William J Stephenson
Bill Stephensen is a scientist in the Earthquake Hazards Program.
Science and Products
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Sedimentary basin effects in Seattle, Washington: Ground-motion observations and 3D simulations Sedimentary basin effects in Seattle, Washington: Ground-motion observations and 3D simulations
Seismograms of local earthquakes recorded in Seattle exhibit surface waves in the Seattle basin and basin-edge focusing of S waves. Spectral ratios of Swaves and later arrivals at 1 Hz for stiff-soil sites in the Seattle basin show a dependence on the direction to the earthquake, with earthquakes to the south and southwest producing higher average amplification. Earthquakes to the...
Authors
Arthur Frankel, William Stephenson, David Carver
Velocity and Density Models Incorporating the Cascadia Subduction Zone for 3D Earthquake Ground Motion Simulations Velocity and Density Models Incorporating the Cascadia Subduction Zone for 3D Earthquake Ground Motion Simulations
In support of earthquake hazards and ground motion studies in the Pacific Northwest, three-dimensional P- and S-wave velocity (3D Vp and Vs) and density (3D rho) models incorporating the Cascadia subduction zone have been developed for the region encompassed from about 40.2°N to 50°N latitude, and from about -122°W to -129°W longitude. The model volume includes elevations from 0 km to 60...
Authors
William J. Stephenson
Seismic Hazard Maps for Seattle, Washington, Incorporating 3D Sedimentary Basin Effects, Nonlinear Site Response, and Rupture Directivity Seismic Hazard Maps for Seattle, Washington, Incorporating 3D Sedimentary Basin Effects, Nonlinear Site Response, and Rupture Directivity
This report presents probabilistic seismic hazard maps for Seattle, Washington, based on over 500 3D simulations of ground motions from scenario earthquakes. These maps include 3D sedimentary basin effects and rupture directivity. Nonlinear site response for soft-soil sites of fill and alluvium was also applied in the maps. The report describes the methodology for incorporating source...
Authors
Arthur D. Frankel, William J. Stephenson, David L. Carver, Robert A. Williams, Jack K. Odum, Susan Rhea
Near-Surface Shear Wave Velocity Versus Depth Profiles, VS30, and NEHRP Classifications for 27 Sites in Puerto Rico Near-Surface Shear Wave Velocity Versus Depth Profiles, VS30, and NEHRP Classifications for 27 Sites in Puerto Rico
In 2004 and 2005 the Puerto Rico Seismic Network (PRSN), Puerto Rico Strong Motion Program (PRSMP) and the Geology Department at the University of Puerto Rico-Mayaguez (UPRM) collaborated with the U.S. Geological Survey to study near-surface shear-wave (Vs) and compressional-wave (Vp) velocities in and around major urban areas of Puerto Rico. Using noninvasive seismic refraction...
Authors
Jack K. Odum, Robert A. Williams, William J. Stephenson, David M. Worley, Christa von Hillebrandt-Andrade, Eugenio Asencio, Harold Irizarry, Antonio Cameron
Wagon loads of sand blows in White County, Illinois Wagon loads of sand blows in White County, Illinois
Several anecdotal accounts provide compelling evidence that liquefaction occurred at several sites in Illinois during the 1811-1812 New Madrid sequence, as much as 250 km north of the New Madrid seismic zone (NMSZ). At one Wabash Valley location, sand blows are still evident near Big Prairie, Illinois, a location described in a particularly detailed and precise historic account. This...
Authors
Susan E. Hough, Roger Bilham, Karl Mueller, William Stephenson, Robert Williams, Jack Odum
High-Resolution Imaging within the Urban Environment -- "What's beneath our streets"! High-Resolution Imaging within the Urban Environment -- "What's beneath our streets"!
No abstract available.
Authors
Jackson K. Odum, Robert A. Williams, William J. Stephenson, David M. Worley
Shear- and compressional- wave velocity measurements from two 150-m-deep boreholes in Seattle, Washington, USA Shear- and compressional- wave velocity measurements from two 150-m-deep boreholes in Seattle, Washington, USA
No abstract available.
Authors
Jack K. Odum, William J. Stephenson, Kathy Goetz-Troost, David M. Worley, Arthur D. Frankel, Robert A. Williams, Jake Fryer
Seismic Velocities from High-Resolution Surface-Seismic Imaging at Six ANSS Sites near Memphis, Tennessee Seismic Velocities from High-Resolution Surface-Seismic Imaging at Six ANSS Sites near Memphis, Tennessee
No abstract available.
Authors
Robert A. Williams, William J. Stephenson, Jack K. Odum, David M. Worley
Near-surface S-wave and P-wave seismic velocities of primary geological formations on the Piedmont and Atlantic Coastal Plain of South Carolina, USA Near-surface S-wave and P-wave seismic velocities of primary geological formations on the Piedmont and Atlantic Coastal Plain of South Carolina, USA
No abstract available.
