Abstract Deep sedimentary basins amplify long‐period shaking from seismic waves, increasing the hazard for cities sited on such basins. We perform 3‐D simulations of point source earthquakes distributed around Seattle and Tacoma in Washington State to examine dependence basin amplification azimuth, depth, earthquake type. For periods between 1 10 s, pattern is spatially heterogeneous differs considerably with source‐to‐site azimuth. close‐in earthquakes, greatest occurs toward farside ground...

Seismic reflection data show that the densely populated Puget Lowland of western Washington state is underlain by subhorizontal Paleogene and Neogene sedimentary rocks deformed west northwest trending faults folds. From south to north beneath Lowland, features seen on seismic include: horizontally‐stratified, 3.5 km thick Tacoma basin; Seattle uplift with dipping (∼20°) strata its flank steeply (50° 90°) west‐trending fault flank; 7.5 thick, northward‐thinning antiformal Kingston arch;...

The Ventura Avenue anticline is one of the fastest uplifting structures in southern California, rising at ∼5 mm=yr.We use well data and seismic reflection profiles to show that underlain by fault, which extends seismogenic depth.Fault offset increases with depth, implying a fault-propagation fold.A decrease uplift rate since ∼30 10 ka consistent fault breaking through surface time implies has recent dip-slip ∼4:4-6:9 mm=yr.To west, fold trend continues offshore as Pitas Point its associated...

Abstract On 7 May 2015, a M w 4.0 earthquake occurred near Venus, northeast Johnson County, Texas, in an area of the Bend Arch‐Fort Worth Basin that reports long‐term, high‐volume wastewater disposal and has hosted felt earthquakes since 2009. In weeks following earthquake, we deployed local seismic network purchased nearby active‐source reflection data to capture additional events, characterize causative fault, explore potential links between ongoing industry activity seismicity. Hypocenter...

Research Article| September 01, 2000 Potential seismic hazards and tectonics of the upper Cook Inlet basin, Alaska, based on analysis Pliocene younger deformation Peter J. Haeussler; Haeussler 1U.S. Geological Survey, 4200 University Drive, Anchorage, Alaska 99508, USA Search for other works by this author on: GSW Google Scholar Ronald L. Bruhn; Bruhn 2Department Geology Geophysics, Utah, Salt Lake City, Utah 84112, Thomas Pratt 3U.S. Survey—School Oceanography, Washington, P.O. Box 357940,...

Research Article| June 01, 1989 Major Proterozoic basement features of the eastern midcontinent North America revealed by recent COCORP profiling T. Pratt; Pratt 1Institute for Study Continents (INSTOC) and Department Geological Sciences, Cornell University, Ithaca, New York 14853 Search other works this author on: GSW Google Scholar R. Culotta; Culotta E. Hauser; Hauser D. Nelson; Nelson L. Brown; Brown S. Kaufman; Kaufman J. Oliver; Oliver W. Hinze 2Department Earth Atmospheric Purdue West...

A pair of oppositely dipping, crustal-scale shear zones imaged within Grenville basement beneath the Paleozoic cover Ohio can be correlated, via geopotential lineaments, with similarly oriented geologic and seismically structures hundreds kilometres to northeast southwest, suggesting a relatively simple structural framework for eastern midcontinent region. An east-dipping zone extending from Lake Huron through western Ohio, possibly farther marks edge province. Perhaps greater consequence an...

A regional seismic reflection line (I‐64) across the Virginia Piedmont has provided a stacked section suitable for an integrated interpretation of geophysical data in region. highly reflective upper crust, allochthonous Blue Ridge Province, underlying thrust sheets including master decollement, and basal decollement at depth about 9 km (3 s) are confirmed on data. Immediately east Appalachian structures plunge to as much 12 (4 depth. The Evington Group, Hardware terrane, Chopawamsic...

Recordings of the 1999 M w 7.6 Chi-Chi (Taiwan) earthquake, two local earthquakes, and five blasts show seismic-wave amplification over a large sedimentary basin in U.S. Pacific Northwest. For weak ground motions from Seattle amplified 0.2- to 0.8-Hz waves by factors 8 16 relative bedrock sites west basin. The peak frequency change during coda: initial S -wave arrivals (0–30 sec) had maximum amplifications 12 at 0.5–0.8 Hz, whereas later (35–65 reached 0.3–0.5 Hz. Analysis events 1.0-...

Abstract The extent of damage in Washington, DC, from the 2011 M w 5.8 Mineral, VA, earthquake was surprising for an epicenter 130 km away; U.S. Geological Survey “Did‐You‐Feel‐It” reports suggest that Atlantic Coastal Plain and other unconsolidated sediments amplified ground motions city. We measure this amplification relative to bedrock sites using signals recorded on a temporary seismometer array. spectral ratios show strong 0.7 4 Hz frequency range sediments. This overlaps with resonant...

Megathrust splay faults are a common feature of accretionary prisms and can be important for generating tsunamis during some subduction zone earthquakes. Here we provide new evidence from Alaska that megathrust have been conduits focused exhumation in the last 5 Ma. In most central Prince William Sound, published low-temperature thermochronology data indicate little to no permanent rock uplift over tens thousands earthquake cycles. However, southern Sound on Montague Island, apatite...

