Hello. I am a geophysicist with the United States Geological Survey, specializing in active-source, land-based seismology. I use a variety of techniques such as refraction tomography, reflection imaging, Vp/Vs measurements, and guided wave data to locate faults in the near subsurface.
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High-resolution seismic data acquired near seismic station CE.57213 in Fremont, California
In September 2021, the U.S. Geological Survey acquired high-resolution P- and S-wave data near seismic station CE.57213 in Fremont, California, approximately 100 m east of the mapped trace of the Hayward Fault. We acquired the seismic data to evaluate the time-averaged shear-wave velocity in the upper 30 m (VS30) and to better understand ground-shaking near the station CE.57213. The seismic data w
High-resolution seismic data acquired at northern Ano Nuevo, California
The U.S. Geological Survey acquired high-resolution P- and S-wave seismic data across the Frijoles Fault strand of the San Gregorio Fault Zone (SGFZ) at northern Ano Nuevo, California in 2012. SGFZ is a right-lateral fault system that is mainly offshore, and prior studies provide highly variable slip estimates, which indicates uncertainty about the seismic hazard it poses. Therefore, the primary g
High-resolution seismic data acquired at six Southern California Seismic Network (SCSN) recording stations in 2017
In August 2017, the U.S. Geological Survey acquired high-resolution P- and S-wave seismic data near six Southern California Seismic Network (SCSN) recording stations in southern California: CI.OLI Olinda; CI.SRN Serrano; CI.MUR Murrieta; CI.LCG La Cienega; CI.RUS Rush; and CI.STC Santa Clara (Figure 1). These strong-motion recording stations are located inside Southern California Edison electrical
High-resolution seismic data acquired at six seismic network recording stations in San Bernardino County, California in 2019
In May 2019, the U.S. Geological Survey acquired high resolution P- and S-wave seismic data near six seismic network recording stations in San Bernardino County, California: Southern California Seismic Network CI.CLT Calelectic, CI.MLS Mira Loma, CI.CJM Cajon Mountain and CI.HLN Highland; California Strong Motion Instrumentation Program station CE.23542; and US National Strong-Motion Network stati
Data Release for a 2020 High-Resolution Seismic Survey across Northeastern Edwards Air Force Base, Kern County, California
In June of 2020, the U.S. Geological Survey conducted a high-resolution seismic survey at Edwards Air Force Base in Kern County, California. Seismic data were acquired using a DTCC SmartSolo 3-component nodal seismometer system ("node"), which continuously recorded at 2000 samples per second. Nodes were deployed 5 meters apart along a southwest-northeast trend to create an approximately 3-km-long
Data Release for the 2016 East Bay Seismic Imaging Investigation of the Hayward Fault Zone
In October 2016, we acquired an approximately 15-km-long seismic profile along a linear transect across the East Bay region of the San Francisco Bay area. Our goal was to image previously unknown strands of the Hayward Fault zone and to better delineate the structure and geometry of the main trace of the Hayward Fault. Our profile started near the southern border of San Leandro, California at the
Data Release for the 2018 U.S. Geological Survey - California Geological Survey Fault-Imaging Surveys Across the Hollywood and Santa Monica Faults, Los Angeles County, California
We acquired multiple types of controlled-source seismic data across the Hollywood Fault in Hollywood, Calif., and the Santa Monica Fault in Beverly Hills, Calif., in May and June of 2018. We acquired two separate profiles across the Hollywood Fault, and from those data we can evaluate multiple seismic datasets and calculate seismic models including guided-wave data, tomographic VP data, tomographi
Data report for line 8 of the 2011 USGS seismic imaging survey at San Andreas Lake, San Mateo County, California
In June of 2011, the U.S. Geological Survey acquired high-resolution P- and S-wave seismic data across the mapped (Schussler, 1906) trace of the San Andreas Fault zone at San Andreas Lake in unincorporated San Mateo County, California. Our seismic survey consisted of seismic reflection, refraction, and guided-wave data along a 60-m-long profile. To acquire the reflection and refraction data we co-
Data Report for Nodal Seismograph Recording at the Byerly Seismographic Vault, University of California, Berkeley, California