Authors
Jack K. Odum, Robert A. Williams, William J. Stephenson, David M. Worley
Reconnaissance shallow seismic investigation of depth-to-bedrock and possible methane-bearing coalbeds, Galena, Alaska Reconnaissance shallow seismic investigation of depth-to-bedrock and possible methane-bearing coalbeds, Galena, Alaska
A reconnaissance shallow seismic reflection/refraction investigation in and around the city of Galena, Alaska suggests that Tertiary and/or Cretaceous bedrock, and possible coalbeds within the Cretaceous, is at least as deep as 550 feet in the immediate vicinity of town. Rock could be deeper than 1000 feet under alternate interpretations. Reflections recorded in these data are believed...
Authors
William J. Stephenson, Robert A. Williams, Jack K. Odum, David M. Worley, Charles E. Barker, Arthur C. Clark, James G. Clough
Interpreting the earthquake source of the Wabash Valley seismic zone (Illinois, Indiana, and Kentucky) from seismic-reflection, gravity, and magnetic-intensity data Interpreting the earthquake source of the Wabash Valley seismic zone (Illinois, Indiana, and Kentucky) from seismic-reflection, gravity, and magnetic-intensity data
Reprocessing of seismic-reflection data reveals new images of upper- to middle-crustal structures beneath the Wabash Valley seismic zone, located north of the New Madrid seismic zone within the seismically active southern Illinois basin. Four intersecting deep seismic profiles (243 km total) indicate an anomalous, 5–10-km-wide zone of dipping reflections and diffractions below the...
Authors
John H. McBride, Thomas G. Hildenbrand, William J. Stephenson, Christopher J. Potter
A test of a mechanical multi-impact shear-wave seismic source A test of a mechanical multi-impact shear-wave seismic source
We modified two gasoline-engine-powered earth tampers, commonly used as compressional-(P) wave seismic energy sources for shallow reflection studies, for use as shear(S)-wave energy sources. This new configuration, termed ?Hacker? (horizontal Wacker?), is evaluated as an alternative to the manual sledgehammer typically used in conjunction with a large timber held down by the front wheels...
Authors
David M. Worley, Jack K. Odum, Robert A. Williams, William J. Stephenson
Science and Products
Filter Total Items: 15
No Result Found
Filter Total Items: 64
Sedimentary basin effects in Seattle, Washington: Ground-motion observations and 3D simulations Sedimentary basin effects in Seattle, Washington: Ground-motion observations and 3D simulations
Seismograms of local earthquakes recorded in Seattle exhibit surface waves in the Seattle basin and basin-edge focusing of S waves. Spectral ratios of Swaves and later arrivals at 1 Hz for stiff-soil sites in the Seattle basin show a dependence on the direction to the earthquake, with earthquakes to the south and southwest producing higher average amplification. Earthquakes to the...
Authors
Arthur Frankel, William Stephenson, David Carver
Velocity and Density Models Incorporating the Cascadia Subduction Zone for 3D Earthquake Ground Motion Simulations Velocity and Density Models Incorporating the Cascadia Subduction Zone for 3D Earthquake Ground Motion Simulations
In support of earthquake hazards and ground motion studies in the Pacific Northwest, three-dimensional P- and S-wave velocity (3D Vp and Vs) and density (3D rho) models incorporating the Cascadia subduction zone have been developed for the region encompassed from about 40.2°N to 50°N latitude, and from about -122°W to -129°W longitude. The model volume includes elevations from 0 km to 60...
Authors
William J. Stephenson
Seismic Hazard Maps for Seattle, Washington, Incorporating 3D Sedimentary Basin Effects, Nonlinear Site Response, and Rupture Directivity Seismic Hazard Maps for Seattle, Washington, Incorporating 3D Sedimentary Basin Effects, Nonlinear Site Response, and Rupture Directivity
This report presents probabilistic seismic hazard maps for Seattle, Washington, based on over 500 3D simulations of ground motions from scenario earthquakes. These maps include 3D sedimentary basin effects and rupture directivity. Nonlinear site response for soft-soil sites of fill and alluvium was also applied in the maps. The report describes the methodology for incorporating source...
