William J Stephenson
Bill Stephensen is a scientist in the Earthquake Hazards Program.
Science and Products
Crustal Characterization
The geophysical structure of the Earth’s crust, from the surface to the Moho, plays a major role in seismic hazard by influencing earthquake source properties and wave propagation from the earthquake to the Earth’s surface. We make field measurements and create models to better characterize the crust and resulting earthquake ground motions.
Untangling Faults at Depth – What Lies Beneath Panamint Valley, California?
Release Date: APRIL 30, 2018 The eastern edge of Panamint Valley,CA has two types of faults that can be seen in the near-surface geology. 150 geophones and a seismic source will help reveal the subsurface picture.
Seismology in the City
Release Date: May 1, 2015 How seismologists can use noise to see under the ground.
Seismic Reflection Profiles Imaging the Seattle Fault Zone Beneath West Seattle, Central Seattle, and Mercer Island, Washington State
The U.S. Geological Survey, with funding from the National Earthquakes Hazard Reduction Program, collected ~24 km of north-south trending land-based P-wave seismic reflection profiles gathered across three urban areas in Seattle, Washington: West Seattle, central Seattle, and Mercer Island. The West Seattle profiles were collected with an accelerated weight drop source and 8 Hz vertical component
Miscellaneous Microtremor Array Datasets from the Puget Lowland, Washington State
Abstract:
We compile three microtremor array datasets acquired in three campaigns in the Seattle and Tacoma basins, Washington State. These datasets were acquired between 2007 and 2018. Dataset 1 includes seven sites in the western Seattle and Tacoma basins acquired to image shear-wave velocity (Vs) in the upper 1 km that are suitable for analysis with microtremor methods not requiring uniform sen
Data Release for the 2023 U.S. 50-State National Seismic Hazard Model - Overview
This data release contains data sets associated with the 2023 50-State National Seismic Hazard Model Update. The 2023 50-State National Seimsic Hazard Model (NSHM) Update includes an update to the NSHMs for the conterminous U.S (CONUS, last updated in 2018), Alaska (AK, last updated in 2007), and Hawaii (last updated in 2001). Data sets include inputs like seismicity catalogs used as input to the
Strike-slip in transtension: Complex crustal architecture of the Warm Springs Valley fault zone, northern Walker Lane
This data release contains field data for two P-wave seismic reflection profiles acquired across the Warm Springs Valley fault zone, part of the Northern Walker Lane, NV. The dataset consists of high-resolution seismic reflection field records in .segy format, shot coordinates in .csv format, and observers? logs in .pdf format. The high-resolution seismic profiles are approximately 4 km long. The
Seismic reflection imaging of the low-angle Panamint normal fault system, eastern California, 2018
A fundamental question in seismic hazard analysis is whether
Digital datasets documenting subsurface data locations, topographic metrics, fault scarp mapping, and revised fault network for Crowley's Ridge, New Madrid Seismic Zone
This release provides the data and interpretations supporting evidence of late Quaternary faulting along Crowleys Ridge in the New Madrid seismic zone. The release includes location information for seismic reflection and airborne electromagnetic (AEM) data over Crowleys Ridge, a table of topographic metrics derived from analysis of the 10m National Elevation Dataset (NED) digital elevation model (
Spatially averaged coherencies (krSPAC) and Rayleigh effective-mode modeling of microtremor data from asymmetric arrays
The datasets for this investigation consist of microtremor array data collected at sites in San Jose, California, Pleasanton, California, and synthetic microtremor array data created as part of a blind shear-wave velocity modeling study as part of the Third International Symposium on the Effects of Surface Geology on Seismic Motion (ESG2006), Grenoble, France, 30 August - 1 September 2006. The dat
A Bayesian Monte-Carlo Inversion of Spatial Auto-Correlation (SPAC) for Near-Surface Vs Structure Applied to Both Broadband and Geophone Data - Data Release