In September and October 2019, the USGS and UC Berkeley (UCB) deployed two nodal seismographs at the Byerly Seismographic Vault (station BRK), east of the UCB campus. One of the nodes was located immediately outside the vault, and the other was located within the vault, adjacent to a broadband seismometer. The objective of this deployment was to compare recordings of local earthquakes and ambient
2017b high resolution seismic imaging of the West Napa Fault Zone, St. Helena, California
In September 2017, the U.S. Geological Survey acquired high resolution P- and S-wave seismic data across the suspected trace of the West Napa Fault zone in St. Helena, California, approximately 70 m north of the previous seismic survey conducted in April 2017 (Chan et al., 2018). We acquired seismic reflection, refraction, and guided-wave data along a 75-m-long profile across the expected trend of
2017 U.S. Geological Survey/BC Hydro seismic data recorded at three dam sites on Vancouver Island, British Columbia, Canada
In May 2017, we acquired high-resolution seismic profiles near three dam sites (Strathcona, Laodre and John Hart dams) located on Vancouver Island, British Columbia, Canada. Our goal was to measure seismic velocities (particularly Vs) at each dam site using body and surface waves. The data were analyzed using refraction tomography and multi-channel analysis of surface waves (MASW), especially in t
2015 high resolution seismic acquisition at Dos Palmas Preserve, Mecca, California
In March 2015, the U.S. Geological Survey acquired seismic reflection and refraction data along an approximately 2.8-km-long profile across northwest-trending San Andreas Fault splays located at the Dos Palmas Preserve east of Salton Sea. To acquire the reflection and refraction data, we collocated shots and geophones, spaced every 3 m along the profile. We used 933 SercelTM L40A P-wave (40-Hz ver
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Evidence of active Quaternary deformation on the Great Valley fault system near Winters, northern California
The Great Valley fault system defines the tectonic boundary between the Coast Ranges and the Central Valley in California, is active throughout the Quaternary, and has been the source of several significant (M > 6) historic earthquakes, including the 1983 M 6.5 Coalinga earthquake and the 1892 Vacaville–Winters earthquake sequence. However, the locations and geometries of individual faults in the
2018 U.S. Geological Survey–California Geological Survey fault-imaging surveys across the Hollywood and Santa Monica Faults, Los Angeles County, California
We acquired multiple types of seismic data across the Hollywood Fault in Hollywood, Calif., and the Santa Monica Fault in Beverly Hills, Calif., in May and June 2018. On the basis of our data, we infer near-surface locations of various traces of these faults.From two separate profiles across the Hollywood Fault, we evaluated multiple seismic datasets and models, including guided-wave data, tomogra
Mechanics of near-field deformation during co- and post-seismic shallow fault slip
Poor knowledge of how faults slip and distribute deformation in the shallow crust hinders efforts to mitigate hazards where faults increasingly intersect with the expanding global population at Earth’s surface. Here we analyze two study sites along the 2014 M 6.0 South Napa, California, earthquake rupture, each dominated by either co- or post-seismic shallow fault slip. We combine mobile laser sca
Seismic evaluation of shallow-depth structure, faulting, and groundwater variations across the Dos Palmas Preserve, Riverside County, California
IntroductionDos Palmas Preserve is a Colorado Desert oasis and wetland in Riverside County, California, located near the base of the Orocopia Mountains and northeast of the Salton Sea. The original source of water for the oasis was artesian springs that developed at the base of the Orocopia Mountains, but more abundant water supplies were later provided to Dos Palmas Preserve when the Coachella Ca
Three-dimensional basin and fault structure from a detailed seismic velocity model of Coachella Valley, Southern California
The Coachella Valley in the northern Salton Trough is known to produce destructive earthquakes, making it a high seismic hazard area. Knowledge of the seismic velocity structure and geometry of the sedimentary basins and fault zones is required to improve earthquake hazard estimates in this region. We simultaneously inverted first P wave travel times from the Southern California Seismic Network (3
