deployment of ocean bottom and land seismographs in 2003-2004 detected four swarms of earthquakes in the overriding plate of the Mariana subduction system between the fore-arc and the back-arc spreading center. Two additional shallow swarms were identified by analyzing the teleseismic earthquake catalogs from 1967 to 2003. Focal mechanism solutions for these swarms, determined from regional waveform inversion for the 2003-2004 events or retrieved from the Centroid Moment Tensor catalog for previous years, suggest a complex system of deformation throughout the arc. We observe arc-parallel extension near volcanic cross chains, arc-perpendicular extension along the frontal arc, and arc-parallel compression farther into the back arc near the Mariana Trough. A swarm beneath the middle and eastern summits of the Diamante cross chain may have recorded magmatic activity. Volcanic cross chains showing evidence of adiabatic decompression melting from extensional upwelling are localized at regions of enhanced along-strike extension. The earthquake data are consistent with recent GPS results indicating 12 mm/a of extension between Guam and Agrihan. The along-arc extension may result from either increasing curvature of the Mariana system with time or from deformation induced by oblique subduction in the northernmost and southernmost regions of the arc.

  18. Geology and mineral resources of the Port Moller region, western Alaska Peninsula, Aleutian arc: A section in USGS research on mineral resources - 1989: Program and abstracts

    USGS Publications Warehouse

    Wilson, Frederic H.; White, Willis H.; Detterman, Robert L.

    1988-01-01

    Geologic mapping of the Port Moller, Stepovak Bay, and Simeonof Island quadrangles was begun under the auspices of the Alaska Mineral Resource Assessment Program (AMRAP) in 1983 . Two important mineral deposits are located in the Port Moller quadrangle; the Pyramid prospect is the largest copper porphyry system in the Aleutian Arc, and the Apollo Mine is the only gold mine to reach production status in the Aleutian Arc.

  19. Ground deformation effects from the M6 earthquakes (2014-2015) on Cephalonia-Ithaca Islands (Western Greece) deduced by GPS observations

    NASA Astrophysics Data System (ADS)

    Szwed, Małgorzata; Pińskwar, Iwona; Kundzewicz, Zbigniew W.; Graczyk, Dariusz; Mezghani, Abdelkader

    2017-03-01

    The implications of the earthquakes that took place in the central Ionian Islands in 2014 (Cephalonia, M w6.1, M w5.9) and 2015 (Lefkas, M w6.4) are described based on repeat measurements of the local GPS networks in Cephalonia and Ithaca, and the available continuous GPS stations in the broader area. The Lefkas earthquake occurred on a branch of the Cephalonia Transform Fault, affecting Cephalonia with SE displacements gradually decreasing from north ( 100 mm) to south ( 10 mm). This earthquake revealed a near N-S dislocation boundary separating Paliki Peninsula in western Cephalonia from the rest of the island, as well as another NW-SE trending fault that separates kinematically the northern and southern parts of Paliki. Strain field calculations during the interseismic period (2014-2015) indicate compression between Ithaca and Cephalonia, while extension appears during the following co-seismic period (2015-2016) including the 2015 Lefkas earthquake. Additional tectonically active zones with differential kinematic characteristics were also identified locally.

  20. Modelling of wave propagation and attenuation in the Osaka sedimentary basin, western Japan, during the 2013 Awaji Island earthquake

    NASA Astrophysics Data System (ADS)

    Asano, Kimiyuki; Sekiguchi, Haruko; Iwata, Tomotaka; Yoshimi, Masayuki; Hayashida, Takumi; Saomoto, Hidetaka; Horikawa, Haruo

    2016-03-01

    On 2013 April 13, an inland earthquake of Mw 5.8 occurred in Awaji Island, which forms the western boundary of the Osaka sedimentary basin in western Japan. The strong ground motion data were collected from more than 100 stations within the basin and it was found that in the Osaka Plain, the pseudo velocity response spectra at a period of around 6.5 s were significantly larger than at other stations of similar epicentral distance outside the basin. The ground motion lasted longer than 3 min in the Osaka Plain where its bedrock depth spatially varies from approximately 1 to 2 km. We modelled long-period (higher than 2 s) ground motions excited by this earthquake, using the finite difference method assuming a point source, to validate the present velocity structure model and to obtain better constraint of the attenuation factor of the sedimentary part of the basin. The effect of attenuation in the simulation was included in the form of Q(f) = Q0(f/f0), where Q0 at a reference frequency f0 was given by a function of the S-wave velocity, Q0 = αVS. We searched for appropriate Q0 values by changing α for a fixed value of f0 = 0.2 Hz. It was found that values of α from 0.2 to 0.5 fitted the observations reasonably well, but that the value of α = 0.3 performed best. Good agreement between the observed and simulated velocity waveforms was obtained for most stations within the Osaka Basin in terms of both amplitude and ground motion duration. However, underestimation of the pseudo velocity response spectra in the period range of 5-7 s was recognized in the central part of the Osaka Plain, which was caused by the inadequate modelling of later phases or wave packets in this period range observed approximately 2 min after the direct S-wave arrival. We analysed this observed later phase and concluded that it was a Love wave originating from the direction of the east coast of Awaji Island.

  1. Radon progeny monitoring at the Eastern North Atlantic (ENA), Graciosa Island ARM facility and a potential earthquake precursory signal

    NASA Astrophysics Data System (ADS)

    Barbosa, Susana; Mendes, Virgilio B.; Azevedo, Eduardo B.

    2016-04-01

    Radon has been considered a promising earthquake precursor, the main rationale being an expected increase in radon exhalation in soil and rocks due to stress associated with the preparatory stages of an earthquake. However, the precursory nature of radon is far from being convincingly demonstrated so far. A major hindrance is the many meteorological and geophysical factors diving radon temporal variability, including the geophysical parameters influencing its emanation (grain size, moisture content, temperature), as well as the meteorological factors (atmospheric pressure, moisture, temperature, winds) influencing its mobility. Despite the challenges, radon remains one of the strongest candidates as a potential earthquake precursor, and it is of crucial importance to investigate the many factors driving its variability and its potential association with seismic events. Continuous monitoring of radon progeny is performed at the Eastern North Atlantic (ENA) facility located in the Graciosa island (Azores, 39N; 28W), a fixed site of the Atmospheric Radiation Measurement programme (ARM), established and supported by the Department of Energy (DOE) of the United States of America with the collaboration of the local government and University of the Azores. The Azores archipelago is associated with a complex geodynamic setting on the Azores triple junction where the American, Eurasian and African litospheric plates meet, resulting in significant seismic and volcanic activity. A considerable advantage of the monitoring site is the availability of a comprehensive dataset of concurrent meteorological observations performed at the ENA facility and freely available from the ARM data archive, enabling a detailed analysis of the environmental factors influencing the temporal variability of radon's progeny. Gamma radiation is being measured continuously every 15 minutes since May 2015. The time series of gamma radiation counts is dominated by sharp peaks lasting a few hours and

  2. 75 FR 52478 - Fisheries of the Economic Exclusive Zone Off Alaska; Pacific Cod in the Bering Sea and Aleutian...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-08-26

    ... Exclusive Zone Off Alaska; Pacific Cod in the Bering Sea and Aleutian Islands AGENCY: National Marine...: Temporary rule; modification of a closure. SUMMARY: NMFS is opening directed fishing for Pacific cod by... 2010 total allowable catch (TAC) of Pacific cod specified for catcher vessels less than 60 feet...

  3. 76 FR 24404 - Fisheries of the Exclusive Economic Zone Off Alaska; Pacific Cod in the Bering Sea and Aleutian...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-05-02

    ... Economic Zone Off Alaska; Pacific Cod in the Bering Sea and Aleutian Islands Management Area AGENCY... cod by catcher vessels less than 60 feet (18.3 meters) length overall (LOA) using hook-and-line or pot... use the 2011 total allowable catch of Pacific cod allocated to catcher vessels less than 60 feet...

  4. 75 FR 19561 - Fisheries of the Economic Exclusive Zone Off Alaska; Pacific Cod in the Bering Sea and Aleutian...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-04-15

    ... Off Alaska; Pacific Cod in the Bering Sea and Aleutian Islands AGENCY: National Marine Fisheries...; modification of a closure. SUMMARY: NMFS is opening directed fishing for Pacific cod by catcher vessels less... catch (TAC) of Pacific cod specified for the BSAI. DATES: Effective 1200 hrs, Alaska local time...

  5. 77 FR 39441 - Fisheries of the Exclusive Economic Zone Off Alaska; Atka Mackerel in the Bering Sea and Aleutian...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-07-03

    ... Economic Zone Off Alaska; Atka Mackerel in the Bering Sea and Aleutian Islands Management Area AGENCY.... ACTION: Temporary rule; closure. SUMMARY: NMFS is prohibiting directed fishing for Atka mackerel in the... total allowable catch (TAC) of Atka mackerel in this area allocated to vessels participating in the...

  6. 78 FR 35771 - Fisheries of the Exclusive Economic Zone Off Alaska; Atka Mackerel in the Bering Sea and Aleutian...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-06-14

    ... Economic Zone Off Alaska; Atka Mackerel in the Bering Sea and Aleutian Islands Management Area AGENCY.... ACTION: Temporary rule; closure. SUMMARY: NMFS is prohibiting directed fishing for Atka mackerel in the... total allowable catch (TAC) of Atka mackerel in this area allocated to vessels participating in the...

  7. 75 FR 14498 - Fisheries of the Exclusive Economic Zone Off Alaska; Atka Mackerel in the Bering Sea and Aleutian...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-03-26

    ... Economic Zone Off Alaska; Atka Mackerel in the Bering Sea and Aleutian Islands Management Area AGENCY.... ACTION: Temporary rule; closure. SUMMARY: NMFS is prohibiting directed fishing for Atka mackerel in the... A season allocation of Atka mackerel in this area allocated to vessels participating in...

  8. 76 FR 10780 - Fisheries of the Exclusive Economic Zone Off Alaska; Atka Mackerel in the Bering Sea and Aleutian...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-02-28

    ... Economic Zone Off Alaska; Atka Mackerel in the Bering Sea and Aleutian Islands Management Area AGENCY.... ACTION: Temporary rule; closure. SUMMARY: NMFS is prohibiting directed fishing for Atka mackerel in the... necessary to prevent exceeding the A season allowance of the 2011 Atka mackerel total allowable catch...

  9. 75 FR 53606 - Fisheries of the Exclusive Economic Zone Off Alaska; Atka Mackerel in the Bering Sea and Aleutian...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-09-01

    ... Zone Off Alaska; Atka Mackerel in the Bering Sea and Aleutian Islands Management Area AGENCY: National...: Temporary rule; closures and openings. SUMMARY: NMFS is prohibiting directed fishing for Atka mackerel in... necessary to prevent exceeding the 2010 total allowable catch (TAC) of Atka mackerel in these areas...

  10. 78 FR 25878 - Fisheries of the Exclusive Economic Zone Off Alaska; Atka Mackerel in the Bering Sea and Aleutian...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-05-03

    ... Economic Zone Off Alaska; Atka Mackerel in the Bering Sea and Aleutian Islands Management Area AGENCY.... ACTION: Temporary rule; closure. SUMMARY: NMFS is prohibiting directed fishing for Atka mackerel in the... season allowance of the 2013 Atka mackerel total allowable catch (TAC) in the CAI allocated to...

  11. 75 FR 6129 - Fisheries of the Exclusive Economic Zone Off Alaska; Atka Mackerel in the Bering Sea and Aleutian...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-02-08

    ... Economic Zone Off Alaska; Atka Mackerel in the Bering Sea and Aleutian Islands Management Area AGENCY.... ACTION: Temporary rule; closure. ] SUMMARY: NMFS is prohibiting directed fishing for Atka mackerel in the... to prevent exceeding the 2010 A season allocation of Atka mackerel in these areas allocated...

  12. 76 FR 65975 - Fisheries of the Exclusive Economic Zone Off Alaska; Atka Mackerel in the Bering Sea and Aleutian...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-10-25

    ... Economic Zone Off Alaska; Atka Mackerel in the Bering Sea and Aleutian Islands Management Area AGENCY.... ACTION: Temporary rule; closure. SUMMARY: NMFS is prohibiting directed fishing for Atka mackerel in the... necessary to prevent exceeding the 2011 total allowable catch (TAC) of Atka mackerel in these...

  13. 77 FR 26212 - Fisheries of the Exclusive Economic Zone Off Alaska; Atka Mackerel in the Bering Sea and Aleutian...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-05-03

    ... Economic Zone Off Alaska; Atka Mackerel in the Bering Sea and Aleutian Islands Management Area AGENCY.... ACTION: Temporary rule; closure. SUMMARY: NMFS is prohibiting directed fishing for Atka mackerel in the... season allowance of the 2012 Atka mackerel total allowable catch (TAC) in the CAI allocated to...

  14. Modeling of Wave Propagation in the Osaka Sedimentary Basin during the 2013 Awaji Island Earthquake (Mw5.8)

    NASA Astrophysics Data System (ADS)

    Asano, K.; Sekiguchi, H.; Iwata, T.; Yoshimi, M.; Hayashida, T.; Saomoto, H.; Horikawa, H.

    2013-12-01

    The three-dimensional velocity structure model for the Osaka sedimentary basin, southwest Japan is developed and improved based on many kinds of geophysical explorations for decades (e.g., Kagawa et al., 1993; Horikawa et al., 2003; Iwata et al., 2008). Recently, our project (Sekiguchi et al., 2013) developed a new three-dimensional velocity model for strong motion prediction of the Uemachi fault earthquake in the Osaka basin considering both geophysical and geological information by adding newly obtained exploration data such as reflection surveys, microtremor surveys, and receiver function analysis (hereafter we call UMC2013 model) . On April 13, 2013, an inland earthquake of Mw5.8 occurred in Awaji Island, which is close to the southwestern boundary of the aftershock area of the 1995 Kobe earthquake. The strong ground motions are densely observed at more than 100 stations in the basin. The ground motion lasted longer than four minutes in the Osaka urban area where its bedrock depth is about 1-2 km. This long-duration ground motions are mainly due to the surface waves excited in this sedimentary basin whereas the magnitude of this earthquake is moderate and the rupture duration is expected to be less than 5 s. In this study, we modeled long-period (more than 2s) ground motions during this earthquake to check the performance of the present UMC2013 model and to obtain a better constraint on the attenuation factor of sedimentary part of the basin. The seismic wave propagation in the region including the source and the Osaka basin is modeled by the finite difference method using the staggered grid solving the elasto-dynamic equations. The domain of 90km×85km×25.5km is modeled and discretized with a grid spacing of 50 m. Since the minimum S-wave velocity of the UMC2013 model is about 250 m/s, this calculation is valid up to the period of about 1 s. The effect of attenuation is included in the form of Q(f)=Q0(T0/T) proposed by Graves (1996). A PML is implemented in

  15. Ionospheric Anomalies Related to the (M = 7.3), August 27, 2012, Puerto Earthquake, (M = 6.8), August 30, 2012 Jan Mayen Island Earthquake, and (M = 7.6), August 31, 2012, Philippines Earthquake: Two-Dimensional Principal Component Analysis

    PubMed Central

    Lin, Jyh-Woei

    2013-01-01

    Two-dimensional principal component analysis (2DPCA) and principal component analysis (PCA) are used to examine the ionospheric total electron content (TEC) data during the time period from 00:00 on August 21 to 12: 45 on August 31 (UT), which are 10 days before the M = 7.6 Philippines earthquake at 12:47:34 on August 31, 2012 (UT) with the depth at 34.9 km. From the results by using 2DPCA, a TEC precursor of Philippines earthquake is found during the time period from 4:25 to 4:40 on August 28, 2012 (UT) with the duration time of at least 15 minutes. Another earthquake-related TEC anomaly is detectable for the time period from 04:35 to 04:40 on August 27, 2012 (UT) with the duration time of at least 5 minutes during the Puerto earthquake at 04: 37:20 on August 27, 2012 (UT) (Mw = 7.3) with the depth at 20.3 km. The precursor of the Puerto earthquake is not detectable. TEC anomaly is not to be found related to the Jan Mayen Island earthquake (Mw = 6.8) at 13:43:24 on August 30, 2012 (UT). These earthquake-related TEC anomalies are detectable by using 2DPCA rather than PCA. They are localized nearby the epicenters of the Philippines and Puerto earthquakes. PMID:23844386

  16. Ionospheric anomalies related to the (M = 7.3), August 27, 2012, Puerto earthquake, (M = 6.8), August 30, 2012 Jan Mayen Island earthquake, and (M = 7.6), August 31, 2012, Philippines earthquake: two-dimensional principal component analysis.

    PubMed

    Lin, Jyh-Woei

    2013-01-01

    Two-dimensional principal component analysis (2DPCA) and principal component analysis (PCA) are used to examine the ionospheric total electron content (TEC) data during the time period from 00:00 on August 21 to 12: 45 on August 31 (UT), which are 10 days before the M = 7.6 Philippines earthquake at 12:47:34 on August 31, 2012 (UT) with the depth at 34.9 km. From the results by using 2DPCA, a TEC precursor of Philippines earthquake is found during the time period from 4:25 to 4:40 on August 28, 2012 (UT) with the duration time of at least 15 minutes. Another earthquake-related TEC anomaly is detectable for the time period from 04:35 to 04:40 on August 27, 2012 (UT) with the duration time of at least 5 minutes during the Puerto earthquake at 04: 37:20 on August 27, 2012 (UT) (M(w) = 7.3) with the depth at 20.3 km. The precursor of the Puerto earthquake is not detectable. TEC anomaly is not to be found related to the Jan Mayen Island earthquake (M w = 6.8) at 13:43:24 on August 30, 2012 (UT). These earthquake-related TEC anomalies are detectable by using 2DPCA rather than PCA. They are localized nearby the epicenters of the Philippines and Puerto earthquakes.

  17. Sea birds as proxies of marine habitats and food webs in the western Aleutian Arc

    USGS Publications Warehouse

    Springer, Alan M.; Piatt, John F.; Van Vliet, Gus B.

    1996-01-01

    We propose that ocean conditions of the Near Islands in the western Aleutian Arc mimic those of the shallow continental shelf of the eastern Bering Sea to the extent that the marine community, including assemblages of forage fishes and their avian predators, has distinctly coastal characteristics. In contrast, marine avifauna and their prey at neighbouring Buldir Island are distinctly oceanic. For example, at the Near Islands, the ratio of thick-billed to common murres, Vria lomvia and U. aalge, is low and black-legged kittiwakes, Rissa tridactyla, but not red-legged kittiwakes, R. brevirostris, nest there. Diets of murres and kittiwakes are dominated by sand lance, Ammodytes hexapterus, an abundant coastal species. At Buldir Island, thick-billed murres greatly outnumber common murres, red-legged kittiwakes and black-legged kittiwakes are both abundant, and diets of the birds consist primarily of oceanic squid and lantern-fish (Myctophidae). This mesoscale difference in food webs is apparently a consequence of the local physiography. A broad escarpment on the Near physiographic block creates a comparatively expansive, shallow, shelflike habitat around the Near Islands, where a pelagic community typical of coastal regions flourishes. Buldir Island is the only emergent feature of the Buldir physiographic block, with little shallow water surrounding it and, apparently, little opportunity for other than oceanic species to exist. Patterns in the distribution of fishes, and thus of sea birds, throughout the Aleutian Islands might be largely explained by the presence or absence of shelf-like habitat and the relationship between physical environments and food webs. In the larger context of fisheries oceanography, this model for the Aleutian Islands improves our ability to interpret physical and biological heterogeneity in the ocean and its relationship to regional community dynamics and trends in the abundance and productivity of individual species at higher trophic levels.

  18. Applying the Time-Domain Moment Tensor Inversion technique to Regional Earthquake Data in the Puerto Rico-Virgin Island Region

    NASA Astrophysics Data System (ADS)

    Martinez-Torres, F. A.; Lopez, A. M.

    2015-12-01

    The quick determination of an earthquake's moment tensor, whose description relate to centroid depth, faulting geometry and size, is crucial for tsunami warning systems. Whether an event possesses the critical parameters to produce a devastating tsunami, tsunami warning centers must knowThis research project seeks to test, well-formulated time-domain moment tensor inversion code in order to obtain in quasi real-time faulting parameters of significant regional earthquakes in the Puerto Rico-Virgin Islands region. The inversion code has been developed by researchers at the Berkeley Seismological Laboratory, whose main attractive is to decrease the time it takes to have an estimate calculation of a moment tensor for any major earthquake using regional data, approximately less than 7 minutes of an earthquake's origin time. Four seismic events in the region have been used as testbed to the inversion code configured for this area. In order to compare our results, previously computed and published moment tensor inversions from the Global CMT and USGS for the same events were used to assess the deviations from results obtained in this study. Our results indicate the inversion method is capable of reproducing the regional and teleseismic solutions, and thus can be incorporated into daily earthquake location operations at the Puerto Rico Seismic Network (PRSN) for quick estimation of faulting mechanisms and tsunami warning purposes.

  19. Sea otter population declines in the Aleutian Archipelago

    USGS Publications Warehouse

    Doroff, Angela; Estes, James A.; Tinker, M. Tim; Burn, Douglas M.; Evans, Thomas J.

    2003-01-01

    Sea otter (Enhydra lutris) populations were exploited to near extinction and began to recover after the cessation of commercial hunting in 1911. Remnant colonies of sea otters in the Aleutian archipelago were among the first to recover; they continued to increase through the 1980s but declined abruptly during the 1990s. We conducted an aerial survey of the Aleutian archipelago in 2000 and compared results with similar surveys conducted in 1965 and 1992. The number of sea otters counted decreased by 75% between 1965 and 2000; 88% for islands at equilibrial density in 1965. The population decline likely began in the mid-1980s and declined at a rate of 17.5%/year in the 1990s. The minimal population estimate was 8,742 sea otters in 2000. The population declined to a uniformly low density in the archipelago, suggesting a common and geographically widespread cause. These data are in general agreement with the hypothesis of increased predation on sea otters. These data chronicle one of the most widespread and precipitous population declines for a mammalian carnivore in recorded history.

  20. Earthquakes, March-April, 1993

    USGS Publications Warehouse

    Person, Waverly J.

    1993-01-01

    Worldwide, only one major earthquake (7.0earthquake, a magnitude 7.2 shock, struck the Santa Cruz Islands region in the South Pacific on March 6. Earthquake-related deaths occurred in the Fiji Islands, China, and Peru.

  1. 49 CFR 71.12 - Hawaii-Aleutian zone.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 1 2013-10-01 2013-10-01 false Hawaii-Aleutian zone. 71.12 Section 71.12 Transportation Office of the Secretary of Transportation STANDARD TIME ZONE BOUNDARIES § 71.12 Hawaii-Aleutian zone. The seventh zone, the Hawaii-Aleutian standard time zone, includes the entire State of Hawaii...

  2. 49 CFR 71.12 - Hawaii-Aleutian zone.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 1 2010-10-01 2010-10-01 false Hawaii-Aleutian zone. 71.12 Section 71.12 Transportation Office of the Secretary of Transportation STANDARD TIME ZONE BOUNDARIES § 71.12 Hawaii-Aleutian zone. The seventh zone, the Hawaii-Aleutian standard time zone, includes the entire State of Hawaii...

  3. 49 CFR 71.12 - Hawaii-Aleutian zone.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 1 2012-10-01 2012-10-01 false Hawaii-Aleutian zone. 71.12 Section 71.12 Transportation Office of the Secretary of Transportation STANDARD TIME ZONE BOUNDARIES § 71.12 Hawaii-Aleutian zone. The seventh zone, the Hawaii-Aleutian standard time zone, includes the entire State of Hawaii...

  4. 49 CFR 71.12 - Hawaii-Aleutian zone.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 1 2011-10-01 2011-10-01 false Hawaii-Aleutian zone. 71.12 Section 71.12 Transportation Office of the Secretary of Transportation STANDARD TIME ZONE BOUNDARIES § 71.12 Hawaii-Aleutian zone. The seventh zone, the Hawaii-Aleutian standard time zone, includes the entire State of Hawaii...

  5. 49 CFR 71.12 - Hawaii-Aleutian zone.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 1 2014-10-01 2014-10-01 false Hawaii-Aleutian zone. 71.12 Section 71.12 Transportation Office of the Secretary of Transportation STANDARD TIME ZONE BOUNDARIES § 71.12 Hawaii-Aleutian zone. The seventh zone, the Hawaii-Aleutian standard time zone, includes the entire State of Hawaii...

  6. Anatahan Island

    Atmospheric Science Data Center

    2013-04-19

    ... deepest ocean trench. Anatahan had no known historical eruptions until May 2003. The evacuation of the island's residents in 1990 was ... earthquake swarm that suggested the possibility of impending volcanic activity. The Micronesian Megapode is an endangered species of ...

  7. Crustal Deformation and the Seismic Cycle Across the Kodiak Islands, Alaska

    NASA Technical Reports Server (NTRS)

    Sauber, Jeanne; Carver, Gary; Cohen, Steven; King, Robert

    2005-01-01

    The Kodiak Islands are located approximately 120 to 250 km from the Alaska-Aleutian Trench - and are within the southern extent of the 1964 Prince William Sound (M(sub w) = 9.2) earthquake rupture zone. Here we report new campaign GPS results (1993-2001) from northern Kodiak Island. The rate and orientation of the horizontal velocities, relative to a fixed North America, range from 25.3 plus or minus 1.4 mm/yr at N32.9 deg. W plus or minus 2.5 to 8.5 plus or minus 1.0 mm/yr at N59.7 deg. W plus or minus 6.5 deg. In addition to the northern Kodiak data, we analyzed data from three southern Kodiak Island stations. The inland stations from both the northern and southern networks indicate a counterclockwise rotation of the velocity vectors. These results are consistent with the hypothesis that the difference between the Pacific-North American plate motion and the orientation of the down going slab would lead to 4-8 mm/yr of left-lateral slip above the unlocked, down-dip portion of the main thrust zone. The northern and southern Kodiak geodetic data are consistent with a model that includes the viscoelastic response to (1) a downgoing Pacific plate interface that is locked at shallow depths, (2) local coseismic slip in the 1964 earthquake, and (3) interseismic creep down dip from the seismogenic zone. Based on the pre-1964 and post-1944 earthquake history, as well as the pattern of interseismic earthquakes across the plate boundary zone, we hypothesize that in southern Kodiak some strain is released in moderate to large earthquakes between the occurrences of great earthquakes like the 1964 event.

  8. Postseismic gravity change after the 2006-2007 great earthquake doublet and constraints on the asthenosphere structure in the central Kuril Islands.

    PubMed

    Han, Shin-Chan; Sauber, Jeanne; Pollitz, Fred

    2016-04-16

    Large earthquakes often trigger viscoelastic adjustment for years to decades depending on the rheological properties and the nature and spatial extent of coseismic stress. The 2006 Mw8.3 thrust and 2007 Mw8.1 normal fault earthquakes of the central Kuril Islands resulted in significant postseismic gravity change in GRACE but without a discernible coseismic gravity change. The gravity increase of ~4 µGal, observed consistently from various GRACE solutions around the epicentral area during 2007-2015, is interpreted as resulting from gradual seafloor uplift by ~6 cm produced by postseismic relaxation. The GRACE data are best fit with a model of 25-35 km for the elastic thickness and ~10(18) Pa s for the Maxwell viscosity of the asthenosphere. The large measurable postseismic gravity change (greater than coseismic change) emphasizes the importance of viscoelastic relaxation in understanding tectonic deformation and fault-locking scenarios in the Kuril subduction zone.

  9. Postseismic Gravity Change After the 2006-2007 Great Earthquake Doublet and Constraints on the Asthenosphere Structure in the Central Kuril Islands

    NASA Technical Reports Server (NTRS)

    Shin-Chan, Han; Sauber, Jeanne; Pollitz, Fred

    2016-01-01

    Large earthquakes often trigger viscoelastic adjustment for years to decades depending on the rheological properties and the nature and spatial extent of coseismic stress. The 2006 Mw8.3 thrust and 2007 Mw8.1 normal fault earthquakes of the central Kuril Islands resulted in significant postseismic gravity change in GRACE but without a discernible coseismic gravity change. The gravity increase of approximately 4 micro-Gal, observed consistently from various GRACE solutions around the epicentral area during 2007-2015, is interpreted as resulting from gradual seafloor uplift by (is) approximately 6 cm produced by postseismic relaxation. The GRACE data are best fit with a model of 25-35 km for the elastic thickness and approximately 10(exp 18) Pa s for the Maxwell viscosity of the asthenosphere. The large measurable postseismic gravity change (greater than coseismic change) emphasizes the importance of viscoelastic relaxation in understanding tectonic deformation and fault-locking scenarios in the Kuril subduction zone.

  10. Water in Aleutian Arc Volcanoes

    NASA Astrophysics Data System (ADS)

    Plank, T.; Zimmer, M. M.; Hauri, E. H.

    2011-12-01

    In the past decade, baseline data have been obtained on pre-eruptive water contents for several volcanic arcs worldwide. One surprising observation is that parental magmas contain ~ 4 wt% H2O on average at each arc worldwide [1]. Within each arc, the variation from volcano to volcano is from 2 to 6 w% H2O, with few exceptions. The similar averages at different arcs are unexpected given the order of magnitude variations in the concentration of other slab tracers. H2O is clearly different from other tracers, however, being both a major driver of melting in the mantle and a major control of buoyancy and viscosity in the crust. Some process, such as mantle melting or crustal storage, apparently modulates the water content of mafic magmas at arcs. Mantle melting may deliver a fairly uniform product to the Moho, if the wet melt process includes a negative feedback. On the other hand, magmas with variable water content may be generated in the mantle, but a crustal filter may lead to magma degassing up to a common mid-to-upper crustal storage region. Testing between these two end-member scenarios is critical to our understanding of subduction dehydration, global water budgets, magmatic plumbing systems, melt generation and eruptive potential. The Alaska-Aleutian arc is a prime location to explore this fundamental problem in the subduction water cycle, because active volcanoes vary more than elsewhere in the world in parental H2O contents (based on least-degassed, mafic melt inclusions hosted primarily in olivine). For example, Shishaldin volcano taps magma with among the lowest H2O contents globally (~ 2 wt%) and records low pressure crystal fractionation [2], consistent with a shallow magma system (< 1 km bsl). At the other extreme, Augustine volcano is fed by a mafic parent that contains among the highest H2O globally (~ 7 wt%), and has evolved by deep crystal fractionation [2], consistent with a deep magma system (~ 14 km bsl). Do these magmas stall at different depths

  11. Alaska earthquake source for the SAFRR tsunami scenario: Chapter B in The SAFRR (Science Application for Risk Reduction) Tsunami Scenario

    USGS Publications Warehouse

    Kirby, Stephen; Scholl, David; von Huene, Roland; Wells, Ray

    2013-01-01

    Tsunami modeling has shown that tsunami sources located along the Alaska Peninsula segment of the Aleutian-Alaska subduction zone have the greatest impacts on southern California shorelines by raising the highest tsunami waves for a given source seismic moment. The most probable sector for a Mw ~ 9 source within this subduction segment is between Kodiak Island and the Shumagin Islands in what we call the Semidi subduction sector; these bounds represent the southwestern limit of the 1964 Mw 9.2 Alaska earthquake rupture and the northeastern edge of the Shumagin sector that recent Global Positioning System (GPS) observations indicate is currently creeping. Geological and geophysical features in the Semidi sector that are thought to be relevant to the potential for large magnitude, long-rupture-runout interplate thrust earthquakes are remarkably similar to those in northeastern Japan, where the destructive Mw 9.1 tsunamigenic earthquake of 11 March 2011 occurred. In this report we propose and justify the selection of a tsunami source seaward of the Alaska Peninsula for use in the Tsunami Scenario that is part of the U.S. Geological Survey (USGS) Science Application for Risk Reduction (SAFRR) Project. This tsunami source should have the potential to raise damaging tsunami waves on the California coast, especially at the ports of Los Angeles and Long Beach. Accordingly, we have summarized and abstracted slip distribution from the source literature on the 2011 event, the best characterized for any subduction earthquake, and applied this synoptic slip distribution to the similar megathrust geometry of the Semidi sector. The resulting slip model has an average slip of 18.6 m and a moment magnitude of Mw = 9.1. The 2011 Tohoku earthquake was not anticipated, despite Japan having the best seismic and geodetic networks in the world and the best historical record in the world over the past 1,500 years. What was lacking was adequate paleogeologic data on prehistoric earthquakes

  12. Earthquakes; January-March 1976

    USGS Publications Warehouse

    Person, W.J.