The datasets for this investigation consist of microtremor array data collected at: 1) 18 sites in Salt Lake and Utah valleys, Utah, and 2) two sites as part of the Frontier Observatory for Research in Geothermal Energy (FORGE) near Milford, Utah. Each of the 18 sites in the Salt Lake and Utah valleys were acquired with four-sensor arrays with three-component (3C) sensors having flat response from
Shear-wave velocity in the Seattle basin to 2 km depth characterized with the krSPAC microtremor array method: insights for urban basin-scale imaging - Data Release
The dataset for this investigation consists of microtremor array data collected at 11 sites in the Seattle basin, Washington State. Ten of the arrays consisted of seven Nanometrics Trillium Compact broadband sensors deployed in asymmetric nested triangles (sites ST01, BA02, SP04, LF05, UW06, SN07, RD08, EL09, CH10, and KG11) that recorded for up to six hours. The eleventh array, at site NW03, was
Data for Holocene fault reactivation in the eastern Cascades, WA
Significant uncertainty remains in how and where crustal shortening occurs throughout the eastern Cascade Range in Washington State. Using lidar imagery, we identified a ~5 km long lineament in Swakane canyon near Wenatchee, roughly coincident with a strand of the Entiat fault. Topographic profiles across the lineament reveal a southwest-side-up break in slope with an average of ~3 m of vertical s
Data for P- and S-wave Seismic Velocity Models Incorporating the Cascadia Subduction Zone for 3D Earthquake Ground Motion simulations- Update for Open-File Report 2007-1348
The data for this release is an ASCII file containing grid points of Cascadia P- and S-wave velocity models. The model volume was developed to include the Cascadia subduction zone for purposes of ground motion simulation. The description of the model and background of its development is provided in the associated Open-File Report. The grid points are given in Universal Transverse Mercator (UTM) Zo
Filter Total Items: 53
Empirical ground-motion basin response in the California Great Valley, Reno, Nevada, and Portland, Oregon
We assess how well the Next-Generation Attenuation-West 2 (NGA-West2) ground-motion models (GMMs), which are used in the US Geological Survey’s (USGS) National Seismic Hazard Model (NSHM) for crustal faults in the western United States, predict the observed basin response in the Great Valley of California, the Reno basin in Nevada, and Portland and Tualatin basins in Oregon. These GMMs rely on sit
Authors
Sean Kamran Ahdi, Brad T. Aagaard, Morgan P. Moschetti, Grace Alexandra Parker, Oliver S. Boyd, William J. Stephenson
The 2023 US 50-State National Seismic Hazard Model: Overview and implications
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 for public policy and other engineering applications (defined for return periods greater than ∼475 or less than ∼10,000 years). Changes in 2023 time-independent seismic hazard (both increase
Authors
Mark D. Petersen, Allison Shumway, Peter M. Powers, Ned Field, Morgan P. Moschetti, Kishor S. Jaiswal, Kevin R. Milner, Sanaz Rezaeian, Arthur Frankel, Andrea L. Llenos, Andrew J. Michael, Jason M. Altekruse, Sean Kamran Ahdi, Kyle Withers, Charles Mueller, Yuehua Zeng, Robert E. Chase, Leah M. Salditch, Nico Luco, Kenneth S. Rukstales, Julie A Herrick, Demi Leafar Girot, Brad T. Aagaard, Adrian Bender, Michael L. Blanpied, Richard W. Briggs, Oliver S. Boyd, Brandon Clayton, Christopher DuRoss, Eileen L. Evans, Peter J. Haeussler, Alexandra Elise Hatem, Kirstie Lafon Haynie, Elizabeth H. Hearn, Kaj M. Johnson, Zachary Alan Kortum, N. Simon Kwong, Andrew James Makdisi, Henry (Ben) Mason, Daniel McNamara, Devin McPhillips, P. Okubo, Morgan T. Page, Frederick Pollitz, Justin Rubinstein, Bruce E. Shaw, Zheng-Kang Shen, Brian Shiro, James Andrew Smith, William J. Stephenson, Eric M. Thompson, Jessica Ann Thompson Jobe, Erin Wirth, Robert C. Witter
Implementation of basin models and sediment depth terms in the 2023 update of the U.S. National Seismic Hazard Model: Example from Reno, Nevada