Authors
Arthur D. Frankel, William J. Stephenson, David L. Carver, Robert A. Williams, Jack K. Odum, Susan Rhea
Near-Surface Shear Wave Velocity Versus Depth Profiles, VS30, and NEHRP Classifications for 27 Sites in Puerto Rico Near-Surface Shear Wave Velocity Versus Depth Profiles, VS30, and NEHRP Classifications for 27 Sites in Puerto Rico
In 2004 and 2005 the Puerto Rico Seismic Network (PRSN), Puerto Rico Strong Motion Program (PRSMP) and the Geology Department at the University of Puerto Rico-Mayaguez (UPRM) collaborated with the U.S. Geological Survey to study near-surface shear-wave (Vs) and compressional-wave (Vp) velocities in and around major urban areas of Puerto Rico. Using noninvasive seismic refraction...
Authors
Jack K. Odum, Robert A. Williams, William J. Stephenson, David M. Worley, Christa von Hillebrandt-Andrade, Eugenio Asencio, Harold Irizarry, Antonio Cameron
Wagon loads of sand blows in White County, Illinois Wagon loads of sand blows in White County, Illinois
Several anecdotal accounts provide compelling evidence that liquefaction occurred at several sites in Illinois during the 1811-1812 New Madrid sequence, as much as 250 km north of the New Madrid seismic zone (NMSZ). At one Wabash Valley location, sand blows are still evident near Big Prairie, Illinois, a location described in a particularly detailed and precise historic account. This...
Authors
Susan E. Hough, Roger Bilham, Karl Mueller, William Stephenson, Robert Williams, Jack Odum
High-Resolution Imaging within the Urban Environment -- "What's beneath our streets"! High-Resolution Imaging within the Urban Environment -- "What's beneath our streets"!
No abstract available.
Authors
Jackson K. Odum, Robert A. Williams, William J. Stephenson, David M. Worley
Shear- and compressional- wave velocity measurements from two 150-m-deep boreholes in Seattle, Washington, USA Shear- and compressional- wave velocity measurements from two 150-m-deep boreholes in Seattle, Washington, USA
No abstract available.
Authors
Jack K. Odum, William J. Stephenson, Kathy Goetz-Troost, David M. Worley, Arthur D. Frankel, Robert A. Williams, Jake Fryer
Seismic Velocities from High-Resolution Surface-Seismic Imaging at Six ANSS Sites near Memphis, Tennessee Seismic Velocities from High-Resolution Surface-Seismic Imaging at Six ANSS Sites near Memphis, Tennessee
No abstract available.
Authors
Robert A. Williams, William J. Stephenson, Jack K. Odum, David M. Worley
Near-surface S-wave and P-wave seismic velocities of primary geological formations on the Piedmont and Atlantic Coastal Plain of South Carolina, USA Near-surface S-wave and P-wave seismic velocities of primary geological formations on the Piedmont and Atlantic Coastal Plain of South Carolina, USA
No abstract available.
Authors
Jack K. Odum, Robert A. Williams, William J. Stephenson, David M. Worley
Reconnaissance shallow seismic investigation of depth-to-bedrock and possible methane-bearing coalbeds, Galena, Alaska Reconnaissance shallow seismic investigation of depth-to-bedrock and possible methane-bearing coalbeds, Galena, Alaska
A reconnaissance shallow seismic reflection/refraction investigation in and around the city of Galena, Alaska suggests that Tertiary and/or Cretaceous bedrock, and possible coalbeds within the Cretaceous, is at least as deep as 550 feet in the immediate vicinity of town. Rock could be deeper than 1000 feet under alternate interpretations. Reflections recorded in these data are believed...
Authors
William J. Stephenson, Robert A. Williams, Jack K. Odum, David M. Worley, Charles E. Barker, Arthur C. Clark, James G. Clough
Interpreting the earthquake source of the Wabash Valley seismic zone (Illinois, Indiana, and Kentucky) from seismic-reflection, gravity, and magnetic-intensity data Interpreting the earthquake source of the Wabash Valley seismic zone (Illinois, Indiana, and Kentucky) from seismic-reflection, gravity, and magnetic-intensity data
Reprocessing of seismic-reflection data reveals new images of upper- to middle-crustal structures beneath the Wabash Valley seismic zone, located north of the New Madrid seismic zone within the seismically active southern Illinois basin. Four intersecting deep seismic profiles (243 km total) indicate an anomalous, 5–10-km-wide zone of dipping reflections and diffractions below the...
Authors
John H. McBride, Thomas G. Hildenbrand, William J. Stephenson, Christopher J. Potter
A test of a mechanical multi-impact shear-wave seismic source A test of a mechanical multi-impact shear-wave seismic source
We modified two gasoline-engine-powered earth tampers, commonly used as compressional-(P) wave seismic energy sources for shallow reflection studies, for use as shear(S)-wave energy sources. This new configuration, termed ?Hacker? (horizontal Wacker?), is evaluated as an alternative to the manual sledgehammer typically used in conjunction with a large timber held down by the front wheels...
Authors
David M. Worley, Jack K. Odum, Robert A. Williams, William J. Stephenson