    1976-01-01

    The year 1976 started out quite active, seismically. Four major earthquakes occurred in different parts of the world during the first 3 months of the year. Three earthquakes rattled the western rim of the Pacific Ocean from the Kuril Islands to the Kermadec Islands. The fourth major earthquake struck Guatemala, killing thousands of people, injuring many, and leaving thousands homeless. Earthquakes in Kentucky and Arkansas caused little damage but were felt in several States. Arizona experienced a sharp earthquake in the Chico Valley, which caused very little damage. Other States experienced earthquakes, but none caused damage. 

  13. Surface deformation associated with the March 1996 earthquake swarm at Akutan Island, Alaska, revealed by C-band ERS and L-band JERS radar interferometry

    USGS Publications Warehouse

    Lu, Zhiming; Wicks, C.; Kwoun, O.; Power, J.A.; Dzurisin, D.

    2005-01-01

    In March 1996, an intense earthquake swarm beneath Akutan Island, Alaska, was accompanied by extensive ground cracking but no eruption of Akutan volcano. Radar interferograms produced from L-band JERS-1 and C-band ERS-1/2 images show uplift associated with the swarm by as much as 60 cm on the western part of the island. The JERS-1 interferogram has greater coherence, especially in areas with loose surface material or thick vegetation. It also shows subsidence of similar magnitude on the eastern part of the island and displacements along faults reactivated during the swarm. The axis of uplift and subsidence strikes about N70??W, which is roughly parallel to a zone of fresh cracks on the northwest flank of the volcano, to normal faults that cut the island and to the inferred maximum compressive stress direction. A common feature of models that fit the deformation is the emplacement of a shallow dike along this trend beneath the northwest flank of the volcano. Both before and after the swarm, the northwest flank was uplifted 5-20 mm/year relative to the southwest flank, probably by magma intrusion. The zone of fresh cracks subsided about 20 mm during 1996-1997 and at lesser rates thereafter, possibly because of cooling and degassing of the intrusion. ?? 2005 CASI.

  14. Comprehensive study of the seismotectonics of the eastern Aleutian ARC and associated volcanic systems

    NASA Astrophysics Data System (ADS)

    Jacob, K. H.; Hauksson, E.; Sykes, L. R.; Davies, J.; House, L.; Morl, J.; McNutt, S.; Johnson, D.; Peterson, J.; Hauptman, J.

    Assessment of the seismic potential for occurrence of great earthquakes in three seismic gaps (Shumagin Islands, Unalaska Island, and Yakataga-Kayak regions) was completed. In the best instrumented seismic gap in the Shumagin Islands region, the likelihood for a great earthquake within the next two decades is high. Analysis of earthquake data collected from a telemetered network operated in the Shumagin seismic gap shows near quiescence in the shallow portion of the main thrust zone. High time resolution data (0.01 sec), and wider frequency bandpass data (0.5 to 30 Hz) are being collected. Seismic data for two eruptive sequences of Pavlof volcano were obtained.

  15. Tectonic tremor on Vancouver Island, Cascadia, modulated by the body and surface waves of the Mw 8.6 and 8.2, 2012 East Indian Ocean earthquakes

    NASA Astrophysics Data System (ADS)

    Kundu, Bhaskar; Ghosh, Abhijit; Mendoza, Manuel; Bürgmann, Roland; Gahalaut, V. K.; Saikia, Dipankar

    2016-09-01

    The 2012 East Indian Ocean earthquake (Mw 8.6), so far the largest intraoceanic plate strike-slip event ever recorded, modulated tectonic tremors in the Cascadia subduction zone. The rate of tremor activity near Vancouver Island increased by about 1.5 times from its background level during the passage of seismic waves of this earthquake. In most cases of dynamic modulation, large-amplitude and long-period surface waves stimulate tremors. However, in this case even the small stress change caused by body waves generated by the 2012 earthquake modulated tremor activity. The tremor modulation continued during the passage of the surface waves, subsequent to which the tremor activity returned to background rates. Similar tremor modulation is observed during the passage of the teleseismic waves from the Mw 8.2 event, which occurs about 2 h later near the Mw 8.6 event. We show that dynamic stresses from back-to-back large teleseismic events can strongly influence tremor sources.

  16. Observations of deep long-period (DLP) seismic events beneath Aleutian arc volcanoes; 1989-2002

    USGS Publications Warehouse

    Power, J.A.; Stihler, S.D.; White, R.A.; Moran, S.C.

    2004-01-01

    Between October 12, 1989 and December 31, 2002, the Alaska Volcano Observatory (AVO) located 162 deep long-period (DLP) events beneath 11 volcanic centers in the Aleutian arc. These events generally occur at mid- to lower-crustal depths (10-45 km) and are characterized by emergent phases, extended codas, and a strong spectral peak between 1.0 and 3.0 Hz. Observed wave velocities and particle motions indicate that the dominant phases are P- and S-waves. DLP epicenters often extend over broad areas (5-20 km) surrounding the active volcanoes. The average reduced displacement of Aleutian DLPs is 26.5 cm2 and the largest event has a reduced displacement of 589 cm2 (or ML2.5). Aleutian DLP events occur both as solitary events and as sequences of events with several occurring over a period of 1-30 min. Within the sequences, individual DLPs are often separated by lower-amplitude volcanic tremor with a similar spectral character. Occasionally, volcano-tectonic earthquakes that locate at similar depths are contained within the DLP sequences.At most, Aleutian volcanoes DLPs appear to loosely surround the main volcanic vent and occur as part of background seismicity. A likely explanation is that they reflect a relatively steady-state process of magma ascent over broad areas in the lower and middle portions of the crust. At Mount Spurr, DLP seismicity was initiated by the 1992 eruptions and then slowly declined until 1997. At Shishaldin Volcano, a short-lived increase in DLP seismicity occurred about 10 months prior to the April 19, 1999 eruption. These observations suggest a link between eruptive activity and magma flux in the mid- to lower-crust and uppermost mantle.

  17. Insights into the 2011-2012 submarine eruption off the coast of El Hierro (Canary Islands, Spain) from statistical analyses of earthquake activity

    NASA Astrophysics Data System (ADS)

    Ibáñez, J. M.; De Angelis, S.; Díaz-Moreno, A.; Hernández, P.; Alguacil, G.; Posadas, A.; Pérez, N.

    2012-08-01

    The purpose of this work is to gain insights into the 2011-2012 eruption of El Hierro (Canary Islands) by mapping the evolution of the seismic b-value. The El Hierro seismic sequence offers a rather unique opportunity to investigate the process of reawakening of an oceanic intraplate volcano after a long period of repose. The 2011-2012 eruption is a submarine volcanic event that took place about 2 km off of the southern coast of El Hierro. The eruption was accompanied by an intense seismic swarm and surface manifestations of activity. The earthquake catalogue during the period of unrest includes over 12 000 events, the largest with magnitude 4.6. The seismic sequence can be grouped into three distinct phases, which correspond to well-separated spatial clusters and distinct earthquake regimes. The estimated b-value is of 1.18 ± 0.03, and a magnitude of completeness of 1.3, for the entire catalogue. B is very close to 1.0, which indicates completeness of the earthquake catalogue with only minor departures from the linearity of Gutenberg-Richter frequency-magnitude distribution. The most straightforward interpretation of this result is that the seismic swarm reached its final stages, and no additional large magnitude events should be anticipated, similarly to what one would expect for non-volcanic earthquake sequences. The results, dividing the activity in different phases, illustrate remarkable differences in the estimate of b-value during the early and late stages of the eruption. The early pre-eruptive activity was characterized by a b-value of 2.25. In contrast, the b-value was 1.25 during the eruptive phase. Based on our analyses, and the results of other studies, we propose a scenario that may account for the observations reported in this work. We infer that the earthquakes that occurred in the first phase reflect magma migration from the upper mantle to crustal depths. The area where magma initially intruded into the crust, because of its transitional nature

  18. GLORIA imagery links sedimentation in Aleutian Trench to Yakutat margin via surveyor channel

    SciTech Connect

    Carlson, P.R.; Bruns, T.R.; Mann, D.M.; Stevenson, A.J. ); Huggett, Q.J. )

    1990-06-01

    GLORIA side-scan sonar imagery shows that the continental slope developing along the active margin of the Gulf of Alaska is devoid of large submarine canyons, in spite of the presence of large glacially formed sea valleys that cross the continental shelf. In the western and northern Gulf, discontinuous, actively growing deformation structures disrupt or divert the downslope transport of sediment into the Aleutian Trench. To the east of Middleton Island, the slope is intensively gullied and incised only by relatively small canyons. At the base of the gullied slope between Pamplona Spur and Alsek Valley, numerous small slope gullies coalesce into three turbidity current channels that merge to form the Surveyor deep-sea channel. About 350 km from the margin, the channel crosses the structural barrier formed by the Kodiak-Bowie Seamount chain and heads south for another 150 km where it bends northerly, perhaps influenced by the oceanic basement relief of the Patton Seamounts. The channel, now up to 5 km wide and deeply entrenched to 450 m, continues northerly for 200 km where it intercepts the Aleutian Trench, some 700 km from the Yakutat margin. South of Surveyor Channel, GLORIA imagery revealed evidence of another older channel. The older channel meanders through a gap in the seamount chain and eventually bends northwesterly. This now inactive, largely buried channel may have carried turbidity currents to the Aleutian Trench concurrent with the active Surveyor Channel.

  19. Paleo-earthquake signatures from the South Wagad Fault (SWF), Wagad Island, Kachchh, Gujarat, western India: A potential seismic hazard

    NASA Astrophysics Data System (ADS)

    Malik, Javed N.; Gadhavi, Mahendrasinh S.; Kothyari, Girish Ch; Satuluri, Sravanthi

    2017-02-01

    In last 500 years, Kachchh experienced several large magnitude earthquakes (6.0 ≥ M ≤ 7.8), however, not all accompanied surface rupture. The 1819 Allah Bund earthquake (Mw7.8) accompanied surface rupture, whereas, the 2001 Bhuj event (Mw7.6) occurred at a depth of 23 km on E-W striking south dipping thrust fault remained blind. Discontinuities between the denser-brittle basement (?) and overlying ductile-softer Mesozoic-Tertiary-Quaternary succession resulted in a different geometry of faulting. Normal faults associated with rift were reactivated as reverse faults during inversion tectonics, propagated in sedimentary succession and arrested. Thrust-ramps developed along the discontinuities accompanied surface ruptures. Folded structures along the South Wagad Fault (SWF) - an active thrust, exhibits lateral-propagation of fold segments and linkage, suggestive of fault-related-fold growth. Paleoseismic investigations revealed evidence of at least three paleo-earthquakes. Event I occurred before BCE 5080; Event II between BCE 4820 and 2320, and was probably responsible for a massive damage at Dholavira - Harappan site. Event III was between BCE 1230 and 04, most likely caused severe damage to Dholavira. Archaeo-seismological Quality Factor (AQF) of 0.5 suggests that the Dholavira is vulnerable to earthquakes from nearby active faults. With 1500-2000 yr of recurrence interval, occurrence of a large magnitude earthquake on SWF cannot be ruled out.

  20. Earthquakes, January-February 1992

    USGS Publications Warehouse

    Person, W.J.

    1992-01-01

    In terms of seismic activity, the first two months of 1992 were somewhat quiet. There was one major earthquake (7.0-7.9) during this reporting period-a magntidue 7.1 earthquake in the Vanuatu Islands. There were no earthquake-related deaths for the first two months.

  1. Earthquakes, March-April 1978

    USGS Publications Warehouse

    Person, W.J.

    1978-01-01

    Earthquakes caused fatalities in Mexico and Sicily; injuries and damage were sustained in eastern Kazakh SSR and Yugoslavia. There were four major earthquakes; one south of Honshu, Japan, two in the Kuril Islands region, and one in the Soviet Union. The United States experienced a number of earthquakes, but only very minor damage was reported. 

  2. Earthquakes, November-December 1991

    USGS Publications Warehouse

    Person, W.J.

    1992-01-01

    There were three major earthquakes (7.0-7.9) during the last two months of the year: a magntidue 7.0 on November 19 in Columbia, a magnitude 7.4 in the Kuril Islands on December 22, and a magnitude 7.1 in the South Sandwich Islands on December 27. Earthquake-related deaths were reported in Colombia, Yemen, and Iran. there were no significant earthquakes in the United States during this reporting period. 

  3. Pacific Basin tsunami hazards associated with mass flows in the Aleutian arc of Alaska

    USGS Publications Warehouse

    Waythomas, Christopher F.; Watts, Philip; Shi, Fengyan; Kirby, James T.

    2009-01-01

    We analyze mass-flow tsunami generation for selected areas within the Aleutian arc of Alaska using results from numerical simulation of hypothetical but plausible mass-flow sources such as submarine landslides and volcanic debris avalanches. The Aleutian arc consists of a chain of volcanic mountains, volcanic islands, and submarine canyons, surrounded by a low-relief continental shelf above about 1000–2000 m water depth. Parts of the arc are fragmented into a series of fault-bounded blocks, tens to hundreds of kilometers in length, and separated from one another by distinctive fault-controlled canyons that are roughly normal to the arc axis. The canyons are natural regions for the accumulation and conveyance of sediment derived from glacial and volcanic processes. The volcanic islands in the region include a number of historically active volcanoes and some possess geological evidence for large-scale sector collapse into the sea. Large scale mass-flow deposits have not been mapped on the seafloor south of the Aleutian Islands, in part because most of the area has never been examined at the resolution required to identify such features, and in part because of the complex nature of erosional and depositional processes. Extensive submarine landslide deposits and debris flows are known on the north side of the arc and are common in similar settings elsewhere and thus they likely exist on the trench slope south of the Aleutian Islands. Because the Aleutian arc is surrounded by deep, open ocean, mass flows of unconsolidated debris that originate either as submarine landslides or as volcanic debris avalanches entering the sea may be potential tsunami sources. To test this hypothesis we present a series of numerical simulations of submarine mass-flow initiated tsunamis from eight different source areas. We consider four submarine mass flows originating in submarine canyons and four flows that evolve from submarine landslides on the trench slope. The flows have lengths

  4. Relationship between two Solomon Islands Earthquakes in 2007 (M8.1), 2010 (M7.1), and Seismic Gap along the Subduction Zone, Revealed by ALOS/PALSAR

    NASA Astrophysics Data System (ADS)

    Miyagi, Y.; Ozawa, T.

    2010-12-01

    The Solomon Islands are located in the southwest of the Pacific Ocean. The Australian, Woodlark, and Solomon Sea plates subduct toward the northeast beneath the Pacific plate. Interaction among these four plates cause complicated tectonics around the Solomon Islands, and have caused interplate earthquakes in the subduction zone (e.g. Lay and Kanamori, 1980; Xu and Schwarts, 1993). On April 1, 2007 (UTC), an M8.1 interplate earthquake occurred in the subduction zone between the Pacific Plate and the Australian Plate. This earthquake was accompanied by a large tsunami and caused considerable damage in the area. The Japan Aerospace Exploration Agency (JAXA) carried out emergency observations using the Phased Array type L-band Synthetic Aperture Rader (PALSAR) installed on Advanced Land Observing Satellite (ALOS), and detected more than 2m of maximum displacement using differential interferometric SAR (DInSAR) technique. Miyagi et al. (2009) estimated a slip distribution of the seismic fault mainly from the PALSAR/DInSAR data and suggested that most of a seismic gap was filled by the 2007 events, but a small seismic gap connecting to an Mw7.0-sized earthquake still remained. On January 3, 2010, an M7.1 earthquake occurred in the vicinity of the remnant seismic gap. ALOS/PALSAR observed epicentral area both before and after the event, and detected crustal deformation associated with the earthquake. We inferred fault model using the PALSAR/DInSAR data and concluded that the 2010 event was the supposed thrust earthquake filling the remnant seismic gap. A distribution of coulomb failure stress change in the epicentral area after the 2007 event suggested the possibility that the 2010 event was triggered by the 2007 earthquake.

  5. Andaman-Sumatra island arc: II. The December 26, 2004 earthquake as one of the key episodes in seismogenic activation of the arc in the beginning of XXI century

    NASA Astrophysics Data System (ADS)

    Balakina, L. M.; Moskvina, A. G.

    2013-03-01

    The interpretation of the nature and parameters of the source for the earthquake that occurred in Sumatra on December 26, 2004 is suggested. Our study relies on a variety of data on the geological structure of the region, long-term seismicity, spatial distribution of the foreshocks and aftershocks, and focal mechanisms; and the pattern of shaking and tsunami, regularities in the occurrence of the earthquakes, and the genetic relationship between the seismic and geological parameters inherent in various types of seismogenic zones including island arcs. The source of the Sumatran earthquake is a steep reverse fault striking parallel to the island arc and dipping towards the ocean. The length of the fault is ˜450 km, and its probable bedding depth is ˜70-100 km. The magnitude of this seismic event corresponding to the length of its source is 8.9-9.0. The vertical displacement in the source probably reached 9-13 m. The fault is located near the inner boundary of the Aceh Depression between the epicenter of the earthquake and the northern tip of the depression. The strike-slip and strike-slip reverse the faults cutting the island arc form the northern and southern borders of the source. The location and source parameters in the suggested interpretation account quite well for the observed pattern of shaking and tsunami. The Aceh Depression and its environs probably also host other seismic sources in the form of large reverse faults. The Sumatran earthquake, which was the culmination of the seismogenic activation of the Andaman-Sumatra island arc in the beginning of XXI century, is a typical tsunamigenic island-arc earthquake. By its characteristics, this event is an analogue to the M W = 9 Kamchatka earthquake of November 4, 1952. The spatial distribution of the epicenters and the focal mechanisms of the aftershocks indicate that the repeated shocks during the Sumatran event were caused by the activation of a complex system of geological structures in various parts of

  6. Uplifted marine terraces in Davao Oriental Province, Mindanao Island, Philippines and their implications for large prehistoric offshore earthquakes along the Philippine trench

    NASA Astrophysics Data System (ADS)

    Ramos, Noelynna T.; Tsutsumi, Hiroyuki; Perez, Jeffrey S.; Bermas, Percival P.

    2012-02-01

    We conducted systematic mapping of Holocene marine terraces in eastern Mindanao Island, Philippines for the first time. Raised marine platforms along the 80-km-long coastline of eastern Davao Oriental Province are geomorphic evidence of tectonic deformation resulting from the westward subduction of the Philippine Sea plate along the Philippine trench. Holocene coral platforms consist of up to four terrace steps: T1: 1-5 m, T2: 3-6 m, T3: 6-10 m, and T4: 8-12 m amsl, from the lowest to highest, respectively. Terraces are subhorizontal, exposing cemented coral shingle and eroded coral heads, while terrace risers are 1-3 m high. Radiocarbon ages, 8080-4140 cal yr BP, reveal that erosional surfaces were carved onto the Holocene transgressive reef complex which grew upward until ˜8000 years ago. The maximum uplift rate is ˜1.5 mm/yr based on the highest Holocene terrace at <11.4 m amsl. The staircase topography and meter-scale terrace risers infer that at least four large earthquakes have uplifted the coast in the past ˜8000 years. The deformation pattern of the terraces further suggests that seismic sources are probably located offshore. However, historical earthquakes as large as M W 7.5 along the Philippine trench were not large enough to produce meter-scale coastal uplift, suggesting that much larger earthquakes occurred in the past. A long-term tectonic uplift rate of ˜1.3 mm/yr was also estimated based on Late Pleistocene terraces.

  7. Postseismic gravity change after the 2006–2007 great earthquake doublet and constraints on the asthenosphere structure in the central Kuril Islands

    USGS Publications Warehouse

    Han, Shin-Chan; Sauber, Jeanne; Pollitz, Fred

    2016-01-01

    Large earthquakes often trigger viscoelastic adjustment for years to decades depending on the rheological properties and the nature and spatial extent of coseismic stress. The 2006 Mw8.3 thrust and 2007 Mw8.1 normal fault earthquakes of the central Kuril Islands resulted in significant postseismic gravity change in Gravity Recovery and Climate Experiment (GRACE) but without a discernible coseismic gravity change. The gravity increase of ~4 μGal, observed consistently from various GRACE solutions around the epicentral area during 2007–2015, is interpreted as resulting from gradual seafloor uplift by ~6 cm produced by postseismic relaxation. The GRACE data are best fit with a model of 25–35 km for the elastic thickness and ~1018 Pa s for the Maxwell viscosity of the asthenosphere. The large measurable postseismic gravity change (greater than coseismic change) emphasizes the importance of viscoelastic relaxation in understanding tectonic deformation and fault-locking scenarios in the Kuril subduction zone.

  8. High-frequency earthquakes at White Island volcano, New Zealand: insights into the shallow structure of a volcano-hydrothermal system

    NASA Astrophysics Data System (ADS)

    Nishi, Yuji; Sherburn, Steven; Scott, Bradley J.; Sugihara, Mituhiko

    1996-08-01

    Volcano-tectonic earthquakes at White Island are concentrated in a single seismically active zone, southeast of the active vents and at depths of less than 1 km. A few deeper earthquakes also occur beneath the active vents. A composite focal mechanism indicates that the stress regime in the shallow seismic zone is N-S extensional. Shallow seismicity occurs within the main volume of the volcano-hydrothermal system that underlies the Main Crater floor, and we interpret this as a region where the rocks have been weakened by past magmatic intrusions, elevated pore fluid pressure and physico-chemical effects of acid volcanic fluids, thereby allowing preferential seismic failure. Brittle seismic failure within this region requires a temperature less than about 400 °C, and implies high horizontal temperature gradients close to the active craters and fumaroles. Spasmodic bursts events are also a result of brittle failure, but occur close to zones of significant permeability in response to changes in local fluid pressure.

  9. Multi-centennial reconstruction of Aleutian climate from coralline algae

    NASA Astrophysics Data System (ADS)

    Williams, B.; Halfar, J.; DeLong, K. L.; Smith, E.; Steneck, R.; Lebednik, P.; Jacob, D. E.; Fietzke, J.; Moore, K.

    2015-12-01

    Long-lived encrusting coralline algae yield robust reconstructions of mid-to-high latitude environmental change from their annually-banded high-magnesium calcite skeleton. The magnesium to calcium ratio measured in their skeleton reflects ambient seawater temperature at the time of formation. Thus, reconstructions from these algae are important to understanding the role of natural modes of climate variability versus that of external carbon dioxide in controlling climate in data sparse regions such as the northern North Pacific Ocean/southern Bering Sea. Here, we reconstruct regional seawater temperature from the skeletons of nine algae specimens from two islands in the Aleutian Archipelago. We find that seawater temperature increased ~1.4°C degrees over the past 350 years. The detrended seawater reconstruction correlates with storminess because storms moving across the North Pacific Ocean bring warmer water to the archipelago. Comparison of the algal seawater temperature reconstruction with instrumental and terrestrial proxy reconstructions reveals that atmospheric teleconnections to North America via the North Pacific storm tracks are not robust before the 20th century. This indicates that North Pacific climate processes inferred from the instrumental records should be cautiously extrapolated when describing earlier non-analogous climates or future climate change.

  10. Oxygen isotope constraints on the petrogenesis of Aleutian arc magmas

    SciTech Connect

    Singer, B.S.; O'Neil, J.R. ); Brophy, J.G. )

    1992-04-01

    The first measurement of {sup 18}O/{sup 16}O ratios of plagioclase, clinopyroxene, orthopyroxene, and titanomagnetite phenocrysts from modern Aleutian island-arc lavas provides new insight and independent constraints on magma sources and intracrustal processes. Basalts are heterogeneous on the scale of the entire arc and individual volcanic centers. Combined with Sr isotope and trace element data {delta}{sup 18}O{sub plag} values suggest a variable magma source characterized by differences in the mantle wedge or the subducted sediment component along the volcanic front. Seven tholeiitic basalt to rhyodacite lavas from the Seguam volcanic center have nearly identical {delta}{sup 18}O{sub plag} values of 6.0{per thousand} {plus minus} 0.2{per thousand}, reflecting extensive closed-system plagioclase-dominated crystal fractionation. Oxygen isotope thermometry and pyroxene and oxide equilibria indicate that differentiation occurred between 1,150 {plus minus} 100C (basalt) and 950 {plus minus} 100C (rhyodacite). In contrast, {delta}{sup 18}O{sub plag} values of 12 calc-alkalic basaltic andesites and andesites from the smaller Kanaga volcanic center span a broader range of 5.9{per thousand}-6.6{per thousand}, and consist of mostly higher values. Isotopic disequilibrium in the Kanaga system is manifest in two ways: two types of basaltic inclusions with contrasting {delta}{sup 18}O values occur in one andesite, and in two other andesites plagioclase-titanomagnetite and clinopyroxene-titanomagnetite oxygen isotope temperatures are inconsistent.

  11. Discrete Scaling in Earthquake Precursory Phenomena: Evidence in the Kobe Earthquake, Japan

    NASA Astrophysics Data System (ADS)

    Johansen, Anders; Sornette, Didier; Wakita, Hiroshi; Tsunogai, Urumu; Newman, William I.; Saleur, Hubert

    1996-10-01

    We analyze the ion concentration of groundwater issuing from deep wells located near the epicenter of the recent earthquake of magnitude 6.9 near Kobe, Japan, on January 17, 1995. These concentrations are well fitted by log-periodic modulations around a leading power law. The exponent (real and imaginary parts) is very close to those already found for the fits of precursory seismic activity for Loma Prieta and the Aleutian Islands. This brings further support for the general hypothesis that complex critical exponents are a general phenomenon in irreversible self-organizing systems and particularly in rupture and earthquake phenomena. Nous analysons les fluctuations de concentrations ioniques de l'eau issue de puits profonds situés à proximité de l'épicentre du récent tremblement de terre de magnitude 6.9 proche de Kobe au Japon, le 17 janvier 1995. Ces fluctuations sont bien reproduites par des modulations log-périodiques autour d'une loi de puissance. Les parties réelle et imaginaire de l'exposant sont très proches de celles trouvées précédemment pour les tremblements de terre de Loma Prieta et des Iles Aléoutiennes. Ces résultats renforcent l'hypothèse que des exposants critiques complexes sont une propriété générale des phénomènes de croissance irréversible, et en particulier des problèmes de rupture et des tremblements de terre.

  12. Stress Changes Induced by Earthquakes and Secular Stress Accumulation in the Buller Region, South Island, New Zealand (1929 2002)

    NASA Astrophysics Data System (ADS)

    Hincapie, Jaime O.; Doser, Diane I.; Robinson, Russell

    2005-02-01

    Between 1929 and 1968 the Buller region, located west of the strike-slip Alpine fault system, experienced two Mw > 7.1 earthquakes along high-angle reverse faults. We have modeled induced changes in Coulomb failure stress (ΔCFS) to determine whether stress triggering could have occurred during the 1929 and 1968 sequences and to determine how these earthquakes have affected stress along the Alpine fault and neighboring strike-slip faults located to the east of the Alpine fault. We have included the effects of secular stress accumulation on the five most rapidly slipping fault systems in the region (Alpine, Wairau, Awatere, Clarence, and Hope), but have neglected the effects of viscoelastic relaxation. Our results suggest that larger aftershocks of the 1929 Buller mainshock and moderate (Mw < 6.0) events following the 1968 Inangahua mainshock may have been triggered or hastened by the mainshocks. The 1929 mainshock does not appear to have been significantly hastened by previous Mw > 7.0 events in 1848 and 1888 along strike-slip faults to the east of the Buller region or by secular stress accumulation since 1848. The 1929 Buller earthquake may have delayed the 1968 Inangahua mainshock. Present values of ΔCFS along segments of the major strike-slip faults located east of the Buller region indicate that every fault segment except the North Westlands North segment of the Alpine fault contains regions of negative ΔCFS that are related to the coseismic effects of Mw > 7.0 earthquakes occurring between 1848 and 1968. The complex variation in ΔCFS along most major strike-slip faults in the region highlights the difficulty in evaluating which faults may presently be the closest to failure.

  13. Plume Structures in the Central Aleutian Basin

    NASA Astrophysics Data System (ADS)

    Yankovsky, E. A.; Terry, D. A.; Knapp, C. C.