We present a framework to evaluate the inclusion of candidate basin depth models in the U.S. Geological Survey National Seismic Hazard Model. We compute intensity measures (peak and spectral amplitudes) from uniformly processed earthquake ground motions in and around the basin of interest and compare these to ground-motion model (GMM) estimates over a range of oscillator periods. The GMMs use dept
Authors
Sean Kamran Ahdi, Morgan P. Moschetti, Brad T. Aagaard, Kaitlyn Abernathy, Oliver S. Boyd, William J. Stephenson
Introduction to the special issue of the Consortium of Organizations for Strong Motion Observation Systems (COSMOS) international guidelines for applying noninvasive geophysical techniques to characterize seismic site conditions
Knowledge about local seismic site conditions provides critical information to account for site effects that are commonly observed in strong motion recordings. Certainly, other wave propagation effects can influence these observations, which are attributable to variations in material properties of the paths traveled by the waves, as well as the characteristics of the seismic source. However, local
Authors
Alan Yong, Aysegul Askan, John Cassidy, Sebastiano D'Amico, Stefano Parolai, Marco Pilz, William J. Stephenson
Flexible multimethod approach for seismic site characterization
We describe the flexible multimethod seismic site characterization technique for obtaining shear-wave velocity (VS) profiles and derivative information, such as the time-averaged VS of the upper 30 m (VS30). Simply stated, the multimethod approach relies on the application of multiple independent noninvasive site characterization acquisition and analysis techniques utilized in a flexible field-bas
Authors
William J. Stephenson, Alan Yong, Antony Martin
Microtremor array method using spatial autocorrelation analysis of Rayleigh‑wave data
Microtremor array measurements (MAM) and passive surface wave methods in general, have been increasingly used to non-invasively estimate shear-wave velocity structures (Vs) for various purposes. The methods estimate dispersion curves and invert them for retrieving S-wave velocity profiles. This paper summarizes principles, limitations, data collection and processing methods. It intends to enable s
Authors
Koichi Hayashi, Michael W. Asten, William J. Stephenson, Cécile Cornou, Manuel Hobiger, Marco Pilz, Hiroaki Yamanaka
Seismic site characterization with shear wave (SH) reflection and refraction methods
Reflection and critically refracted seismic methods use traveltime measurements of body waves propagating between a source and a series of receivers on the ground surface to calculate subsurface velocities. Body wave energy is refracted or reflected at boundaries where there is a change in seismic impedance, defined as the product of material density and seismic velocity. This article provides pra
Authors
James A. Hunter, Heather L. Crow, William J. Stephenson, André J.-M. Pugin, Robert Williams, James B. Harris, Jackson K. Odum, Edward W Woolery
An assessment of uncertainties in VS profiles obtained from microtremor observations in the phased 2018 COSMOS blind trials
Site response is a critical consideration when assessing earthquake hazards. Site characterization is key to understanding site effects as influenced by seismic site conditions of the local geology. Thus, a number of geophysical site characterization methods were developed to meet the demand for accurate and cost-effective results. As a consequence, a number of studies have been administered perio
Authors
Michael W. Asten, Alan Yong, Sebastiano Foti, Koichi Hayashi, Antony J. Martin, William J. Stephenson, John F. Cassidy, Jacie Coleman, Robert L. Nigbor, Silvia Castellaro, Kosuke Chimoto, Ikuo Cho, Cécile Cornou, Takumi Hayashida, Manuel Hobiger, Chun-Hsiang Kuo, Albert Macau, E. Diego Mercerat, Sheri Molnar, Passakorn Pananont, Marco Pilz, Nakhorn Poovarodom, Esteban Sáez, Marc Wathelet, Hiroaki Yamanaka, Toshiaki Yokoi, Don Zhao
Geophysical constraints on the crustal architecture of the transtensional Warm Springs Valley fault zone, northern Walker Lane, western Nevada, USA
The Walker Lane is a zone of distributed transtension where normal faults are overprinted by strike-slip motion. We use two newly-acquired high-resolution seismic reflection profiles and a reprocessed Consortium for Continental Reflection Profiling (COCORP) deep crustal reflection profile to assess the subsurface geometry of the Holocene-active, transtensional Warm Springs Valley fault zone (WSVFZ
