William J Stephenson
Bill Stephensen is a scientist in the Earthquake Hazards Program.
Science and Products
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P- and S-wave velocity models incorporating the Cascadia subduction zone for 3D earthquake ground motion simulations, Version 1.6—Update for Open-File Report 2007–1348 P- and S-wave velocity models incorporating the Cascadia subduction zone for 3D earthquake ground motion simulations, Version 1.6—Update for Open-File Report 2007–1348
In support of earthquake hazard studies and ground motion simulations in the Pacific Northwest, three-dimensional P- and S-wave velocity (VP and VS, respectively) models incorporating the Cascadia subduction zone were previously developed for the region encompassed from about 40.2°N. to 50°N. latitude, and from about 122°W. to 129°W. longitude. This report describes updates to the...
Authors
William J. Stephenson, Nadine G. Reitman, Stephen J. Angster
Geophysical characterization of seismic station sites in the United States – The importance of a flexible, multi-method approach Geophysical characterization of seismic station sites in the United States – The importance of a flexible, multi-method approach
Noninvasive geophysical site characterization methods were used in two recent projects to obtain shear-wave velocity (VS) profiles to a minimum depth of 30 m and the time-averaged VS of the upper 30 meters (VS30) at seismic station sites. These projects include the 2009 American Recovery and Reinvestment Act (ARRA) funded U.S. Geological Survey site characterization project for 191 sites...
Authors
Antony Martin, Alan Yong, William J. Stephenson, J. Boatwright, John Diehl
3D ground‐motion simulations of Mw 7 earthquakes on the Salt Lake City segment of the Wasatch fault zone: Variability of long‐period (T≥1 s) ground motions and sensitivity to kinematic rupture parameters 3D ground‐motion simulations of Mw 7 earthquakes on the Salt Lake City segment of the Wasatch fault zone: Variability of long‐period (T≥1 s) ground motions and sensitivity to kinematic rupture parameters
We examine the variability of long‐period (T≥1 s) earthquake ground motions from 3D simulations of Mw 7 earthquakes on the Salt Lake City segment of the Wasatch fault zone, Utah, from a set of 96 rupture models with varying slip distributions, rupture speeds, slip velocities, and hypocenter locations. Earthquake ruptures were prescribed on a 3D fault representation that satisfies...
Authors
Morgan P. Moschetti, Stephen H. Hartzell, Leonardo Ramirez-Guzman, Arthur D. Frankel, Stephen J. Angster, William J. Stephenson
The story of a Yakima fold and how it informs Late Neogene and Quaternary backarc deformation in the Cascadia subduction zone, Manastash anticline, Washington, USA The story of a Yakima fold and how it informs Late Neogene and Quaternary backarc deformation in the Cascadia subduction zone, Manastash anticline, Washington, USA
The Yakima folds of central Washington, USA, are prominent anticlines that are the primary tectonic features of the backarc of the northern Cascadia subduction zone. What accounts for their topographic expression and how much strain do they accommodate and over what time period? We investigate Manastash anticline, a north vergent fault propagation fold typical of structures in the fold...
Authors
Harvey M. Kelsey, Tyler C. Ladinsky, Lydia M. Staisch, Brian Sherrod, Richard J. Blakely, Thomas Pratt, William J. Stephenson, Jackson K. Odum, Elmira Wan
3-D simulations of M9 earthquakes on the Cascadia Megathrust: Key parameters and uncertainty 3-D simulations of M9 earthquakes on the Cascadia Megathrust: Key parameters and uncertainty
Geologic and historical records indicate that the Cascadia subduction zone is capable of generating large, megathrust earthquakes up to magnitude 9. The last great Cascadia earthquake occurred in 1700, and thus there is no direct measure on the intensity of ground shaking or specific rupture parameters from seismic recordings. We use 3-D numerical simulations to generate broadband (0-10...
Authors
Erin Wirth, Arthur D. Frankel, John Vidale, Nasser A. Marafi, William J. Stephenson
Continuity of the Reelfoot fault across the Cottonwood Grove and Ridgely faults of the New Madrid Seismic Zone Continuity of the Reelfoot fault across the Cottonwood Grove and Ridgely faults of the New Madrid Seismic Zone
Previous investigators have argued that the northwest-striking Reelfoot fault of northwest Tennessee and southeastern Missouri is segmented. One segment boundary is at the intersection of the northeast-striking Cottonwood Grove and Ridgely strike-slip faults with the Reelfoot fault. We use seismic reflection and geologic mapping to locate and determine the history of the Reelfoot South...