ABSTRACT We examine the effects that Atlantic Coastal Plain (ACP) strata have on ground motions in eastern and southeastern United States. The ACP consist of widespread, nearly flat-lying sediments, upper portions which are unconsolidated or semiconsolidated. sediments deposited primarily crystalline basement rocks, creating large velocity density contrasts with underlying rocks. At 211 sites to thicknesses 4000 m, we compute spectral ratios relative average four bedrock west northwest...

With the recent successful accounting of basin depth ground-motion adjustments in seismic hazard analyses for select areas western United States, we move toward implementing similar Atlantic and Gulf Coastal Plains by constructing a sediment thickness model evaluating multiple relevant site amplification models central eastern States analyses. We digitize combine existing data sets into composite surface that delineates base Cretaceous sediments under Plain Mesozoic Plain. Amplification...

Abstract High‐resolution sparker and crustal‐scale air gun seismic reflection data, coupled with repeat bathymetric surveys, document a region of repeated coseismic uplift on the portion Alaska subduction zone that ruptured in 1964. This area defines western limit Prince William Sound. Differencing vintage modern surveys shows greatest related to 1964 Great earthquake was focused along series subparallel faults beneath Sound adjacent Gulf shelf. Bathymetric differencing indicates 12 m...

Seismicity in the New Madrid seismic zone (NMSZ) of central United States is generally attributed to a stepover structure which Reelfoot thrust fault transfers slip between parallel strike-slip faults. However, some arms do not fit this simple model. Comparison NMSZ with an analog sandbox model restraining explains all seismicity as only part extensive pattern faults that characterizes structures. Computer models show may form because differences trends lower crustal shearing and inherited...

ABSTRACT Damaging ground motions from the 2011 Mw 5.8 Virginia earthquake were likely increased due to site amplification unconsolidated sediments of Atlantic Coastal Plain (ACP), highlighting need understand response on these widespread strata along coastal regions eastern United States. The horizontal-to-vertical spectral ratio (HVSR) method, using either signals or ambient noise as input, offers an appealing method for measuring laterally extensive sediments, because it requires a single...

ABSTRACT The moment magnitude (Mw) ∼7 earthquake that struck Charleston, South Carolina, on 31 August 1886 is the largest historical in United States east of Appalachian Mountains. fault(s) ruptured during this has never been conclusively identified, and conflicting fault models have proposed. Here we interpret reprocessed seismic reflection profiles, legacy aeromagnetic data, newly collected ground penetrating radar (GPR) profiles to delineate faults deforming Cretaceous younger Atlantic...

Abstract The last National Seismic Hazard Model (NSHM) for Puerto Rico and the U.S. Virgin Islands (PRVI) was published in 2003. In advance of 2025 PRVI NSHM update, we created three geologic input databases to summarize new onshore offshore fault source information northern Caribbean region between 62°–70° W 16°–21° N. These databases, sections, fault-zone polygons, estimates activity (fault-slip rate earthquake recurrence intervals) at specific sites, document updates parameters used prior...

In 1985, 180 km of regional vibroseis profiles were acquired in the Carolinas and Georgia, southeastern United States, as part Appalachian Ultra-Deep Core Hole (ADCOH) Site Study. The data quality is excellent, with large-amplitude reflections from faults crystalline rocks, lower Palaeozoic shelf strata within autochthonous Grenville basement. image subsurface more clearly than other available allow possibility alternative interpretations important elements tectonic framework southern...

Detailed analysis of continuously cored boreholes and cone penetrometer tests (CPTs), high-resolution seismic-reflection data, luminescence 14C dates from Holocene strata folded above the tip Ventura blind thrust fault constrain ages displacements two (or more) most recent earthquakes. These earthquakes, which are identified by a prominent surface fold scarp stratigraphic sequence that thickens across an older buried scarp, occurred before 235-yr-long historic era after 805 ± 75 yr ago (most...

Research Article| March 01, 2017 Accelerating slip rates on the Puente Hills blind thrust fault system beneath metropolitan Los Angeles, California, USA Kristian J. Bergen; Bergen 1Department of Earth and Planetary Sciences, Harvard University, Cambridge, Massachusetts 02138, Search for other works by this author on: GSW Google Scholar John H. Shaw; Shaw * *E-mail: shaw@eps.harvard.edu Lorraine A. Leon; Leon 2Department University Southern California 90089, †Current address: Chevron North...

Research Article| February 01, 1998 Near-surface structural model for deformation associated with the 7, 1812, New Madrid, Missouri, earthquake Jack K. Odum; Odum 1U.S. Geological Survey, M.S. 966, Box 25046, Denver, Colorado 80225 Search other works by this author on: GSW Google Scholar William J. Stephenson; Stephenson Kaye M. Shedlock; Shedlock Thomas L. Pratt 2U.S. University of Washington, School Oceanography, Seattle, Washington 98195 GSA Bulletin (1998) 110 (2): 149–162....

High‐resolution seismic reflection profiles at two different scales were acquired across the transpressional Santa Monica Fault of north Los Angeles as part an integrated hazard assessment fault. The data confirm location fault and related shallow faulting seen in a trench to deeper structures known from regional studies. shows series near‐vertical strike‐slip faults beneath topographic scarp inferred be caused by thrusting on Analysis disruption soil horizons indicates multiple earthquakes...