Victoria Langenheim
Vickie is a Research Geophysicist with the Geology, Minerals, Energy, and Geophysics Science Center
Science and Products
San Andreas Fault System in Southern California
Southern California is home to nearly 24 million people and countless visitors who live, recreate, consume resources, and face the risk of natural hazards in the region. This project produces high-quality, multi-purpose geologic maps, databases, and reports that portray our understanding of the region’s four-dimensional geologic framework. We conduct stratigraphic, structural, geomorphological...
2D and 3D Geologic Mapping and Earthquake Hazards of California
This project uses geologic and geophysical mapping to build an earth-science framework for scientific investigations that include assessments of critical resources, such as groundwater, and of hazards, such as those resulting from earthquakes, in California west of and including the Sierra Nevada and Cascade arc. Questions of particular interest include: What are the geometries, slip rates, and...
Filter Total Items: 36
Seismic-reflection profiles in Chuckwalla Valley, southeastern California Seismic-reflection profiles in Chuckwalla Valley, southeastern California
Two industry seismic-reflection profiles in Chuckwalla Valley (southeastern California) were donated by Buckhorn Petroleum to the CALCRUST program in ~1987. USGS personnel Jeff Wilson, Eric Geist, and Jill McCarthy reprocessed the seismic reflection data, concentrating on imaging reflections below the Cenozoic basin fill using pre-stack techniques. This data release describes the...
Geophysical grids, horizontal gradient maxima and depth to bedrock of the Blythe region, California and Arizona Geophysical grids, horizontal gradient maxima and depth to bedrock of the Blythe region, California and Arizona
This data release contains (1) geophysical grids, (2) horizontal gravity and residual magnetic gradient maxima and (3) inputs to a gravity inversion of Cenozoic basin thickness based on gravity measurements of the Blythe region of California and Arizona. Gridded data (geotiffs.zip) consist of the input isostatic gravity grid as well as grids of Cenozoic basin thickness and bedrock...
Gravity and physical property data of northeastern California (ver. 2.0, December 2025) Gravity and physical property data of northeastern California (ver. 2.0, December 2025)
This data release contains principal facts of gravity measurements by previous studies and collected by the U.S. Geological Survey in 1994-2023 and a compilation of existing and new density and magnetic susceptibility data in northeastern California. Gravity data are processed to isostatic anomalies using reduction densities of 2670 and 2200 kilogram/cubic meter. This region is at the...
Gravity data and basin thickness grids for "Geophysical evidence for wedging in the San Gorgonio Pass structural knot, southern San Andreas fault zone, southern California" Gravity data and basin thickness grids for "Geophysical evidence for wedging in the San Gorgonio Pass structural knot, southern San Andreas fault zone, southern California"
This data release contains (1) principal facts of gravity measurements collected by the U.S. Geological Survey in 2000-2004 (usgs_iso.csv) and (2) inputs to a gravity inversion of Cenozoic basin thickness based on those gravity and previous measurements. Gridded data (geotiffs.zip) consist of the input isostatic gravity grid as well as grids of Cenozoic basin thickness and basement...
Gravity data, geophysical grids, and horizontal gradient maxima of the Healdsburg 30 by 60 minute quadrangle, California Gravity data, geophysical grids, and horizontal gradient maxima of the Healdsburg 30 by 60 minute quadrangle, California
This data release contains (1) principal facts of gravity measurements by previous studies and collected by the U.S. Geological Survey in 2006-2024, (2) geophysical grids, and (3) horizontal gradient maxima derived from gravity and magnetic potential fields of the Healdsburg 30 by 60 minute quadrangle, California. Gridded data are provided in geotiff format. These data support modeling...
Gravity and physical property data of the 2019 Ridgecrest earthquakes region, Mojave Desert, California Gravity and physical property data of the 2019 Ridgecrest earthquakes region, Mojave Desert, California
This data release presents point data associated with studies to understand the crustal structure of the 2019 Ridgecrest earthquakes epicentral region and the interaction of the northeast-to-east-striking Garlock fault with the northwest-striking faults of the Eastern California Shear Zone and Walker Lane. Data include principal fact information for new gravity measurements collected by...