    2013-12-01

    It is widely accepted that deep ocean basins are suitable for gas hydrate formation with appropriate temperature and pressure conditions but the assumption has been that they lack a sufficient source of methane and thus cannot generate gas hydrates. The Aleutian Basin of the Bering Sea, however, may be an exception due to the influx of methane-generating sediment in the region. The basin is unique in this respect because it is enclosed by the Aleutian Arc on the south as well as land on the north. Terrigenous sediments from these land masses reach the basin, and through accumulation over time, become sources of methane. In this study, we are analyzing a newly acquired seismic data set (Scholl et al, 2012) from the central Aleutian Basin to test for the presence of gas hydrates in the region. Previous seismic evidence from the region led to the discovery of VAMPs - velocity amplitude anomaly structures - characterized by pull-ups and push-downs in the seismic horizons. This study is aimed at testing the hypothesis first proposed by Scholl and Hart (1993) that methane plumes are responsible for the velocity push-downs, while gas hydrates (which condense above the plume) cause the pull-ups. We have constructed geologic models based on a velocity analysis obtained from performing inversions on the pre-stack CMP gathers (using GDMI, a recently developed inversion code from the Naval Research Laboratory). We present a one-dimensional geologic model of rock properties for a region within the study area adjacent to a VAMP structure (but itself lacking the characteristic velocity anomalies). We also show a two-dimensional geologic model for the region in which the VAMP structure is present. The interpretation of a flat-lying geology incorporating a methane hydrate plume guided the creation of the two-dimensional model from the velocity analysis. Our next goal, using full-waveform forward seismic modeling (TESSERAL software), is to generate a synthetic seismic section that

  14. The Mw6.5 earthquake of 17 November 2015 in Lefkada Island and the seismotectonics in the Cephalonia Transform Fault (Ionian Sea, Greece)

    NASA Astrophysics Data System (ADS)

    Papadopoulos, Gerassimos A.; Agalos, Apostolos; Bocchini, Gian Maria; Chousianitis, Konstantinos; Karastathis, Vassilis; Triantafyllou, Ioanna; Kontoes, Charis; Papoutsis, Ioannis; Svigkas, Nikos; Koukouvelas, Ioannis; Zygouri, Vasiliki; Tselentis, Akis

    2016-04-01

    On 17 November 2015 a Mw6.5 earthquake ruptured offshore Lefkada Isl. in Ionian Sea, Greece, causing two victims, damage and ground failures particularly in the SW part of the island, which is consistent with the ground deformation pattern shown by InSAR analysis. Fault plane solutions released by CMT, NOA and other institutes are consistent indicating strike-slip right-lateral faulting, which is typical for the area, e.g. 2003 earthquake in the same fault zone. The analysis of 30-s daily observations of the permanent GPS stations operated by NOA showed displacement vectors with a motion pattern which is in agreement with the right-lateral kinematics of the rupture. The seismic plane was striking/dipping about N24E/W75.The seismic sequence for the period from 17 Nov. to 8 Dec. 2015 was relocated, with and without the use of time residuals, applying the NNLoc algorithm on a slightly modified 9-layer seismic velocity model (Haslinger et al., 1999) and by using only phases at stations closer than 120 km from the mainshock in order to avoid the use of Pn phases. The relocation procedure obtained without the use of residuals was repeated with the HypoDD algorithm. All relocations showed that the aftershock cloud follows the fault plane strike and consists of one north and one south clusters distributed in the seismogenic layer of 4-12 km. The south cluster started to develop a few hours after the mainshock, while it presents different statistical properties as compared to the north one. These results indicate that the south cluster was likely the result of triggering effect. Digital broadband P-wave teleseismic records, selected from GDSN stations to achieve the best possible azimuthal coverage, were used to invert for the mainshock rupture history. The teleseismic waveforms were corrected for instrument response, integrated to displacement, band-pass filtered from 0.01 to 1 Hz using a Butterworth filter and finally re-sampled to 0.2 samples/s. The finite fault

  15. Tectonics of the March 27, 1964, Alaska earthquake: Chapter I in The Alaska earthquake, March 27, 1964: regional effects

    USGS Publications Warehouse

    Plafker, George

    1969-01-01

    The March 27, 1964, earthquake was accomp anied by crustal deformation-including warping, horizontal distortion, and faulting-over probably more than 110,000 square miles of land and sea bottom in south-central Alaska. Regional uplift and subsidence occurred mainly in two nearly parallel elongate zones, together about 600 miles long and as much as 250 miles wide, that lie along the continental margin. From the earthquake epicenter in northern Prince William Sound, the deformation extends eastward 190 miles almost to long 142° and southwestward slightly more than 400 miles to about long 155°. It extends across the two zones from the chain of active volcanoes in the Aleutian Range and Wrangell Mountains probably to the Aleutian Trench axis. Uplift that averages 6 feet over broad areas occurred mainly along the coast of the Gulf of Alaska, on the adjacent Continental Shelf, and probably on the continental slope. This uplift attained a measured maximum on land of 38 feet in a northwest-trending narrow belt less than 10 miles wide that is exposed on Montague Island in southwestern Prince William Sound. Two earthquake faults exposed on Montague Island are subsidiary northwest-dipping reverse faults along which the northwest blocks were relatively displaced a maximum of 26 feet, and both blocks were upthrown relative to sea level. From Montague Island, the faults and related belt of maximum uplift may extend southwestward on the Continental Shelf to the vicinity of the Kodiak group of islands. To the north and northwest of the zone of uplift, subsidence forms a broad asymmetrical downwarp centered over the Kodiak-Kenai-Chugach Mountains that averages 2½ feet and attains a measured maximum of 7½ feet along the southwest coast of the Kenai Peninsula. Maximum indicated uplift in the Alaska and Aleutian Ranges to the north of the zone of subsidence was l½ feet. Retriangulation over roughly 25,000 square miles of the deformed region in and around Prince William Sound

  16. Darwin's earthquake.

    PubMed

    Lee, Richard V

    2010-07-01

    Charles Darwin experienced a major earthquake in the Concepción-Valdivia region of Chile 175 years ago, in February 1835. His observations dramatically illustrated the geologic principles of James Hutton and Charles Lyell which maintained that the surface of the earth was subject to alterations by natural events, such as earthquakes, volcanoes, and the erosive action of wind and water, operating over very long periods of time. Changes in the land created new environments and fostered adaptations in life forms that could lead to the formation of new species. Without the demonstration of the accumulation of multiple crustal events over time in Chile, the biologic implications of the specific species of birds and tortoises found in the Galapagos Islands and the formulation of the concept of natural selection might have remained dormant.

  17. Coseismic slip in the 1964 Prince William Sound earthquake: A new geodetic inversion

    NASA Astrophysics Data System (ADS)

    Holdahl, Sandford R.; Sauber, Jeanne

    1994-03-01

    The 1964 Prince William Sound earthquake (March 28, 1964; M w =9.2) caused crustal deformation over an area of approximately 140,000 km2 in south central Alaska. In this study geodetic and geologic measurements of this surface deformation were inverted for the slip distribution on the 1964 rupture surface. Previous seismologic, geologic, and geodetic studies of this region were used to constrain the geometry of the fault surface. In the Kodiak Island region, 28 rectangular planes (50 by 50 km each) oriented ˜218°N, with a dip varying from 8o nearest the Aleutian trench to 9o below Kodiak Island, define the rupture surface. In the Prince William Sound region 39 planes with variable dimensions (˜40 by 50 km near the trench, ˜64 by 50 km inland) and orientation (218°N in the west and 270°N in the east) were used to approximate the complex faulting. Prior information was introduced to constrain offshore dip-slip values, the strike-slip component, and slip variation between adjacent planes. Our results suggest a variable dip-slip component with local slip maximums occurring near Montague Island (up to ˜30 m), further to the east near Kayak Island (up to ˜14 m), and trenchward of the northeast segment of Kodiak Island (up to ˜17m). A single fault plane dipping 30°NW, corresponding to the Patton Bay fault, with a slip value of ˜8 m modeled the localized but large uplift on Montague Island. The moment calculated on the basis of our geodetically derived slip model of 5.0×1029 dyne cm is 30% less than the seismic moment of 7.5×1029 dyne cm calculated from long-period surface waves ( Kanamori, 1970) but is close to the seismic moment of 5.9×1029 dyne cm obtained by Kikuchi and Fukao (1987).

  18. The Battle of Attu and the Aleutian Island Campaign

    DTIC Science & Technology

    2014-05-22

    adversaries, was becoming a reality. The Joint Planning Board prepared five contemporary contingency plans labeled the “ Rainbow Plans”21 – a term...allies, enemies, and theaters of operation in predicted future conflicts. The five plans consisted of: 1. Rainbow 1: Defense of Western hemisphere...north of ten degrees latitude (Panama). No major allies. 2. Rainbow 2: Allied with France and Britain. 3. Rainbow 3: Same as the Orange plan after

  19. Ports and Waterways Safety Assessment Workshop Report for Aleutian Islands

    DTIC Science & Technology

    2006-07-25

    USCG for assistance, medical advice; can contact via email / satellite phone • If cruise ship evacuation: − Multitude of fishing vessels would...emergency communication to others • Drills: − Cruise ship industry sponsors annual voluntary drills with USCG (i.e., mass rescue scenario

  20. Earthquakes, January-February 1974

    USGS Publications Warehouse

    Person, W.J.

    1974-01-01

    During the first 2 months of 1974, earthquakes caused fatalities in Peru and Turkey. The largest earthquake during the period was a magnitude 7.2 shock in the New Hebrides Islands. A local tsunami was generated by a magnitude 7.0 earthquake in the Solomon Islands. The relative quiet that characterized world seismicity during the last year continued through the period. There have been no great earthquakes (magnitude 8.0 or larger) since January 10, 1971, when a magnitude 8.1 shock occurred in western New Guinea. 

  1. Accurate Source Depths and Focal Mechanisms of Shallow Earthquakes in Western South America and in the New Hebrides Island Arc

    NASA Astrophysics Data System (ADS)

    Chinn, Douglas S.; Isacks, Bryan L.

    1983-12-01

    Synthetic seismograms are matched to long-period P waveforms in order to obtain accurate depths of shallow earthquakes with known focal mechanisms. Accurate depths are obtained for a large sample of moderate-sized (6 < Ms < 7) events which produced relatively simple P waveforms and do not require intensive analysis. The estimated error in the determination of depth is about ±5 km or less for most of the events considered. The procedure is applied to two suites of events, one in South America (83 events) and one in the New Hebrides (61 events). In these two areas of contrasting styles of subduction, the accurate depths provide new information on the bending of descending plates near trenches, the seismicity and tectonics of the upper plate, and the geometry and structure of the zone of contact between the upper and descending plates. Depths of suboceanic earthquakes which occurred near the trench and which have either tensional and compressional horizontal stress axes agree well with Chapple and Forsyth's (1979) preferred model of a bending elastic-perfectly plastic plate. However, an unusually deep event occurred beneath the Fiji plateau in an area of young ocean floor supposed to have been formed by sea floor spreading processes only since late Miocene time. The calculated depth of the event, 48 km, places it below the lithosphere-asthenosphere boundary derived from thermal models. Vertical cross sections through the shallow parts of the subduction zones show that most of the earthquakes with thrust faulting focal mechanisms can be interpreted to be interplate events located in a thin (<10 km thick) curved zone of contact dipping arcward or landward from the trench axis. However, a few events with focal mechanisms similar to the interplate events do not fit on the inferred thin zone of contact. These events would be accommodated by an interplate zone 15 km thick. In both subduction zones, interplate events occur at depths between about 15 and 50 km. However, the

  2. Source Rupture Models and Tsunami Simulations of Destructive October 28, 2012 Queen Charlotte Islands, British Columbia (Mw: 7.8) and September 16, 2015 Illapel, Chile (Mw: 8.3) Earthquakes

    NASA Astrophysics Data System (ADS)

    Taymaz, Tuncay; Yolsal-Çevikbilen, Seda; Ulutaş, Ergin

    2016-04-01

    The finite-fault source rupture models and numerical simulations of tsunami waves generated by 28 October 2012 Queen Charlotte Islands (Mw: 7.8), and 16 September 2015 Illapel-Chile (Mw: 8.3) earthquakes are presented. These subduction zone earthquakes have reverse faulting mechanisms with small amount of strike-slip components which clearly reflect the characteristics of convergence zones. The finite-fault slip models of the 2012 Queen Charlotte and 2015 Chile earthquakes are estimated from a back-projection method that uses teleseismic P- waveforms to integrate the direct P-phase with reflected phases from structural discontinuities near the source. Non-uniform rupture models of the fault plane, which are obtained from the finite fault modeling, are used in order to describe the vertical displacement on seabed. In general, the vertical displacement of water surface was considered to be the same as ocean bottom displacement, and it is assumed to be responsible for the initial water surface deformation gives rise to occurrence of tsunami waves. In this study, it was calculated by using the elastic dislocation algorithm. The results of numerical tsunami simulations are compared with tide gauges and Deep-ocean Assessment and Reporting of Tsunami (DART) buoy records. De-tiding, de-trending, low-pass and high-pass filters were applied to detect tsunami waves in deep ocean sensors and tide gauge records. As an example, the observed records and results of simulations showed that the 2012 Queen Charlotte Islands earthquake generated about 1 meter tsunami-waves in Maui and Hilo (Hawaii), 5 hours and 30 minutes after the earthquake. Furthermore, the calculated amplitudes and time series of the tsunami waves of the recent 2015 Illapel (Chile) earthquake are exhibiting good agreement with the records of tide and DART gauges except at stations Valparaiso and Pichidangui (Chile). This project is supported by The Scientific and Technological Research Council of Turkey (TUBITAK

  3. Re-colonization by common eiders Somateria mollissima in the Aleutian Archipelago following removal of introduced arctic foxes Vulpes lagopus

    USGS Publications Warehouse

    Petersen, Margaret R.; Sonsthagen, Sarah A.; Sexson, Matthew G.

    2015-01-01

    Islands provide refuges for populations of many species where they find safety from predators, but the introduction of predators frequently results in elimination or dramatic reductions in island-dwelling organisms. When predators are removed, re-colonization for some species occurs naturally, and inter-island phylogeographic relationships and current movement patterns can illuminate processes of colonization. We studied a case of re-colonization of common eiders Somateria mollissima following removal of introduced arctic foxes Vulpes lagopus in the Aleutian Archipelago, Alaska. We expected common eiders to resume nesting on islands cleared of foxes and to re-colonize from nearby islets, islands, and island groups. We thus expected common eiders to show limited genetic structure indicative of extensive mixing among island populations. Satellite telemetry was used to record current movement patterns of female common eiders from six islands across three island groups. We collected genetic data from these and other nesting common eiders at 14 microsatellite loci and the mitochondrial DNA control region to examine population genetic structure, historical fluctuations in population demography, and gene flow. Our results suggest recent interchange among islands. Analysis of microsatellite data supports satellite telemetry data of increased dispersal of common eiders to nearby areas and little between island groups. Although evidence from mtDNA is suggestive of female dispersal among island groups, gene flow is insufficient to account for recolonization and rapid population growth. Instead, near-by remnant populations of common eiders contributed substantially to population expansion, without which re-colonization would have likely occurred at a much lower rate. Genetic and morphometric data of common eiders within one island group two and three decades after re-colonization suggests reduced movement of eiders among islands and little movement between island groups after

  4. Indirect food web interactions: Sea otters and kelp forest fishes in the Aleutian archipelago

    USGS Publications Warehouse

    Reisewitz, S.E.; Estes, J.A.; Simenstad, C.A.

    2006-01-01

    Although trophic cascades - the effect of apex predators on progressively lower trophic level species through top-down forcing - have been demonstrated in diverse ecosystems, the broader potential influences of trophic cascades on other species and ecosystem processes are not well studied. We used the overexploitation, recovery and subsequent collapse of sea otter (Enhydra lutris) populations in the Aleutian archipelago to explore if and how the abundance and diet of kelp forest fishes are influenced by a trophic cascade linking sea otters with sea urchins and fleshy macroalgae. We measured the abundance of sea urchins (biomass density), kelp (numerical density) and fish (Catch per unit effort) at four islands in the mid-1980s (when otters were abundant at two of the islands and rare at the two others) and in 2000 (after otters had become rare at all four islands). Our fish studies focused on rock greenling (Hexagrammos lagocephalus), the numerically dominant species in this region. In the mid-1980s, the two islands with high-density otter populations supported dense kelp forests, relatively few urchins, and abundant rock greenling whereas the opposite pattern (abundant urchins, sparse kelp forests, and relatively few rock greenling) occurred at islands where otters were rare. In the 2000, the abundances of urchins, kelp and greenling were grossly unchanged at islands where otters were initially rare but had shifted to the characteristic pattern of otter-free systems at islands where otters were initially abundant. Significant changes in greenling diet occurred between the mid-1980s and the 2000 although the reasons for these changes were difficult to assess because of strong island-specific effects. Whereas urchin-dominated communities supported more diverse fish assemblages than kelp-dominated communities, this was not a simple effect of the otter-induced trophic cascade because all islands supported more diverse fish assemblages in 2000 than in the mid-1980s

  5. Indirect food web interactions: sea otters and kelp forest fishes in the Aleutian archipelago.

    PubMed

    Reisewitz, Shauna E; Estes, James A; Simenstad, Charles A

    2006-01-01

    Although trophic cascades-the effect of apex predators on progressively lower trophic level species through top-down forcing-have been demonstrated in diverse ecosystems, the broader potential influences of trophic cascades on other species and ecosystem processes are not well studied. We used the overexploitation, recovery and subsequent collapse of sea otter (Enhydra lutris) populations in the Aleutian archipelago to explore if and how the abundance and diet of kelp forest fishes are influenced by a trophic cascade linking sea otters with sea urchins and fleshy macroalgae. We measured the abundance of sea urchins (biomass density), kelp (numerical density) and fish (Catch per unit effort) at four islands in the mid-1980s (when otters were abundant at two of the islands and rare at the two others) and in 2000 (after otters had become rare at all four islands). Our fish studies focused on rock greenling (Hexagrammos lagocephalus), the numerically dominant species in this region. In the mid-1980s, the two islands with high-density otter populations supported dense kelp forests, relatively few urchins, and abundant rock greenling whereas the opposite pattern (abundant urchins, sparse kelp forests, and relatively few rock greenling) occurred at islands where otters were rare. In the 2000, the abundances of urchins, kelp and greenling were grossly unchanged at islands where otters were initially rare but had shifted to the characteristic pattern of otter-free systems at islands where otters were initially abundant. Significant changes in greenling diet occurred between the mid-1980s and the 2000 although the reasons for these changes were difficult to assess because of strong island-specific effects. Whereas urchin-dominated communities supported more diverse fish assemblages than kelp-dominated communities, this was not a simple effect of the otter-induced trophic cascade because all islands supported more diverse fish assemblages in 2000 than in the mid-1980s.

  6. The paleopathology of an Aleutian mummy.

    PubMed

    Zimmerman, M R; Trinkaus, E; LeMay, M; Aufderheide, A C; Reyman, T A; Marrocco, G R; Ortel, R W; Benitez, J T; Laughlin, W S; Horne, P D; Schultes, R E; Coughlin, E A

    1981-12-01

    A multidisciplinary team examined an Aleutian mummy from the collection of the Peabody Museum of Archeology and Ethnology of Harvard University, Cambridge, Mass. The mummy, dating from the early 18th century, was of a middle-aged woman who had suffered from pulmonary and ear infections, atherosclerosis, pediculosis, and degenerative joint disease. Another finding was anthracosis, common in ancient bodies and related to indoor heating and cooking fires. Skeletal lead was not found, in contrast with the high levels seen in modern persons. No neoplasms were identified, again consistent with the results of previous studies of ancient human remains. Such comparisons of ancient and modern morbidity and mortality provide a historical perspective on the evolution and cause of human disease.

  7. Locations and focal mechanisms of deep long period events beneath Aleutian Arc volcanoes using back projection methods

    NASA Astrophysics Data System (ADS)

    Lough, A. C.; Roman, D. C.; Haney, M. M.

    2015-12-01

    Deep long period (DLP) earthquakes are commonly observed in volcanic settings such as the Aleutian Arc in Alaska. DLPs are poorly understood but are thought to be associated with movements of fluids, such as magma or hydrothermal fluids, deep in the volcanic plumbing system. These events have been recognized for several decades but few studies have gone beyond their identification and location. All long period events are more difficult to identify and locate than volcano-tectonic (VT) earthquakes because traditional detection schemes focus on high frequency (short period) energy. In addition, DLPs present analytical challenges because they tend to be emergent and so it is difficult to accurately pick the onset of arriving body waves. We now expect to find DLPs at most volcanic centers, the challenge lies in identification and location. We aim to reduce the element of human error in location by applying back projection to better constrain the depth and horizontal position of these events. Power et al. (2004) provided the first compilation of DLP activity in the Aleutian Arc. This study focuses on the reanalysis of 162 cataloged DLPs beneath 11 volcanoes in the Aleutian arc (we expect to ultimately identify and reanalyze more DLPs). We are currently adapting the approach of Haney (2014) for volcanic tremor to use back projection over a 4D grid to determine position and origin time of DLPs. This method holds great potential in that it will allow automated, high-accuracy picking of arrival times and could reduce the number of arrival time picks necessary for traditional location schemes to well constrain event origins. Back projection can also calculate a relative focal mechanism (difficult with traditional methods due to the emergent nature of DLPs) allowing the first in depth analysis of source properties. Our event catalog (spanning over 25 years and volcanoes) is one of the longest and largest and enables us to investigate spatial and temporal variation in DLPs.

  8. Earthquakes; July-August 1977

    USGS Publications Warehouse

    Person, W.J.

    1978-01-01

    July and August were somewhat active seismically speaking, compared to previous months of this year. There were seven earthquakes having magnitudes of 6.5 or greater. The largest was a magnitudes of 6.5 or greater. The largest was a magnitude 8.0 earthquake south of Sumbawa Island on August 19 that killed at least 111. The United States experienced a number of earthquakes during this period, but only one, in California, caused some minor damage. 

  9. Earthquakes, September-October 1980

    USGS Publications Warehouse

    Person, W.J.

    1981-01-01

    There were two major (magnitudes 7.0-7.9) earthquakes during this reporting period; a magnitude (M) 7.3 in Algeria where many people were killed or injured and extensive damage occurred, and an M=7.2 in the Loyalty Islands region of the South Pacific. Japan was struck by a damaging earthquake on September 24, killing two people and causing injuries. There were no damaging earthquakes in the United States. 

  10. Earthquakes; May-June 1977

    USGS Publications Warehouse

    Person, W.J.

    1977-01-01

    The months of May and June were somewhat quiet seismically speaking. There was only on significant earthquake, a magnitude 7.2 on June 22 in teh Tonga Islands. In teh United States, the two largest earthquakes occurred in California and on Hawaii. 

  11. Heavy tails and earthquake probabilities

    USGS Publications Warehouse

    Ellsworth, William L.

    2012-01-01

    The 21st century has already seen its share of devastating earthquakes, some of which have been labeled as “unexpected,” at least in the eyes of some seismologists and more than a few journalists. A list of seismological surprises could include the 2004 Sumatra-Andaman Islands; 2008 Wenchuan, China; 2009 Haiti; 2011 Christchurch, New Zealand; and 2011 Tohoku, Japan, earthquakes

  12. The cyclic and fractal seismic series preceding an mb 4.8 earthquake on 1980 February 14 near the Virgin Islands

    USGS Publications Warehouse

    Varnes, D.J.; Bufe, C.G.

    1996-01-01

    Seismic activity in the 10 months preceding the 1980 February 14, mb 4.8 earthquake in the Virgin Islands, reported on by Frankel in 1982, consisted of four principal cycles. Each cycle began with a relatively large event or series of closely spaced events, and the duration of the cycles progressively shortened by a factor of about 3/4. Had this regular shortening of the cycles been recognized prior to the earthquake, the time of the next episode of setsmicity (the main shock) might have been closely estimated 41 days in advance. That this event could be much larger than the previous events is indicated from time-to-failure analysis of the accelerating rise in released seismic energy, using a non-linear time- and slip-predictable foreshock model. Examination of the timing of all events in the sequence shows an even higher degree of order. Rates of seismicity, measured by consecutive interevent times, when plotted on an iteration diagram of a rate versus the succeeding rate, form a triangular circulating trajectory. The trajectory becomes an ascending helix if extended in a third dimension, time. This construction reveals additional and precise relations among the time intervals between times of relatively high or relatively low rates of seismic activity, including period halving and doubling. The set of 666 time intervals between all possible pairs of the 37 recorded events appears to be a fractal; the set of time points that define the intervals has a finite, non-integer correlation dimension of 0.70. In contrast, the average correlation dimension of 50 random sequences of 37 events is significantly higher, dose to 1.0. In a similar analysis, the set of distances between pairs of epicentres has a fractal correlation dimension of 1.52. Well-defined cycles, numerous precise ratios among time intervals, and a non-random temporal fractal dimension suggest that the seismic series is not a random process, but rather the product of a deterministic dynamic system.

  13. Characterization of Aleutian disease virus as a parvovirus.

    PubMed Central

    Bloom, M E; Race, R E; Wolfinbarger, J B

    1980-01-01

    We characterized a strain of Aleutian disease virus adapted to growth in Crandall feline kidney cells at 31.8 degrees C. When purified from infected cells, Aleutian disease virus had a density in CsCl of 1.42 to 1.44 g/ml and was 24 to 26 nm in diameter. [3H]thymidine could be incorporated into the viral genome, and the viral DNA was then studied. In alkaline sucrose gradients, Aleutian disease virus DNA was a single species that cosedimented at 15.5S with single-stranded DNA from adeno-associated virus. When the DNA was analyzed on neutral sucrose gradients, a single species was again observed, which sedimented at 21S and was clearly distinct from 16S duplex adeno-associated virus DNA. A similar result was obtained even after incubation under annealing conditions, implying that the bulk of Aleutian disease virus virions contained a single non-complementary strand with a molecular weight of about 1.4 X 10(6). In addition, two major virus-associated polypeptides with molecular weights of 89,100 and 77,600 were demonstrated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis of virus purified from infected cultures labeled with [35S]methionine. These data suggest that Aleutian disease virus is a nondefective parvovirus. Images PMID:6252342

  14. Immunoglobulin classes of Aleutian disease virus antibody.

    PubMed Central

    Porter, D D; Porter, H G; Suffin, S C; Larsen, A E

    1984-01-01

    Aleutian disease virus (ADV) persistently infects mink and causes marked hypergammaglobulinemia. Immunoglobulin class-specific antisera were used to define the total immunoglobulin of each class by radial immunodiffusion and the immunoglobulin class of ADV-specific antibody by immunofluorescence in experimentally and naturally infected mink. Electrophoretic gamma globulin closely reflects the immunoglobulin G (IgG) level in mink, and the majority of the increased immunoglobulin and ADV antibody in infected mink is IgG. IgM becomes elevated within 6 days after infection, reaches peak levels by 15 to 18 days, and returns to normal by 60 days after infection. The first ADV antibody demonstrable is IgM, and most mink have virus-specific IgM antibody for at least 85 days postinfection. Serum IgA levels in normal mink are not normally distributed, and ADV infection causes a marked elevation of IgA. Low levels of ADV-specific IgA antibody can be shown throughout the course of infection. Failure of large amounts of virus-specific IgG antibody to inhibit the reaction of virus-specific IgM and IgA antibodies suggests that the various classes of antibodies are directed against spatially different antigenic determinants. The IgM and IgA were shown not to be rheumatoid factors. PMID:6319283

  15. Heavy metals in fish from the Aleutians: interspecific and locational differences.

    PubMed

    Burger, Joanna; Gochfeld, Michael; Jeitner, Christian; Pittfield, Taryn; Donio, Mark

    2014-05-01

    The objectives of this study were to examine levels of arsenic, cadmium, lead, mercury and selenium in edible tissue of seven species of marine fish collected from several Aleutian islands (in 2004) to determine: (1) interspecific differences, (2) locational differences (among Aleutian Islands), (3) size-related differences in any metal levels within a species, and (4) potential risk to the fish or to predators on the fish, including humans. We also compared metals levels to those of three other fish species previously examined in detail, as well as examining metals in the edible tissue of octopus (Octopus dofleini). Octopus did not have the highest levels of any metal. There were significant interspecific differences in all metal levels among the fish species, although the differences were less than an order of magnitude, except for arsenic (mean of 19,500 ppb in Flathead sole, Hippoglossoides elassodon). Significant intraisland variation occurred among the four sites on Amchitka, but there was not a consistent pattern. There were significant interisland differences for some metals and species. Mercury levels increased significantly with size for several species; lead increased significantly for only one fish species; and cadmium and selenium decreased significantly with size for halibut (Hippoglossus stenolepis). The Alaskan Department of Health and Social Services supports unrestricted consumption of most Alaskan fish species for all people, including pregnant women. Most mean metal concentrations were well below the levels known to adversely affect the fish themselves, or predators that consume them (including humans), except for mercury in three fish species (mean levels just below 0.3 ppm), and arsenic in two fish species. However, even at low mercury levels, people who consume fish almost daily will exceed guideline values from the Centers for Disease Control and the Environmental Protection Agency.

  16. Heavy metals in fish from the Aleutians: Interspecific and locational differences

    SciTech Connect

    Burger, Joanna; Gochfeld, Michael; Jeitner, Christian; Pittfield, Taryn; Donio, Mark

    2014-05-01

    The objectives of this study were to examine levels of arsenic, cadmium, lead, mercury and selenium in edible tissue of seven species of marine fish collected from several Aleutian islands (in 2004) to determine: (1) interspecific differences, (2) locational differences (among Aleutian Islands), (3) size-related differences in any metal levels within a species, and (4) potential risk to the fish or to predators on the fish, including humans. We also compared metals levels to those of three other fish species previously examined in detail, as well as examining metals in the edible tissue of octopus (Octopus dofleini). Octopus did not have the highest levels of any metal. There were significant interspecific differences in all metal levels among the fish species, although the differences were less than an order of magnitude, except for arsenic (mean of 19,500 ppb in Flathead sole, Hippoglossoides elassodon). Significant intraisland variation occurred among the four sites on Amchitka, but there was not a consistent pattern. There were significant interisland differences for some metals and species. Mercury levels increased significantly with size for several species; lead increased significantly for only one fish species; and cadmium and selenium decreased significantly with size for halibut (Hippoglossus stenolepis). The Alaskan Department of Health and Social Services supports unrestricted consumption of most Alaskan fish species for all people, including pregnant women. Most mean metal concentrations were well below the levels known to adversely affect the fish themselves, or predators that consume them (including humans), except for mercury in three fish species (mean levels just below 0.3 ppm), and arsenic in two fish species. However, even at low mercury levels, people who consume fish almost daily will exceed guideline values from the Centers for Disease Control and the Environmental Protection Agency. - Highlights: • Cadmium, lead, mercury and selenium

  17. Griddlestones from Adak Island, Alaska: Their provenance and the biological origins of organic residues from cooking

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Burned stone slabs, historically called griddlestones, were recovered from Components 1 (2390-2590 RCYPB) and 2 (170-415 RCYBP) at archaeological site ADK-011 on Adak Island, Aleutian Islands, Alaska. The griddlestones show evidence of fire exposure and have a dark, often greasy, matrix of decompose...

  18. Earthquakes, May-June 1981

    USGS Publications Warehouse

    Person, W.J.

    1981-01-01

    The months of May and June were somewhat quiet, seismically speaking. There was one major earthquake (7.0-7.9) off the west coast of South Island, New Zealand. The most destructive earthquake during this reporting period was in southern Iran on June 11 which caused fatalities and extensive damage. Peru also experienced a destructive earthquake on June 22 which caused fatalities and damage. In the United States, a number of earthquakes were experienced, but none caused significant damage. 

  19. Earthquakes, July-August 1992

    USGS Publications Warehouse

    Person, W.J.

    1992-01-01

    There were two major earthquakes (7.0≤M<8.0) during this reporting period. A magnitude 7.5 earthquake occurred in Kyrgyzstan on August 19 and a magnitude 7.0 quake struck the Ascension Island region on August 28. In southern California, aftershocks of the magnitude 7.6 earthquake on June 28, 1992, continued. One of these aftershocks caused damage and injuries, and at least one other aftershock caused additional damage. Earthquake-related fatalities were reportred in Kyrgzstan and Pakistan. 

  20. On subduction zone earthquakes and the Pacific Northwest seismicity

    SciTech Connect

    Chung, Dae H.

