William J Stephenson
Bill Stephensen is a scientist in the Earthquake Hazards Program.
Science and Products
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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
Preliminary simulation of a M6.5 earthquake on the Seattle Fault using 3D finite-difference modeling Preliminary simulation of a M6.5 earthquake on the Seattle Fault using 3D finite-difference modeling
A three-dimensional finite-difference simulation of a moderate-sized (M 6.5) thrust-faulting earthquake on the Seattle fault demonstrates the effects of the Seattle Basin on strong ground motion in the Puget lowland. The model area includes the cities of Seattle, Bremerton and Bellevue. We use a recently developed detailed 3D-velocity model of the Seattle Basin in these simulations. The...
Authors
William J. Stephenson, Arthur D. Frankel
High-resolution seismic reflection surveys and modeling across an area of high damage from the 1994 Northridge earthquake, Sherman Oaks, California High-resolution seismic reflection surveys and modeling across an area of high damage from the 1994 Northridge earthquake, Sherman Oaks, California
Approximately 3.6 km of P-wave seismic-reflection data were acquired along two orthogonal profiles in Sherman Oaks, California to determine whether shallow (less than 1-km depth) geologic structures contributed to the dramatic localized damage resulting from the 1994 Northridge earthquake. Both lines, one along Matilija Avenue and one along Milbank Street, crossed areas of both high and...
Authors
William J. Stephenson, Robert A. Williams, Jack K. Odum, David M. Worley
High-resolution surface-seismic imaging techniques for NEHRP soil profile classifications and earthquake hazard assessments in urban areas High-resolution surface-seismic imaging techniques for NEHRP soil profile classifications and earthquake hazard assessments in urban areas
No abstract available.
Authors
Robert A. Williams, William J. Stephenson, Jack K. Odum, David M. Worley
Characterization of the Cottonwood Grove and Ridgely faults near Reelfoot Lake, Tennessee, from high-resolution seismic reflection data Characterization of the Cottonwood Grove and Ridgely faults near Reelfoot Lake, Tennessee, from high-resolution seismic reflection data
In the winter of 1811-12, three of the largest historic earthquakes in the United States occurred near New Madrid, Missouri. Seismicity continues to the present day throughout a tightly clustered pattern of epicenters centered on the bootheel of Missouri, including parts of northeastern Arkansas, northwestern Tennessee, western Kentucky, and southern Illinois. In 1990, the New Madrid...
Authors
William J. Stephenson, Kaye M. Shedlock, Jack K. Odum
Science and Products
Filter Total Items: 15
No Result Found
Filter Total Items: 67
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
Preliminary simulation of a M6.5 earthquake on the Seattle Fault using 3D finite-difference modeling Preliminary simulation of a M6.5 earthquake on the Seattle Fault using 3D finite-difference modeling
A three-dimensional finite-difference simulation of a moderate-sized (M 6.5) thrust-faulting earthquake on the Seattle fault demonstrates the effects of the Seattle Basin on strong ground motion in the Puget lowland. The model area includes the cities of Seattle, Bremerton and Bellevue. We use a recently developed detailed 3D-velocity model of the Seattle Basin in these simulations. The...
Authors
William J. Stephenson, Arthur D. Frankel
High-resolution seismic reflection surveys and modeling across an area of high damage from the 1994 Northridge earthquake, Sherman Oaks, California High-resolution seismic reflection surveys and modeling across an area of high damage from the 1994 Northridge earthquake, Sherman Oaks, California
Approximately 3.6 km of P-wave seismic-reflection data were acquired along two orthogonal profiles in Sherman Oaks, California to determine whether shallow (less than 1-km depth) geologic structures contributed to the dramatic localized damage resulting from the 1994 Northridge earthquake. Both lines, one along Matilija Avenue and one along Milbank Street, crossed areas of both high and...
Authors
William J. Stephenson, Robert A. Williams, Jack K. Odum, David M. Worley
High-resolution surface-seismic imaging techniques for NEHRP soil profile classifications and earthquake hazard assessments in urban areas High-resolution surface-seismic imaging techniques for NEHRP soil profile classifications and earthquake hazard assessments in urban areas
No abstract available.
Authors
Robert A. Williams, William J. Stephenson, Jack K. Odum, David M. Worley
Characterization of the Cottonwood Grove and Ridgely faults near Reelfoot Lake, Tennessee, from high-resolution seismic reflection data Characterization of the Cottonwood Grove and Ridgely faults near Reelfoot Lake, Tennessee, from high-resolution seismic reflection data
In the winter of 1811-12, three of the largest historic earthquakes in the United States occurred near New Madrid, Missouri. Seismicity continues to the present day throughout a tightly clustered pattern of epicenters centered on the bootheel of Missouri, including parts of northeastern Arkansas, northwestern Tennessee, western Kentucky, and southern Illinois. In 1990, the New Madrid...
Authors
William J. Stephenson, Kaye M. Shedlock, Jack K. Odum