Authors
M.L. Greenwood, Edward W Woolery, R. B. Van Arsdale, William J. Stephenson, Gary L. Patterson
The Evergreen basin and the role of the Silver Creek fault in the San Andreas fault system, San Francisco Bay region, California The Evergreen basin and the role of the Silver Creek fault in the San Andreas fault system, San Francisco Bay region, California
The Evergreen basin is a 40-km-long, 8-km-wide Cenozoic sedimentary basin that lies mostly concealed beneath the northeastern margin of the Santa Clara Valley near the south end of San Francisco Bay (California, USA). The basin is bounded on the northeast by the strike-slip Hayward fault and an approximately parallel subsurface fault that is structurally overlain by a set of west-verging...
Authors
Robert C. Jachens, Carl M. Wentworth, Russell W. Graymer, Robert Williams, David A. Ponce, Edward A. Mankinen, William J. Stephenson, Victoria E. Langenheim
Seismic imaging beneath an InSAR anomaly in eastern Washington State: Shallow faulting associated with an earthquake swarm in a low-hazard area Seismic imaging beneath an InSAR anomaly in eastern Washington State: Shallow faulting associated with an earthquake swarm in a low-hazard area
In 2001, a rare swarm of small, shallow earthquakes beneath the city of Spokane, Washington, caused ground shaking as well as audible booms over a five‐month period. Subsequent Interferometric Synthetic Aperture Radar (InSAR) data analysis revealed an area of surface uplift in the vicinity of the earthquake swarm. To investigate the potential faults that may have caused both the...
Authors
William J. Stephenson, Jackson K. Odum, Charles W. Wicks, Thomas L. Pratt, Richard J. Blakely
Preliminary assessment of a previously unknown fault zone beneath the Daytona Beach sand blow cluster near Marianna, Arkansas Preliminary assessment of a previously unknown fault zone beneath the Daytona Beach sand blow cluster near Marianna, Arkansas
We collected new high‐resolution P‐wave seismic‐reflection data to explore for possible faults beneath a roughly linear cluster of early to mid‐Holocene earthquake‐induced sand blows to the south of Marianna, Arkansas. The Daytona Beach sand blow deposits are located in east‐central Arkansas about 75 km southwest of Memphis, Tennessee, and about 80 km south of the southwestern end of the...
Authors
Jackson K. Odum, Robert Williams, William J. Stephenson, Martitia P. Tuttle, Hadar Al-Shukri
Comparisons between vs30 and spectral response for 30 sites in Newcastle, Australia from collocated seismic cone penetrometer, active- and passive-source vs data Comparisons between vs30 and spectral response for 30 sites in Newcastle, Australia from collocated seismic cone penetrometer, active- and passive-source vs data
Although the time‐averaged shear‐wave velocity down to 30 m depth (VS30) can be a proxy for estimating earthquake ground‐motion amplification, significant controversy exists about its limitations when used as a single parameter for the prediction of amplification. To examine this question in absence of relevant strong‐motion records, we use a range of different methods to measure the...
Authors
Theodora Volti, David Burbidge, Clive Collins, Michael W. Asten, Jackson K. Odum, William J. Stephenson, Chris Pascal, Josef Holzschuh
High-resolution seismic reflection imaging of growth folding and shallow faults beneath the Southern Puget Lowland, Washington State High-resolution seismic reflection imaging of growth folding and shallow faults beneath the Southern Puget Lowland, Washington State
Marine seismic reflection data from southern Puget Sound, Washington, were collected to investigate the nature of shallow structures associated with the Tacoma fault zone and the Olympia structure. Growth folding and probable Holocene surface deformation were imaged within the Tacoma fault zone beneath Case and Carr Inlets. Shallow faults near potential field anomalies associated with...
Authors
Jackson K. Odum, William J. Stephenson, Thomas L. Pratt, Richard J. Blakely
Compilation of VS30 Data for the United States Compilation of VS30 Data for the United States
VS30, the time-averaged shear-wave velocity (VS) to a depth of 30 meters, is a key index adopted by the earthquake engineering community to account for seismic site conditions. VS30 is typically based on geophysical measurements of VS derived from invasive and noninvasive techniques at sites of interest. Owing to cost considerations, as well as logistical and environmental concerns, VS30...