Preliminary Digital Database for the Portola 30' x 60' Geologic and Geophysical Map, California Preliminary Digital Database for the Portola 30' x 60' Geologic and Geophysical Map, California
This geospatial dataset compiles, in digital form, geologic and geophysical data for the Portola 30’x 60’ quadrangle, located in the northern Sierra Nevada, California. This geologic map of the Portola 30’x 60’ quadrangle integrates decades of published and unpublished mapping in the northern Sierra Nevada. In conjunction with geophysical data, including more than 1000 new gravity...
Gravity and physical property data of the Blythe region, California and Arizona Gravity and physical property data of the Blythe region, California and Arizona
This data release presents point data associated with studies to understand the crustal structure of the Blythe region, where strands of the pre-Quaternary Eastern California Shear zone project across this region in California and Arizona. Data include principal fact information for new gravity measurements collected by the U.S. Geological Survey from 2020 to 2025, previously unpublished...
Tabular uranium-lead and trace-element compositional data of zircons and whole-rock geochemistry of plutonic rocks in the Sierra Nevada, California Tabular uranium-lead and trace-element compositional data of zircons and whole-rock geochemistry of plutonic rocks in the Sierra Nevada, California
This dataset consists of zircon uranium-lead (U-Pb) isotopic compositions, ages, and trace-element compositions in addition to whole-rock chemical compositions from plutons within the Sierra Nevada, California. These samples primarily collected from 2015 to 2023, although some legacy data are included. Zircon crystals were analyzed using the Sensitive High-Resolution Ion Micro-Probe...
P- and S-Wave Suspension Velocity Logs in the San Francisco Bay Region, Alameda, Santa Clara, and Sonoma Counties, California P- and S-Wave Suspension Velocity Logs in the San Francisco Bay Region, Alameda, Santa Clara, and Sonoma Counties, California
This data release contains P- and S-wave velocity data from logs of nine wells in three large sedimentary basins in the San Francisco Bay region. The logs were collected between 2000 and 2006 for the U.S. Geological Survey under contract by R.A. Steller of GeoVision using an Oyo suspension logging system. Well depths range from 215 to 407 meters and sample spacing in the wells ranges...
Digitized sonic velocity and density log data of the Eel River area, northern California Digitized sonic velocity and density log data of the Eel River area, northern California
Sonic velocity and density well logs in the Eel River area in northern California (Ferndale north Arcata) were digitized by hand. These logs are available as scanned files (pdfs and tiffs) on the California Division of Oil, Gas, and Geothermal Resources website (https://maps.conservation.ca.gov/doggr/wellfinder/). The data consist of transit times and bulk density measured downhole in...
Geophysical data and grids of the Grouse Creek and Utah part of the Jackpot 30' x 60' quadrangles, Utah Geophysical data and grids of the Grouse Creek and Utah part of the Jackpot 30' x 60' quadrangles, Utah
New geophysical data, including density and magnetic susceptibility measurements, were collected in the Grouse Creek and Utah part of the Jackpot 30' x 60' quadrangles in Box Elder County, Utah and Cassia County, Idaho. The release contains 324 new gravity measurements merged with a 2013 compilation. These data were inverted for basin thickness and basement density variations. The...
Filter Total Items: 191
Implications of geophysical analysis on basin geometry and fault offsets in the northern Colorado River extensional corridor and adjoining Lake Mead region, Nevada and Arizona Implications of geophysical analysis on basin geometry and fault offsets in the northern Colorado River extensional corridor and adjoining Lake Mead region, Nevada and Arizona
The northern Colorado River extensional corridor and Lake Mead region are characterized by prominent gravity and magnetic anomalies that provide insight into the geometry of extensional basins, amount of vertical and strike-slip offset on faults that bound these basins, and composition of major basement blocks. Although large-magnitude extension throughout the extensional corridor and...
Authors
Victoria E. Langenheim, L. Sue Beard, James E. Faulds
Three-dimensional geologic modeling of the Santa Rosa Plain, California Three-dimensional geologic modeling of the Santa Rosa Plain, California
New three-dimensional (3D) lithologic and stratigraphic models of the Santa Rosa Plain (California, USA) delineate the thickness, extent, and distribution of subsurface geologic units and allow integration of diverse data sets to produce a lithologic, stratigraphic, and structural architecture for the region. This framework can be used to predict pathways of groundwater flow beneath the...