    1991-12-01

    A short review of subduction zone earthquakes and the seismicity of the Pacific Northwest region of the United States is provided for the purpose of a basis for assessing issues related to earthquake hazard evaluations for the region. This review of seismotectonics regarding historical subduction zone earthquakes and more recent seismological studies pertaining to rupture processes of subduction zone earthquakes, with specific references to the Pacific Northwest, is made in this brief study. Subduction zone earthquakes tend to rupture updip and laterally from the hypocenter. Thus, the rupture surface tends to become more elongated as one considers larger earthquakes (there is limited updip distance that is strongly coupled, whereas rupture length can be quite large). The great Aleutian-Alaska earthquakes of 1957, 1964, and 1965 had rupture lengths of greater than 650 km. The largest earthquake observed instrumentally, the M{sub W} 9.5, 1960 Chile Earthquake, had a rupture length over 1000 km. However, earthquakes of this magnitude are very unlikely on Cascadia. The degree of surface shaking has a very strong dependency on the depth and style of rupture. The rupture surface during a great earthquake shows heterogeneous stress drop, displacement, energy release, etc. The high strength zones are traditionally termed asperities and these asperities control when and how large an earthquake is generated. Mapping of these asperities in specific subduction zones is very difficult before an earthquake. They show up more easily in inversions of dynamic source studies of earthquake ruptures, after an earthquake. Because seismic moment is based on the total radiated-energy from an earthquake, the moment-based magnitude M{sub W} is superior to all other magnitude estimates, such as M{sub L}, m{sub b}, M{sub bLg}, M{sub S}, etc Probably, just to have a common language, non-moment magnitudes should be converted to M{sub W} in any discussions of subduction zone earthquakes.

  1. Sources of organochlorine contaminants and mercury in seabirds from the Aleutian archipelago of Alaska: inferences from spatial and trophic variation.

    PubMed

    Ricca, Mark A; Keith Miles, A; Anthony, Robert G

    2008-11-15

    Persistent organochlorine compounds and mercury (Hg) have been detected in numerous coastal organisms of the Aleutian archipelago of Alaska, yet sources of these contaminants are unclear. We collected glaucous-winged gulls, northern fulmars, and tufted puffins along a natural longitudinal gradient across the western and central Aleutian Islands (Buldir, Kiska, Amchitka, Adak), and an additional 8 seabird species representing different foraging and migratory guilds from Buldir Island to evaluate: 1) point source input from former military installations, 2) westward increases in contaminant concentrations suggestive of distant source input, and 3) effects of trophic status (delta15N) and carbon source (delta13C) on contaminant accumulation. Concentrations of Sigma polychlorinated biphenyls (PCBs) and most chlorinated pesticides in glaucous-winged gulls consistently exhibited a 'U'-shaped pattern of high levels at Buldir and the east side of Adak and low levels at Kiska and Amchitka. In contrast, concentrations of Sigma PCBs and chlorinated pesticides in northern fulmars and tufted puffins did not differ among islands. Hg concentrations increased westward in glaucous-winged gulls and were highest in northern fulmars from Buldir. Among species collected only at Buldir, Hg was notably elevated in pelagic cormorants, and relatively high Sigma PCBs were detected in black-legged kittiwakes. Concentrations of Sigma PCBs, dichlorodiphenyldichloroethylene (p,p' DDE), and Hg were positively correlated with delta15N across all seabird species, indicating biomagnification across trophic levels. The east side of Adak Island (a former military installation) was a likely point source of Sigma PCBs and p,p' DDE, particularly in glaucous-winged gulls. In contrast, elevated levels of these contaminants and Hg, along with PCB congener and chlorinated pesticide compositional patterns detected at Buldir Island indicated exposure from distant sources influenced by a combination of

  2. Sources of organochlorine contaminants and mercury in seabirds from the Aleutian archipelago of Alaska: Inferences from spatial and trophic variation

    USGS Publications Warehouse

    Ricca, Mark A.; Miles, A. Keith; Anthony, Robert G.

    2008-01-01

    Persistent organochlorine compounds and mercury (Hg) have been detected in numerous coastal organisms of the Aleutian archipelago of Alaska, yet sources of these contaminants are unclear. We collected glaucous-winged gulls, northern fulmars, and tufted puffins along a natural longitudinal gradient across the western and central Aleutian Islands (Buldir, Kiska, Amchitka, Adak), and an additional 8 seabird species representing different foraging and migratory guilds from Buldir Island to evaluate: 1) point source input from former military installations, 2) westward increases in contaminant concentrations suggestive of distant source input, and 3) effects of trophic status (δ15N) and carbon source (δ13C) on contaminant accumulation. Concentrations of Σ polychlorinated biphenyls (PCBs) and most chlorinated pesticides in glaucous-winged gulls consistently exhibited a ‘U’-shaped pattern of high levels at Buldir and the east side of Adak and low levels at Kiska and Amchitka. In contrast, concentrations of Σ PCBs and chlorinated pesticides in northern fulmars and tufted puffins did not differ among islands. Hg concentrations increased westward in glaucous-winged gulls and were highest in northern fulmars from Buldir. Among species collected only at Buldir, Hg was notably elevated in pelagic cormorants, and relatively high Σ PCBs were detected in black-legged kittiwakes. Concentrations of Σ PCBs, dichlorodiphenyldichloroethylene (p,p′ DDE), and Hg were positively correlated with δ15N across all seabird species, indicating biomagnification across trophic levels. The east side of Adak Island (a former military installation) was a likely point source of Σ PCBs and p,p′ DDE, particularly in glaucous-winged gulls. In contrast, elevated levels of these contaminants and Hg, along with PCB congener and chlorinated pesticide compositional patterns detected at Buldir Island indicated exposure from distant sources influenced by a combination of atmospheric

  3. Cascades/Aleutian Play Fairway Analysis: Data and Map Files

    SciTech Connect

    Lisa Shevenell

    2015-11-15

    Contains Excel data files used to quantifiably rank the geothermal potential of each of the young volcanic centers of the Cascade and Aleutian Arcs using world power production volcanic centers as benchmarks. Also contains shapefiles used in play fairway analysis with power plant, volcano, geochemistry and structural data.

  4. Why the 1964 Great Alaska Earthquake matters 50 years later

    USGS Publications Warehouse

    West, Michael E.; Haeussler, Peter J.; Ruppert, Natalia A.; Freymueller, Jeffrey T.; ,

    2014-01-01

    Spring was returning to Alaska on Friday 27 March 1964. A two‐week cold snap had just ended, and people were getting ready for the Easter weekend. At 5:36 p.m., an earthquake initiated 12 km beneath Prince William Sound, near the eastern end of what is now recognized as the Alaska‐Aleutian subduction zone. No one was expecting this earthquake that would radically alter the coastal landscape, influence the direction of science, and indelibly mark the growth of a burgeoning state.

  5. Relationship between shallow-and intermediate-depth seismicity in the eastern aleutian subduction zone

    SciTech Connect

    Abers, G.A. )

    1992-10-23

    The transition from shallow interplate thrusting to intermediate-depth seismicity is often poorly observed, but critical for understanding the fate of the downgoing slab. In order to better examine the transition, 1448 earthquakes are relocated from data recorded by a regional seismic network in the eastern Aleutian arc, using an improved three-dimensional velocity model and accurate ray tracing. Single-event first-motion solutions are determined from these rays for 31 slab events. The interplate thrust zone is a planar fault zone, dipping 10-15[degrees] at 25-35 km depth, and is no more than 5-10 km wide. Most intermediate-depth earthquakes are localized to a plane no wider than 5 km near the top of the descending plate. Fault-plane solution orientations for these events vary by several tens of degrees in orientation, although 73% show T axes aligned within 45[degrees] of the slab dip. A parallel seismic zone, 20-25 km deeper into the slab, also shows down-dip plunges of T axes for 3 to 5 solutions. The fault-plane solutions are poorly explained by plate bending ur unbending about a neutral fiber. Hypocenters show that intermediate-depth events are confined near the subducted oceanic crust, supporting compositional rather than pure thermal control of intermediate-depth seismicity. One explanation is that the upper-plane events are an indirect consequence of phase changes in subducted crust. Perhaps similar processes are important in producing earthquakes in the lower, parallel zone. 26 refs., 4 figs.

  6. Tidal triggering of earthquakes in the Northeast Pacific Ocean

    NASA Astrophysics Data System (ADS)

    Wilcock, William S. D.

    2009-11-01

    There have been many searches for evidence of tidal triggering in earthquake catalogues. With the exception of volcanically active regions, the more rigorous studies in continental settings tend to find no correlation or only a very weak correlation. In the oceans, the effect of loading by the ocean tides can increase tidal stresses by about an order of magnitude over continental settings. In recent years, several studies have reported evidence of tidal triggering in oceanic regions and such observations can represent a useful constraint on models of earthquake rupture. In this paper, I systematically search for a link between ocean tide height and the incidence of earthquakes in the Northeast Pacific Ocean, a region of high-amplitude open ocean tides. The focal mechanisms of most of the earthquakes in these catalogues are unknown but it can be shown that tidal stresses will in most instances promote failure at low tides. I investigate three declustered data sets comprising (1) earthquakes from 1980 to 2007 on the Juan de Fuca plate and in the Queen Charlotte Fault region from land based catalogues; (2) earthquakes from 1992 to 2001 on the Juan de Fuca plate located with the US Navy's Sound Surveillance System (SOSUS) hydrophone array and (3) earthquakes from 1980 to 2001 south of Alaska and the Aleutians located with land based networks. I look at the distributions of earthquakes with ocean tide phase, height, and tidal range and apply Schuster and binomial tests and Monte Carlo simulations to determine if they deviate significantly from random. The results show no evidence of triggering during intervals of increased tidal range but all three data sets show a significant increase in earthquake incidence at low tides. The signal is particularly strong in the land-based catalogue for the Juan de Fuca Plate and Queen Charlotte Fault regions where there is a 15 per cent increase in the rate of seismicity within 15° of the lowest tides. The signal is weakest in the

  7. Mt. St. Augustine, Alaska: Geochemical evolution of an eastern Aleutian volcanic center

    SciTech Connect

    Johnson, K.E. . Dept. of Geology); Harmon, R.S. . Kingsley Dunham Centre); Moorbath, S. . Dept. of Earth Sciences); Sigmarsson, O. )

    1993-04-01

    Mt. St. Augustine is a calc-alkaline Quaternary volcano, situated within Cook Inlet, Alaska. The island is composed of low- to medium-K andesite and dacite domes and pyroclastic flows. Major element variations indicate the magmatic evolution is dominantly influenced by fractionation and magma-mixing processes. Incompatible element and isotopic compositions suggest that despite its continental location, crustal assimilation is not significant factor in magmatic evolution. Alkali contents for Augustine are generally lower than elsewhere in the Aleutians (e.g. Augustine Cs/Rb = 0.016--0.024, K/Rb = 372--553; Aleutians Cs/Rb = 0.016--0.17, K/Rb = 231--745). Sr- and Nd-isotope ratios encompass narrow ranges ([sup 87]Sr/[sup 86]Sr = 0.70317--0.70343; [sup 143]Nd/[sup 144]Nd = 0.513011--0.513085), characteristic of uncontaminated mantle-derived melts. U-Th disequilibrium isotopic values also indicate little or no assimilation of evolved continental crust. Pb-isotopic ranges are also relatively restricted ([sup 206]Pb/[sup 204]Pb = 18.62--18.82; [sup 207]Pb/[sup 204]Pb = 15.54--15.57; [sup 208]Pb/[sup 204]Pb = 38.18--38.34) and comparison with north Pacific enriched (OIB) and depleted (MORB) mantle sources suggest the incorporation of only a small percentage of subducted terrigenous sediments. A model for Augustine magma genesis is proposed where parental magmas are generated by 5--20% partial melting of a lherzolite mantle with up to a 5% subducted terrigenous sediment component. The major influence of the thickened continental crust is to prevent the ascent and eruption of basaltic magma. The data exhibit no temporal variations, indicating that the magmatic system which produced the historic eruptions is well established.

  8. Identification of a nonvirion protein of Aleutian disease virus: mink with Aleutian disease have antibody to both virion and nonvirion proteins.

    PubMed Central

    Bloom, M E; Race, R E; Wolfinbarger, J B

    1982-01-01

    We studied Aleutian disease virus polypeptides in Crandall feline kidney (CRFK) cells. When CRFK cells labeled with [35S]methionine at 60 h postinfection were studied by immunoprecipitation with sera from infected mink, the major Aleutian disease virus virion polypeptides (p85 and p75) were consistently identified, as was a 71,000-dalton nonvirion protein (p71). The peptide maps of p85 and p75 were similar, but the map of p71 was different. p85, p75, and p71 were all precipitated by sera from Aleutian disease virus-infected mink, including those with signs of progressive disease, but heterologous sera raised against purified Aleutian disease virus did not precipitate the nonvirion p71. These results indicated that the nonvirion p71 was unrelated to p85 and p75 and further suggested that mink infected with Aleutian disease virus develop antibody to nonvirion, as well as structural, viral proteins. Images PMID:6287034

  9. Earthquakes, May-June, 1992

    USGS Publications Warehouse

    Person, Waverly J.

    1992-01-01

    The months of May and June were very active in terms of earthquake occurrence. Six major earthquakes (7.0earthquakes included a magnitude 7.1 in Papua New Guinea on May 15, a magnitude 7.1 followed by a magnitude 7.5 in the Philippine Islands on May 17, a magnitude 7.0 in the Cuba region on May 25, and a magnitude 7.3 in the Santa Cruz Islands of the Pacific on May 27. In the United States, a magnitude 7.6 earthquake struck in southern California on June 28 followed by a magnitude 6.7 quake about three hours later.

  10. Recent earthquake prediction research in Japan.

    PubMed

    Mogi, K

    1986-07-18

    Japan has experienced many major earthquake disasters in the past. Early in this century research began that was aimed at predicting the occurrence of earthquakes, and in 1965 an earthquake prediction program was started as a national project. In 1978 a program for constant monitoring and assessment was formally inaugurated with the goal of forecasting the major earthquake that is expected to occur in the near future in the Tokai district of central Honshu Island. The issue of predicting the anticipated Tokai earthquake is discussed in this article as well as the results of research on major recent earthquakes in Japan-the Izu earthquakes (1978 and 1980) and the Japan Sea earthquake (1983).

  11. Tremor and the Depth Extent of Slip in Large Earthquakes

    NASA Astrophysics Data System (ADS)

    BEroza, G. C.; Brown, J. R.; Ide, S.

    2013-05-01

    We survey the evidence for the distribution of tremor and mainshock slip. In Southwest Japan, where tremor is well located, it outlines the down-dip edge of slip in the 1944 and 1946 Nankai earthquakes. In Alaska and the Aleutians, tremor location and slip distributions in slip are subject to greater uncertainty, but within that uncertainty they are consistent with the notion that tremor outlines the down-dip limit of mainshock slip. In Mexico, tremor locations and the extent of rupture in large (M > 7) earthquakes are also uncertain, but show a similar relationship. Taken together, these observations suggest that tremor may provide important information on the depth extent of rupture in large earthquakes where there have been no large earthquakes to test that hypothesis. If applied to the Cascadia subduction zone, it suggests slip will extend farther inland than previously assumed. If applied to the San Andreas Fault, it suggests slip will extend deeper than has previously been assumed.

  12. Where did all the Aleut men go? Aleut male attrition and related patterns in Aleutian historical demography and social organization.

    PubMed

    Reedy-Maschner, Katherine

    2010-12-01

    Historical, economic, and political influences on Aleut demography and social organization are considered in relation to an apparent deficit of Aleut males in the early 20th century. Ethnohistoric records detail persistent waves of explorers, fur hunters, missionaries, bureaucrats, and foreign fishermen coming to the Aleutian region for economic exploitation, with some making it their home. The first major wave consisted of Russian and Siberian crews in pursuit of sea otters and fur seals. These entrepreneurs moved Aleut men to hunting grounds and replaced a large portion of them in the villages. The second wave consisted of Scandinavian and other European immigrants who followed cod, halibut, and herring fisheries and who married into eastern Aleut villages. These movements resulted in two genealogical deficits of Aleut men with concomitant shifts in social organization and economic emphases that contribute to the modern diversity of Aleut society. Aleut evacuation during World War II exacerbated these sex imbalances in the villages of the western Aleutian and Pribilof islands.

  13. Swarms of repeating long-period earthquakes at Shishaldin Volcano, Alaska, 2001-2004

    USGS Publications Warehouse

    Petersen, Tanja

    2007-01-01

    During 2001–2004, a series of four periods of elevated long-period seismic activity, each lasting about 1–2 months, occurred at Shishaldin Volcano, Aleutian Islands, Alaska. The time periods are termed swarms of repeating events, reflecting an abundance of earthquakes with highly similar waveforms that indicate stable, non-destructive sources. These swarms are characterized by increased earthquake amplitudes, although the seismicity rate of one event every 0.5–5 min has remained more or less constant since Shishaldin last erupted in 1999. A method based on waveform cross-correlation is used to identify highly repetitive events, suggestive of spatially distinct source locations. The waveform analysis shows that several different families of similar events co-exist during a given swarm day, but generally only one large family dominates. A network of hydrothermal fractures may explain the events that do not belong to a dominant repeating event group, i.e. multiple sources at different locations exist next to a dominant source. The dominant waveforms exhibit systematic changes throughout each swarm, but some of these waveforms do reappear over the course of 4 years indicating repeatedly activated source locations. The choked flow model provides a plausible trigger mechanism for the repeating events observed at Shishaldin, explaining the gradual changes in waveforms over time by changes in pressure gradient across a constriction within the uppermost part of the conduit. The sustained generation of Shishaldin's long-period events may be attributed to complex dynamics of a multi-fractured hydrothermal system: the pressure gradient within the main conduit may be regulated by temporarily sealing and reopening of parallel flow pathways, by the amount of debris within the main conduit and/or by changing gas influx into the hydrothermal system. The observations suggest that Shishaldin's swarms of repeating events represent time periods during which a dominant source

  14. Earthquake Facts

    MedlinePlus

    ... May 22, 1960. The earliest reported earthquake in California was felt in 1769 by the exploring expedition ... by wind or tides. Each year the southern California area has about 10,000 earthquakes . Most of ...

  15. A record of long-time rift activity and earthquake-induced ground effects in Pleistocene deposits of southern Tenerife (Canary Islands, Spain)

    NASA Astrophysics Data System (ADS)

    Buchner, Elmar; Kröchert, Jörg

    2009-09-01

    Faults with a well-defined strike direction that precisely coincides with the southern rift fault system occur in the study area in southern Tenerife. This fault system was generated contemporaneously with a chain of cinder cones ~948 ka. Open fractures in ignimbrites (~668 ka) and fossil beach deposits (~42 ka) of the El Médano area suggest that the rift-associated fault system was seismically active in the aftermath of the initial volcanic activity (~948 ka) and is probably still active. A second fault system striking perpendicular to the rift-related faults probably originates from a Holocene paleoearthquake of moderate intensity. Earthquake-induced ground effects in fossil beach deposits within the study area are consistent with seismically induced ground effects of several recent and well-documented earthquakes, as well as gravitational sliding triggered by an intense earthquake in the Nicoya Peninsula of Costa Rica in 1990. Both, the rift-associated and the earthquake-induced fault system, initially produced open fractures that were occupied by plants and subsequently stabilized by cementation, forming conspicuous sediment structures in fossil beach deposits of the El Médano site in southern Tenerife.

  16. Fault zones ruptured during the early 2014 Cephalonia Island (Ionian Sea, Western Greece) earthquakes (January 26 and February 3, Mw 6.0) based on the associated co-seismic surface ruptures

    NASA Astrophysics Data System (ADS)

    Lekkas, Efthymios L.; Mavroulis, Spyridon D.

    2016-01-01

    The early 2014 Cephalonia Island (Ionian Sea, Western Greece) earthquake sequence comprised two main shocks with almost the same magnitude (moment magnitude (Mw) 6.0) occurring successively within a short time (January 26 and February 3) and space (Paliki peninsula in Western Cephalonia) interval. Εach earthquake was induced by the rupture of a different pre-existing onshore active fault zone and produced different co-seismic surface rupture zones. Co-seismic surface rupture structures were predominantly strike-slip-related structures including V-shaped conjugate surface ruptures, dextral and sinistral strike-slip surface ruptures, restraining and releasing bends, Riedel structures ( R, R', P, T), small-scale bookshelf faulting, and flower structures. An extensional component was present across surface rupture zones resulting in ground openings (sinkholes), small-scale grabens, and co-seismic dip-slip (normal) displacements. A compressional component was also present across surface rupture zones resulting in co-seismic dip-slip (reverse) displacements. From the comparison of our field geological observations with already published surface deformation measurements by DInSAR Interferometry, it is concluded that there is a strong correlation among the surface rupture zones, the ruptured active fault zones, and the detected displacement discontinuities in Paliki peninsula.

  17. Seismic swarm associated with the 2008 eruption of Kasatochi Volcano, Alaska: Earthquake locations and source parameters

    USGS Publications Warehouse

    Ruppert, N.A.; Prejean, S.; Hansen, R.A.

    2011-01-01

    An energetic seismic swarm accompanied an eruption of Kasatochi Volcano in the central Aleutian volcanic arc in August of 2008. In retrospect, the first earthquakes in the swarm were detected about 1 month prior to the eruption onset. Activity in the swarm quickly intensified less than 48 h prior to the first large explosion and subsequently subsided with decline of eruptive activity. The largest earthquake measured as moment magnitude 5.8, and a dozen additional earthquakes were larger than magnitude 4. The swarm exhibited both tectonic and volcanic characteristics. Its shear failure earthquake features were b value = 0.9, most earthquakes with impulsive P and S arrivals and higher-frequency content, and earthquake faulting parameters consistent with regional tectonic stresses. Its volcanic or fluid-influenced seismicity features were volcanic tremor, large CLVD components in moment tensor solutions, and increasing magnitudes with time. Earthquake location tests suggest that the earthquakes occurred in a distributed volume elongated in the NS direction either directly under the volcano or within 5-10 km south of it. Following the MW 5.8 event, earthquakes occurred in a new crustal volume slightly east and north of the previous earthquakes. The central Aleutian Arc is a tectonically active region with seismicity occurring in the crusts of the Pacific and North American plates in addition to interplate events. We postulate that the Kasatochi seismic swarm was a manifestation of the complex interaction of tectonic and magmatic processes in the Earth's crust. Although magmatic intrusion triggered the earthquakes in the swarm, the earthquakes failed in context of the regional stress field. Copyright ?? 2011 by the American Geophysical Union.

  18. Seismic swarm associated with the 2008 eruption of Kasatochi Volcano, Alaska: earthquake locations and source parameters

    USGS Publications Warehouse

    Ruppert, Natalia G.; Prejean, Stephanie G.; Hansen, Roger A.

    2011-01-01

    An energetic seismic swarm accompanied an eruption of Kasatochi Volcano in the central Aleutian volcanic arc in August of 2008. In retrospect, the first earthquakes in the swarm were detected about 1 month prior to the eruption onset. Activity in the swarm quickly intensified less than 48 h prior to the first large explosion and subsequently subsided with decline of eruptive activity. The largest earthquake measured as moment magnitude 5.8, and a dozen additional earthquakes were larger than magnitude 4. The swarm exhibited both tectonic and volcanic characteristics. Its shear failure earthquake features were b value = 0.9, most earthquakes with impulsive P and S arrivals and higher-frequency content, and earthquake faulting parameters consistent with regional tectonic stresses. Its volcanic or fluid-influenced seismicity features were volcanic tremor, large CLVD components in moment tensor solutions, and increasing magnitudes with time. Earthquake location tests suggest that the earthquakes occurred in a distributed volume elongated in the NS direction either directly under the volcano or within 5-10 km south of it. Following the MW 5.8 event, earthquakes occurred in a new crustal volume slightly east and north of the previous earthquakes. The central Aleutian Arc is a tectonically active region with seismicity occurring in the crusts of the Pacific and North American plates in addition to interplate events. We postulate that the Kasatochi seismic swarm was a manifestation of the complex interaction of tectonic and magmatic processes in the Earth's crust. Although magmatic intrusion triggered the earthquakes in the swarm, the earthquakes failed in context of the regional stress field.

  19. Forecasting Earthquakes

    NASA Technical Reports Server (NTRS)

    1994-01-01

    In this video there are scenes of damage from the Northridge Earthquake and interviews with Dr. Andrea Donnelan, Geophysics at JPL, and Dr. Jim Dolan, earthquake geologist from Cal. Tech. The interviews discuss earthquake forecasting by tracking changes in the earth's crust using antenna receiving signals from a series of satellites called the Global Positioning System (GPS).

  20. Nowcasting earthquakes

    NASA Astrophysics Data System (ADS)

    Rundle, J. B.; Turcotte, D. L.; Donnellan, A.; Grant Ludwig, L.; Luginbuhl, M.; Gong, G.

    2016-11-01

    Nowcasting is a term originating from economics and finance. It refers to the process of determining the uncertain state of the economy or markets at the current time by indirect means. We apply this idea to seismically active regions, where the goal is to determine the current state of the fault system and its current level of progress through the earthquake cycle. In our implementation of this idea, we use the global catalog of earthquakes, using "small" earthquakes to determine the level of hazard from "large" earthquakes in the region. Our method does not involve any model other than the idea of an earthquake cycle. Rather, we define a specific region and a specific large earthquake magnitude of interest, ensuring that we have enough data to span at least 20 or more large earthquake cycles in the region. We then compute the earthquake potential score (EPS) which is defined as the cumulative probability distribution P(n < n(t)) for the current count n(t) for the small earthquakes in the region. From the count of small earthquakes since the last large earthquake, we determine the value of EPS = P(n < n(t)). EPS is therefore the current level of hazard and assigns a number between 0% and 100% to every region so defined, thus providing a unique measure. Physically, the EPS corresponds to an estimate of the level of progress through the earthquake cycle in the defined region at the current time.

  1. Hidden Earthquakes.

    ERIC Educational Resources Information Center

    Stein, Ross S.; Yeats, Robert S.

    1989-01-01

    Points out that large earthquakes can take place not only on faults that cut the earth's surface but also on blind faults under folded terrain. Describes four examples of fold earthquakes. Discusses the fold earthquakes using several diagrams and pictures. (YP)

  2. Using ecological function to develop recovery criteria for depleted species: sea otters and kelp forests in the Aleutian archipelago

    USGS Publications Warehouse

    Estes, James A.; Tinker, M. Tim; Bodkin, James L.

    2010-01-01

    Recovery criteria for depleted species or populations normally are based on demographic measures, the goal being to maintain enough individuals over a sufficiently large area to assure a socially tolerable risk of future extinction. Such demographically based recovery criteria may be insufficient to restore the functional roles of strongly interacting species. We explored the idea of developing a recovery criterion for sea otters (Enhydra lutris) in the Aleutian archipelago on the basis of their keystone role in kelp forest ecosystems. We surveyed sea otters and rocky reef habitats at 34 island-time combinations. The system nearly always existed in either a kelp-dominated or deforested phase state, which was predictable from sea otter density. We used a resampling analysis of these data to show that the phase state at any particular island can be determined at 95% probability of correct classification with information from as few as six sites. When sea otter population status (and thus the phase state of the kelp forest) was allowed to vary randomly among islands, just 15 islands had to be sampled to estimate the true proportion that were kelp dominated (within 10%) with 90% confidence. We conclude that kelp forest phase state is a more appropriate, sensitive, and cost-effective measure of sea otter recovery than the more traditional demographically based metrics, and we suggest that similar approaches have broad potential utility in establishing recovery criteria for depleted populations of other functionally important species.

  3. Using ecological function to develop recovery criteria for depleted species: sea otters and kelp forests in the Aleutian archipelago.

    PubMed

    Estes, James A; Tinker, M Tim; Bodkin, James L

    2010-06-01

    Recovery criteria for depleted species or populations normally are based on demographic measures, the goal being to maintain enough individuals over a sufficiently large area to assure a socially tolerable risk of future extinction. Such demographically based recovery criteria may be insufficient to restore the functional roles of strongly interacting species. We explored the idea of developing a recovery criterion for sea otters (Enhydra lutris) in the Aleutian archipelago on the basis of their keystone role in kelp forest ecosystems. We surveyed sea otters and rocky reef habitats at 34 island-time combinations. The system nearly always existed in either a kelp-dominated or deforested phase state, which was predictable from sea otter density. We used a resampling analysis of these data to show that the phase state at any particular island can be determined at 95% probability of correct classification with information from as few as six sites. When sea otter population status (and thus the phase state of the kelp forest) was allowed to vary randomly among islands, just 15 islands had to be sampled to estimate the true proportion that were kelp dominated (within 10%) with 90% confidence. We conclude that kelp forest phase state is a more appropriate, sensitive, and cost-effective measure of sea otter recovery than the more traditional demographically based metrics, and we suggest that similar approaches have broad potential utility in establishing recovery criteria for depleted populations of other functionally important species.

  4. Bald eagles and sea otters in the Aleutian Archipelago: indirect effects of trophic cascades.

    PubMed

    Anthony, Robert G; Estes, James A; Ricca, Mark A; Miles, A Keith; Forsman, Eric D

    2008-10-01

    Because sea otters (Enhydra lutris) exert a wide array of direct and indirect effects on coastal marine ecosystems throughout their geographic range, we investigated the potential influence of sea otters on the ecology of Bald Eagles (Haliaeetus leucocephalus) in the Aleutian Islands, Alaska, USA. We studied the diets, productivity, and density of breeding Bald Eagles on four islands during 1993-1994 and 2000-2002, when sea otters were abundant and scarce, respectively. Bald Eagles depend on nearshore marine communities for most of their prey in this ecosystem, so we predicted that the recent decline in otter populations would have an indirect negative effect on diets and demography of Bald Eagles. Contrary to our predictions, we found no effects on density of breeding pairs on four islands from 1993-1994 to 2000-2002. In contrast, diets and diet diversity of Bald Eagles changed considerably between the two time periods, likely reflecting a change in prey availability resulting from the increase and subsequent decline in sea otter populations. The frequency of sea otter pups, rock greenling (Hexagammus lagocephalus), and smooth lumpsuckers (Aptocyclus ventricosus) in the eagle's diet declined with corresponding increases in Rock Ptarmigan (Lagopus mutus), Glaucous-winged Gulls (Larus glaucescens), Atka mackerel (Pleurogrammus monopterygius), and various species of seabirds during the period of the recent otter population decline. Breeding success and productivity of Bald Eagles also increased during this time period, which may be due to the higher nutritional quality of avian prey consumed in later years. Our results provide further evidence of the wide-ranging indirect effects of sea otter predation on nearshore marine communities and another apex predator, the Bald Eagle. Although the indirect effects of sea otters are widely known, this example is unique because the food-web pathway transcended five species and several trophic levels in linking one apex predator

  5. Bald eagles and sea otters in the Aleutian Archipelago: indirect effects of trophic cascades.

    USGS Publications Warehouse

    Anthony, R.G.; Estes, J.A.; Ricca, M.A.; Miles, A.K.; Forsman, E.D.