Authors
Richard W. Briggs, William J. Stephenson, J.H. McBride, Jackson K. Odum, Nadine G. Reitman, Ryan D. Gold
Shear-wave velocity site characterization in Oklahoma from joint inversion of multi-method surface seismic measurements: Implications for central U.S. Ground Motion Prediction
We analyze multimethod shear (SH)‐wave velocity (VS) site characterization data acquired at three permanent and 25 temporary seismograph stations in Oklahoma that recorded M 4+ earthquakes within a 50 km hypocentral distance of at least one of the 2016 M 5.1 Fairview, M 5.8 Pawnee, or M 5.0 Cushing earthquakes to better constrain earthquake ground‐motion modeling in the region. We acquired active
Authors
William J. Stephenson, Jackson K. Odum, Stephen H. Hartzell, Alena L. Leeds, Robert Williams
Seismic reflection imaging of the low-angle Panamint normal fault system, eastern California
Shallowly dipping (<30°) low‐angle normal faults (LANFs) have been documented globally; however, examples of active LANFs in continental settings are limited. The western margin of the Panamint Range in eastern California is defined by a LANF that dips west beneath Panamint Valley and has evidence of Quaternary motion. In addition, high‐angle dextral‐oblique normal faults displace middle to late Q
Authors
Ryan D. Gold, William J. Stephenson, Richard W. Briggs, Christopher DuRoss, Eric Kirby, Edward W Woolery, Jaime Delano, Jackson K. Odum
Graphical Dispersion Plot Editor (DPE) for seismic-site characterization by using multiple surface-wave methods
IntroductionTo understand the behavior of potentially damaging ground motions during earthquakes, seismic-site effects are routinely characterized by using the dispersion of surface waves. Many methods exist to measure dispersion; these methods have various advantages and disadvantages, but they all yield dispersion data that must be inverted for shear-wave velocity. This report presents a graphic
Authors
Devin McPhillips, Alan K. Yong, Antony Martin, William J. Stephenson
Science and Products
Crustal Characterization
The geophysical structure of the Earth’s crust, from the surface to the Moho, plays a major role in seismic hazard by influencing earthquake source properties and wave propagation from the earthquake to the Earth’s surface. We make field measurements and create models to better characterize the crust and resulting earthquake ground motions.
Untangling Faults at Depth – What Lies Beneath Panamint Valley, California?
Release Date: APRIL 30, 2018 The eastern edge of Panamint Valley,CA has two types of faults that can be seen in the near-surface geology. 150 geophones and a seismic source will help reveal the subsurface picture.
Seismology in the City
Release Date: May 1, 2015 How seismologists can use noise to see under the ground.
Seismic Reflection Profiles Imaging the Seattle Fault Zone Beneath West Seattle, Central Seattle, and Mercer Island, Washington State
The U.S. Geological Survey, with funding from the National Earthquakes Hazard Reduction Program, collected ~24 km of north-south trending land-based P-wave seismic reflection profiles gathered across three urban areas in Seattle, Washington: West Seattle, central Seattle, and Mercer Island. The West Seattle profiles were collected with an accelerated weight drop source and 8 Hz vertical component
Miscellaneous Microtremor Array Datasets from the Puget Lowland, Washington State
Abstract:
We compile three microtremor array datasets acquired in three campaigns in the Seattle and Tacoma basins, Washington State. These datasets were acquired between 2007 and 2018. Dataset 1 includes seven sites in the western Seattle and Tacoma basins acquired to image shear-wave velocity (Vs) in the upper 1 km that are suitable for analysis with microtremor methods not requiring uniform sen
Data Release for the 2023 U.S. 50-State National Seismic Hazard Model - Overview
This data release contains data sets associated with the 2023 50-State National Seismic Hazard Model Update. The 2023 50-State National Seimsic Hazard Model (NSHM) Update includes an update to the NSHMs for the conterminous U.S (CONUS, last updated in 2018), Alaska (AK, last updated in 2007), and Hawaii (last updated in 2001). Data sets include inputs like seismicity catalogs used as input to the