Authors
Donald S. Sweetkind, Emily M. Taylor, Craig A. McCabe, Victoria E. Langenheim, Robert J. McLaughlin
Geophysical framework of the northern San Francisco Bay region, California Geophysical framework of the northern San Francisco Bay region, California
We use geophysical data to examine the structural framework of the northern San Francisco Bay region, an area that hosts the northward continuation of the East Bay fault system. Although this fault system has accommodated ∼175 km of right-lateral offset since 12 Ma, how this offset is partitioned north of the bay is controversial and important for understanding where and how strain is...
Authors
Victoria E. Langenheim, Russell W. Graymer, Robert C. Jachens, Robert J. McLaughlin, D.L. Wagner, Donald S. Sweetkind
Gravity and Magnetic Investigations of the Mojave National Preserve and Adjacent Areas, California and Nevada Gravity and Magnetic Investigations of the Mojave National Preserve and Adjacent Areas, California and Nevada
Gravity and aeromagnetic data provide the underpinnings of a hydrogeologic framework for the Mojave National Preserve by estimating the thickness of Cenozoic deposits and locating inferred structural features that influence groundwater flow. An inversion of gravity data indicates that thin (
Authors
V.E. Langenheim, S. Biehler, R. Negrini, K. Mickus, D. M. Miller, R. J. Miller
Aeromagnetic survey map of the central California Coast Ranges Aeromagnetic survey map of the central California Coast Ranges
This aeromagnetic survey was flown as part of a Cooperative Research and Development Agreement (CRADA) with the Pacific Gas and Electric Company and is intended to promote further understanding of the geology and structure in the central California Coast Ranges by serving as a basis for geophysical interpretations and by supporting geological mapping, mineral and water resource...
Authors
V.E. Langenheim, R.C. Jachens, K. Moussaoui
Regional three-dimensional seismic velocity model of the crust and uppermost mantle of northern California Regional three-dimensional seismic velocity model of the crust and uppermost mantle of northern California
We present a three-dimensional (3D) tomographic model of the P wave velocity (Vp) structure of northern California. We employed a regional-scale double-difference tomography algorithm that incorporates a finite-difference travel time calculator and spatial smoothing constraints. Arrival times from earthquakes and travel times from controlled-source explosions, recorded at network and/or...
Authors
C. Thurber, H. Zhang, T. Brocher, V. Langenheim
Recent developments in understanding the tectonic evolution of the Southern California offshore area: Implications for earthquake-hazard analysis Recent developments in understanding the tectonic evolution of the Southern California offshore area: Implications for earthquake-hazard analysis
During late Mesozoic and Cenozoic time, three main tectonic episodes affected the Southern California offshore area. Each episode imposed its unique structural imprint such that early-formed structures controlled or at least influenced the location and development of later ones. This cascaded structural inheritance greatly complicates analysis of the extent, orientation, and activity of...
Authors
M. A. Fisher, V.E. Langenheim, C. Nicholson, H. F. Ryan, R. W. Sliter
Basin geometry and cumulative offsets in the Eastern Transverse Ranges, southern California: Implications for transrotational deformation along the San Andreas fault system Basin geometry and cumulative offsets in the Eastern Transverse Ranges, southern California: Implications for transrotational deformation along the San Andreas fault system
The Eastern Transverse Ranges, adjacent to and southeast of the big left bend of the San Andreas fault, southern California, form a crustal block that has rotated clockwise in response to dextral shear within the San Andreas system. Previous studies have indicated a discrepancy between the measured magnitudes of left slip on through-going east-striking fault zones of the Eastern...
Authors
V.E. Langenheim, R. E. Powell
An integrated geophysical approach for groundwater and seismic hazard management in Joshua Tree National Park, southern California An integrated geophysical approach for groundwater and seismic hazard management in Joshua Tree National Park, southern California
Two‐dimensional inversion of audiomagnetotelluric (AMT) sounding data define buried resistivity distributions that reflect subsurface geology and structure within the upper kilometer beneath Pleasant Valley, a 1–2 km‐deep pull‐apart basin in Joshua Tree National Park, southern California. The Park lies within the Eastern California Shear Zone just east of the San Andreas Fault, and is...