    2008-01-01

    Because sea otters (Enhydra lutris) exert a wide array of direct and indirect effects on coastal marine ecosystems throughout their geographic range, we investigated the potential influence of sea otters on the ecology of Bald Eagles (Haliaeetus leucocephalus) in the Aleutian Islands, Alaska, USA. We studied the diets, productivity, and density of breeding Bald Eagles on four islands during 1993–1994 and 2000–2002, when sea otters were abundant and scarce, respectively. Bald Eagles depend on nearshore marine communities for most of their prey in this ecosystem, so we predicted that the recent decline in otter populations would have an indirect negative effect on diets and demography of Bald Eagles. Contrary to our predictions, we found no effects on density of breeding pairs on four islands from 1993–1994 to 2000–2002. In contrast, diets and diet diversity of Bald Eagles changed considerably between the two time periods, likely reflecting a change in prey availability resulting from the increase and subsequent decline in sea otter populations. The frequency of sea otter pups, rock greenling (Hexagammus lagocephalus), and smooth lumpsuckers (Aptocyclus ventricosus) in the eagle's diet declined with corresponding increases in Rock Ptarmigan (Lagopus mutus), Glaucous-winged Gulls (Larus glaucescens), Atka mackerel (Pleurogrammus monopterygius), and various species of seabirds during the period of the recent otter population decline. Breeding success and productivity of Bald Eagles also increased during this time period, which may be due to the higher nutritional quality of avian prey consumed in later years. Our results provide further evidence of the wide-ranging indirect effects of sea otter predation on nearshore marine communities and another apex predator, the Bald Eagle. Although the indirect effects of sea otters are widely known, this example is unique because the food-web pathway transcended five species and several trophic levels in linking one apex

  6. 76 FR 65972 - Fisheries of the Exclusive Economic Zone Off Alaska; Pacific Ocean Perch in the Eastern Aleutian...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-10-25

    ... Economic Zone Off Alaska; Pacific Ocean Perch in the Eastern Aleutian District of the Bering Sea and... directed fishing for Pacific ocean perch in the Eastern Aleutian District of the Bering Sea and Aleutian... action is necessary to prevent exceeding the 2011 allocation of Pacific ocean perch in this...

  7. 77 FR 39440 - Fisheries of the Exclusive Economic Zone Off Alaska; Pacific Ocean Perch in the Central Aleutian...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-07-03

    ... Economic Zone Off Alaska; Pacific Ocean Perch in the Central Aleutian District of the Bering Sea and... directed fishing for Pacific ocean perch in the Central Aleutian District of the Bering Sea and Aleutian... action is necessary to prevent exceeding the 2012 allocation of Pacific ocean perch in this...

  8. 76 FR 43933 - Fisheries of the Exclusive Economic Zone Off Alaska; Pacific Ocean Perch in the Western Aleutian...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-07-22

    ... Economic Zone Off Alaska; Pacific Ocean Perch in the Western Aleutian District of the Bering Sea and... directed fishing for Pacific ocean perch in the Western Aleutian District of the Bering Sea and Aleutian... action is necessary to prevent exceeding the 2011 allocation of Pacific ocean perch in this...

  9. 77 FR 34262 - Fisheries of the Exclusive Economic Zone Off Alaska; Pacific Ocean Perch in the Western Aleutian...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-06-11

    ... Economic Zone Off Alaska; Pacific Ocean Perch in the Western Aleutian District of the Bering Sea and... directed fishing for Pacific ocean perch in the Western Aleutian District of the Bering Sea and Aleutian... action is necessary to prevent exceeding the 2012 allocation of Pacific ocean perch in this...

  10. The Spatiotemporal Earthquake Distributions for the Pacific Region: Within-Year Irregularities.

    NASA Astrophysics Data System (ADS)

    Sasorova, E. V.; Levin, B. W.

    2006-12-01

    The earthquake (EQ) occurrence is considered now as a random phenomenon. But it was observed during written history that the seismic events occur in various regions of the Earth in some months of a year significantly more often than in another. If the variability exists, then occurrences of the seismic events depend on the position of the Earth -Moon system on ecliptic plane or on factors that are varied during motion of the Earth-Moon system along ecliptic plane. The goal of our work is testing of hypothesis about within-year variability existence for the events of various energy levels (from Mb >= 4.0) for the Pacific region (PO). The whole PO was subdivided into 31 subregions (Japan, Kuril Islands, Kamchatka, Aleutian Islands, Alaska, California, and so on along the perimeter of the Pacific). The worldwide catalog ISC was used for analysis of annual earthquake distributions. The aftershocks were canceled from the list. All events for each region were divided into following magnitude levels: 4 <= Mb < 4.5; 4.5 <= Mb < 5; 5 <= Mb < 5.5; 5.5 <= Mb < 6.0; 6 <= Mb. And the events in each magnitude level were subdivided once again into two groups: shallow events (H <= Htr) and deep events (H > Htr), where Htr is depth threshold value. Then we are checking if the distributions of the events during the year period are uniform or these distributions are nonuniform. We are testing it separately for each region, for every magnitude level and for every depth level. It was disproved the null hypothesis about uniform EQ distributions in the course of year for shallow events (with less than 5 percents of significance level), and it was confirmed the null hypothesis for deep earthquakes. It was found that the Htr boundary between the shallow and deep events was arranged at deep 60-80 km. The noticeable increase number of seismic events in short time intervals as a rule two times in year, and significant reducing of seismic activity in the rest part of the year was shown. It was

  11. Subducting fracture zones control earthquake distribution and upper plate properties: examples from Sumatra and Kamchatka

    NASA Astrophysics Data System (ADS)

    Gaedicke, C.; Freitag, R.; Barckhausen, U.; Franke, D.; Ladage, S.; Schnabel, M.; Tsukanov, N.

    2010-12-01

    With newly acquired marine geophysical data from the oceanic crust off Sumatra and Kamchatka (SO186 and SO201) we investigate the influence of the relief of the downgoing plate on seismicity and fore arc structure, architecture and properties along two different active margins, namely the Sumatra and the Kamchatka subduction zones. Off northern Sumatra two mega-thrust events occurred on 26.12.2004 (Mw=9.1-9.3) and on 28.03.2005 (Mw=8.6). Seismological investigations, GPS measurements and in-situ and remote observation of vertical motion on fore arc islands show both, an abrupt southern termination of the large 12/2004 rupture and a sharp northern termination of the rupture zone of the 03/2005 mega-thrust. Wide-angle/refraction seismic and MCS data show an abrupt arc parallel depth change of 3 km within 40 km in the oceanic crust beneath the fore arc SW of Simeulue Island. We interpret the abrupt depth change originates from a ramp or tear in the subducted oceanic crust. The discontinuity in the oceanic crust likely trends NNE and is located east of a continuation of an extinct FZ on the subducting Indo-Australian plate. This indicates a pervasive lower plate control on margin structure, particularly its segmentation. The tear might be the reason for rupture propagation termination of the great Sumatra-Andaman earthquakes. During RV Sonne cruise SO201 we collected geophysical profiles in the NW Pacific off Kamchatka and the Aleutian arc crossing the Emperor Seamount Chain and the Krusenstern FZ. The Krusenstern FZ is being subducted at the Kamchatka margin. It comprises a maximum vertical offset of about 1080 m. From our data we suggest that the Krusenstern FZ is reactivated in the vicinity of the Kamchatka margin due to the load of the subducting/colliding Meiji Guyot. It enters the subduction zone right off Kronotsky Peninsula, where a major segment boundary separates domains of different properties of the fore arc: It differs in terms of exhumation, uplift and

  12. Selected 1970 Census Data for Alaska Communities. Part 4 - Bristol Bay-Aleutian Region.

    ERIC Educational Resources Information Center

    Alaska State Dept. of Community and Regional Affairs, Juneau. Div. of Community Planning.

    As 1 of 6 regional reports supplying statistical information on Alaska's incorporated and unincorporated communities (those of 25 or more people), this report on Alaska's Bristol Bay-Aleutian Region presents data derived from the 1970 U.S. Census first-count microfilm. Organized via the 3 Bristol Bay-Aleutian census divisions, data are presented…

  13. Variations in Melt Generation and Migration along the Aleutian Arc (Invited)

    NASA Astrophysics Data System (ADS)

    Plank, T. A.; Van Keken, P. E.

    2013-12-01

    The generation and ascent of mantle melt beneath volcanic arcs sets the course for how magmas differentiate to form the continental crust and erupt explosively from volcanoes. Although the basic framework of melting at subduction zones is understood to involve the convective influx of hot mantle (Tp ≥ 1300°C) and advective transport of water-rich fluids from the subducting slab, the P-T paths that melts follow during melt generation and migration are still not well known. The Aleutian Arc provides an opportunity to explore the conditions of mantle melting in the context of volcanoes that span an unusually large range in the depth to the slab, from Seguam island, with among the shallowest depths to the slab worldwide (~65 km, [1]) to Bogoslof island, behind the main volcanic front and twice the depth to the slab (~130 km). Here we combine thermal models tuned to Aleutian subduction parameters [after 2] with petrological estimates of the T and P of mantle-melt equilibration, using a major element geothermometer [3] and estimates of H2O and fO2 from olivine-hosted melt inclusion measurements [4] for basaltic magmas from 6 volcanoes in the central Aleutians (Korovin, Seguam, Bogoslof, Pakushin, Akutan, Shishaldin). We find mantle-melt equilibration conditions to vary systematically as a function of the depth to the slab, from 30 km and 1220°C (for Seguam) to 60 km and 1300°C (for Bogoslof). Such shallow depths, which extend up to the Moho, define a region perched well above the hot core of the mantle wedge predicted from thermal models, even considering the shallow depths of slab-mantle coupling (< 60 km) required to supply hot mantle beneath Seguam. Thus, even though the greatest melt production will occur in the hot core of the wedge (50-100 km depth), melts apparently ascend and re-equilibrate in the shallowest mantle. Volcanoes that overlie the greatest depth to the slab, and lie furthest from the wedge corner, stall at greater depths (~60 km), at the base of

  14. First breeding records of whooping swan and brambling in North America at Attu Island, Alaska

    USGS Publications Warehouse

    Sykes, P.W.; Sonneborn, D.W.

    1998-01-01

    We document the first breeding records of Whooper Swan (Cygnus cygnus) and Brambling (Fringilla montifringilla) in Alaska and North America on Attu Island in the Western Aleutians in the spring of 1996. Five cygnets were seen with adults and the nest located, and a territorial pair of Bramblings was observed and a nest with eggs found.

  15. Sedimentation and deformation in the Amlia Fracture Zone sector of the Aleutian Trench

    USGS Publications Warehouse

    Scholl, D. W.; Vallier, T.L.; Stevenson, A.J.

    1982-01-01

    A wedge-shaped, landward thickening mass of sedimentary deposits composed chiefly of terrigenous turbidite beds underlies the west-south west-trending Amlia sector (172??20???-173??30???W) of the Aleutian Trench. Pacific oceanic crust dips northward beneath the sector's sedimentary wedge and obliquely underthrusts (30?? off normal) the adjacent Aleutian Ridge. The trench floor and subsurface strata dip gently northward toward the base of the inner trench slope. The dip of the trench deposits increases downsection from about 0.2?? at the trench floor to as much as 6-7?? just above basement. The wedge is typically 2-2.5 km thick, but it is thickest (3.7-4.0 km) near the base of the inner slope overlying the north-trending Amlia Fracture Zone and also east of this structure. Slight undulations and relatively abrupt offsets of the trench floor reflect subsurface and generally west-trending structures within the wedge that are superimposed above ridges and swales in the underlying oceanic basement. The southern or seaward side of some of these structures are bordered by high-angle faults or abrupt flexures. Across these offsets the northern side of the trench floor and underlying wedge is typically upthrown. West-flowing turbidity currents originating along the Alaskan segment of the trench (1200 km to the east) probably formed the greater part of the Amlia wedge during the past 0.5 m.y. The gentle northward or cross-trench inclination of the trench floor and underlying wedge probably reflects regional downbending of the oceanic lithosphere and trench-floor basement faulting and rotation. Much of the undulatory flexuring of the trench wedge can be attributed to differential compaction over buried basement relief. However, abrupt structural offsets attest to basement faulting. Faulting is associated with extensional earthquakes in the upper crust. The west-trending basement offsets are probably normal faults that dip steeply south or antithetic to the north dip of the

  16. Photocopy of photograph (original located at Mare Island Archives). Original ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Photocopy of photograph (original located at Mare Island Archives). Original photographer unknown. View of sawmill after earthquake of 1898. - Mare Island Naval Shipyard, East of Nave Drive, Vallejo, Solano County, CA

  17. Three-dimensional velocity structure and high-precision earthquake relocations at Augustine, Akutan, and Makushin Volcanoes, Alaska

    NASA Astrophysics Data System (ADS)

    Syracuse, E. M.; Thurber, C. H.; Power, J. A.; Prejean, S. G.

    2010-12-01

    Alaska contains over 100 volcanoes, 21 of which have been active within the past 20 years, including Augustine in Cook Inlet, and Akutan and Makushin in the central Aleutian arc. We incorporate 14-15 years of earthquake data from the Alaska Volcano Observatory (AVO) to obtain P-wave velocity structure and high-precision earthquake locations at each volcano. At Augustine, most relocated seismicity is beneath the summit at an average depth of 0.6 km. In the weeks leading to the 2006 eruption, seismicity shallowed and focused on a NW-SE line, suggestive of an inflating dike. Through August 2006, intermittent seismicity was observed at 1 to 4.5 km depth, pointing to an association with the transport of magma. Active-source data are also incorporated into the tomographic inversion, illuminating a high-velocity column beneath the summit, and elevated velocities on the south flank. The high-velocity column surrounds the observed deeper seismicity and is likely due to intruded volcanic material. The elevated velocities on the south flank are associated with uplifted zeolitzed sandstones. Akutan most recently erupted in 1992, before the seismic network was installed. Most seismicity is above 9 km depth, with 10% occurring between 14 to30 km depth. Seismicity is separated into two main groups that dip away from the caldera—one to the east and one to the west. The eastern group contains earthquakes from a swarm in early 1996 and the western group contains earthquakes from mid-1996 through the present that form rough lines radiating from the summit. Ongoing seismicity also occurs in a broader region beneath the caldera. Makushin most recently erupted in 1995, also prior to seismic monitoring by AVO. Relocations here show that most seismicity is at 3 to 13 km depth and either beneath the caldera or within one of two dipping clusters 20 km to the northeast. Additional seismicity occurs at up to 25 km depth beneath the summit, as well as scattered throughout the island at

  18. Eastern Aleutian volcanic arc digital model - version 1.0

    USGS Publications Warehouse

    Saltus, R.W.; Barnett, Adrienne

    2000-01-01

    A 3-dimensional model (Figure 1) of the interaction of oceanic and continental tectonic plates along the eastern portion of the Aleutian volcanic arc helps in the visualization of basic tectonic, geodetic, and geophysical data in this active plate boundary region. The model is constrained by topographic, bathymetric, and seismic data and by the principle of isostasy. Examination of free-air gravity anomalies over the region indicates where the flexural strength of the down-going oceanic slab disturbs local isostatic balance and where low-density sediments have accumulated in the trench and forearc regions.

  19. Changes in hot spring temperature and hydrogeology of the Alpine Fault hanging wall, New Zealand, induced by distal South Island earthquakes

    NASA Astrophysics Data System (ADS)

    Cox, S.; Menzies, C. D.; Sutherland, R.; Denys, P. H.; Chamberlain, C. J.; Teagle, D. A. H.

    2014-12-01

    In response to large distant earthquakes Copland hot spring cooled c.1 °C and changed fluid chemistry. Thermal springs in the Southern Alps, New Zealand, originate through penetration of fluids into a thermal anomaly generated by rapid uplift and exhumation on the Alpine Fault. Copland hot spring (43.629S, 169.946E) is one of the most vigorously flowing, hottest of the springs, discharging strongly effervescent CO2-rich 56-58 °C water at 6 ± 1 Ls-1. Shaking from the Mw7.8 Dusky Sound (Fiordland) 2009 and Mw7.1 Darfield (Canterbury) 2010 earthquakes, 350 and 180 km from the spring respectively, resulted in a characteristic c. 1 °C delayed-cooling over five days. The cooling responses occurred at low shaking intensities (MM III-IV) and seismic energy densities (~10-1 Jm-3) from intermediate-field distances, independent of variations in spectral frequency, without the need for post-seismic recovery before the next cooling occurred. Such shaking can be expected approximately every 1-10 years in central Southern Alps. Observed temperature and fluid chemistry responses are inferred to reflect subtle changes in the fracture permeability of schist mountains adjacent to the spring. Relatively low intensity shaking induced small permanent 10-7-10-6 strains across the Southern Alps - opening fractures which enhance mixing of relatively cool near-surface groundwater with upwelling hot water. Hydrothermal systems situated in places of active deformation, tectonic and topographic stress may be particularly susceptible to earthquake-induced transience, that if monitored may provide important information on difficult to measure hydrogeological properties within active orogens.

  20. Long-range Receiver Function Profile of Crustal and Mantle Discontinuities From the Aleutian Arc to Tierra del Fuego

    NASA Astrophysics Data System (ADS)

    Spieker, Kathrin; Rondenay, Stéphane; Sawade, Lucas

    2016-04-01

    The Circum-Pacific belt, also called the Pacific Ring of Fire, is the most seismically active region on Earth. Multiple plate boundaries form a zone characterized by frequent volcanic eruptions and seismicity. While convergent plate boundaries such as the Peru-Chile trench dominate the Circum-Pacific belt, divergent and transform boundaries are present as well. The eastern section of the Circum-Pacific belt extends from the Aleutian arc, through the Cascadia subduction zone, San Andreas Fault, middle America trench and the Andean margin down to Tierra del Fuego. Due to the significant hazards posed by this tectonic activity, the region has been densely instrumented by thousands of seismic stations deployed across fifteen countries, over a distance of more than 15000 km. Various seismological studies, including receiver function analyses, have been carried out to investigate the crustal and mantle structure beneath local segments of the eastern Circum-Pacific belt (i.e., at ~100-500 km scale). However, to the best of our knowledge, no study to date has ever attempted to combine all available seismic data from the eastern Circum-Pacific belt to generate a continuous profile of seismic discontinuities extending from the Aleutians to Tierra del Fuego. Here, we use results from the "Global Imaging using Earthquake Records" (GLImER) P-wave receiver function database to create a long-range profile of crustal and upper mantle discontinuities across the entire eastern portion of the Circum-Pacific belt. We image intermittent crustal and mantle discontinuities along the profile, and examine them with regard to their behaviour and properties across transitions between different tectonic regimes.

  1. Crustal Deformation and the Seismic Cycle across the Kodiak Islands, Alaska

    NASA Technical Reports Server (NTRS)

    Sauber, Jeanne; Carver, G.; Cohen, Steven C.; King, Robert

    2004-01-01

    The Kodiak Islands are located approximately 130 to 250 km from the Alaska-Aleutian Trench where the Pacific plate is underthrusting the North American plate at a rate of about 57 mm/yr. The southern extent of the 1964 Prince William Sound (${M-w}$ = 9.2) earthquake rupture occurred offshore and beneath the eastern portion of the Kodiak Islands. Here we report GPS results (1993-2001) from northern Kodiak Island that span the transition between the 1964 uplift region along the eastern coast and the region of coseismic subsidence further inland. The horizontal velocity vectors range from 22.9 $\\pm$ 2.2 mm/yr at N26.3$\\deg$W $\\pm$ 2.5$\\deg$, about 150 km from the trench, to 5.9 $\\pm$ 1.3 mm/yr at N65.9$\\deg$W $\\pm$ 6.6$\\deg$, about 190 km from the trench. Near the northeastern coast of Kodiak the velocity vector above the shallow, locked main thrust zone is between the orientation of PCFC-NOAM plate motion (N22$/deg$W) and the trench-normal (N3O$\\deg$W). Further west, our geodetic results suggest the accumulation of shear strain that will be released eventually as left-lateral motion on upper plate faults such as the Kodiak Island fault. These results are consistent with the hypothesis that the difference between the Pacific-North American plate motion and the orientation of the down going slab would lead to 4-8 mm/yr of left-lateral slip. Short-term geodetic uplift rates range from 2 - 14 mm/yr, with the maximum uplift located near the axis of maximum subsidence during the 1964 earthquake. We evaluated alternate interseismic models for Kodiak to test the importance of various mechanisms responsible for crustal deformation rates. These models are based on the plate interface slip history inferred from earlier modeling of coseismic and post-seismic geodetic results. The horizontal (trench perpendicular) and vertical deformation rates across Kodiak are consistent with a model that includes the viscoelastic response to : (1) a downgoing Pacific plate interface

  2. Temporal variation in fish mercury concentrations within lakes from the western Aleutian Archipelago, Alaska

    USGS Publications Warehouse

    Kenney, Leah A.; Eagles-Smith, Collin A.; Ackerman, Joshua T.; von Hippel, Frank A.

    2014-01-01

    We assessed temporal variation in mercury (Hg) concentrations of threespine stickleback (Gasterosteus aculeatus) from Agattu Island, Aleutian Archipelago, Alaska. Total Hg concentrations in whole-bodied stickleback were measured at two-week intervals from two sites in each of two lakes from June 1 to August 10, 2011 during the time period when lakes were ice-free. Across all sites and sampling events, stickleback Hg concentrations ranged from 0.37–1.07 µg/g dry weight (dw), with a mean (± SE) of 0.55±0.01 µg/g dw. Mean fish Hg concentrations declined by 9% during the study period, from 0.57±0.01 µg/g dw in early June to 0.52±0.01 µg/g dw in mid-August. Mean fish Hg concentrations were 6% higher in Loon Lake (0.56±0.01 µg/g dw) than in Lake 696 (0.53±0.01 µg/g dw), and 4% higher in males (0.56±0.01 µg/g dw) than in females (0.54±0.01 µg/g dw). Loon Lake was distinguished from Lake 696 by the presence of piscivorous waterbirds during the breeding season. Mercury concentrations in stickleback from Agattu Island were higher than would be expected for an area without known point sources of Hg pollution, and high enough to be of concern to the health of piscivorous wildlife.

  3. Temporal Variation in Fish Mercury Concentrations within Lakes from the Western Aleutian Archipelago, Alaska

    PubMed Central

    Kenney, Leah A.; Eagles-Smith, Collin A.; Ackerman, Joshua T.; von Hippel, Frank A.

    2014-01-01

    We assessed temporal variation in mercury (Hg) concentrations of threespine stickleback (Gasterosteus aculeatus) from Agattu Island, Aleutian Archipelago, Alaska. Total Hg concentrations in whole-bodied stickleback were measured at two-week intervals from two sites in each of two lakes from June 1 to August 10, 2011 during the time period when lakes were ice-free. Across all sites and sampling events, stickleback Hg concentrations ranged from 0.37–1.07 µg/g dry weight (dw), with a mean (± SE) of 0.55±0.01 µg/g dw. Mean fish Hg concentrations declined by 9% during the study period, from 0.57±0.01 µg/g dw in early June to 0.52±0.01 µg/g dw in mid-August. Mean fish Hg concentrations were 6% higher in Loon Lake (0.56±0.01 µg/g dw) than in Lake 696 (0.53±0.01 µg/g dw), and 4% higher in males (0.56±0.01 µg/g dw) than in females (0.54±0.01 µg/g dw). Loon Lake was distinguished from Lake 696 by the presence of piscivorous waterbirds during the breeding season. Mercury concentrations in stickleback from Agattu Island were higher than would be expected for an area without known point sources of Hg pollution, and high enough to be of concern to the health of piscivorous wildlife. PMID:25029042

  4. Sedimentation in the central segment of the Aleutian Trench: Sources, transport, and depositional style

    SciTech Connect

    Stevenson, A.J.; Scholl, D.W.; Vallier, T.L. ); Underwood, M.B. )

    1990-05-01

    The central segment of the Aleutian Trench (162{degree}W to 175{degree}E) is an intraoceanic subduction zone that contains an anomalously thick sedimentary fill (4 km maximum). The fill is an arcward-thickening and slightly tilted wedge of sediment characterized acoustically by laterally continuous, closely spaced, parallel reflectors. These relations are indicative of turbidite deposition. The trench floor and reflection horizons are planar, showing no evidence of an axial channel or any transverse fan bodies. Cores of surface sediment recover turbidite layers, implying that sediment transport and deposition occur via diffuse, sheetlike, fine-grained turbidite flows that occupy the full width of the trench. The mineralogy of Holocene trench sediments document a mixture of island-arc (dominant) and continental source terranes. GLORIA side-scan sonar images reveal a westward-flowing axial trench channel that conducts sediment to the eastern margin of the central segment, where channelized flow cases. Much of the sediment transported in this channel is derived from glaciated drainages surrounding the Gulf of Alaska which empty into the eastern trench segment via deep-sea channel systems (Surveyor and others) and submarine canyons (Hinchinbrook and others). Insular sediment transport is more difficult to define. GLORIA images show the efficiency with which the actively growing accretionary wedge impounds sediment that manages to cross a broad fore-arc terrace. It is likely that island-arc sediment reaches the trench either directly via air fall, via recycling of the accretionary prism, or via overtopping of the accretionary ridges by the upper parts of thick turbidite flows.

  5. GLORIA side-scan imagery of Aleutian basin, Bering Sea slope and Abyssal plain

    SciTech Connect

    Carlson, P.R.; Cooper, A.K.; Gardner, J.V.; Karl, H.A.; Marlow, M.S.; Stevenson, A.J.; Huggett, Q.; Kenyon, N.; Parson, L.

    1987-05-01

    During July-September 1986, about 700,000 km/sup 2/ of continental slope and abyssal plain of the Aleutian basin, Bering Sea, were insonified with GLORIA (Geological Long Range Inclined Asdic) side-scane sonar. A sonar mosaic displays prominent geomorphic features including the massive submarine canyons of the Beringian and the northern Aleutian Ridge slopes and shows well-defined sediment patterns including large deep-sea channels and fan systems on the Aleutian basin abyssal plain. Dominant erosional and sediment transport processes on both the Beringian and the Aleutian Ridge slopes include varieties of mass movement that range from small debris flows and slides to massive slides and slumps of blocks measuring kilometers in dimension. Sediment-flow patterns that appear to be formed by sheet flow rather than channelized flow extend basinward from the numerous canyons and gullies that incise the slopes of the Beringian margin and of Bowers Ridge and some places along the Aleutian Ridge. These Beringian and Bowers canyon sediment sources, however, appear to have contributed less modern sediment to the Aleutian basin than the large, well-defined channel systems that emanate from Bering, Umnak, and Amchitka submarine canyons and extend for several hundred kilometers across the abyssal plain. This GLORIA imagery emphasizes the important contribution of the Aleutian Ridge to modern sedimentation in the deep Bering Sea.

  6. Earthquake prediction

    NASA Technical Reports Server (NTRS)

    Turcotte, Donald L.

    1991-01-01

    The state of the art in earthquake prediction is discussed. Short-term prediction based on seismic precursors, changes in the ratio of compressional velocity to shear velocity, tilt and strain precursors, electromagnetic precursors, hydrologic phenomena, chemical monitors, and animal behavior is examined. Seismic hazard assessment is addressed, and the applications of dynamical systems to earthquake prediction are discussed.

  7. Earthquake Hazards.

    ERIC Educational Resources Information Center

    Donovan, Neville

    1979-01-01

    Provides a survey and a review of earthquake activity and global tectonics from the advancement of the theory of continental drift to the present. Topics include: an identification of the major seismic regions of the earth, seismic measurement techniques, seismic design criteria for buildings, and the prediction of earthquakes. (BT)

  8. Analog earthquakes

    SciTech Connect

    Hofmann, R.B.

    1995-09-01

    Analogs are used to understand complex or poorly understood phenomena for which little data may be available at the actual repository site. Earthquakes are complex phenomena, and they can have a large number of effects on the natural system, as well as on engineered structures. Instrumental data close to the source of large earthquakes are rarely obtained. The rare events for which measurements are available may be used, with modfications, as analogs for potential large earthquakes at sites where no earthquake data are available. In the following, several examples of nuclear reactor and liquified natural gas facility siting are discussed. A potential use of analog earthquakes is proposed for a high-level nuclear waste (HLW) repository.

  9. Six large tsunamis in the past ~1700 years at Stardust Bay, Sedanka Island, Alaska

    NASA Astrophysics Data System (ADS)

    Witter, R. C.; Carver, G. A.; Bender, A. M.; Briggs, R. W.; Gelfenbaum, G. R.; Koehler, R. D.

    2013-12-01

    Two great earthquakes in 1946 (Unimak Island, Mw 8.1) and 1957 (Andreanof Islands, Mw 8.6) ruptured parts of the central Alaska-Aleutian subduction zone, generating deadly pan-Pacific tsunamis that hit Hawaii. Here, we provide the first estimates of recurrence intervals of such destructive Aleutian-born tsunamis from evidence for tsunami inundation at Stardust Bay on the Pacific coast of Sedanka Island, ~25 km southeast of Dutch Harbor, Alaska. We used soil augers, outcrops and shallow pits to map 6 continuous sand deposits across four depositional environments in a ~500-m-wide, 35-hectare valley. Successive sandy deposits mantled the crests of beach ridges, buried peat formed in freshwater wetlands and upland muskeg, and accumulated to form unusual terrace remnants along the valley's inland margin. Dark, basaltic tephras interbedded in peat underlying two of the sands guided stratigraphic correlation across the study area. Thin, peaty horizons separate the six gray sand beds that can be distinguished from black tephra deposits by their compositions, which consist of subangular volcanic lithics similar to Stardust Bay beach sand. The youngest sand, often the thinnest (<1-13 cm) of the six deposits, underlies drift logs scattered across the landscape at elevations up to 18.5 m and as far as 800 m inland, which provide minimum limits on inundation for the most recent tsunami. The older sands vary in thickness from 6-50 cm and often have rounded gravel at the bases of multiple, normally-graded sand beds, some of which contain ripped-up mud or peat clasts. The sheet-like sand beds blanket topography, thinning over beach ridges and thickening in swales and bogs. Although marine foraminifera are absent in the sandy and peaty deposits in the valley, we infer a tsunami origin for the sand beds, based on their physical properties. The activity of 210Pb and 137Cs in organic-rich sediment above and below the youngest sand bed suggest it predates 1963, consistent with

  10. Mutual Information Between GPS Measurements and Earthquakes

    NASA Astrophysics Data System (ADS)

    Wang, T.; Bebbington, M. S.

    2009-12-01

    Prior to the wide deployment of Continuous GPS stations in the early 1990s, there were a number of well-documented deformation rate changes observed before large earthquakes. GPS measurements provide the opportunity for systematic investigation of pre-, co- and post-seismic deformation anomalies, but contain much noise that needs to be filtered out of the observations. Assuming the existence of an earthquake cycle (for example, mainshock--aftershock--quiescence--precursory seismicity), a hidden Markov model (HMM) provides a natural framework for analyzing the observed GPS data. For two case studies of a) deep earthquakes in the central North Island, New Zealand, and b) shallow earthquakes in Southern California, an HMM fitted to the trend ranges of the GPS measurements can classify the deformation data into different patterns which form proxies for states of the earthquake cycle. Mutual information can be used to examine whether there is any relation between these patterns, in particular the Viterbi path, and subsequent (or previous) earthquakes. One class of GPS movements (identified by the HMM as having the largest range of deformation rate changes) appears to have some precursory character for earthquakes with minimum magnitude 5.1 (central North Island, New Zealand, 26 earthquakes in 1747 days) and 4.5 (Southern California, 50 earthquakes in 3815 days). We define a ``Time of Increased Probability'' (TIP) as being a 10-day interval (central North Island, New Zealand) or a 20-day interval (Southern California) following entry (as identified by the Viterbi algorithm) to the `precursory' hidden state, and examine the performance of this in probabilistically forecasting subsequent earthquakes.