Strike-slip in transtension: Complex crustal architecture of the Warm Springs Valley fault zone, northern Walker Lane
This data release contains field data for two P-wave seismic reflection profiles acquired across the Warm Springs Valley fault zone, part of the Northern Walker Lane, NV. The dataset consists of high-resolution seismic reflection field records in .segy format, shot coordinates in .csv format, and observers? logs in .pdf format. The high-resolution seismic profiles are approximately 4 km long. The
Seismic reflection imaging of the low-angle Panamint normal fault system, eastern California, 2018
A fundamental question in seismic hazard analysis is whether
Digital datasets documenting subsurface data locations, topographic metrics, fault scarp mapping, and revised fault network for Crowley's Ridge, New Madrid Seismic Zone
This release provides the data and interpretations supporting evidence of late Quaternary faulting along Crowleys Ridge in the New Madrid seismic zone. The release includes location information for seismic reflection and airborne electromagnetic (AEM) data over Crowleys Ridge, a table of topographic metrics derived from analysis of the 10m National Elevation Dataset (NED) digital elevation model (
Spatially averaged coherencies (krSPAC) and Rayleigh effective-mode modeling of microtremor data from asymmetric arrays
The datasets for this investigation consist of microtremor array data collected at sites in San Jose, California, Pleasanton, California, and synthetic microtremor array data created as part of a blind shear-wave velocity modeling study as part of the Third International Symposium on the Effects of Surface Geology on Seismic Motion (ESG2006), Grenoble, France, 30 August - 1 September 2006. The dat
A Bayesian Monte-Carlo Inversion of Spatial Auto-Correlation (SPAC) for Near-Surface Vs Structure Applied to Both Broadband and Geophone Data - Data Release
The datasets for this investigation consist of microtremor array data collected at: 1) 18 sites in Salt Lake and Utah valleys, Utah, and 2) two sites as part of the Frontier Observatory for Research in Geothermal Energy (FORGE) near Milford, Utah. Each of the 18 sites in the Salt Lake and Utah valleys were acquired with four-sensor arrays with three-component (3C) sensors having flat response from
Shear-wave velocity in the Seattle basin to 2 km depth characterized with the krSPAC microtremor array method: insights for urban basin-scale imaging - Data Release
The dataset for this investigation consists of microtremor array data collected at 11 sites in the Seattle basin, Washington State. Ten of the arrays consisted of seven Nanometrics Trillium Compact broadband sensors deployed in asymmetric nested triangles (sites ST01, BA02, SP04, LF05, UW06, SN07, RD08, EL09, CH10, and KG11) that recorded for up to six hours. The eleventh array, at site NW03, was
Data for Holocene fault reactivation in the eastern Cascades, WA
Significant uncertainty remains in how and where crustal shortening occurs throughout the eastern Cascade Range in Washington State. Using lidar imagery, we identified a ~5 km long lineament in Swakane canyon near Wenatchee, roughly coincident with a strand of the Entiat fault. Topographic profiles across the lineament reveal a southwest-side-up break in slope with an average of ~3 m of vertical s
Data for P- and S-wave Seismic Velocity Models Incorporating the Cascadia Subduction Zone for 3D Earthquake Ground Motion simulations- Update for Open-File Report 2007-1348
The data for this release is an ASCII file containing grid points of Cascadia P- and S-wave velocity models. The model volume was developed to include the Cascadia subduction zone for purposes of ground motion simulation. The description of the model and background of its development is provided in the associated Open-File Report. The grid points are given in Universal Transverse Mercator (UTM) Zo
Filter Total Items: 53
Empirical ground-motion basin response in the California Great Valley, Reno, Nevada, and Portland, Oregon
