A5044189796- Seismic Waves and Analysis
- earthquake and tectonic studies
- Seismic Imaging and Inversion Techniques
- Seismology and Earthquake Studies
- Seismic Performance and Analysis
- Geological and Geochemical Analysis
- Geophysics and Sensor Technology
- Geological Modeling and Analysis
- Geology and Paleoclimatology Research
- Earthquake Detection and Analysis
- Geophysical Methods and Applications
- Landslides and related hazards
- Underwater Acoustics Research
- High-pressure geophysics and materials
- Geological formations and processes
- Reservoir Engineering and Simulation Methods
- Structural Health Monitoring Techniques
- Meteorological Phenomena and Simulations
- Antenna Design and Optimization
- Hydraulic Fracturing and Reservoir Analysis
- Botany, Ecology, and Taxonomy Studies
- Sparse and Compressive Sensing Techniques
- Railway Engineering and Dynamics
- Air Traffic Management and Optimization
- Advanced Aircraft Design and Technologies
United States Geological Survey
2015-2024
Geologic Hazards Science Center
2014-2024
Denver Federal Center
1998-2018
Institute of Geosciences and Earth Resources
2007
United States Air Force Research Laboratory
2007
University of California, Riverside
1996
The US National Seismic Hazard Model (NSHM) was updated in 2023 for all 50 states using new science on seismicity, fault ruptures, ground motions, and probabilistic techniques to produce a standard of practice public policy other engineering applications (defined return periods greater than ∼475 or less ∼10,000 years). Changes time-independent seismic hazard (both increases decreases compared previous NSHMs) are substantial because the model considers more data earthquake rupture forecasts...
We update the ground-motion characterization for 2023 National Seismic Hazard Model (NSHM) conterminous United States. The includes use of new models (GMMs) in Cascadia subduction zone; an adjustment to central and eastern States (CEUS) GMMs reduce misfits with observed data; updated boundary application shallow, crustal earthquakes active tectonic regions (i.e. western (WUS)) stable continental CEUS); improved site response deep sedimentary basins WUS CEUS. Site updates include basin...
Multichannel analysis of surface waves (MASW) and refraction micro- tremor (ReMi) are two the most recently developed acquisition techniques for determining shallow shear-wave velocity. We conducted a blind comparison MASW ReMi results with four boreholes logged to at least 260 m shear vel- ocity in Santa Clara Valley, California, determine how closely these meth- ods match downhole measurements. Average velocity estimates depths 30, 50, 100 demonstrate that methods as implemented this study...
Research Article| August 07, 2018 Broadband Synthetic Seismograms for Magnitude 9 Earthquakes on the Cascadia Megathrust Based 3D Simulations and Stochastic Synthetics, Part 2: Rupture Parameters Variability Erin A. Wirth; Wirth aU.S. Geological Survey, University of Washington, Box 351310, Seattle, Washington 98195, ewirth@usgs.goveFormerly at Department Earth Space Sciences, 98195. Search other works by this author on: GSW Google Scholar Arthur D. Frankel; Frankel ewirth@usgs.gov Nasser...
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...
Abstract Microtremor array measurements, and passive surface wave methods in general, have been increasingly used to non-invasively estimate shear-wave velocity structures for various purposes. The dispersion curves invert them retrieving S-wave profiles. This paper summarizes principles, limitations, data collection, processing methods. It intends enable students practitioners understand the principles needed plan a microtremor investigation, record process data, evaluate quality of...
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;...
We characterize the shear‐wave velocity (Vs) of soil deposits in lower Manhattan at six sites using SPAC and HVSR microtremor methods. The Vs ranges from 140 m/s to 300 over bedrock. believe that bedrock depth is constrained ±15% with these data, but an accurate quantification unattainable because low spectral coherency frequencies below 3 Hz. data corroborate results based on good alignment theoretical Rayleigh ellipticity peaks, 1D SH amplifications, peak HVSR. Resonant vary between 1.4...
First posted December 20, 2017 Revised September 24, 2019 For additional information, contact: Center Director, Geologic Hazards Science U.S. Geological SurveyBox 25046 Mail Stop 966 Denver, CO 80225 In support of earthquake hazard studies and ground motion simulations in the Pacific Northwest, three-dimensional P- S-wave velocity (VP VS, respectively) models incorporating Cascadia subduction zone were previously developed for region encompassed from about 40.2°N. to 50°N. latitude, 122°W....
Many interesting inverse problems in geophysics are non-linear and multimodal. Parametrization of these leads to an objective function, or measure agreement between data model predictions, that has a complex topography with many local minima. Optimization algorithms rely on gradients the function search space locally may become trapped By combining simulated annealing downhill simplex method, hybrid global algorithm is presented this paper for non-linear, multimodal, problems. The shares...
Correction| December 04, 2018 Erratum to Broadband Synthetic Seismograms for Magnitude 9 Earthquakes on the Cascadia Megathrust Based 3D Simulations and Stochastic Synthetics, Part 1: Methodology Overall Results Arthur Frankel; Frankel aU.S. Geological Survey, University of Washington, Box 351310, Seattle, Washington 98195, afrankel@usgs.gov Search other works by this author on: GSW Google Scholar Erin Wirth; Wirth Nasser Marafi; Marafi bDepartment Civil Environmental Engineering, 98195 John...