  11. Mechanism of the wintertime Aleutian Low-Icelandic Low seesaw

    NASA Astrophysics Data System (ADS)

    Sun, Jie; Tan, Benkui

    2013-08-01

    The driving mechanism for the wintertime (December-March) Aleutian Low-Icelandic Low (AL-IL) seesaw is investigated with National Centers for Environmental Prediction/National Center for Atmospheric Research reanalysis data for 1948-2009. It is shown that the AL and the IL are dynamically linked through the eastern Pacific wave train (EPW) and that both the EPWs and the stratospheric polar vortex are found to work cooperatively to produce a significant AL-IL seesaw. In general, it is found that wave reflection by the polar vortex is crucial for the formation of the AL-IL seesaw. However, when the EPWs are extremely strong, the AL-IL seesaw appears to be caused primarily by horizontal wave propagation. It is further shown that the Pacific center of the traditional Arctic Oscillation pattern is present when the AL-IL seesaw is active, but it disappears when the AL-IL seesaw is absent.

  12. Satellite magnetic anomalies over subduction zones - The Aleutian Arc anomaly

    NASA Technical Reports Server (NTRS)

    Clark, S. C.; Frey, H.; Thomas, H. H.

    1985-01-01

    Positive magnetic anomalies seen in MAGSAT average scalar anomaly data overlying some subduction zones can be explained in terms of the magnetization contrast between the cold subducted oceanic slab and the surrounding hotter, nonmagnetic mantle. Three-dimensional modeling studies show that peak anomaly amplitude and location depend on slab length and dip. A model for the Aleutian Arc anomaly matches the general trend of the observed MAGSAT anomaly if a slab thickness of 7 km and a relatively high (induced plus viscous) magnetization contrast of 4 A/m are used. A second source body along the present day continental margin is required to match the observed anomaly in detail, and may be modeled as a relic slab from subduction prior to 60 m.y. ago.

  13. Comparative pathogenicity of four strains of Aleutian disease virus for pastel and sapphire mink.

    PubMed Central

    Hadlow, W J; Race, R E; Kennedy, R C

    1983-01-01

    Information was sought on the comparative pathogenicity of four North American strains (isolates) of Aleutian disease virus for royal pastel (a non-Aleutian genotype) and sapphire (an Aleutian genotype) mink. The four strains (Utah-1, Ontario [Canada], Montana, and Pullman [Washington]), all of mink origin, were inoculated intraperitoneally and intranasally in serial 10-fold dilutions. As indicated by the appearance of specific antibody (counterimmunoelectrophoresis test), all strains readily infected both color phases of mink, and all strains were equally pathogenic for sapphire mink. Not all strains, however, regularly caused Aleutian disease in pastel mink. Infection of pastel mink with the Utah-1 strain invariably led to fatal disease. Infection with the Ontario strain caused fatal disease nearly as often. The Pullman strain, by contrast, almost never caused disease in infected pastel mink. The pathogenicity of the Montana strain for this color phase was between these extremes. These findings emphasize the need to distinguish between infection and disease when mink are exposed to Aleutian disease virus. The distinction has important implications for understanding the natural history of Aleutian disease virus infection in ranch mink. PMID:6193063

  14. Earthquake Facts

    MedlinePlus

    ... the source of earthquakes. Moonquakes (“earthquakes” on the moon) do occur, but they happen less frequently and ... with the varying distance between the Earth and Moon. They also occur at great depth, about halfway ...

  15. Earthquake Analysis.

    ERIC Educational Resources Information Center

    Espinoza, Fernando

    2000-01-01

    Indicates the importance of the development of students' measurement and estimation skills. Analyzes earthquake data recorded at seismograph stations and explains how to read and modify the graphs. Presents an activity for student evaluation. (YDS)

  16. Deep Earthquakes.

    ERIC Educational Resources Information Center

    Frohlich, Cliff

    1989-01-01

    Summarizes research to find the nature of deep earthquakes occurring hundreds of kilometers down in the earth's mantle. Describes further research problems in this area. Presents several illustrations and four references. (YP)

  17. Catalog of Hawaiian earthquakes, 1823-1959

    USGS Publications Warehouse

    Klein, Fred W.; Wright, Thomas L.

    2000-01-01

    This catalog of more than 17,000 Hawaiian earthquakes (of magnitude greater than or equal to 5), principally located on the Island of Hawaii, from 1823 through the third quarter of 1959 is designed to expand our ability to evaluate seismic hazard in Hawaii, as well as our knowledge of Hawaiian seismic rhythms as they relate to eruption cycles at Kilauea and Mauna Loa volcanoes and to subcrustal earthquake patterns related to the tectonic evolution of the Hawaiian chain.

  18. Earthquake watch

    USGS Publications Warehouse

    Hill, M.

    1976-01-01

     When the time comes that earthquakes can be predicted accurately, what shall we do with the knowledge? This was the theme of a November 1975 conference on earthquake warning and response held in San Francisco called by Assistant Secretary of the Interior Jack W. Carlson. Invited were officials of State and local governments from Alaska, California, Hawaii, Idaho, Montana, Nevada, utah, Washington, and Wyoming and representatives of the news media. 

  19. Fault trends on the seaward slope of the Aleutian Trench: Implications for a laterally changing stress field tied to a westward increase in oblique convergence

    USGS Publications Warehouse

    Mortera-Gutierrez, C. A.; Scholl, D. W.; Carlson, R.L.

    2003-01-01

    Normal faults along the seaward trench slope (STS) commonly strike parallel to the trench in response to bending of the oceanic plate into the subduction zone. This is not the circumstance for the Aleutian Trench, where the direction of convergence gradually changes westward, from normal to transform motion. GLORIA side-scan sonar images document that the Aleutian STS is dominated by faults striking oblique to the trench, west of 179??E and east of 172??W. These images also show a pattern of east-west trending seafloor faults that are aligned parallel to the spreading fabric defined by magnetic anomalies. The stress-strain field along the STS is divided into two domains west and east, respectively, of 179??E. Over the western domain, STS faults and nodal planes of earthquakes are oriented oblique (9??-46??) to the trench axis and (69??-90??) to the magnetic fabric. West of 179??E, STS fault strikes change by 36?? from the E-W trend of STS where the trench-parallel slip gets larger than its orthogonal component of convergence. This rotation indicates that horizontal stresses along the western domain of the STS are deflected by the increasing obliquity in convergence. An analytical model supports the idea that strikes of STS faults result from a superposition of stresses associated with the dextral shear couple of the oblique convergence and stresses caused by plate bending. For the eastern domain, most nodal planes of earthquakes strike parallel to the outer rise, indicating bending as the prevailing mechanism causing normal faulting. East of 172??W, STS faults strike parallel to the magnetic fabric but oblique (10??-26??) to the axis of the trench. On the basis of a Coulomb failure criterion the trench-oblique strikes probably result from reactivation of crustal faults generated by spreading. Copyright 2003 by the American Geophysical Union.

  20. Insights into Magma Evolution in the Islands of the Four Mountains, Alaska

    NASA Astrophysics Data System (ADS)

    Fulton, A. A.; Izbekov, P. E.; Nicolaysen, K. P.

    2015-12-01

    The Islands of the Four Mountains (IFM) is a group of small volcanoes in the central region of Alaska's Aleutian island arc. There are few studies of this remote group of islands despite their rich archeological history and diverse eruptive histories. This study focuses on silicic deposits from the IFM to shed light on the area's history of large explosive eruptions and the IFM's chemical relationship to the rest of the central Aleutian Islands. This study applies whole rock geochemistry, detailed petrographic analysis, and electron microprobe analysis to samples of volcanic deposits from Tana, Cleveland, Carlisle, and Herbert volcanoes, including the first documented ignimbrite deposit in the IFM, found on northern Tana. The IFM lavas range from basaltic to dacitic and follow typical island arc and calc-alkaline chemical trends, providing evidence of high aqueous fluid input to the mantle wedge, as well as varying levels of influence from subducted sediments. Tana, the largest (~12 km2) and most siliceous of the IFM volcanoes, expresses anomalies in K and Rb concentrations that may aid in the refinement of the continental-oceanic crust boundary location along the Aleutian arc. Plagioclase phenocryst disequilibrium textures and compositions provide evidence of mixing and recharge in the IFM magma chambers. Multiple plagioclase phenocryst populations, euhedral pyroxene crystals in disequilibrium with the melt, and angular xenolithic clasts in the Tana ignimbrite suggest a rapid mixing and heating event that triggered its large explosive eruption during the Pleistocene.

  1. Observation and modelling of turbulent mixing in the Kuril and Aleutian Straits and impact of its 18.6-year period tidal cycle on ocean and climate

    NASA Astrophysics Data System (ADS)

    Yasuda, I.; Tanaka, Y.; Itoh, S.; Hasumi, H.; Komatsu, K.; Osafune, S.; Yagi, M.; Tanaka, T.; Kaneko, H.; Ikeya, T.; Konda, S.; Nishioka, J.; Nakatsuka, T.; Katsumata, K.; Tatebe, H.; Watanabe, Y.; Hiroe, Y.; Nakamura, T.

    2012-12-01

    Direct turbulent observations in the Kuril Straits and Aleutian Straits reveal that tide-induced strong vertical mixing corresponds to strong shear of combined diurnal tidal and/or mean currents and significantly modifies the water-mass and potential vorticity distribution. Bi-decadal variability synchronized with 18.6-year period moon-tidal cycle were found in various parts of the ocean and climate indices: water-mass variability in the subarctic North Pacific, especially near the strong diurnal tide regions as Kuril Straits and Aleutian Islands, and in long-term climate indices as Pacific Decadal Oscillation (PDO) and El-Nino and Southern Oscillation (ENSO) in proxy-reconstructed records. In low-frequency part of the PDO and SOI records, negative (positive)-PDO and positive (negative)-SOI tend to occur in the 4-6-th (10-12-th) year after the maximum diurnal tide, which is consistent with the climate model experiments with locally enhanced vertical mixing around Kuril Straits showing that tidal mixing and its variability could generate bi-decadal variability in ocean and climate. Ocean and climate model experiments with parameterized tidal mixing explain some of the water-mass modifications and bi-decadal variability of water-masses and climate.

  2. Loss estimation of Membramo earthquake

    NASA Astrophysics Data System (ADS)

    Damanik, R.; Sedayo, H.

    2016-05-01

    Papua Tectonics are dominated by the oblique collision of the Pacific plate along the north side of the island. A very high relative plate motions (i.e. 120 mm/year) between the Pacific and Papua-Australian Plates, gives this region a very high earthquake production rate, about twice as much as that of Sumatra, the western margin of Indonesia. Most of the seismicity occurring beneath the island of New Guinea is clustered near the Huon Peninsula, the Mamberamo region, and the Bird's Neck. At 04:41 local time(GMT+9), July 28th 2015, a large earthquake of Mw = 7.0 occurred at West Mamberamo Fault System. The earthquake focal mechanism are dominated by northwest-trending thrust mechanisms. GMPE and ATC vulnerability curve were used to estimate distribution of damage. Mean of estimated losses was caused by this earthquake is IDR78.6 billion. We estimated insurance loss will be only small portion in total general due to deductible.

  3. Evolution and petroleum geology of Amlia and Amukta intra-arc summit basins, Aleutian Ridge

    USGS Publications Warehouse

    Geist, E.L.; Childs, J. R.; Scholl, D. W.

    1987-01-01

    Amlia and Amukta Basins are the largest of many intra-arc basins formed in late Cenozoic time along the crest of the Aleutian Arc. Both basins are grabens filled with 2-5 km of arc-derived sediment. A complex system of normal faults deformed the basinal strata. Although initial deposits of late Micocene age may be non-marine in origin, by early Pliocene time, most of the basinfill consisted of pelagic and hemipelagic debris and terrigenous turbidite deposits derived from wavebase and subaerial erosion of the arc's crestal areas. Late Cenozoic volcanism along the arc commenced during or shortly after initial subsidence and greatly contributed to active deposition in Amlia and Amukta Basins. Two groups of normal faults occur: major boundary faults common to both basins and 'intra-basin' faults that arise primarily from arc-parallel extension of the arc. The most significant boundary fault, Amlia-Amukta fault, is a south-dipping growth fault striking parallel to the trend of the arc. Displacement across this fault forms a large half-graben that is separated into the two depocentres of Amlia and Amukta Basins by the formation of a late Cenozoic volcanic centre, Seguam Island. Faults of the second group reflect regional deformation of the arc and offset the basement floor as well as the overlying basinal section. Intra-basin faults in Amlia Basin are predominantly aligned normal to the trend of the arc, thereby indicating arc-parallel extension. Those in Amukta basin are aligned in multiple orientations and probably indicate a more complex mechanism of faulting. Displacement across intra-basin faults is attributed to tectonic subsidence of the massif, aided by depositional loading within the basins. In addition, most intra-basin faults are listric and are associated with high growth rates. Although, the hydrocarbon potential of Amlia and Amukta Basins is difficult to assess based on existing data, regional considerations imply that an adequate thermal history conducive

  4. Deep earthquakes

    SciTech Connect

    Frohlich, C.

    1989-01-01

    Earthquakes are often recorded at depths as great as 650 kilometers or more. These deep events mark regions where plates of the earth's surface are consumed in the mantle. But the earthquakes themselves present a conundrum: the high pressures and temperatures at such depths should keep rock from fracturing suddenly and generating a tremor. This paper reviews the research on this problem. Almost all deep earthquakes conform to the pattern described by Wadati, namely, they generally occur at the edge of a deep ocean and define an inclined zone extending from near the surface to a depth of 600 kilometers of more, known as the Wadati-Benioff zone. Several scenarios are described that were proposed to explain the fracturing and slipping of rocks at this depth.

  5. Amchitka Island, Alaska, special sampling project 1997

    SciTech Connect

    U.S. Department of Energy, Nevada Operations Office

    2000-06-28

    This 1997 special sampling project represents a special radiobiological sampling effort to augment the 1996 Long-Term Hydrological Monitoring Program (LTHMP) for Amchitka Island in Alaska. Lying in the western portion of the Aleutian Islands arc, near the International Date Line, Amchitka Island is one of the southernmost islands of the Rat Island Chain. Between 1965 and 1971, the U.S. Atomic Energy Commission conducted three underground nuclear tests on Amchitka Island. In 1996, Greenpeace collected biota samples and speculated that several long-lived, man-made radionuclides detected (i.e., americium-241, plutonium-239 and -240, beryllium-7, and cesium-137) leaked into the surface environment from underground cavities created during the testing. The nuclides of interest are detected at extremely low concentrations throughout the environment. The objectives of this special sampling project were to scientifically refute the Greenpeace conclusions that the underground cavities were leaking contaminants to the surface. This was achieved by first confirming the presence of these radionuclides in the Amchitka Island surface environment and, second, if the radionuclides were present, determining if the source is the underground cavity or worldwide fallout. This special sampling and analysis determined that the only nonfallout-related radionuclide detected was a low level of tritium from the Long Shot test, which had been previously documented. The tritium contamination is monitored and continues a decreasing trend due to radioactive decay and dilution.

  6. Heat Islands

    EPA Pesticide Factsheets

    EPA's Heat Island Effect Site provides information on heat islands, their impacts, mitigation strategies, related research, a directory of heat island reduction initiatives in U.S. communities, and EPA's Heat Island Reduction Program.

  7. Searching for Seismic Signatures of a Plume Source at the Base of the Mantle Below the Galapagos Island Hotspot

    NASA Astrophysics Data System (ADS)

    Vanacore, E.; Niu, F.

    2007-12-01

    This study analyzes SKS and SKKS waveforms recorded on the BOLIVAR array in Venezuela and the BANJO array in South America from earthquake sources located in Tonga and Alaska regions to characterize the lower mantle beneath the Galapagos Islands. The data analysis applies two independent methods, residual differential SKKS-SKS travel times and anisotropy measurements, to examine the historically unsampled region. The residual differential travel time observations were performed using 21 earthquakes from the Tonga trench with magnitudes greater than 5.5 Mw that were recorded on the Bolivar array. Only data that was deemed to have a high SNR for both the SKS and SKKS phases were retained for analysis. Significant positive values of differential travel time that indicate low velocity along the SKKS raypaths are detected east of ~\\m270° longitude. The anisotropy data set consists of 31 intermediate and deep focus earthquakes from the Tonga and Aleutian trenches recorded on the BOLIVAR and BANJO arrays respectively. The anisotropy fast axis angle and time lag of the two phases are calculated using the 1-layer cross-convolution method of Menke and Levin (2003) with a maximum time lag window of 3 seconds. We retain results with an amplitude normalized squared L2 norm value of 0.6 or less for analysis. Because the raypaths of the SKS and SKKS phases are similar in the upper mantle and sample different regions of the lower mantle, we attribute inconsistencies between the two anisotropy to difference of the mantle structure near the CMB. We define significant difference in the azimuth of the fast axis as any difference between the SKSac and SKKSac measurements greater than 15 degrees. The dataset is dominated by inconsistent fast axis azimuth measurements between the SKSac and SKKSac phases, but does not isolate a single geographic region. Comparison of the splitting time measurements yields that inconsistency between the two phases is more significant, greater than 0.5 s

  8. Buldir Depression - A Late Tertiary graben on the Aleutian Ridge, Alaska

    USGS Publications Warehouse

    Marlow, M. S.; Scholl, D. W.; Buffington, E.C.; Boyce, R.E.; Alpha, T.R.; Smith, P.J.; Shipek, C.J.

    1970-01-01

    Buldir Depression is a large, rectilinear basin that lies on the northern edge of the Aleutian Ridge and is aligned with the arcuate chain of active volcanoes on the ridge crest. The depression appears to be a volcanic-tectonic feature, which began to form in Late Tertiary time and which is still forming. It is a graben formed by extensional rifting and accompanied by contemporaneous volcanism on the Aleutian Ridge. Subsidence rates for the depression are estimated at 20-70 cm/1,000 years. Sediments in the depression are 300 m thick and are probably pelagic and turbidite deposits of Pleistocene age. The turbidites were apparently derived from the plateau area of the Aleutian Ridge surrounding the depression. Older sediments on the northern slope of the Aleutian Ridge have a maximum thickness of 550 m and are deformed and slumped toward the Bering Sea. These sediments are postulated to overlie a mid-flank terrace on the northern Aleutian Ridge that titled to the north during the formation of Buldir Depression. ?? 1970.

  9. Demonstration of heavy and light density populations of Aleutian disease virus.

    PubMed Central

    Cho, H J

    1977-01-01

    A highly purified and concentrated suspension of aleutian disease virus was prepared from large quantities of early infected mink tissues using repeated fluorocarbon extraction procedures. Equilibrium centrifugation of the aleutian disease virus preparation in a cesium chloride gradient yielded three distinct bands at buoyant densities of 1.295, 1.332, and 1.405--1.416 g/cm(3). Electron microscopic observations of these three bands revealed mainly empty particles in the first band. In the second band complete particles with a flattened appearnce predominated and there were also some empty particles. In the third band both complete and empty particles were observed. The size of the aleutian disease virus particles observed in all of the three densities was 23 nm. Light aleutian disease virions (density of 1.332 g/cm3) had a particle to counterimmunoelectrophoresis antigen ratio comparable to that of dense aleutian disease virions (density of 1.405--1.416 g/cm3) but possessed much lower infectivity as determined by mink inoculation. Images Fig. 1. Fig. 2. PMID:193625

  10. Time-predictable recurrence model for large earthquakes

    SciTech Connect

    Shimazaki, K.; Nakata, T.

    1980-04-01

    We present historical and geomorphological evidence of a regularity in earthquake recurrence at three different sites of plate convergence around the Japan arcs. The regularity shows that the larger an earthquake is, the longer is the following quiet period. In other words, the time interval between two successive large earthquakes is approximately proportional to the amount of coseismic displacement of the preceding earthquake and not of the following earthquake. The regularity enables us, in principle, to predict the approximate occurrence time of earthquakes. The data set includes 1) a historical document describing repeated measurements of water depth at Murotsu near the focal region of Nankaido earthquakes, 2) precise levelling and /sup 14/C dating of Holocene uplifted terraces in the southern boso peninsula facing the Sagami trough, and 3) similar geomorphological data on exposed Holocene coral reefs in Kikai Island along the Ryukyu arc.

  11. Microscopic analysis of feather and hair fragments associated with human mummified remains from Kagamil Island, Alaska

    USGS Publications Warehouse

    Dove, C.J.; Peurach, S.C.; Frohlich, Bruno; Harper, Albert B.; Gilberg, Rolf

    2002-01-01

    Human mummified remains of 34 different infant and adult individuals from Kagamil Island, Alaska, are accessioned in the Department of Anthropology, National Museum of Natural History, Smithsonian Institution. Kagamil Island is one of the small islands in the Island of Four Mountains group of the Aleutian Islands, Alaska and is well known for the mummy caves located on the southwest coast of the island. The Kagamil mummy holdings at the Smithsonian represent one of the largest, best documented and preserved collections of this type. Although these specimens are stored in ideal conditions, many small feather and hair fragments have become loose or disassociated from the actual mummies over the years. This preliminary investigation of fragmentary fiber material retrieved from these artifacts is the first attempt to identify bird and mammal species associated with the mummified remains of the Kagamil Island, Alaska collection and is part of the ongoing research connected with these artifacts.

  12. Earthquake engineering research: 1982

    NASA Astrophysics Data System (ADS)

    The Committee on Earthquake Engineering Research addressed two questions: What progress has research produced in earthquake engineering and which elements of the problem should future earthquake engineering pursue. It examined and reported in separate chapters of the report: Applications of Past Research, Assessment of Earthquake Hazard, Earthquake Ground Motion, Soil Mechanics and Earth Structures, Analytical and Experimental Structural Dynamics, Earthquake Design of Structures, Seismic Interaction of Structures and Fluids, Social and Economic Aspects, Earthquake Engineering Education, Research in Japan.

  13. Earthquake Testing

    NASA Technical Reports Server (NTRS)

    1979-01-01

    During NASA's Apollo program, it was necessary to subject the mammoth Saturn V launch vehicle to extremely forceful vibrations to assure the moonbooster's structural integrity in flight. Marshall Space Flight Center assigned vibration testing to a contractor, the Scientific Services and Systems Group of Wyle Laboratories, Norco, California. Wyle-3S, as the group is known, built a large facility at Huntsville, Alabama, and equipped it with an enormously forceful shock and vibration system to simulate the liftoff stresses the Saturn V would encounter. Saturn V is no longer in service, but Wyle-3S has found spinoff utility for its vibration facility. It is now being used to simulate earthquake effects on various kinds of equipment, principally equipment intended for use in nuclear power generation. Government regulations require that such equipment demonstrate its ability to survive earthquake conditions. In upper left photo, Wyle3S is preparing to conduct an earthquake test on a 25ton diesel generator built by Atlas Polar Company, Ltd., Toronto, Canada, for emergency use in a Canadian nuclear power plant. Being readied for test in the lower left photo is a large circuit breaker to be used by Duke Power Company, Charlotte, North Carolina. Electro-hydraulic and electro-dynamic shakers in and around the pit simulate earthquake forces.

  14. Clinical Chemical Studies in Aleutian Disease of Mink

    PubMed Central

    Gershbein, Leon L.; Spencer, Kathryn L.

    1964-01-01

    Clinical chemical determinations were carried out on blood removed by cardiac puncture from 49 mink affected with Aleutian disease and 25 normal animals and the respective differences tested for statistical significance. Blood urea nitrogen, serum total protein and globulin, thymol turbidity, glutamic oxalacetic and glutamic pyruvic transaminases and amylase were definitely elevated in the affected animals whereas serum calcium, albumin and A/G ratio were depressed. No statistically significant difference was apparent between the two groups in the comparison of inorganic phosphorus, alkaline and acid phosphatases, bilirubin, total cholesterol and esters, cephalin-cholesterol flocculation (3+ in each case), sodium, potassium, chloride, CO2-combining power, leucine aminopeptidase and lactic dehydrogenase (means: over 2,000 u./ml.). For both the control and affected mink, the distribution of serum lactic dehydrogenase isozymes resembled that of human homologous serum hepatitis. Electrophoresis of serum proteins confirmed earlier findings of hypergammaglobulinemia in the diseased animals but a fast-moving or pre-albumin component, averaging 4% of the total protein, occurred in both the diseased and normal mink. ImagesFigure 1. PMID:17649484

  15. Earthquake tectonics

    SciTech Connect

    Steward, R.F. )

    1991-02-01

    Earthquakes release a tremendous amount of energy into the subsurface in the form of seismic waves. The seismic wave energy of the San Francisco 1906 (M = 8.2) earthquake was equivalent to over 8 billion tons of TNT (3.3 {times} 10{sup 19} joules). Four basic wave types are propagated form seismic sources, two non-rotational and two rotational. As opposed to the non-rotational R and SH waves, the rotational compressional (RC) and rotational shear (RS) waves carry the bulk of the energy from a seismic source. RC wavefronts propagate in the subsurface and refract similarly to P waves, but are considerably slower. RC waves are critically refracted beneath the air surface interface at velocities less than the velocity of sound in air because they refract at the velocity of sound in air minus the retrograde particle velocity at the top of the wave. They propagate at tsunami waves in the open ocean, and produce loud sounds on land that are heard by humans and animals during earthquakes. The energy of the RS wave dwarfs that of the P, SH, and even the RC wave. The RS wave is the same as what is currently called the S wave in earthquake seismology, and produces both folding and strike-slip faulting at considerable distances from the epicenter. RC and RS waves, propagated during earthquakes from the Santa Ynez fault and a right-slip fault on trend with the Red Mountain fault, produced the Santa Ynez Mountains in California beginning in the middle Pliocene and continuing until the present.

  16. New earthquake catalog reexamines Hawaii's seismic history

    USGS Publications Warehouse

    Wright, Thomas L.; Klein, Fred W.

    2000-01-01

    On April 2,1868, an earthquake of magnitude 7.9 occurred beneath the southern part of the island of Hawaii. The quake, which was felt throughout all of the Hawaiian Islands, had a Modified Mercalli (MM) intensity of XII near its source.The destruction caused by a quake that large is nearly complete. A landslide triggered by the quake buried a small village, killing 31 people, and a tsunami that swept over coastal settlements added to the death toll. We know as much as we do about this and other early earthquakes thanks to detailed records kept by Hawaiian missionaries, including the remarkable diary maintained by the Lyman family that documented every earthquake felt at their home in Hilo between 1833 and 1917 [Wyss et al., 1992].Our analysis of these and other historical records indicates that Hawaii was at least as intensely seismic in the 19th century and first half of the 20th century as in its more recent past, with 26 M ≥6.0 earthquakes occurring from 1823 to 1903 and 20 M ≥6.0 earthquakes from 1904 to 1959. Just five M ≥6.0 earthquakes occurred from 1960 to 1999. The potential damage caused by a repeat of some of the larger historic events could be catastrophic today.

  17. Queen Charlotte 2001 Earthquake Aftershock Sequence

    NASA Astrophysics Data System (ADS)

    Mulder, T.; Rogers, G. C.

    2012-12-01

    On Oct 12, 2001, an Mw=6.3 earthquake occurred off the Queen Charlotte Islands, BC. It was felt throughout Haida Gwaii (Queen Charlotte Islands) and the adjoining mainland. It generated a small tsunami recorded on Vancouver Island tide gauges. Moment tensor solutions show almost pure thrust faulting. There was a significant aftershock sequence associated with this event. Relocation of the catalogue aftershock sequence with respect to a key calibration event with various subsets of common stations show significant movement in the event locations. The aftershocks define an ~30 degree dipping fault plane.

  18. Patterns of growth and body condition in sea otters from the Aleutian archipelago before and after the recent population decline

    USGS Publications Warehouse

    Laidre, K.L.; Estes, J.A.; Tinker, M.T.; Bodkin, J.; Monson, D.; Schneider, K.

    2006-01-01

    3In addition to larger asymptotic values for mass and length, the rate of growth towards asymptotic values was more rapid in the 1990s than in the 1960s/70s: sea otters reached 95% of asymptotic body mass and body length 1–2 years earlier in the 1990s.4Body condition (as measured by the log mass/log length ratio) was significantly greater in males than in females. There was also an increasing trend from the 1960s/70s through 2004 despite much year-to-year variation.5Population age structures differed significantly between the 1960s/70s and the 1990s with the latter distribution skewed toward younger age classes (indicating an altered lxfunction) suggesting almost complete relaxation of age-dependent mortality patterns (i.e. those typical of food-limited populations).6This study spanned a period of time over which the population status of sea otters in the Aleutian archipelago declined precipitously from levels at or near equilibrium densities at some islands in the 1960s/70s to < 5% of estimated carrying capacity by the late 1990s. The results of this study indicate an improved overall health of sea otters over the period of decline and suggest that limited nutritional resources were not the cause of the observed reduced population abundance. Our findings are consistent with the hypothesis that the decline was caused by increased killer whale predation.

  19. Alaskan Stream Circulation and Exchanges through the Aleutian Island Passes: 1979-2003 Model Results

    DTIC Science & Technology

    2006-03-01

    only accessible waterways into the Bering Sea from the North Pacific, might become a major thoroughfare for countries such as North 6 Korea, India ...balancing the northward volume transport through the Bering Sea. The model bathymetry was derived from both the International Bathymetric Chart of the

  20. 50 CFR Table 23 to Part 679 - Aleutian Islands Coral Habitat Protection Areas

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 53.11 E 51 53.10 N 179 46.55 E 51 48.84 N 179 46.55 E 51 48.89 N 179 53.11 E Note: Each area is... Areas 23 Table 23 to Part 679 Wildlife and Fisheries FISHERY CONSERVATION AND MANAGEMENT, NATIONAL... Areas Area No. Name Latitude Longitude 1 Great Sitkin I 52 9.56 N 176 6.14 W 52 9.56 N 176 12.44 W 52...

  1. 50 CFR 600.1103 - Bering Sea and Aleutian Islands (BSAI) Crab species program.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... harvest of crab, from each reduction endorsement fishery and from the Norton Sound fishery during the most... more reduction endorsement fisheries, regardless of whether it is also endorsed for the Norton Sound... history of the bidder's -reduction/history vessel. Norton Sound fishery means the non-reduction...

  2. 50 CFR 600.1103 - Bering Sea and Aleutian Islands (BSAI) Crab species program.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... harvest of crab, from each reduction endorsement fishery and from the Norton Sound fishery during the most... more reduction endorsement fisheries, regardless of whether it is also endorsed for the Norton Sound... history of the bidder's -reduction/history vessel. Norton Sound fishery means the non-reduction...

  3. 50 CFR Figure 1 to Part 679 - Bering Sea and Aleutian Islands Statistical and Reporting Areas

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    .... Those waters inside the Russian 200 mile limit as described in the current editions of NOAA chart INT 813 Bering Sea (Southern Part) and NOAA chart INT 814 Bering Sea (Northern Part). 400 Chukchi Sea... edition of NOAA chart INT 814 Bering Sea (Northern Part). 508 South of 58°00′ N between the...

  4. 50 CFR Figure 1 to Part 679 - Bering Sea and Aleutian Islands Statistical and Reporting Areas

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    .... Those waters inside the Russian 200 mile limit as described in the current editions of NOAA chart INT 813 Bering Sea (Southern Part) and NOAA chart INT 814 Bering Sea (Northern Part). 400 Chukchi Sea... edition of NOAA chart INT 814 Bering Sea (Northern Part). 508 South of 58°00′ N between the...