Authors
Alan Yong, Eric M. Thompson, David J. Wald, Keith L. Knudsen, Jack K. Odum, William J. Stephenson, Scott Haefner
Science and Products
Filter Total Items: 15
No Result Found
Filter Total Items: 64
P- and S-wave velocity models incorporating the Cascadia subduction zone for 3D earthquake ground motion simulations, Version 1.6—Update for Open-File Report 2007–1348 P- and S-wave velocity models incorporating the Cascadia subduction zone for 3D earthquake ground motion simulations, Version 1.6—Update for Open-File Report 2007–1348
In support of earthquake hazard studies and ground motion simulations in the Pacific Northwest, three-dimensional P- and S-wave velocity (VP and VS, respectively) models incorporating the Cascadia subduction zone were previously developed for the region encompassed from about 40.2°N. to 50°N. latitude, and from about 122°W. to 129°W. longitude. This report describes updates to the...
Authors
William J. Stephenson, Nadine G. Reitman, Stephen J. Angster
Geophysical characterization of seismic station sites in the United States – The importance of a flexible, multi-method approach Geophysical characterization of seismic station sites in the United States – The importance of a flexible, multi-method approach
Noninvasive geophysical site characterization methods were used in two recent projects to obtain shear-wave velocity (VS) profiles to a minimum depth of 30 m and the time-averaged VS of the upper 30 meters (VS30) at seismic station sites. These projects include the 2009 American Recovery and Reinvestment Act (ARRA) funded U.S. Geological Survey site characterization project for 191 sites...
Authors
Antony Martin, Alan Yong, William J. Stephenson, J. Boatwright, John Diehl
3D ground‐motion simulations of Mw 7 earthquakes on the Salt Lake City segment of the Wasatch fault zone: Variability of long‐period (T≥1 s) ground motions and sensitivity to kinematic rupture parameters 3D ground‐motion simulations of Mw 7 earthquakes on the Salt Lake City segment of the Wasatch fault zone: Variability of long‐period (T≥1 s) ground motions and sensitivity to kinematic rupture parameters
We examine the variability of long‐period (T≥1 s) earthquake ground motions from 3D simulations of Mw 7 earthquakes on the Salt Lake City segment of the Wasatch fault zone, Utah, from a set of 96 rupture models with varying slip distributions, rupture speeds, slip velocities, and hypocenter locations. Earthquake ruptures were prescribed on a 3D fault representation that satisfies...
Authors
Morgan P. Moschetti, Stephen H. Hartzell, Leonardo Ramirez-Guzman, Arthur D. Frankel, Stephen J. Angster, William J. Stephenson
The story of a Yakima fold and how it informs Late Neogene and Quaternary backarc deformation in the Cascadia subduction zone, Manastash anticline, Washington, USA The story of a Yakima fold and how it informs Late Neogene and Quaternary backarc deformation in the Cascadia subduction zone, Manastash anticline, Washington, USA
The Yakima folds of central Washington, USA, are prominent anticlines that are the primary tectonic features of the backarc of the northern Cascadia subduction zone. What accounts for their topographic expression and how much strain do they accommodate and over what time period? We investigate Manastash anticline, a north vergent fault propagation fold typical of structures in the fold...
Authors
Harvey M. Kelsey, Tyler C. Ladinsky, Lydia M. Staisch, Brian Sherrod, Richard J. Blakely, Thomas Pratt, William J. Stephenson, Jackson K. Odum, Elmira Wan
3-D simulations of M9 earthquakes on the Cascadia Megathrust: Key parameters and uncertainty 3-D simulations of M9 earthquakes on the Cascadia Megathrust: Key parameters and uncertainty
Geologic and historical records indicate that the Cascadia subduction zone is capable of generating large, megathrust earthquakes up to magnitude 9. The last great Cascadia earthquake occurred in 1700, and thus there is no direct measure on the intensity of ground shaking or specific rupture parameters from seismic recordings. We use 3-D numerical simulations to generate broadband (0-10...
Authors
Erin Wirth, Arthur D. Frankel, John Vidale, Nasser A. Marafi, William J. Stephenson
Continuity of the Reelfoot fault across the Cottonwood Grove and Ridgely faults of the New Madrid Seismic Zone Continuity of the Reelfoot fault across the Cottonwood Grove and Ridgely faults of the New Madrid Seismic Zone
Previous investigators have argued that the northwest-striking Reelfoot fault of northwest Tennessee and southeastern Missouri is segmented. One segment boundary is at the intersection of the northeast-striking Cottonwood Grove and Ridgely strike-slip faults with the Reelfoot fault. We use seismic reflection and geologic mapping to locate and determine the history of the Reelfoot South...