Authors
Darcy K. McPhee, Victoria E. Langenheim, Bruce A. Chuchel, Louise Pellerin
Geologic and Geophysical Framework of the Santa Rosa 7.5' Quadrangle, Sonoma County, California Geologic and Geophysical Framework of the Santa Rosa 7.5' Quadrangle, Sonoma County, California
The geologic and geophysical maps of Santa Rosa 7.5? quadrangle and accompanying structure sections portray the sedimentary and volcanic stratigraphy and crustal structure of the Santa Rosa 7.5? quadrangle and provide a context for interpreting the evolution of volcanism and active faulting in this region. The quadrangle is located in the California Coast Ranges north of San Francisco...
Authors
R. J. McLaughlin, V.E. Langenheim, A.M. Sarna-Wojcicki, R.J. Fleck, D.K. McPhee, C. W. Roberts, C.A. McCabe, Elmira Wan
Preliminary Isostatic Gravity Map of Joshua Tree National Park and Vicinity, Southern California Preliminary Isostatic Gravity Map of Joshua Tree National Park and Vicinity, Southern California
This isostatic residual gravity map is part of an effort to map the three-dimensional distribution of rocks in Joshua Tree National Park, southern California. This map will serve as a basis for modeling the shape of basins beneath the Park and in adjacent valleys and also for determining the location and geometry of faults within the area. Local spatial variations in the Earth's gravity...
Authors
V.E. Langenheim, Shawn Biehler, D.K. McPhee, C.A. McCabe, J. T. Watt, M.L. Anderson, B. A. Chuchel, P. Stoffer
Relatively simple through-going fault planes at large-earthquake depth may be concealed by the surface complexity of strike-slip faults Relatively simple through-going fault planes at large-earthquake depth may be concealed by the surface complexity of strike-slip faults
At the surface, strike-slip fault stepovers, including abrupt fault bends, are typically regions of complex, often disconnected faults. This complexity has traditionally led geologists studying the hazard of active faults to consider such stepovers as important fault segment boundaries, and to give lower weight to earthquake scenarios that involve rupture through the stepover zone...
Authors
Russell W. Graymer, Victoria E. Langenheim, Robert W. Simpson, Robert C. Jachens, David A. Ponce
Science and Products
San Andreas Fault System in Southern California
Southern California is home to nearly 24 million people and countless visitors who live, recreate, consume resources, and face the risk of natural hazards in the region. This project produces high-quality, multi-purpose geologic maps, databases, and reports that portray our understanding of the region’s four-dimensional geologic framework. We conduct stratigraphic, structural, geomorphological...
2D and 3D Geologic Mapping and Earthquake Hazards of California
This project uses geologic and geophysical mapping to build an earth-science framework for scientific investigations that include assessments of critical resources, such as groundwater, and of hazards, such as those resulting from earthquakes, in California west of and including the Sierra Nevada and Cascade arc. Questions of particular interest include: What are the geometries, slip rates, and...
Filter Total Items: 36
Seismic-reflection profiles in Chuckwalla Valley, southeastern California Seismic-reflection profiles in Chuckwalla Valley, southeastern California
Two industry seismic-reflection profiles in Chuckwalla Valley (southeastern California) were donated by Buckhorn Petroleum to the CALCRUST program in ~1987. USGS personnel Jeff Wilson, Eric Geist, and Jill McCarthy reprocessed the seismic reflection data, concentrating on imaging reflections below the Cenozoic basin fill using pre-stack techniques. This data release describes the...
Geophysical grids, horizontal gradient maxima and depth to bedrock of the Blythe region, California and Arizona Geophysical grids, horizontal gradient maxima and depth to bedrock of the Blythe region, California and Arizona
This data release contains (1) geophysical grids, (2) horizontal gravity and residual magnetic gradient maxima and (3) inputs to a gravity inversion of Cenozoic basin thickness based on gravity measurements of the Blythe region of California and Arizona. Gridded data (geotiffs.zip) consist of the input isostatic gravity grid as well as grids of Cenozoic basin thickness and bedrock...
Gravity and physical property data of northeastern California (ver. 2.0, December 2025) Gravity and physical property data of northeastern California (ver. 2.0, December 2025)
This data release contains principal facts of gravity measurements by previous studies and collected by the U.S. Geological Survey in 1994-2023 and a compilation of existing and new density and magnetic susceptibility data in northeastern California. Gravity data are processed to isostatic anomalies using reduction densities of 2670 and 2200 kilogram/cubic meter. This region is at the...
