William J Stephenson
Bill Stephensen is a scientist in the Earthquake Hazards Program.
Science and Products
Filter Total Items: 15
Data Release for the 2023 U.S. 50-State National Seismic Hazard Model - Overview 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...
Strike-slip in transtension: Complex crustal architecture of the Warm Springs Valley fault zone, northern Walker Lane 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...
Seismic reflection imaging of the low-angle Panamint normal fault system, eastern California, 2018 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 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...
Spatially averaged coherencies (krSPAC) and Rayleigh effective-mode modeling of microtremor data from asymmetric arrays 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...
A Bayesian Monte-Carlo Inversion of Spatial Auto-Correlation (SPAC) for Near-Surface Vs Structure Applied to Both Broadband and Geophone Data - Data Release 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...
Filter Total Items: 63
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 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...
Authors
Alan Yong, Aysegul Askan, John Cassidy, Sebastiano D’Amico, Stefano Parolai, Marco Pilz, William Stephenson
Flexible multimethod approach for seismic site characterization 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...
Authors
William Stephenson, Alan Yong, Antony Martin
Microtremor array method using spatial autocorrelation analysis of Rayleigh‑wave data 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...
Authors
Koichi Hayashi, Michael Asten, William Stephenson, Cecile Cornou, Manuel Hobiger, Marco Pilz, Hiroaki Yamanaka
Seismic site characterization with shear wave (SH) reflection and refraction methods 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...
Authors
James Hunter, Heather Crow, William Stephenson, Andre Pugin, Robert Williams, James Harris, Jackson Odum, Edward Woolery
An assessment of uncertainties in VS profiles obtained from microtremor observations in the phased 2018 COSMOS blind trials 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...
Authors
Michael Asten, Alan Yong, Sebastiano Foti, Koichi Hayashi, Antony Martin, William Stephenson, John Cassidy, Jacie Coleman, Robert Nigbor, Silvia Castellaro, Kosuke Chimoto, Ikuo Cho, Cecile Cornou, Takumi Hayashida, Manuel Hobiger, Chun-Hsiang Kuo, Albert Macau, E. Mercerat, Sheri Molnar, Passakorn Pananont, Marco Pilz, Nakhorn Poovarodom, Esteban Saez, 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 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...
Authors
Richard Briggs, William Stephenson, J.H. McBride, Jackson K. Odum, Nadine Reitman, Ryan Gold
Science and Products
Filter Total Items: 15
Data Release for the 2023 U.S. 50-State National Seismic Hazard Model - Overview 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...
Strike-slip in transtension: Complex crustal architecture of the Warm Springs Valley fault zone, northern Walker Lane 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...
Seismic reflection imaging of the low-angle Panamint normal fault system, eastern California, 2018 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 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...
Spatially averaged coherencies (krSPAC) and Rayleigh effective-mode modeling of microtremor data from asymmetric arrays 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...
A Bayesian Monte-Carlo Inversion of Spatial Auto-Correlation (SPAC) for Near-Surface Vs Structure Applied to Both Broadband and Geophone Data - Data Release 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...
Filter Total Items: 63
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 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...
Authors
Alan Yong, Aysegul Askan, John Cassidy, Sebastiano D’Amico, Stefano Parolai, Marco Pilz, William Stephenson
Flexible multimethod approach for seismic site characterization 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...
Authors
William Stephenson, Alan Yong, Antony Martin
Microtremor array method using spatial autocorrelation analysis of Rayleigh‑wave data 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...
Authors
Koichi Hayashi, Michael Asten, William Stephenson, Cecile Cornou, Manuel Hobiger, Marco Pilz, Hiroaki Yamanaka
Seismic site characterization with shear wave (SH) reflection and refraction methods 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...
Authors
James Hunter, Heather Crow, William Stephenson, Andre Pugin, Robert Williams, James Harris, Jackson Odum, Edward Woolery
An assessment of uncertainties in VS profiles obtained from microtremor observations in the phased 2018 COSMOS blind trials 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...
Authors
Michael Asten, Alan Yong, Sebastiano Foti, Koichi Hayashi, Antony Martin, William Stephenson, John Cassidy, Jacie Coleman, Robert Nigbor, Silvia Castellaro, Kosuke Chimoto, Ikuo Cho, Cecile Cornou, Takumi Hayashida, Manuel Hobiger, Chun-Hsiang Kuo, Albert Macau, E. Mercerat, Sheri Molnar, Passakorn Pananont, Marco Pilz, Nakhorn Poovarodom, Esteban Saez, 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 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...
Authors
Richard Briggs, William Stephenson, J.H. McBride, Jackson K. Odum, Nadine Reitman, Ryan Gold