We assess how well the Next-Generation Attenuation-West 2 (NGA-West2) ground-motion models (GMMs), which are used in the US Geological Survey’s (USGS) National Seismic Hazard Model (NSHM) for crustal faults in the western United States, predict the observed basin response in the Great Valley of California, the Reno basin in Nevada, and Portland and Tualatin basins in Oregon. These GMMs rely on sit
Authors
Sean Kamran Ahdi, Brad T. Aagaard, Morgan P. Moschetti, Grace Alexandra Parker, Oliver S. Boyd, William J. Stephenson
The 2023 US 50-State National Seismic Hazard Model: Overview and implications
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 for public policy and other engineering applications (defined for return periods greater than ∼475 or less than ∼10,000 years). Changes in 2023 time-independent seismic hazard (both increase
Authors
Mark D. Petersen, Allison Shumway, Peter M. Powers, Ned Field, Morgan P. Moschetti, Kishor S. Jaiswal, Kevin R. Milner, Sanaz Rezaeian, Arthur Frankel, Andrea L. Llenos, Andrew J. Michael, Jason M. Altekruse, Sean Kamran Ahdi, Kyle Withers, Charles Mueller, Yuehua Zeng, Robert E. Chase, Leah M. Salditch, Nico Luco, Kenneth S. Rukstales, Julie A Herrick, Demi Leafar Girot, Brad T. Aagaard, Adrian Bender, Michael L. Blanpied, Richard W. Briggs, Oliver S. Boyd, Brandon Clayton, Christopher DuRoss, Eileen L. Evans, Peter J. Haeussler, Alexandra Elise Hatem, Kirstie Lafon Haynie, Elizabeth H. Hearn, Kaj M. Johnson, Zachary Alan Kortum, N. Simon Kwong, Andrew James Makdisi, Henry (Ben) Mason, Daniel McNamara, Devin McPhillips, P. Okubo, Morgan T. Page, Frederick Pollitz, Justin Rubinstein, Bruce E. Shaw, Zheng-Kang Shen, Brian Shiro, James Andrew Smith, William J. Stephenson, Eric M. Thompson, Jessica Ann Thompson Jobe, Erin Wirth, Robert C. Witter
Implementation of basin models and sediment depth terms in the 2023 update of the U.S. National Seismic Hazard Model: Example from Reno, Nevada
We present a framework to evaluate the inclusion of candidate basin depth models in the U.S. Geological Survey National Seismic Hazard Model. We compute intensity measures (peak and spectral amplitudes) from uniformly processed earthquake ground motions in and around the basin of interest and compare these to ground-motion model (GMM) estimates over a range of oscillator periods. The GMMs use dept
Authors
Sean Kamran Ahdi, Morgan P. Moschetti, Brad T. Aagaard, Kaitlyn Abernathy, Oliver S. Boyd, William J. Stephenson
Introduction to the special issue of the Consortium of Organizations for Strong Motion Observation Systems (COSMOS) international guidelines for applying noninvasive geophysical techniques to characterize seismic site conditions
Knowledge about local seismic site conditions provides critical information to account for site effects that are commonly observed in strong motion recordings. Certainly, other wave propagation effects can influence these observations, which are attributable to variations in material properties of the paths traveled by the waves, as well as the characteristics of the seismic source. However, local
Authors
Alan Yong, Aysegul Askan, John Cassidy, Sebastiano D'Amico, Stefano Parolai, Marco Pilz, William J. Stephenson
Flexible multimethod approach for seismic site characterization
We describe the flexible multimethod seismic site characterization technique for obtaining shear-wave velocity (VS) profiles and derivative information, such as the time-averaged VS of the upper 30 m (VS30). Simply stated, the multimethod approach relies on the application of multiple independent noninvasive site characterization acquisition and analysis techniques utilized in a flexible field-bas
Authors
William J. Stephenson, Alan Yong, Antony Martin
Microtremor array method using spatial autocorrelation analysis of Rayleigh‑wave data
Microtremor array measurements (MAM) and passive surface wave methods in general, have been increasingly used to non-invasively estimate shear-wave velocity structures (Vs) for various purposes. The methods estimate dispersion curves and invert them for retrieving S-wave velocity profiles. This paper summarizes principles, limitations, data collection and processing methods. It intends to enable s
Authors