Gravity data and basin thickness grids for "Geophysical evidence for wedging in the San Gorgonio Pass structural knot, southern San Andreas fault zone, southern California" Gravity data and basin thickness grids for "Geophysical evidence for wedging in the San Gorgonio Pass structural knot, southern San Andreas fault zone, southern California"
This data release contains (1) principal facts of gravity measurements collected by the U.S. Geological Survey in 2000-2004 (usgs_iso.csv) and (2) inputs to a gravity inversion of Cenozoic basin thickness based on those gravity and previous measurements. Gridded data (geotiffs.zip) consist of the input isostatic gravity grid as well as grids of Cenozoic basin thickness and basement...
Gravity data, geophysical grids, and horizontal gradient maxima of the Healdsburg 30 by 60 minute quadrangle, California Gravity data, geophysical grids, and horizontal gradient maxima of the Healdsburg 30 by 60 minute quadrangle, California
This data release contains (1) principal facts of gravity measurements by previous studies and collected by the U.S. Geological Survey in 2006-2024, (2) geophysical grids, and (3) horizontal gradient maxima derived from gravity and magnetic potential fields of the Healdsburg 30 by 60 minute quadrangle, California. Gridded data are provided in geotiff format. These data support modeling...
Gravity and physical property data of the 2019 Ridgecrest earthquakes region, Mojave Desert, California Gravity and physical property data of the 2019 Ridgecrest earthquakes region, Mojave Desert, California
This data release presents point data associated with studies to understand the crustal structure of the 2019 Ridgecrest earthquakes epicentral region and the interaction of the northeast-to-east-striking Garlock fault with the northwest-striking faults of the Eastern California Shear Zone and Walker Lane. Data include principal fact information for new gravity measurements collected by...
Preliminary Digital Database for the Portola 30' x 60' Geologic and Geophysical Map, California Preliminary Digital Database for the Portola 30' x 60' Geologic and Geophysical Map, California
This geospatial dataset compiles, in digital form, geologic and geophysical data for the Portola 30’x 60’ quadrangle, located in the northern Sierra Nevada, California. This geologic map of the Portola 30’x 60’ quadrangle integrates decades of published and unpublished mapping in the northern Sierra Nevada. In conjunction with geophysical data, including more than 1000 new gravity...
Gravity and physical property data of the Blythe region, California and Arizona Gravity and physical property data of the Blythe region, California and Arizona
This data release presents point data associated with studies to understand the crustal structure of the Blythe region, where strands of the pre-Quaternary Eastern California Shear zone project across this region in California and Arizona. Data include principal fact information for new gravity measurements collected by the U.S. Geological Survey from 2020 to 2025, previously unpublished...
Tabular uranium-lead and trace-element compositional data of zircons and whole-rock geochemistry of plutonic rocks in the Sierra Nevada, California Tabular uranium-lead and trace-element compositional data of zircons and whole-rock geochemistry of plutonic rocks in the Sierra Nevada, California
This dataset consists of zircon uranium-lead (U-Pb) isotopic compositions, ages, and trace-element compositions in addition to whole-rock chemical compositions from plutons within the Sierra Nevada, California. These samples primarily collected from 2015 to 2023, although some legacy data are included. Zircon crystals were analyzed using the Sensitive High-Resolution Ion Micro-Probe...
P- and S-Wave Suspension Velocity Logs in the San Francisco Bay Region, Alameda, Santa Clara, and Sonoma Counties, California P- and S-Wave Suspension Velocity Logs in the San Francisco Bay Region, Alameda, Santa Clara, and Sonoma Counties, California
This data release contains P- and S-wave velocity data from logs of nine wells in three large sedimentary basins in the San Francisco Bay region. The logs were collected between 2000 and 2006 for the U.S. Geological Survey under contract by R.A. Steller of GeoVision using an Oyo suspension logging system. Well depths range from 215 to 407 meters and sample spacing in the wells ranges...