We used the 3D finite-difference method to model observed seismograms of two earthquakes ( M L 4.9 and 3.5) in Seattle region simulate ground motions for hypothetical 6.5 5.0 on fault, periods greater than 2 sec. A velocity Basin was constructed from studies that analyzed seismic-reflection surveys, borehole logs, gravity aeromagnetic data. The observations simulations highlight importance long-period motions. For occurring just south basin, edge basin variation thickness Quaternary deposits...
Margin‐parallel shortening of the Cascadia forearc is a consequence oblique subduction Juan de Fuca plate beneath North America. Strike‐slip, thrust, and crustal faults densely populated Puget Lowland accommodate much this north‐south compression, resulting in large earthquakes. To better understand deformation improve earthquake hazard assessment, we here use seismic reflection surveys, coastal exposures Pleistocene strata, potential‐field data, airborne laser swath mapping to document...
Abstract We examine the variability of long‐period ( T ≥1 s) earthquake ground motions from 3D simulations M w 7 earthquakes on Salt Lake City segment Wasatch fault zone, Utah, a set 96 rupture models with varying slip distributions, speeds, velocities, and hypocenter locations. Earthquake ruptures were prescribed representation that satisfies geologic constraints maintained distinct strands for Warm Springs East Bench Cottonwood faults. Response spectral accelerations (SA; 1.5–10 s; 5%...
Abstract Reflection and critically refracted seismic methods use traveltime measurements of body waves propagating between a source series receivers on the ground surface to calculate subsurface velocities. Body wave energy is or reflected at boundaries where there change in impedance, defined as product material density velocity. This article provides practical guidance horizontally shear (SH-wave) refraction reflection determine velocity function depth for near-surface site...
Abstract Site response is a critical consideration when assessing earthquake hazards. characterization key to understanding site effects as influenced by seismic conditions of the local geology. Thus, number geophysical methods were developed meet demand for accurate and cost-effective results. As consequence, studies have been administered periodically blind trials evaluate state-of-practice on-site characterization. We present results from Consortium Organizations Strong Motion Observation...
This report presents probabilistic seismic hazard maps for Seattle, Washington, based on over 500 3D simulations of ground motions from scenario earthquakes. These include sedimentary basin effects and rupture directivity. Nonlinear site response soft-soil sites fill alluvium was also applied in the maps. The describes methodology incorporating source dependent amplification factors into a calculation. were conducted various earthquake sources that can affect Seattle: Seattle fault zone,...
Abstract The Grizzly Valley fault system (GVFS) strikes northwestward across Sierra Valley, a low‐relief basin situated within network of active dextral slip faults in the northern Walker Lane, California. Quaternary motion along has not been previously documented. We used high‐resolution (0.25 m) airborne lidar data combination with high‐resolution, P wave, seismic reflection imaging to evaluate deformation associated GVFS. identified suspected tectonic lineaments using and collected six...
For additional information, contact: Contact Information, Menlo Park, Calif. Office—Earthquake Science Center U.S. Geological Survey 345 Middlefield Road, MS 977 CA 94025 http://earthquake.usgs.gov/ VS30, the time-averaged shear-wave velocity (VS) to a depth of 30 meters, is key index adopted by earthquake engineering community account for seismic site conditions. VS30 typically based on geophysical measurements VS derived from invasive and noninvasive techniques at sites interest. Owing...
Abstract The Reelfoot Lake basin, Tennessee, is structurally complex and of great interest seismologically because it located at the junction two seismicity trends New Madrid seismic zone. To better understand structure this location, a 7.5-km-long reflection profile was acquired on roads along southern margin Lake. line reveals westerly dipping basin bounded west by reverse fault zone, Ridgely right-lateral transpressive zone east, Cottonwood Grove strike-slip in middle basin. displacement...
In support of earthquake hazards and ground motion studies in the Pacific Northwest, three-dimensional P- S-wave velocity (3D Vp Vs) density rho) models incorporating Cascadia subduction zone have been developed for region encompassed from about 40.2°N to 50°N latitude, -122°W -129°W longitude. The model volume includes elevations 0 km 60 (elevation is opposite depth coordinates). Stephenson Frankel (2003) presented preliminary simulations valid up 0.1 Hz using an earlier version these...
Research Article| October 01, 2013 VS30 and Spectral Response from Collocated Shallow, Active‐, Passive‐Source VS Data at 27 Sites in Puerto Rico Jack K. Odum; Odum U.S. Geological Survey, P.O. Box 25046, MS‐966, Denver, Colorado 80225‐0046 Search for other works by this author on: GSW Google Scholar William J. Stephenson; Stephenson Robert A. Williams; Williams Christa von Hillebrandt‐Andrade NOAA NWS CTWP, Residence 2a, 259 Alfonso Valdes, Mayaguez, 00681‐9017 Bulletin of the Seismological...