  5. 50 CFR Figure 1 to Part 679 - Bering Sea and Aleutian Islands Statistical and Reporting Areas

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    .... Those waters inside the Russian 200 mile limit as described in the current editions of NOAA chart INT 813 Bering Sea (Southern Part) and NOAA chart INT 814 Bering Sea (Northern Part). 400 Chukchi Sea... edition of NOAA chart INT 814 Bering Sea (Northern Part). 508 South of 58°00′ N between the...

  6. 50 CFR Figure 1 to Part 679 - Bering Sea and Aleutian Islands Statistical and Reporting Areas

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    .... Those waters inside the Russian 200 mile limit as described in the current editions of NOAA chart INT 813 Bering Sea (Southern Part) and NOAA chart INT 814 Bering Sea (Northern Part). 400 Chukchi Sea... edition of NOAA chart INT 814 Bering Sea (Northern Part). 508 South of 58°00′ N between the...

  7. 50 CFR Figure 1 to Part 679 - Bering Sea and Aleutian Islands Statistical and Reporting Areas

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    .... Those waters inside the Russian 200 mile limit as described in the current editions of NOAA chart INT 813 Bering Sea (Southern Part) and NOAA chart INT 814 Bering Sea (Northern Part). 400 Chukchi Sea... edition of NOAA chart INT 814 Bering Sea (Northern Part). 508 South of 58°00′ N between the...

  8. Connecting slow earthquakes to huge earthquakes.

    PubMed

    Obara, Kazushige; Kato, Aitaro

    2016-07-15

    Slow earthquakes are characterized by a wide spectrum of fault slip behaviors and seismic radiation patterns that differ from those of traditional earthquakes. However, slow earthquakes and huge megathrust earthquakes can have common slip mechanisms and are located in neighboring regions of the seismogenic zone. The frequent occurrence of slow earthquakes may help to reveal the physics underlying megathrust events as useful analogs. Slow earthquakes may function as stress meters because of their high sensitivity to stress changes in the seismogenic zone. Episodic stress transfer to megathrust source faults leads to an increased probability of triggering huge earthquakes if the adjacent locked region is critically loaded. Careful and precise monitoring of slow earthquakes may provide new information on the likelihood of impending huge earthquakes.

  9. Volcanic earthquake swarms at Mt. Erebus, Antarctica

    NASA Astrophysics Data System (ADS)

    Kaminuma, Katsutada; Ueki, Sadato; Juergen, Kienle

    1985-04-01

    Mount Erebus is an active volcano in Antarctica located on Ross Island. A convecting lava lake occupies the summit crater of Mt. Erebus. Since December 1980 the seismic activity of Mt. Erebus has been continuously monitored using a radio-telemetered network of six seismic stations. The seismic activity observed by the Ross Island network during the 1982-1983 field season shows that: (1)Strombolian eruptions occur frequently at the Erebus summit lava lake at rates of 2-5 per day; (2)centrally located earthquakes map out a nearly vertical, narrow conduit system beneath the lava lake; (3)there are other source regions of seismicity on Ross Island, well removed from Mt. Erebus proper. An intense earthquake swarm recorded in October 1982 near Abbott Peak, 10 km northwest of the summit of Mt. Erebus, and volcanic tremor accompanying the swarm, may have been associated with new dike emplacement at depth.

  10. Mink Farms Predict Aleutian Disease Exposure in Wild American Mink

    PubMed Central

    Nituch, Larissa A.; Bowman, Jeff; Beauclerc, Kaela B.; Schulte-Hostedde, Albrecht I.

    2011-01-01

    Background Infectious diseases can often be of conservation importance for wildlife. Spillover, when infectious disease is transmitted from a reservoir population to sympatric wildlife, is a particular threat. American mink (Neovison vison) populations across Canada appear to be declining, but factors thus far explored have not fully explained this population trend. Recent research has shown, however, that domestic mink are escaping from mink farms and hybridizing with wild mink. Domestic mink may also be spreading Aleutian disease (AD), a highly pathogenic parvovirus prevalent in mink farms, to wild mink populations. AD could reduce fitness in wild mink by reducing both the productivity of adult females and survivorship of juveniles and adults. Methods To assess the seroprevalence and geographic distribution of AD infection in free-ranging mink in relation to the presence of mink farms, we conducted both a large-scale serological survey, across the province of Ontario, and a smaller-scale survey, at the interface between a mink farm and wild mink. Conclusions/Significance Antibodies to AD were detected in 29% of mink (60 of 208 mink sampled); however, seroprevalence was significantly higher in areas closer to mink farms than in areas farther from farms, at both large and small spatial scales. Our results indicate that mink farms act as sources of AD transmission to the wild. As such, it is likely that wild mink across North America may be experiencing increased exposure to AD, via disease transmission from mink farms, which may be affecting wild mink demographics across their range. In light of declining mink populations, high AD seroprevalence within some mink farms, and the large number of mink farms situated across North America, improved biosecurity measures on farms are warranted to prevent continued disease transmission at the interface between mink farms and wild mink populations. PMID:21789177

  11. Identifying active structures in the Kayak Island and Pamplona Zones: Implications for offshore tectonics of the Yakutat Microplate, Gulf of Alaska

    NASA Astrophysics Data System (ADS)

    Worthington, Lindsay L.; Gulick, Sean P. S.; Pavlis, Terry L.

    Within the northern Gulf of Alaska, the Yakutat (YAK) microplate obliquely collides with and subducts beneath the North American (NA) continent at near-Pacific plate velocities. We investigate the extent that thin-skinned deformation on offshore structures located within the western portion of the unsubducted YAK block accommodates YAK-NA convergence. We compare faulting and folding observed on high-resolution and basin-scale multichannel seismic (MCS) reflection data with earthquake locations and surface ruptures observed on high-resolution bathymetric data. Holocene sediments overlying the Kayak Island fault zone (KIZ), previously interpreted as a region of active contraction, are relatively flat-lying, suggesting that active convergence within the KIZ is waning. Seismic reflection profiles east of KIZ show up to ˜200 m of undisturbed sediments overlying older folds in the Bering Trough, indicating that this area has been tectonically inactive since at least the last ˜1.3 Ma. Farther east, MCS profiles image active deformation in surface sediments along the eastern edge of the Pamplona zone (PZ) fold-and-thrust belt, that are collocated with a concentration of earthquake events that continues southwest to Khitrov Ridge and onshore through Icy Bay. These observations suggest that during the late Quaternary offshore shallow deformation style changed from distributed across the western Yakutat block to localized at the eastern edge of the PZ with extrusion of sediments southwest through the Khitrov Ridge area to the Aleutian Trench. This shallow deformation is interpreted as deformation of an accretionary complex above a shallow decollement.

  12. Modelling guided waves in the Alaskan-Aleutian subduction zone

    NASA Astrophysics Data System (ADS)

    Coulson, Sophie; Garth, Thomas; Reitbrock, Andreas

    2016-04-01

    Subduction zone guided wave arrivals from intermediate depth earthquakes (70-300 km depth) have a huge potential to tell us about the velocity structure of the subducting oceanic crust as it dehydrates at these depths. We see guided waves as the oceanic crust has a slower seismic velocity than the surrounding material, and so high frequency energy is retained and delayed in the crustal material. Lower frequency energy is not retained in this crustal waveguide and so travels at faster velocities of the surrounding material. This gives a unique observation at the surface with low frequency energy arriving before the higher frequencies. We constrain this guided wave dispersion by comparing the waveforms recorded in real subduction zones with simulated waveforms, produced using finite difference full waveform modelling techniques. This method has been used to show that hydrated minerals in the oceanic crust persist to much greater depths than accepted thermal petrological subduction zone models would suggest in Northern Japan (Garth & Rietbrock, 2014a), and South America (Garth & Rietbrock, in prep). These observations also suggest that the subducting oceanic mantle may be highly hydrated at intermediate depth by dipping normal faults (Garth & Rietbrock 2014b). We use this guided wave analysis technique to constrain the velocity structure of the down going ~45 Ma Pacific plate beneath Alaska. Dispersion analysis is primarily carried out on guided wave arrivals recorded on the Alaskan regional seismic network. Earthquake locations from global earthquake catalogues (ISC and PDE) and regional earthquake locations from the AEIC (Alaskan Earthquake Information Centre) catalogue are used to constrain the slab geometry and to identify potentially dispersive events. Dispersed arrivals are seen at stations close to the trench, with high frequency (>2 Hz) arrivals delayed by 2 - 4 seconds. This dispersion is analysed to constrain the velocity and width of the proposed waveguide

  13. Comment on "Ultra low frequency (ULF) electromagnetic anomalies associated with large earthquakes in Java Island, Indonesia by using wavelet transform and detrended fluctuation analysis" by Febriani et al. (2014)

    NASA Astrophysics Data System (ADS)

    Masci, F.; Thomas, J. N.

    2015-12-01

    We examine the recent report of Febriani et al. (2014) in which the authors show changes in ULF magnetic field data prior to the M7.5 Tasikmalaya earthquake that occurred south of Java, Indonesia, on 2 September 2009. Febriani et al. (2014) state that the magnetic changes they found may be related to the impending earthquake. We do not agree that the pre-earthquake magnetic changes shown in Febriani et al. (2014) are seismogenic. These magnetic changes, indeed, are too closely related to global geomagnetic disturbances to be regarded as being of seismic origin.

  14. The surface latent heat flux anomalies related to major earthquake

    NASA Astrophysics Data System (ADS)

    Jing, Feng; Shen, Xuhui; Kang, Chunli; Xiong, Pan; Hong, Shunying

    2011-12-01

    SLHF (Surface Latent Heat Flux) is an atmospheric parameter, which can describe the heat released by phase changes and dependent on meteorological parameters such as surface temperature, relative humidity, wind speed etc. There is a sharp difference between the ocean surface and the land surface. Recently, many studies related to the SLHF anomalies prior to earthquakes have been developed. It has been shown that the energy exchange enhanced between coastal surface and atmosphere prior to earthquakes can increase the rate of the water-heat exchange, which will lead to an obviously increases in SLHF. In this paper, two earthquakes in 2010 (Haiti earthquake and southwest of Sumatra in Indonesia earthquake) have been analyzed using SLHF data by STD (standard deviation) threshold method. It is shows that the SLHF anomaly may occur in interpolate earthquakes or intraplate earthquakes and coastal earthquakes or island earthquakes. And the SLHF anomalies usually appear 5-6 days prior to an earthquake, then disappear quickly after the event. The process of anomaly evolution to a certain extent reflects a dynamic energy change process about earthquake preparation, that is, weak-strong-weak-disappeared.

  15. Defeating Earthquakes

    NASA Astrophysics Data System (ADS)

    Stein, R. S.

    2012-12-01

    The 2004 M=9.2 Sumatra earthquake claimed what seemed an unfathomable 228,000 lives, although because of its size, we could at least assure ourselves that it was an extremely rare event. But in the short space of 8 years, the Sumatra quake no longer looks like an anomaly, and it is no longer even the worst disaster of the Century: 80,000 deaths in the 2005 M=7.6 Pakistan quake; 88,000 deaths in the 2008 M=7.9 Wenchuan, China quake; 316,000 deaths in the M=7.0 Haiti, quake. In each case, poor design and construction were unable to withstand the ferocity of the shaken earth. And this was compounded by inadequate rescue, medical care, and shelter. How could the toll continue to mount despite the advances in our understanding of quake risk? The world's population is flowing into megacities, and many of these migration magnets lie astride the plate boundaries. Caught between these opposing demographic and seismic forces are 50 cities of at least 3 million people threatened by large earthquakes, the targets of chance. What we know for certain is that no one will take protective measures unless they are convinced they are at risk. Furnishing that knowledge is the animating principle of the Global Earthquake Model, launched in 2009. At the very least, everyone should be able to learn what his or her risk is. At the very least, our community owes the world an estimate of that risk. So, first and foremost, GEM seeks to raise quake risk awareness. We have no illusions that maps or models raise awareness; instead, earthquakes do. But when a quake strikes, people need a credible place to go to answer the question, how vulnerable am I, and what can I do about it? The Global Earthquake Model is being built with GEM's new open source engine, OpenQuake. GEM is also assembling the global data sets without which we will never improve our understanding of where, how large, and how frequently earthquakes will strike, what impacts they will have, and how those impacts can be lessened by

  16. Molecular cloning of the Aleutian disease virus genome: expression of Aleutian disease virus antigens by a recombinant plasmid.

    PubMed Central

    Mayer, L W; Aasted, B; Garon, C F; Bloom, M E

    1983-01-01

    Three nonoverlapping segments representing approximately 80% of the 4.8-kilobase pair Aleutian disease virus (ADV-G) duplex genome were molecularly cloned into either bacteriophage M13mp9 (M13bm2 = 0.07 to 0.15 map unit; M13bm1 = 0.15 to 0.54 map unit) or plasmid pUC8 (pBM1 = 0.54 to 0.88 map units). In addition the 0.54- to 0.88-map unit segment of a Danish isolate of ADV (DK ADV) was also cloned into pUC8 (pBM2). The recombinant plasmids pBM1 and pBM2 induced expression of several polypeptides in Escherichia coli JM103 that were specifically recognized by sera from mink infected with ADV. The same three proteins with approximate molecular weights of 55,000, 34,000, and 27,000 were detected both by immune blotting and by immunoprecipitation of [35S]methionine-labeled JM103 (pBM1). None of these proteins were recognized in JM103 or JM103 (pUC8), nor were they detected by sera from normal mink. Purified pBM1 and pBM2 DNA appeared identical in size by gel analysis and contour length measurement, and electron microscopic heteroduplex mapping revealed no visible areas of heterology. However, restriction endonuclease mapping showed that pBM2 was different from pBM1, indicating that this segment of the ADV genome was similar but not identical for two strains of ADV (ADV-G and DK ADV). Furthermore, when cloned DNA from ADV-G was labeled with [32P]dCTP by nick translation, DNA relatedness to several field strains of ADV (Utah I, Pullman, and DK), but not to mink enteritis virus or cellular DNA, was shown by Southern blot hybridization. Images PMID:6313959

  17. The Nankai Trough earthquake tsunamis in Korea: numerical studies of the 1707 Hoei earthquake and physics-based scenarios

    NASA Astrophysics Data System (ADS)

    Kim, SatByul; Saito, Tatsuhiko; Fukuyama, Eiichi; Kang, Tae-Seob

    2016-04-01

    Historical documents in Korea and China report abnormal waves in the sea and rivers close to the date of the 1707 Hoei earthquake, which occurred in the Nankai Trough, off southwestern Japan. This indicates that the tsunami caused by the Hoei earthquake might have reached Korea and China, which suggests a potential hazard in Korea from large earthquakes in the Nankai Trough. We conducted tsunami simulations to study the details of tsunamis in Korea caused by large earthquakes. Our results showed that the Hoei earthquake (Mw 8.8) tsunami reached the Korean Peninsula about 200 min after the earthquake occurred. The maximum tsunami height was ~0.5 m along the Korean coast. The model of the Hoei earthquake predicted a long-lasting tsunami whose highest peak arrived 600 min later after the first arrival near the coastline of Jeju Island. In addition, we conducted tsunami simulations using physics-based scenarios of anticipated earthquakes in the Nankai subduction zone. The maximum tsunami height in the scenarios (Mw 8.5-8.6) was ~0.4 m along the Korean coast. As a simple evaluation of larger possible tsunamis, we increased the amount of stress released by the earthquake by a factor of two and three, resulting in scenarios for Mw 8.8 and 8.9 earthquakes, respectively. The tsunami height increased by 0.1-0.4 m compared to that estimated by the Hoei earthquake.

  18. Mercury and other metals in eggs and feathers of glaucous-winged gulls (Larus glaucescens) in the Aleutians

    PubMed Central

    Gochfeld, Michael; Jeitner, Christian; Burke, Sean; Volz, Conrad D.; Snigaroff, Ronald; Snigaroff, Daniel; Shukla, Tara; Shukla, Sheila

    2014-01-01

    Levels of mercury and other contaminants should be lower in birds nesting on isolated oceanic islands and at high latitudes without any local or regional sources of contamination, compared to more urban and industrialized temperate regions. We examined concentrations of arsenic, cadmium, chromium, lead, manganese, mercury and selenium in the eggs, and the feathers of fledgling and adult glaucous-winged gulls (Larus glaucescens) nesting in breeding colonies on Adak, Amchitka, and Kiska Islands in the Aleutian Chain of Alaska in the Bering Sea/North Pacific. We tested the following null hypotheses: 1) There were no differences in metal levels among eggs and feathers of adult and fledgling glaucous-winged gulls, 2) There were no differences in metal levels among gulls nesting near the three underground nuclear test sites (Long Shot 1965, Milrow 1969, Cannikin 1971) on Amchitka, 3) There were no differences in metal levels among the three islands, and 4) There were no gender-related differences in metal levels. All four null hypotheses were rejected at the 0.05 level, although there were few differences among the three test sites on Amchitka. Eggs had the lowest levels of cadmium, lead, and mercury, and the feathers of adults had the lowest levels of selenium. Comparing only adults and fledglings, adults had higher levels of cadmium, chromium, lead and mercury, and fledglings had higher levels of arsenic, manganese and selenium. There were few consistent interisland differences, although levels were generally lower for eggs and feathers from gulls on Amchitka compared to the other islands. Arsenic was higher in both adult feathers and eggs from Amchitka compared to Adak, and chromium and lead were higher in adult feathers and eggs from Adak compared to Amchitka. Mercury and arsenic, and chromium and manganese levels were significantly correlated in the feathers of both adult and fledgling gulls. The feathers of males had significantly higher levels of chromium and

  19. The use of biota sampling for environmental contaminant analysis for characterization of benthic communities in the Aleutians.

    PubMed

    Burger, Joanna; Jewett, Stephen; Gochfeld, Michael; Hoberg, Max; Harper, Shawn; Chenelot, Heloise; Jeitner, Christian; Burke, Sean

    2006-10-01

    It is increasingly clear that the public, native tribes, and governmental agencies are interested in assessing the well-being of natural resources and ecosystems. This may take the form of understanding species presence, monitoring population status and trends, measuring behavior, or quantifying physiology, biological stresses, or chemical/radiological exposure through biomarkers. Often there is a separation between understanding the biological aspects of species well-being and assessing exposure to contaminants. In this paper we examine the applicability of using scuba sampling aimed primarily at specimen collection for radionuclide analysis to assess species presence/absence and to compare among sampling sites and depths. We were especially interested in whether dive transects could provide information on species presence and potential exposure to environmental contaminants. In June/July 2004 we sampled at 49 depth stations along 19 transects at Amchitka and Kiska Islands in the western Aleutian Islands in the Northern Pacific/Bering Sea region. Amchitka Island, a former World War II U.S. Navy base, was the site of three underground nuclear test shots from 1965 to 1971. Four to six transects were established at three Amchitka sites and two Kiska Sites, and 2 to 4 stations were sampled on each transect. Bottom conditions, weather and currents prevented a complete sampling of all stations. There were interspecific differences in the percent of stations where biota were found and collected, in their occurrence near the three test shots on Amchitka, and in the depth where they were found. There were no significant differences between Amchitka and Kiska Island in the percent of stations where species were found. These data suggest that information gathered incidentally to the collection of specimens for chemical/radiological analysis can prove useful for understanding the presence of benthic organisms along particular transects, at given depths, and at different

  20. Imperial Japanese Navy Campaign Planning and Design of the Aleutian-Midway Campaign

    DTIC Science & Technology

    2013-05-23

    campaign was to achieve. iii ACKNOWLEDGMENTS I would like to thank Dr . William J. Gregor and COL James E. Barren who provided the motivation...Title: Imperial Japanese Navy Campaign Planning and Design of the Aleutian-Midway Campaign Approved by: , Monograph Director William J. Gregor

  1. Presumed drowning of Aleutian Canada geese on the Pacific coast of California and Oregon

    USGS Publications Warehouse

    Springer, P.F.; Lowe, R.W.; Stroud, R.K.; Gullett, Patricia A.

    1989-01-01

    Carcasses of 42 and 17 Aleutian Canada geese (Branta canadensis leucopareia), a federally listed endangered species, were found on ocean beaches near Crescent City, California, and near Pacific City, Oregon, respectively, following severe storms. Necropsies and other information suggest that the birds were flushed during the storms and somehow entered the water where they were washed into the surf and drowned.

  2. Earthquake swarms on Mount Erebus, Antarctica

    NASA Astrophysics Data System (ADS)

    Kaminuma, Katsutada; Baba, Megumi; Ueki, Sadato

    1986-12-01

    Mount Erebus (3794 m), located on Ross Island in McMurdo Sound, is one of the few active volcanoes in Antartica. A high-sensitivity seismic network has been operated by Japanese and US parties on and around the Volcano since December, 1980. The results of these observations show two kinds of seismic activity on Ross Island: activity concentrated near the summit of Mount Erebus associated with Strombolian eruptions, and micro-earthquake activity spread through Mount Erebus and the surrounding area. Seismicity on Mount Erebus has been quite high, usually exceeding 20 volcanic earthquakes per day. They frequently occur in swarms with daily counts exceeding 100 events. Sixteen earthquake swarms with more than 250 events per day were recorded by the seismic network during the three year period 1982-1984, and three notable earthquake swarms out of the sixteen were recognized, in October, 1982 (named 82-C), March-April, 1984 (84-B) and July, 1984 (84-F). Swarms 84-B and 84-F have a large total number of earthquakes and large Ishimoto-Iida's "m"; hence these two swarms are presumed to constitute on one of the precursor phenomena to the new eruption, which took place on 13 September, 1984, and lasted a few months.

  3. Speculations on the petroleum geology of the accretionary body: an example from the central Aleutians

    USGS Publications Warehouse

    McCarthy, J.; Stevenson, A.J.; Scholl, D. W.; Vallier, T.L.

    1984-01-01

    In the 300 km wide Adak-Amlia sector of the central Aleutian Trench ??? 36 000 km3 of offscraped trench fill makes up the wedge-shaped mass of the Aleutian accretionary body. Within this wedge, seismic reflection profiles reveal an abundance of potential hydrocarbon-trapping structures. These structures include antiforms, thrust and normal faults, and stratigraphic pinchouts. Maximum closure on these features is 2 km. In addition, the silt and possibly sand size sediment within the offscraped turbidite deposits, and the porous diatomaceous pelagic deposits interbedded with and at the base of the wedge, may define suitable reservoirs for the entrapment of hydrocarbons. Potential seals for these reservoirs include diagenetically-altered and -produced siliceous and carbonate sediment. The organic carbon input into the central Aleutian Trench, based on carbon analyses of DSDP Legs 18 and 19 core samples, suggests that the average organic carbon content within the accretionary body is approximately 0.3-0.6%. Heat flow across the Aleutian Terrace indicates that at present the oil generation window lies at a depth of 3-6.5 km. At depths of 8 km (which corresponds to the maximum depth the offscraped sediment has been seismically resolved beneath the lower trench slope), the probable high (170-180??C) temperatures prohibit all but gas generation. The dewatering of trench sediment and subducted oceanic crust should produce an abundance of fluids circulating within the accretionary body. These fluids and gases can conduct hydrocarbons to any of the abundant trapping geometries or be lost from the system through sea floor seepage. In the Aleutian accretionary body all the conditions necessary for the formation of oil and gas deposits exist. The size and ultimate preservation of these deposits, however, are dependent on the deformational history of the prism both during accretion and after the accretion process has been superceded by subsequent tectonic regimes. ?? 1984.

  4. Significant earthquakes on the Enriquillo fault system, Hispaniola, 1500-2010: Implications for seismic hazard

    USGS Publications Warehouse

    Bakun, William H.; Flores, Claudia H.; ten Brink, Uri S.

    2012-01-01

    Historical records indicate frequent seismic activity along the north-east Caribbean plate boundary over the past 500 years, particularly on the island of Hispaniola. We use accounts of historical earthquakes to assign intensities and the intensity assignments for the 2010 Haiti earthquakes to derive an intensity attenuation relation for Hispaniola. The intensity assignments and the attenuation relation are used in a grid search to find source locations and magnitudes that best fit the intensity assignments. Here we describe a sequence of devastating earthquakes on the Enriquillo fault system in the eighteenth century. An intensity magnitude MI 6.6 earthquake in 1701 occurred near the location of the 2010 Haiti earthquake, and the accounts of the shaking in the 1701 earthquake are similar to those of the 2010 earthquake. A series of large earthquakes migrating from east to west started with the 18 October 1751 MI 7.4–7.5 earthquake, probably located near the eastern end of the fault in the Dominican Republic, followed by the 21 November 1751 MI 6.6 earthquake near Port-au-Prince, Haiti, and the 3 June 1770 MI 7.5 earthquake west of the 2010 earthquake rupture. The 2010 Haiti earthquake may mark the beginning of a new cycle of large earthquakes on the Enriquillo fault system after 240 years of seismic quiescence. The entire Enriquillo fault system appears to be seismically active; Haiti and the Dominican Republic should prepare for future devastating earthquakes.

  5. Three-dimensional inversion of regional P and S arrival times in the East Aleutians and sources of subduction zone gravity highs

    SciTech Connect

    Abers, G.A.

    1994-03-10

    Free-air gravity highs over forearcs represent a large fraction of the power in the Earth`s anomalous field, yet their origin remains uncertain. Seismic velocities, as indicators of density, are estimated here as a means to compare the relative importance of upper plate sources for the gravity high with sources in the downgoing plate. P and S arrival times for local earthquakes, recorded by a seismic network in the eastern Aleutians, are inverted for three-dimensional velocity structure between the volcanic arc and the downgoing plate. A three-dimensional ray tracing scheme is used to invert the 7974 P and 6764 S arrivals for seismic velocities and hypocenters of 635 events. One-dimensional inversions show that station P residuals are systematically 0.25 - 0.5 s positive at stations 0-30 km north of the Aleutian volcanic arc, indicating slow material, while residuals at stations 10-30 km south of the arc are 0.1-0.25 s negative. Both features are explained in three-dimensional inversions by velocity variations at depths less than 25-35 km. Tests using a one-dimensional or a two-dimensional slab starting model show that below 100 km depth, velocities are poorly determined and trade off almost completely with hypocenters for earthquakes at these depths. The locations of forearc velocity highs, in the crust of the upper plate, correspond to the location of the gravity high between the trench and volcanic arc. Free-air anomalies, calculated from the three-dimensional velocity inversion result, match observed gravity for a linear density-velocity relationship between 0.1 and 0.3 (Mg m{sup {minus}3})/(km s{sup {minus}1}), when a 50-km-thick slab is included with a density of 0.055{+-}0.005 Mg m{sup {minus}3}. Values outside these ranges do not match the observed gravity. The slab alone contributes one third to one half of the total 75-150 mGal amplitude of the gravity high but predicts a high that is much broader than is observed.

  6. Identification of Deep Earthquakes

    DTIC Science & Technology

    2010-09-01

    develop a ground truth dataset of earthquakes at both normal crustal depths and earthquakes from subduction zones , below the overlying crust. Many...deep earthquakes (depths between about 50 and 300 km). These deep earthquakes are known to occur in the Asia-India continental collision zone ...and/or NIL, as these stations are within a few hundred km of the zone where deep earthquakes are known to occur. To date we have selected about 300

  7. Canary Islands

    NASA Technical Reports Server (NTRS)

    1992-01-01

    This easterly looking view shows the seven major volcanic islands of the Canary Island chain (28.0N, 16.5W) and offers a unique view of the islands that have become a frequent vacation spot for Europeans. The northwest coastline of Africa, (Morocco and Western Sahara), is visible in the background. Frequently, these islands create an impact on local weather (cloud formations) and ocean currents (island wakes) as seen in this photo.

  8. Ischia Island: Historical Seismicity and Dynamics

    NASA Astrophysics Data System (ADS)

    Carlino, S.; Cubellis, E.; Iannuzzi, R.; Luongo, G.; Obrizzo, F.

    2003-04-01

    The seismic energy release in volcanic areas is a complex process and the island of Ischia provides a significant scenario of historical seismicity. This is characterized by the occurence of earthquakes with low energy and high intensity. Information on the seismicity of the island spans about eight centuries, starting from 1228. With regard to effects, the most recent earthquake of 1883 is extensively documented both in the literature and unpublished sources. The earthquake caused 2333 deaths and the destruction of the historical and environmental heritage of some areas of the island. The most severe damage occurred in Casamicciola. This event, which was the first great catastrophe after the unification of Italy in the 1860s (Imax = XI degree MCS), represents an important date in the prevention of natural disasters, in that it was after this earthquake that the first Seismic Safety Act in Italy was passed by which lower risk zones were identified for new settlements. Thanks to such detailed analysis, reliable modelling of the seismic source was also obtained. The historical data onwards makes it possible to identify the area of the epicenter of all known earthquakes as the northern slope of Monte Epomeo, while analysis of the effects of earthquakes and the geological structures allows us to evaluate the stress fields that generate the earthquakes. In a volcanic area, interpretation of the mechanisms of release and propagation of seismic energy is made even more complex as the stress field that acts at a regional level is compounded by that generated from migration of magmatic masses towards the surface, as well as the rheologic properties of the rocks dependent on the high geothermic gradient. Such structural and dynamic conditions make the island of Ischia a seismic area of considerable interest. It would appear necessary to evaluate the expected damage caused by a new event linked to the renewal of dynamics of the island, where high population density and the

  9. Elemental and organochlorine residues in bald eagles from Adak Island, Alaska.

    PubMed

    Stout, Jordan H; Trust, Kimberly A

    2002-07-01

    Adak Island is a remote island in the Aleutian Island archipelago of Alaska (USA) and home to various military activities since World War II. To assess the contaminant burden of one of Adak Island's top predators, livers and kidneys were collected from 26 bald eagle (Haliaeetus leucocephalus) carcasses between 1993 and 1998 for elemental and organochlorine analyses. Mean cadmium, chromium, mercury, and selenium concentrations were consistent with levels observed in other avian studies and were below toxic thresholds. However, elevated concentrations of chromium and mercury in some individuals may warrant concern. Furthermore, although mean polychlorinated biphenyl and pp'-dichlorodiphenyldichloroethylene concentrations were below acute toxic thresholds, they were surprisingly high given Adak Island's remote location.

  10. The nearshore benthic community of Kasatochi Island, one year after the 2008 volcanic eruption

    USGS Publications Warehouse

    Jewett, S.C.; Bodkin, J.L.; Chenelot, H.; Esslinger, G.G.; Hoberg, M.K.

    2010-01-01

    A description is presented of the nearshore benthic community of Kasatochi Island 1012 months after a catastrophic volcanic eruption in 2008. The eruption extended the coastline of the island approximately 400 m offshore, mainly along the south, southeast, and southwest shores, to roughly the 20 m isobath. Existing canopy kelp of Eualaria (Alaria) fistulosa, as well as limited understory algal species and associated fauna (e.g., urchin barrens) on the hard substratum were apparently buried following the eruption. Samples and observations revealed the substrate around the island in 2009 was comprised almost entirely of medium and coarse sands with a depauperate benthic community, dominated by opportunistic pontogeneiid amphipods. Comparisons of habitat and biological communities with other nearby Aleutian Islands, as well as with the Icelandic volcanic island of Surtsey, confirm dramatic reductions in flora and fauna consistent with an early stage of recovery from a large-scale disturbance event. ?? 2010 Regents of the University of Colorado.