Digitized sonic velocity and density log data of the Eel River area, northern California Digitized sonic velocity and density log data of the Eel River area, northern California
Sonic velocity and density well logs in the Eel River area in northern California (Ferndale north Arcata) were digitized by hand. These logs are available as scanned files (pdfs and tiffs) on the California Division of Oil, Gas, and Geothermal Resources website (https://maps.conservation.ca.gov/doggr/wellfinder/). The data consist of transit times and bulk density measured downhole in...
Geophysical data and grids of the Grouse Creek and Utah part of the Jackpot 30' x 60' quadrangles, Utah Geophysical data and grids of the Grouse Creek and Utah part of the Jackpot 30' x 60' quadrangles, Utah
New geophysical data, including density and magnetic susceptibility measurements, were collected in the Grouse Creek and Utah part of the Jackpot 30' x 60' quadrangles in Box Elder County, Utah and Cassia County, Idaho. The release contains 324 new gravity measurements merged with a 2013 compilation. These data were inverted for basin thickness and basement density variations. The...
Filter Total Items: 191
Implications of geophysical analysis on basin geometry and fault offsets in the northern Colorado River extensional corridor and adjoining Lake Mead region, Nevada and Arizona Implications of geophysical analysis on basin geometry and fault offsets in the northern Colorado River extensional corridor and adjoining Lake Mead region, Nevada and Arizona
The northern Colorado River extensional corridor and Lake Mead region are characterized by prominent gravity and magnetic anomalies that provide insight into the geometry of extensional basins, amount of vertical and strike-slip offset on faults that bound these basins, and composition of major basement blocks. Although large-magnitude extension throughout the extensional corridor and...
Authors
Victoria E. Langenheim, L. Sue Beard, James E. Faulds
Three-dimensional geologic modeling of the Santa Rosa Plain, California Three-dimensional geologic modeling of the Santa Rosa Plain, California
New three-dimensional (3D) lithologic and stratigraphic models of the Santa Rosa Plain (California, USA) delineate the thickness, extent, and distribution of subsurface geologic units and allow integration of diverse data sets to produce a lithologic, stratigraphic, and structural architecture for the region. This framework can be used to predict pathways of groundwater flow beneath the...
Authors
Donald S. Sweetkind, Emily M. Taylor, Craig A. McCabe, Victoria E. Langenheim, Robert J. McLaughlin
Geophysical framework of the northern San Francisco Bay region, California Geophysical framework of the northern San Francisco Bay region, California
We use geophysical data to examine the structural framework of the northern San Francisco Bay region, an area that hosts the northward continuation of the East Bay fault system. Although this fault system has accommodated ∼175 km of right-lateral offset since 12 Ma, how this offset is partitioned north of the bay is controversial and important for understanding where and how strain is...
Authors
Victoria E. Langenheim, Russell W. Graymer, Robert C. Jachens, Robert J. McLaughlin, D.L. Wagner, Donald S. Sweetkind
Gravity and Magnetic Investigations of the Mojave National Preserve and Adjacent Areas, California and Nevada Gravity and Magnetic Investigations of the Mojave National Preserve and Adjacent Areas, California and Nevada
Gravity and aeromagnetic data provide the underpinnings of a hydrogeologic framework for the Mojave National Preserve by estimating the thickness of Cenozoic deposits and locating inferred structural features that influence groundwater flow. An inversion of gravity data indicates that thin (
Authors
V.E. Langenheim, S. Biehler, R. Negrini, K. Mickus, D. M. Miller, R. J. Miller
Aeromagnetic survey map of the central California Coast Ranges Aeromagnetic survey map of the central California Coast Ranges
This aeromagnetic survey was flown as part of a Cooperative Research and Development Agreement (CRADA) with the Pacific Gas and Electric Company and is intended to promote further understanding of the geology and structure in the central California Coast Ranges by serving as a basis for geophysical interpretations and by supporting geological mapping, mineral and water resource...
Authors
V.E. Langenheim, R.C. Jachens, K. Moussaoui
Regional three-dimensional seismic velocity model of the crust and uppermost mantle of northern California Regional three-dimensional seismic velocity model of the crust and uppermost mantle of northern California
We present a three-dimensional (3D) tomographic model of the P wave velocity (Vp) structure of northern California. We employed a regional-scale double-difference tomography algorithm that incorporates a finite-difference travel time calculator and spatial smoothing constraints. Arrival times from earthquakes and travel times from controlled-source explosions, recorded at network and/or...
