William J Stephenson
Bill Stephensen is a scientist in the Earthquake Hazards Program.
Science and Products
Recent faulting in western Nevada revealed by multi-scale seismic reflection
The Quaternary Silver Creek Fault Beneath the Santa Clara Valley, California
Velocity and Density Models Incorporating the Cascadia Subduction Zone for 3D Earthquake Ground Motion Simulations
Seismic Hazard Maps for Seattle, Washington, Incorporating 3D Sedimentary Basin Effects, Nonlinear Site Response, and Rupture Directivity
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-reflection profili
High-Resolution Imaging within the Urban Environment -- "What's beneath our streets"!
Shear- and compressional- wave velocity measurements from two 150-m-deep boreholes in Seattle, Washington, USA
Seismic Velocities from High-Resolution Surface-Seismic Imaging at Six ANSS Sites near Memphis, Tennessee
Near-surface S-wave and P-wave seismic velocities of primary geological formations on the Piedmont and Atlantic Coastal Plain of South Carolina, USA
Reconnaissance shallow seismic investigation of depth-to-bedrock and possible methane-bearing coalbeds, Galena, Alaska
Interpreting the earthquake source of the Wabash Valley seismic zone (Illinois, Indiana, and Kentucky) from seismic-reflection, gravity, and magnetic-intensity data
A test of a mechanical multi-impact shear-wave seismic source
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Recent faulting in western Nevada revealed by multi-scale seismic reflection
The main goal of this study is to compare different reflection methods used to image subsurface structure within different physical environments in western Nevada. With all the methods employed, the primary goal is fault imaging for structural information toward geothermal exploration and seismic hazard estimation. We use seismic CHIRP (a swept-frequency marine acquisition system), weight drop (anAuthorsRoxanna N. Frary, John N. Louie, William J. Stephenson, Jackson K. Odum, Annie Kell, Amy Eisses, Graham M. Kent, Neal W. Driscoll, Robert Karlin, Robert L. Baskin, Satish Pullammanappallil, Lee M. LibertyThe Quaternary Silver Creek Fault Beneath the Santa Clara Valley, California
The northwest-trending Silver Creek Fault is a 40-km-long strike-slip fault in the eastern Santa Clara Valley, California, that has exhibited different behaviors within a changing San Andreas Fault system over the past 10-15 Ma. Quaternary alluvium several hundred meters thick that buries the northern half of the Silver Creek Fault, and that has been sampled by drilling and imaged in a detailed seAuthorsCarl M. Wentworth, Robert A. Williams, Robert C. Jachens, Russell W. Graymer, William J. StephensonVelocity 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 km (elevaAuthorsWilliam J. StephensonSeismic 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 and site depAuthorsArthur D. Frankel, William J. Stephenson, David L. Carver, Robert A. Williams, Jack K. Odum, Susan RheaNear-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-reflection profili
AuthorsJack K. Odum, Robert A. Williams, William J. Stephenson, David M. Worley, Christa von Hillebrandt-Andrade, Eugenio Asencio, Harold Irizarry, Antonio CameronHigh-Resolution Imaging within the Urban Environment -- "What's beneath our streets"!
No abstract available.AuthorsJackson K. Odum, Robert A. Williams, William J. Stephenson, David M. WorleyShear- and compressional- wave velocity measurements from two 150-m-deep boreholes in Seattle, Washington, USA
No abstract available.AuthorsJack K. Odum, William J. Stephenson, Kathy Goetz-Troost, David M. Worley, Arthur D. Frankel, Robert A. Williams, Jake FryerSeismic Velocities from High-Resolution Surface-Seismic Imaging at Six ANSS Sites near Memphis, Tennessee
No abstract available.AuthorsRobert A. Williams, William J. Stephenson, Jack K. Odum, David M. WorleyNear-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.AuthorsJack K. Odum, Robert A. Williams, William J. Stephenson, David M. WorleyReconnaissance 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 to be fromAuthorsWilliam J. Stephenson, Robert A. Williams, Jack K. Odum, David M. Worley, Charles E. Barker, Arthur C. Clark, James G. CloughInterpreting 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 western flank ofAuthorsJohn H. McBride, Thomas G. Hildenbrand, William J. Stephenson, Christopher J. PotterA 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 of a vehiAuthorsDavid M. Worley, Jack K. Odum, Robert A. Williams, William J. Stephenson - News