  11. Proceedings of the North Aleutian Basin information status and research planning meeting.

    SciTech Connect

    LaGory, K. E.; Krummel, J. R.; Hayse, J. W.; Hlohowskyj, I.; Stull, E. A.; Gorenflo, L.; Environmental Science Division

    2007-10-26

    The North Aleutian Basin Planning Area of the Minerals Management Service (MMS) is a large geographic area with significant ecological and natural resources. The Basin includes most of the southeastern part of the Bering Sea continental shelf including all of Bristol Bay. The area supports important habitat for a wide variety of species and globally significant habitat for birds and marine mammals including federally listed species. Villages and communities of the Alaska Peninsula and other areas bordering or near the Basin rely on its natural resources (especially commercial and subsistence fishing) for much of their sustenance and livelihood. The offshore area of the North Aleutian Basin is considered to have important hydrocarbon reserves, especially natural gas. In 2006, the MMS released a draft proposed program, Outer Continental Shelf Oil and Gas Leasing Program, 2007-2012 and an accompanying draft programmatic environmental impact statement (EIS). The draft proposed program identified two lease sales proposed in the North Aleutian Basin in 2010 and 2012, subject to restrictions. The area proposed for leasing in the Basin was restricted to the Sale 92 Area in the southwestern portion. Additional EISs will be needed to evaluate the potential effects of specific lease actions, exploration activities, and development and production plans in the Basin. A full range of updated multidisciplinary scientific information will be needed to address oceanography, fate and effects of oil spills, marine ecosystems, fish, fisheries, birds, marine mammals, socioeconomics, and subsistence in the Basin. Scientific staff at Argonne National Laboratory (Argonne) were contracted to assist the MMS Alaska Outer Continental Shelf (OCS) Region in identifying and prioritizing information needs related to the North Aleutian Basin and potential future oil and gas leasing and development activities. The overall approach focused on three related but separate tasks: (1) identification and

  12. Comment on "Ultra low frequency (ULF) electromagnetic anomalies associated with large earthquakes in Java Island, Indonesia by using wavelet transform and detrended fluctuation analysis", by Febriani et al. (2014)

    NASA Astrophysics Data System (ADS)

    Masci, F.; Thomas, J. N.

    2015-09-01

    We examine the recent report of Febriani et al. (2014) where the authors show changes in ULF magnetic field data prior to the M7.5 Tasikmalaya earthquake occurred south of Java, Indonesia, on 2 September 2009. Febriani et al. (2014) state that the magnetic changes they found may be related to the impending earthquake. We do not agree that the preearthquake magnetic changes shown in Febriani et al. (2014) are seismogenic. These magnetic changes, indeed, are too closely related to the global geomagnetic activity level to be regarded as being of seismic origin.

  13. Intraplate Splay Faults and Near-field Tsunami Generation during Giant Megathrust Earthquakes in Chile, Alaska, and Sumatra

    NASA Astrophysics Data System (ADS)

    Plafker, G.; Savage, J. C.; Lee, W. H.

    2010-12-01

    The Mw 9.5 Chile earthquake sequence (21-22/05/1960), the largest instrumentally-recorded seismic event in history, was generated by a megathrust rupture of the southern end of the Peru-Chile Arc about 850 km long and 60-150 km wide down dip. Within Chile, the accompanying tsunami reached 15 m high and took an estimated 1,000 of the more than 2,000 lives lost. The trans-Pacific tsunami killed 230 people in Japan, Hawaii and the Philippine Islands. The tsunami source was primarily due to regional offshore upwarp, with possible superimposed larger local uplift due to displacement on splay faults. The Mw 9.2 Alaska earthquake (27/03/1964) ruptured major segments of the eastern Aleutian Arc 800 km long by 250-350 km wide down dip. Coseismic uplift along splay faults offshore generated a major near-field tsunami reaching 13 m high in Alaska that took at least 21 lives. Local earthquake-triggered submarine landslides in fiords along the rugged Kenai and Chugach mountains generated local (non-tsunami) waves with run up to 52 m high that took about 77 lives and caused major damage to coastal communities. Tectonically-generated tsunami waves were also generated over the continental shelf and slope due to regional uplift that averaged about 2 m; these waves added to the damage in coastal Alaska and caused 15 deaths and local property damage as far away as Oregon and California. The Mw 9.15 Sumatra earthquake (26/12/2004) ruptured segments of the Sunda Arc more than 1200 km long by 150-200 km wide down dip. The accompanying near-field tsunami was as high as 36 m in northern Sumatra where it caused 169,000 casualties along 200 km of shoreline while the far-field tsunami took an additional 63,000 lives throughout the Indian Ocean region. This made it the deadliest tsunami in recorded history. In addition to a few meters of regional uplift caused by slip on the megathrust, large-slip splay fault sources are inferred from intraplate seismicity, and from early tsunami arrival

  14. Earthquake-induced static stress change in promoting volcanic eruptions

    NASA Astrophysics Data System (ADS)

    Bonali, Fabio Luca; Tibaldi, Alessandro; Corazzato, Claudia

    2014-05-01

    The aim of this work is to study how earthquakes could favour new eruptions, focusing the attention on earthquake-induced static effects in two different case sites, where 9 seismic events with Mw ≥ 8 occurred in the last century: the Alaska-Aleutian and Chilean volcanic arcs. We followed a novel approach that resolves the earthquake-induced static stress change normal to the magma pathway of each volcano instead of considering the general crustal volume. We also considered other parameters that may contribute to control eruptions, such as magma composition and viscosity, magma chamber depth and local tectonic settings. The dataset includes a total of 51 eruptions following the earthquakes; 33 represent first new eruptions occurred at each single volcano. Comparison of the eruption rate before and after each earthquake suggests that 26 out of the 33 first new eruptions have a positive relation with the studied earthquakes; 13 out of 26 represent awakening events, which are first new eruptions occurred at volcanoes with non-continuous eruptive activity that had no eruptions in the five years before the earthquake. The sensitivity analysis performed for the 2010 Chile earthquake shows that the N-S- and NE-SW-striking magma pathways suffered a larger unclamping in comparison with those striking NW-SE and E-W. Magma pathway geometry contributes to control the magnitude of the static stress change induced by large earthquakes, with differences of up to 8 times among magma-feeding planes of different orientation at the same volcano. This range of diverse values is larger for the volcanoes closer to the epicentre. The possible error in the estimate of magma chamber depth has a minimum effect on the results since the sensitivity analysis shows that the range of stress changes with depth is about 1.5 orders of magnitude smaller than the range linked to variations in the magma pathway strike. Results suggest that unclamping effect promoted eruptions that occurred at non

  15. 2010 Volcanic activity in Alaska, Kamchatka, and the Kurile Islands: summary of events and response of the Alaska Volcano Observatory

    USGS Publications Warehouse

    Neal, Christina A.; Herrick, Julie; Girina, O.A.; Chibisova, Marina; Rybin, Alexander; McGimsey, Robert G.; Dixon, Jim

    2014-01-01

    The Alaska Volcano Observatory (AVO) responded to eruptions, possible eruptions, volcanic unrest or suspected unrest at 12 volcanic centers in Alaska during 2010. The most notable volcanic activity consisted of intermittent ash emissions from long-active Cleveland volcano in the Aleutian Islands. AVO staff also participated in hazard communication regarding eruptions or unrest at seven volcanoes in Russia as part of an ongoing collaborative role in the Kamchatka and Sakhalin Volcanic Eruption Response Teams.

  16. Driving forces behind the evolution of the Aleutian mink disease parvovirus in the context of intensive farming

    PubMed Central

    Canuti, Marta; O’Leary, Kimberly E.; Hunter, Bruce D.; Spearman, Grant; Ojkic, Davor; Whitney, Hugh G.; Lang, Andrew S.

    2016-01-01

    Aleutian mink disease virus (AMDV) causes plasmacytosis, an immune complex-associated syndrome that affects wild and farmed mink. The virus can also infect other small mammals (e.g., ferrets, skunks, ermines, and raccoons), but the disease in these hosts has been studied less. In 2007, a mink plasmacytosis outbreak began on the Island of Newfoundland, and the virus has been endemic in farms since then. In this study, we evaluated the molecular epidemiology of AMDV in farmed and wild animals of Newfoundland since before the beginning of the outbreak and investigated the epidemic in a global context by studying AMDV worldwide, thereby examining its diffusion and phylogeography. Furthermore, AMDV evolution was examined in the context of intensive farming, where host population dynamics strongly influence viral evolution. Partial NS1 sequences and several complete genomes were obtained from Newfoundland viruses and analyzed along with numerous sequences from other locations worldwide that were either obtained as part of this study or from public databases. We observed very high viral diversity within Newfoundland and within single farms, where high rates of co-infection, recombinant viruses and polymorphisms were observed within single infected individuals. Worldwide, we documented a partial geographic distribution of strains, where viruses from different countries co-exist within clades but form country-specific subclades. Finally, we observed the occurrence of recombination and the predominance of negative selection pressure on AMDV proteins. A surprisingly low number of immunoepitopic sites were under diversifying pressure, possibly because AMDV gains no benefit by escaping the immune response as viral entry into target cells is mediated through interactions with antibodies, which therefore contribute to cell infection. In conclusion, the high prevalence of AMDV in farms facilitates the establishment of co-infections that can favor the occurrence of recombination

  17. Three-dimensional inversion of regional P and S arrival times in the East Aleutians and sources of subduction zone gravity highs

    NASA Astrophysics Data System (ADS)

    Abers, Geoffrey A.

    1994-03-01

    Free-air gravity highs over forearcs represent a large fraction of the power in the Earth's anomalous field, yet their origin remains uncertain. Seismic velocities, as indicators of density, are estimated here as a means to compare the relative importance of upper plate sources for the gravity high with sources in the downgoing plate. P and S arrival times for local earthquakes, recorded by a seismic network in the eastern Aleutians, are inverted for three-dimensional velocity structure between the volcanic arc and the downgoing plate. A three-dimensional ray tracing scheme is used to invert the 7974 P and 6764 S arrivals for seismic velocities and hypocenters of 635 events. One-dimensional inversions show that station P residuals are systematically 0.25-0.5 s positive at stations 0-30 km north of the Aleutian volcanic arc, indicating slow material, while residuals at stations 10-30 km south of the arc are 0.1-0.25 s negative. Both features are explained in three-dimensional inversions by velocity variations at depths less than 25-35 km. Tests using a one-dimensional or a two-dimensional slab starting model show that below 100 km depth, velocities are poorly determined and trade off almost completely with hypocenters for earthquakes at these depths. The locations of forearc velocity highs, in the crust of the upper plate, correspond to the location of the gravity high between the trench and volcanic arc. Free-air anomalies, calculated from the three-dimensional velocity inversion result, match observed gravity for a linear density-velocity relationship between 0.1 and 0.3 (Mg m-3)/(km s-1), when a 50-km-thick slab is included with a density of 0.055±0.005 Mg m-3. Values outside these ranges do not match the observed gravity. The slab alone contributes one third to one half of the total 75-150 mGal amplitude of the gravity high but predicts a high that is much broader than is observed. The inclusion of upper-plate velocity anomalies predicts the correct width of

  18. Literature and information related to the natural resources of the North Aleutian Basin of Alaska.

    SciTech Connect

    Stull, E.A.; Hlohowskyj, I.; LaGory, K. E.; Environmental Science Division

    2008-01-31

    The North Aleutian Basin Planning Area of the Minerals Management Service (MMS) is a large geographic area with significant natural resources. The Basin includes most of the southeastern part of the Bering Sea Outer Continental Shelf, including all of Bristol Bay. The area supports important habitat for a wide variety of species and globally significant habitat for birds and marine mammals, including several federally listed species. Villages and communities of the Alaska Peninsula and other areas bordering or near the Basin rely on its natural resources (especially commercial and subsistence fishing) for much of their sustenance and livelihood. The offshore area of the North Aleutian Basin is considered to have important hydrocarbon reserves, especially natural gas. In 2006, the MMS released a draft proposed program, 'Outer Continental Shelf Oil and Gas Leasing Program, 2007-2012' and an accompanying draft programmatic environmental impact statement (EIS). The draft proposed program identified two lease sales proposed in the North Aleutian Basin in 2010 and 2012, subject to restrictions. The area proposed for leasing in the Basin was restricted to the Sale 92 Area in the southwestern portion. Additional EISs will be needed to evaluate the potential effects of specific lease actions, exploration activities, and development and production plans in the Basin. A full range of updated multidisciplinary scientific information will be needed to address oceanography, fate and effects of oil spills, marine ecosystems, fish, fisheries, birds, marine mammals, socioeconomics, and subsistence in the Basin. Scientific staff at Argonne National Laboratory were contracted to assist MMS with identifying and prioritizing information needs related to potential future oil and gas leasing and development activities in the North Aleutian Basin. Argonne focused on three related tasks: (1) identify and gather relevant literature published since 1996, (2) synthesize and summarize the

  19. Bald Eagles consume Emperor Geese during late-winter in the Aleutian Archipelago

    USGS Publications Warehouse

    Ricca, Mark A.; Anthony, Robert G.; Williams, Jeffrey C.

    2004-01-01

    Emperor Geese (Chen canagica) are a species of concern because their population has declined rapidly since the mid-1960s and continues to remain below management objectives (Petersen et al. 1994). Emperor Geese are restricted primarily to Alaska and exhibit an east-west migration pattern, whereby most birds begin breeding on the Yukon-Kuskokwim Delta by mid-May, stage on the Alaska Peninsula by late September, and migrate westward to winter in the Aleutian Archipelago from late November to mid-April (Eisenhauer and Kirkpatrick 1977, Petersen et al. 1994). Demographic and movement studies have been conducted on breeding grounds and stagmg areas (e.g., Schmutz et al. 1994, 1997); however, the winter ecology of Emperor Geese is poorly understood due in part to the extremely remote nature of the Aleutian Archipelago (Petersen et al. 1994). 

  20. Amchitka Island, Alaska, Biological Monitoring Report 2011 Sampling Results

    SciTech Connect

    2013-09-01

    The Long-Term Surveillance and Maintenance (LTS&M) Plan for the U.S. Department of Energy (DOE) Office of Legacy Management (LM) Amchitka Island sites describes how LM plans to conduct its mission to protect human health and the environment at the three nuclear test sites located on Amchitka Island, Alaska. Amchitka Island, near the western end of the Aleutian Islands, is approximately 1,340 miles west-southwest of Anchorage, Alaska. Amchitka is part of the Aleutian Island Unit of the Alaska Maritime National Wildlife Refuge, which is administered by the U.S. Fish and Wildlife Service (USFWS). Since World War II, Amchitka has been used by multiple U.S. government agencies for various military and research activities. From 1943 to 1950, it was used as a forward air base for the U.S. Armed Forces. During the middle 1960s and early 1970s, the U.S. Department of Defense (DOD) and the U.S. Atomic Energy Commission (AEC) used a portion of the island as a site for underground nuclear tests. During the late 1980s and early 1990s, the U.S. Navy constructed and operated a radar station on the island. Three underground nuclear tests were conducted on Amchitka Island. DOD, in conjunction with AEC, conducted the first nuclear test (named Long Shot) in 1965 to provide data that would improve the United States' capability of detecting underground nuclear explosions. The second nuclear test (Milrow) was a weapons-related test conducted by AEC in 1969 as a means to study the feasibility of detonating a much larger device. Cannikin, the third nuclear test on Amchitka, was a weapons-related test detonated on November 6, 1971. With the exception of small concentrations of tritium detected in surface water shortly after the Long Shot test, radioactive fission products from the tests remain in the subsurface at each test location As a continuation of the environmental monitoring that has taken place on Amchitka Island since before 1965, LM in the summer of 2011 collected biological and

  1. Geological and operational summary, North Aleutian Shelf Coast No. 1 well, Bering Sea, Alaska. Final report

    SciTech Connect

    Turner, R.F.

    1988-11-01

    Discusses the first continental offshore stratigraphic test well drilled in the North Aleutian Basin Planning Area, Bering Sea, Alaska. The well was drilled to determine the hydrocarbon potential of the area. The report covers drilling operations; lithology and core data; velocity analysis; geologic setting and tectonic framework; seismic stratigraphy; well-log interpretation and lithostratigraphy; paleontology and biostratigraphy; geothermal gradient; organic geochemistry; abnormal formation pressure; geologic hazards and shallow geology; and environmental considerations.

  2. Earthquake friction

    NASA Astrophysics Data System (ADS)

    Mulargia, Francesco; Bizzarri, Andrea

    2016-12-01

    Laboratory friction slip experiments on rocks provide firm evidence that the static friction coefficient μ has values ∼0.7. This would imply large amounts of heat produced by seismically active faults, but no heat flow anomaly is observed, and mineralogic evidence of frictional heating is virtually absent. This stands for lower μ values ∼0.2, as also required by the observed orientation of faults with respect to the maximum compressive stress. We show that accounting for the thermal and mechanical energy balance of the system removes this inconsistence, implying a multi-stage strain release process. The first stage consists of a small and slow aseismic slip at high friction on pre-existent stress concentrators within the fault volume but angled with the main fault as Riedel cracks. This introduces a second stage dominated by frictional temperature increase inducing local pressurization of pore fluids around the slip patches, which is in turn followed by a third stage in which thermal diffusion extends the frictionally heated zones making them coalesce into a connected pressurized region oriented as the fault plane. Then, the system enters a state of equivalent low static friction in which it can undergo the fast elastic radiation slip prescribed by dislocation earthquake models.

  3. Tracking Earthquake Cascades

    NASA Astrophysics Data System (ADS)

    Jordan, T. H.

    2011-12-01

    In assessing their risk to society, earthquakes are best characterized as cascades that can propagate from the natural environment into the socio-economic (built) environment. Strong earthquakes rarely occur as isolated events; they usually cluster in foreshock-mainshock-aftershock sequences, seismic swarms, and extended sequences of large earthquakes that propagate along major fault systems. These cascades are regulated by stress-mediated interactions among faults driven by tectonic loading. Within these cascades, each large event can itself cause a chain reaction in which the primary effects of faulting and ground shaking induce secondary effects, including tsunami, landslides, liquefaction, and set off destructive processes within the built environment, such as fires and radiation leakage from nuclear plants. Recent earthquakes have demonstrated how the socio-economic effects of large earthquakes can reverberate for many years. To reduce earthquake risk and improve the resiliency of communities to earthquake damage, society depends on five geotechnologies for tracking earthquake cascades: long-term probabilistic seismic hazard analysis (PSHA), short-term (operational) earthquake forecasting, earthquake early warning, tsunami warning, and the rapid production of post-event information for response and recovery (see figure). In this presentation, I describe how recent advances in earthquake system science are leading to improvements in this geotechnology pipeline. In particular, I will highlight the role of earthquake simulations in predicting strong ground motions and their secondary effects before and during earthquake cascades

  4. Prevention of strong earthquakes: Goal or utopia?

    NASA Astrophysics Data System (ADS)

    Mukhamediev, Sh. A.

    2010-11-01

    In the present paper, we consider ideas suggesting various kinds of industrial impact on the close-to-failure block of the Earth’s crust in order to break a pending strong earthquake (PSE) into a number of smaller quakes or aseismic slips. Among the published proposals on the prevention of a forthcoming strong earthquake, methods based on water injection and vibro influence merit greater attention as they are based on field observations and the results of laboratory tests. In spite of this, the cited proofs are, for various reasons, insufficient to acknowledge the proposed techniques as highly substantiated; in addition, the physical essence of these methods has still not been fully understood. First, the key concept of the methods, namely, the release of the accumulated stresses (or excessive elastic energy) in the source region of a forthcoming strong earthquake, is open to objection. If we treat an earthquake as a phenomenon of a loss in stability, then, the heterogeneities of the physicomechanical properties and stresses along the existing fault or its future trajectory, rather than the absolute values of stresses, play the most important role. In the present paper, this statement is illustrated by the classical examples of stable and unstable fractures and by the examples of the calculated stress fields, which were realized in the source regions of the tsunamigenic earthquakes of December 26, 2004 near the Sumatra Island and of September 29, 2009 near the Samoa Island. Here, just before the earthquakes, there were no excessive stresses in the source regions. Quite the opposite, the maximum shear stresses τmax were close to their minimum value, compared to τmax in the adjacent territory. In the present paper, we provide quantitative examples that falsify the theory of the prevention of PSE in its current form. It is shown that the measures for the prevention of PSE, even when successful for an already existing fault, can trigger or accelerate a catastrophic

  5. Using an extended historical record to assess the temporal behavior of high magnitude earthquakes

    NASA Astrophysics Data System (ADS)

    Bellone, E.; Muir-Wood, R.

    2012-04-01

    Oscillations in the number of worldwide high magnitude earthquakes since 1900 have trigger the question of whether the underlying activity rate can be considered constant. Between 1950 and 1965 there were seven earthquakes of magnitude 8.6 or higher in the space of 15 years followed by a period of 39 years in which there were no earthquakes at or above this size. Including the Mw9.2 2004 Indian Ocean earthquake there have now been four earthquakes at or above this threshold (in seven years) including the 2010 Mw8.8 Maule earthquake in Chile and the Mw9 Tohoku earthquake in Japan. Previous studies, using the earthquake catalogue from 1900 onwards, came to different conclusions on whether these data support a change in the underlying worldwide rate of large magnitude earthquakes. To assist in addressing this issue, we have set out to explore an extended catalogue of extreme magnitude earthquakes spanning at least 300 years. The presentation will report the results of statistical analyses to determine the strength of evidence for temporal clustering of extreme global earthquakes. If we are currently in a period of elevated activity for the largest magnitude earthquakes, what are the implications for assessing subduction zone earthquake risk - as along the Cascadia coastline of Oregon, Washington State and Vancouver Island, or along the coasts of northern Chile and Peru?

  6. Detecting lower-mantle slabs beneath Asia and the Aleutians

    NASA Astrophysics Data System (ADS)

    Schumacher, L.; Thomas, C.

    2016-06-01

    To investigate the descend of subducted slabs we search for and analyse seismic arrivals that reflected off the surface of the slab. In order to distinguish between such arrivals and other seismic phases, we search for waves that reach a seismic array with a backazimuth deviating from the theoretical backazimuth of the earthquake. Source-receiver combinations are chosen in a way that their great circle paths do not intersect the slab region, hence the direct arrivals can serve as reference. We focus on the North and Northwest Pacific region by using earthquakes from Japan, the Philippines and the Hindu Kush area recorded at North American networks (e.g. USArray, Alaska and Canada). Using seismic array techniques for analysing the data and record information on slowness, backazimuth and traveltime of the observed out-of-plane arrivals we use these measurements to trace the wave back through a 1-D velocity model to its scattering/reflection location. We find a number of out-of-plane reflections. Assuming only single scattering, most out-of-plane signals have to travel as P-to-P phases and only a few as S-to-P phases, due to the length of the seismograms we processed. The located reflection points present a view of the 3-D structures within the mantle. In the upper mantle and the transition zone they correlate well with the edges of fast velocity regions in tomographic images. We also find reflection points in the mid- and lower mantle and their locations generally agree with fast velocities mapped by seismic tomography models suggesting that in the subduction regions we map, slabs enter the lower mantle. To validate our approach, we calculate and process synthetic seismograms for 3-D wave field propagation through a model containing a slab-like heterogeneity. We show, that depending on the source-receiver geometry relative to the reflection plane, it is indeed possible to observe and back-trace out-of-plane signals.

  7. Earthquakes: hydrogeochemical precursors

    USGS Publications Warehouse

    Ingebritsen, Steven E.; Manga, Michael

    2014-01-01

    Earthquake prediction is a long-sought goal. Changes in groundwater chemistry before earthquakes in Iceland highlight a potential hydrogeochemical precursor, but such signals must be evaluated in the context of long-term, multiparametric data sets.

  8. The size of earthquakes

    USGS Publications Warehouse

    Kanamori, H.

    1980-01-01

    How we should measure the size of an earthquake has been historically a very important, as well as a very difficult, seismological problem. For example, figure 1 shows the loss of life caused by earthquakes in recent times and clearly demonstrates that 1976 was the worst year for earthquake casualties in the 20th century. However, the damage caused by an earthquake is due not only to its physical size but also to other factors such as where and when it occurs; thus, figure 1 is not necessarily an accurate measure of the "size" of earthquakes in 1976. the point is that the physical process underlying an earthquake is highly complex; we therefore cannot express every detail of an earthquake by a simple straightforward parameter. Indeed, it would be very convenient if we could find a single number that represents the overall physical size of an earthquake. This was in fact the concept behind the Richter magnitude scale introduced in 1935. 

  9. Earthquakes for Kids

    MedlinePlus

    ... lab. Earthquake Animations A trench dug across a fault to learn about past earthquakes. Science Fair Projects ... History A scientist stands in front of a fault scarp in southern California. Damage to badly-constructed ...

  10. Speeding earthquake disaster relief

    USGS Publications Warehouse

    Mortensen, Carl; Donlin, Carolyn; Page, Robert A.; Ward, Peter

    1995-01-01

    In coping with recent multibillion-dollar earthquake disasters, scientists and emergency managers have found new ways to speed and improve relief efforts. This progress is founded on the rapid availability of earthquake information from seismograph networks.

  11. Earthquakes: Predicting the unpredictable?

    USGS Publications Warehouse

    Hough, S.E.

    2005-01-01

    The earthquake prediction pendulum has swung from optimism in the 1970s to rather extreme pessimism in the 1990s. Earlier work revealed evidence of possible earthquake precursors: physical changes in the planet that signal that a large earthquake is on the way. Some respected earthquake scientists argued that earthquakes are likewise fundamentally unpredictable. The fate of the Parkfield prediction experiment appeared to support their arguments: A moderate earthquake had been predicted along a specified segment of the central San Andreas fault within five years of 1988, but had failed to materialize on schedule. At some point, however, the pendulum began to swing back. Reputable scientists began using the "P-word" in not only polite company, but also at meetings and even in print. If the optimism regarding earthquake prediction can be attributed to any single cause, it might be scientists' burgeoning understanding of the earthquake cycle.

  12. Estimating earthquake potential

    USGS Publications Warehouse

    Page, R.A.

    1980-01-01

    The hazards to life and property from earthquakes can be minimized in three ways. First, structures can be designed and built to resist the effects of earthquakes. Second, the location of structures and human activities can be chosen to avoid or to limit the use of areas known to be subject to serious earthquake hazards. Third, preparations for an earthquake in response to a prediction or warning can reduce the loss of life and damage to property as well as promote a rapid recovery from the disaster. The success of the first two strategies, earthquake engineering and land use planning, depends on being able to reliably estimate the earthquake potential. The key considerations in defining the potential of a region are the location, size, and character of future earthquakes and frequency of their occurrence. Both historic seismicity of the region and the geologic record are considered in evaluating earthquake potential. 

  13. Analysis of Recent Major Outer-Rise Earthquake Rupture Characteristics

    NASA Astrophysics Data System (ADS)

    Cleveland, M.; Ammon, C.; Lay, T.; Kanamori, H.

    2009-12-01

    Outer-rise earthquakes can help indicate the degree of seismic coupling of a subduction zone megathrust as well help constrain stress transfer processes in underthrusting oceanic lithosphere during the seismic cycle. In addition, outer rise earthquake-related structures may play a significant role in the transport of water into subduction zones, and possibly provide seismogenic structures re-activated during intermediate-depth earthquakes. And finally, although less frequent than large underthrusting events, large outer-rise earthquakes may pose significant hazard since they have been found to display higher stress drops and greater enrichment in high frequency shaking than comparable size interplate events. In this study we analyze and compare the seismic properties of three specific outer-rise sequences, representing relatively diverse tectonic characteristics, including events from southern Vanuatu (formerly New Hebrides), central Kuril Islands, and the Andaman Islands regions. Similar to several important historic events, these recent large outer rise sequences provide information on the transmission of slab-pull generated stresses and their relationship with large underthrusting earthquakes. To allow comparison with the 13 January (Mw 8.1) 2007 central Kuril Islands sequence that we studied previously, we conduct finite-fault analyses of the 16 May, 1995 Vanuatu, Mw = 7.7 and 10 August, 2009 Andaman Islands, Mw = 7.5, outer-rise events using azimuthally distributed teleseismic P and SH waveforms and Rayleigh-wave effective source time functions. The unique tectonic geometry of the Vanuatu event, occurring near the corner of the overriding Pacific Plate, conveys information about the influence of geometry on the outer-rise character. The Andaman earthquake occurred in a region with substantially oblique plate motion where geometrical plate relationships remain somewhat unclear. Considering their seismic properties and relationship to nearby great underthrusting

  14. Redefining Earthquakes and the Earthquake Machine

    ERIC Educational Resources Information Center

    Hubenthal, Michael; Braile, Larry; Taber, John

    2008-01-01

    The Earthquake Machine (EML), a mechanical model of stick-slip fault systems, can increase student engagement and facilitate opportunities to participate in the scientific process. This article introduces the EML model and an activity that challenges ninth-grade students' misconceptions about earthquakes. The activity emphasizes the role of models…

  15. Children's Ideas about Earthquakes

    ERIC Educational Resources Information Center

    Simsek, Canan Lacin

    2007-01-01

    Earthquake, a natural disaster, is among the fundamental problems of many countries. If people know how to protect themselves from earthquake and arrange their life styles in compliance with this, damage they will suffer will reduce to that extent. In particular, a good training regarding earthquake to be received in primary schools is considered…

  16. Can We Predict Earthquakes?

    SciTech Connect

    Johnson, Paul

    2016-08-31

    The only thing we know for sure about earthquakes is that one will happen again very soon. Earthquakes pose a vital yet puzzling set of research questions that have confounded scientists for decades, but new ways of looking at seismic information and innovative laboratory experiments are offering tantalizing clues to what triggers earthquakes — and when.

  17. Earthquake and Schools. [Videotape].

    ERIC Educational Resources Information Center

    Federal Emergency Management Agency, Washington, DC.

    Designing schools to make them more earthquake resistant and protect children from the catastrophic collapse of the school building is discussed in this videotape. It reveals that 44 of the 50 U.S. states are vulnerable to earthquake, but most schools are structurally unprepared to take on the stresses that earthquakes exert. The cost to the…

  18. School Safety and Earthquakes.

    ERIC Educational Resources Information Center

    Dwelley, Laura; Tucker, Brian; Fernandez, Jeanette

    1997-01-01

    A recent assessment of earthquake risk to Quito, Ecuador, concluded that many of its public schools are vulnerable to collapse during major earthquakes. A subsequent examination of 60 buildings identified 15 high-risk buildings. These schools were retrofitted to meet standards that would prevent injury even during Quito's largest earthquakes. US…

  19. Real Earthquakes, Real Learning

    ERIC Educational Resources Information Center

    Schomburg, Aaron

    2003-01-01

    One teacher took her class on a year long earthquake expedition. The goal was to monitor the occurrences of real earthquakes during the year and mark their locations with push pins on a wall-sized world map in the hallway outside the science room. The purpose of the project was to create a detailed picture of the earthquakes that occurred…

  20. Can We Predict Earthquakes?

    ScienceCinema

    Johnson, Paul

    2016-09-09

    The only thing we know for sure about earthquakes is that one will happen again very soon. Earthquakes pose a vital yet puzzling set of research questions that have confounded scientists for decades, but new ways of looking at seismic information and innovative laboratory experiments are offering tantalizing clues to what triggers earthquakes — and when.