Authors
C. Thurber, H. Zhang, T. Brocher, V. Langenheim
Recent developments in understanding the tectonic evolution of the Southern California offshore area: Implications for earthquake-hazard analysis Recent developments in understanding the tectonic evolution of the Southern California offshore area: Implications for earthquake-hazard analysis
During late Mesozoic and Cenozoic time, three main tectonic episodes affected the Southern California offshore area. Each episode imposed its unique structural imprint such that early-formed structures controlled or at least influenced the location and development of later ones. This cascaded structural inheritance greatly complicates analysis of the extent, orientation, and activity of...
Authors
M. A. Fisher, V.E. Langenheim, C. Nicholson, H. F. Ryan, R. W. Sliter
Basin geometry and cumulative offsets in the Eastern Transverse Ranges, southern California: Implications for transrotational deformation along the San Andreas fault system Basin geometry and cumulative offsets in the Eastern Transverse Ranges, southern California: Implications for transrotational deformation along the San Andreas fault system
The Eastern Transverse Ranges, adjacent to and southeast of the big left bend of the San Andreas fault, southern California, form a crustal block that has rotated clockwise in response to dextral shear within the San Andreas system. Previous studies have indicated a discrepancy between the measured magnitudes of left slip on through-going east-striking fault zones of the Eastern...
Authors
V.E. Langenheim, R. E. Powell
An integrated geophysical approach for groundwater and seismic hazard management in Joshua Tree National Park, southern California An integrated geophysical approach for groundwater and seismic hazard management in Joshua Tree National Park, southern California
Two‐dimensional inversion of audiomagnetotelluric (AMT) sounding data define buried resistivity distributions that reflect subsurface geology and structure within the upper kilometer beneath Pleasant Valley, a 1–2 km‐deep pull‐apart basin in Joshua Tree National Park, southern California. The Park lies within the Eastern California Shear Zone just east of the San Andreas Fault, and is...
Authors
Darcy K. McPhee, Victoria E. Langenheim, Bruce A. Chuchel, Louise Pellerin
Geologic and Geophysical Framework of the Santa Rosa 7.5' Quadrangle, Sonoma County, California Geologic and Geophysical Framework of the Santa Rosa 7.5' Quadrangle, Sonoma County, California
The geologic and geophysical maps of Santa Rosa 7.5? quadrangle and accompanying structure sections portray the sedimentary and volcanic stratigraphy and crustal structure of the Santa Rosa 7.5? quadrangle and provide a context for interpreting the evolution of volcanism and active faulting in this region. The quadrangle is located in the California Coast Ranges north of San Francisco...
Authors
R. J. McLaughlin, V.E. Langenheim, A.M. Sarna-Wojcicki, R.J. Fleck, D.K. McPhee, C. W. Roberts, C.A. McCabe, Elmira Wan
Preliminary Isostatic Gravity Map of Joshua Tree National Park and Vicinity, Southern California Preliminary Isostatic Gravity Map of Joshua Tree National Park and Vicinity, Southern California
This isostatic residual gravity map is part of an effort to map the three-dimensional distribution of rocks in Joshua Tree National Park, southern California. This map will serve as a basis for modeling the shape of basins beneath the Park and in adjacent valleys and also for determining the location and geometry of faults within the area. Local spatial variations in the Earth's gravity...
Authors
V.E. Langenheim, Shawn Biehler, D.K. McPhee, C.A. McCabe, J. T. Watt, M.L. Anderson, B. A. Chuchel, P. Stoffer
Relatively simple through-going fault planes at large-earthquake depth may be concealed by the surface complexity of strike-slip faults Relatively simple through-going fault planes at large-earthquake depth may be concealed by the surface complexity of strike-slip faults
At the surface, strike-slip fault stepovers, including abrupt fault bends, are typically regions of complex, often disconnected faults. This complexity has traditionally led geologists studying the hazard of active faults to consider such stepovers as important fault segment boundaries, and to give lower weight to earthquake scenarios that involve rupture through the stepover zone...
Authors
Russell W. Graymer, Victoria E. Langenheim, Robert W. Simpson, Robert C. Jachens, David A. Ponce