Koichi Hayashi, Michael W. Asten, William J. Stephenson, Cécile Cornou, Manuel Hobiger, Marco Pilz, Hiroaki Yamanaka
Seismic site characterization with shear wave (SH) reflection and refraction methods
Reflection and critically refracted seismic methods use traveltime measurements of body waves propagating between a source and a series of receivers on the ground surface to calculate subsurface velocities. Body wave energy is refracted or reflected at boundaries where there is a change in seismic impedance, defined as the product of material density and seismic velocity. This article provides pra
Authors
James A. Hunter, Heather L. Crow, William J. Stephenson, André J.-M. Pugin, Robert Williams, James B. Harris, Jackson K. Odum, Edward W Woolery
An assessment of uncertainties in VS profiles obtained from microtremor observations in the phased 2018 COSMOS blind trials
Site response is a critical consideration when assessing earthquake hazards. Site characterization is key to understanding site effects as influenced by seismic site conditions of the local geology. Thus, a number of geophysical site characterization methods were developed to meet the demand for accurate and cost-effective results. As a consequence, a number of studies have been administered perio
Authors
Michael W. Asten, Alan Yong, Sebastiano Foti, Koichi Hayashi, Antony J. Martin, William J. Stephenson, John F. Cassidy, Jacie Coleman, Robert L. Nigbor, Silvia Castellaro, Kosuke Chimoto, Ikuo Cho, Cécile Cornou, Takumi Hayashida, Manuel Hobiger, Chun-Hsiang Kuo, Albert Macau, E. Diego Mercerat, Sheri Molnar, Passakorn Pananont, Marco Pilz, Nakhorn Poovarodom, Esteban Sáez, Marc Wathelet, Hiroaki Yamanaka, Toshiaki Yokoi, Don Zhao
Geophysical constraints on the crustal architecture of the transtensional Warm Springs Valley fault zone, northern Walker Lane, western Nevada, USA
The Walker Lane is a zone of distributed transtension where normal faults are overprinted by strike-slip motion. We use two newly-acquired high-resolution seismic reflection profiles and a reprocessed Consortium for Continental Reflection Profiling (COCORP) deep crustal reflection profile to assess the subsurface geometry of the Holocene-active, transtensional Warm Springs Valley fault zone (WSVFZ
Authors
Richard W. Briggs, William J. Stephenson, J.H. McBride, Jackson K. Odum, Nadine G. Reitman, Ryan D. Gold
Shear-wave velocity site characterization in Oklahoma from joint inversion of multi-method surface seismic measurements: Implications for central U.S. Ground Motion Prediction
We analyze multimethod shear (SH)‐wave velocity (VS) site characterization data acquired at three permanent and 25 temporary seismograph stations in Oklahoma that recorded M 4+ earthquakes within a 50 km hypocentral distance of at least one of the 2016 M 5.1 Fairview, M 5.8 Pawnee, or M 5.0 Cushing earthquakes to better constrain earthquake ground‐motion modeling in the region. We acquired active
Authors
William J. Stephenson, Jackson K. Odum, Stephen H. Hartzell, Alena L. Leeds, Robert Williams
Seismic reflection imaging of the low-angle Panamint normal fault system, eastern California
Shallowly dipping (<30°) low‐angle normal faults (LANFs) have been documented globally; however, examples of active LANFs in continental settings are limited. The western margin of the Panamint Range in eastern California is defined by a LANF that dips west beneath Panamint Valley and has evidence of Quaternary motion. In addition, high‐angle dextral‐oblique normal faults displace middle to late Q
Authors
Ryan D. Gold, William J. Stephenson, Richard W. Briggs, Christopher DuRoss, Eric Kirby, Edward W Woolery, Jaime Delano, Jackson K. Odum
Graphical Dispersion Plot Editor (DPE) for seismic-site characterization by using multiple surface-wave methods
IntroductionTo understand the behavior of potentially damaging ground motions during earthquakes, seismic-site effects are routinely characterized by using the dispersion of surface waves. Many methods exist to measure dispersion; these methods have various advantages and disadvantages, but they all yield dispersion data that must be inverted for shear-wave velocity. This report presents a graphic
Authors
Devin McPhillips, Alan K. Yong, Antony Martin, William J. Stephenson