Authors
M.L. Greenwood, Edward W Woolery, R. B. Van Arsdale, William J. Stephenson, Gary L. Patterson
The Evergreen basin and the role of the Silver Creek fault in the San Andreas fault system, San Francisco Bay region, California The Evergreen basin and the role of the Silver Creek fault in the San Andreas fault system, San Francisco Bay region, California
The Evergreen basin is a 40-km-long, 8-km-wide Cenozoic sedimentary basin that lies mostly concealed beneath the northeastern margin of the Santa Clara Valley near the south end of San Francisco Bay (California, USA). The basin is bounded on the northeast by the strike-slip Hayward fault and an approximately parallel subsurface fault that is structurally overlain by a set of west-verging...
Authors
Robert C. Jachens, Carl M. Wentworth, Russell W. Graymer, Robert Williams, David A. Ponce, Edward A. Mankinen, William J. Stephenson, Victoria E. Langenheim
Seismic imaging beneath an InSAR anomaly in eastern Washington State: Shallow faulting associated with an earthquake swarm in a low-hazard area Seismic imaging beneath an InSAR anomaly in eastern Washington State: Shallow faulting associated with an earthquake swarm in a low-hazard area
In 2001, a rare swarm of small, shallow earthquakes beneath the city of Spokane, Washington, caused ground shaking as well as audible booms over a five‐month period. Subsequent Interferometric Synthetic Aperture Radar (InSAR) data analysis revealed an area of surface uplift in the vicinity of the earthquake swarm. To investigate the potential faults that may have caused both the...
Authors
William J. Stephenson, Jackson K. Odum, Charles W. Wicks, Thomas L. Pratt, Richard J. Blakely
Preliminary assessment of a previously unknown fault zone beneath the Daytona Beach sand blow cluster near Marianna, Arkansas Preliminary assessment of a previously unknown fault zone beneath the Daytona Beach sand blow cluster near Marianna, Arkansas
We collected new high‐resolution P‐wave seismic‐reflection data to explore for possible faults beneath a roughly linear cluster of early to mid‐Holocene earthquake‐induced sand blows to the south of Marianna, Arkansas. The Daytona Beach sand blow deposits are located in east‐central Arkansas about 75 km southwest of Memphis, Tennessee, and about 80 km south of the southwestern end of the...
Authors
Jackson K. Odum, Robert Williams, William J. Stephenson, Martitia P. Tuttle, Hadar Al-Shukri
Comparisons between vs30 and spectral response for 30 sites in Newcastle, Australia from collocated seismic cone penetrometer, active- and passive-source vs data Comparisons between vs30 and spectral response for 30 sites in Newcastle, Australia from collocated seismic cone penetrometer, active- and passive-source vs data
Although the time‐averaged shear‐wave velocity down to 30 m depth (VS30) can be a proxy for estimating earthquake ground‐motion amplification, significant controversy exists about its limitations when used as a single parameter for the prediction of amplification. To examine this question in absence of relevant strong‐motion records, we use a range of different methods to measure the...
Authors
Theodora Volti, David Burbidge, Clive Collins, Michael W. Asten, Jackson K. Odum, William J. Stephenson, Chris Pascal, Josef Holzschuh
High-resolution seismic reflection imaging of growth folding and shallow faults beneath the Southern Puget Lowland, Washington State High-resolution seismic reflection imaging of growth folding and shallow faults beneath the Southern Puget Lowland, Washington State
Marine seismic reflection data from southern Puget Sound, Washington, were collected to investigate the nature of shallow structures associated with the Tacoma fault zone and the Olympia structure. Growth folding and probable Holocene surface deformation were imaged within the Tacoma fault zone beneath Case and Carr Inlets. Shallow faults near potential field anomalies associated with...
Authors
Jackson K. Odum, William J. Stephenson, Thomas L. Pratt, Richard J. Blakely
Compilation of VS30 Data for the United States Compilation of VS30 Data for the United States
VS30, the time-averaged shear-wave velocity (VS) to a depth of 30 meters, is a key index adopted by the earthquake engineering community to account for seismic site conditions. VS30 is typically based on geophysical measurements of VS derived from invasive and noninvasive techniques at sites of interest. Owing to cost considerations, as well as logistical and environmental concerns, VS30...
Authors
Alan Yong, Eric M. Thompson, David J. Wald, Keith L. Knudsen, Jack K. Odum, William J. Stephenson, Scott Haefner