Two-dimensional seismic velocities and structural variations at three British Columbia Hydro and Power Authority (BC Hydro) dam sites, Vancouver Island, British Columbia, Canada
SummaryIn June, 2017, we acquired seismic data along five linear profiles at three British Columbia Hydro and Power Authority (BC Hydro, a Canadian provincial Crown Corporation) dam sites (John Hart, Ladore, and Strathcona Dams) on Vancouver Island, British Columbia, Canada. We also attempted to acquire linear seismic profiles at two additional BC Hydro dam sites (Ruskin Dam and Stave Falls Dam) e
VS30 at three strong-motion recording stations in Napa and Solano Counties, California — Lovall Valley Road, Broadway Street and Sereno Drive in Vallejo, and Vallejo Fire Station — Calculations determined from S-wave refraction tomography and multichannel
The August 24, 2014, moment magnitude (Mw) 6.0 South Napa earthquake caused an estimated $400 million in structural damage to the City of Napa, California. In 2015, we acquired high-resolution P- and S-wave seismic data near three strong-motion recording stations in Napa and Solano Counties where high peak ground accelerations (PGAs) were recorded during the South Napa earthquake. In this report,
VS30 at three strong-motion recording stations in Napa and Napa County, California — Main Street in downtown Napa, Napa fire station number 3, and Kreuzer Lane — Calculations determined from s-wave refraction tomography and multichannel analysis of surfac
The August 24, 2014, moment magnitude (Mw) 6.0 South Napa earthquake caused an estimated $400 million in structural damage to the City of Napa, California. In 2015, we acquired high-resolution P- and S-wave seismic data near three strong-motion recording stations in Napa County where high peak ground accelerations (PGAs) were recorded during the South Napa earthquake. In this report, we present re
Subsurface geometry of the San Andreas fault in southern California: Results from the Salton Seismic Imaging Project (SSIP) and strong ground motion expectations
The San Andreas fault (SAF) is one of the most studied strike‐slip faults in the world; yet its subsurface geometry is still uncertain in most locations. The Salton Seismic Imaging Project (SSIP) was undertaken to image the structure surrounding the SAF and also its subsurface geometry. We present SSIP studies at two locations in the Coachella Valley of the northern Salton trough. On our line 4, a
Shallow-depth location and geometry of the Piedmont Reverse splay of the Hayward Fault, Oakland, California
The Piedmont Thrust Fault, herein referred to as the Piedmont Reverse Fault (PRF), is a splay of the Hayward Fault that trends through a highly populated area of the City of Oakland, California (fig. 1A). Although the PRF is unlikely to generate a large-magnitude earthquake, slip on the PRF or high-amplitude seismic energy traveling along the PRF may cause considerable damage during a large earthq
Subsurface fault damage zone of the 2014 Mw 6.0 South Napa, California, earthquake viewed from fault‐zone trapped waves
The aftershocks of the 24 August 2014 Mw 6.0 South Napa earthquake generated prominent fault‐zone trapped waves (FZTWs) that were recorded on two 1.9‐km‐long seismic arrays deployed across the northern projection (array 1, A1) and the southern part (A2) of the surface rupture of the West Napa fault zone (WNFZ). We also observed FZTWs on an array (A3) deployed across the intersection of the Frankli
Reply to “Comment on ‘Near-surface location, geometry, and velocities of the Santa Monica fault zone, Los Angeles, California’ by R. D. Catchings, G. Gandhok, M. R. Goldman, D. Okaya, M. J. Rymer, and G. W. Bawden” by T. L. Pratt and J. F. Dolan
In a comment on our 2008 paper (Catchings, Gandhok, et al., 2008) on the Santa Monica fault in Los Angeles, California, Pratt and Dolan (2010) (herein referred to as P&D) cite numerous objections to our work, inferring that our study is flawed. However, as shown in our reply, their objections contradict their own published works, published works of others, and proven seismic methodologies. Rather
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High-resolution seismic data acquired near seismic station CE.57213 in Fremont, California
In September 2021, the U.S. Geological Survey acquired high-resolution P- and S-wave data near seismic station CE.57213 in Fremont, California, approximately 100 m east of the mapped trace of the Hayward Fault. We acquired the seismic data to evaluate the time-averaged shear-wave velocity in the upper 30 m (VS30) and to better understand ground-shaking near the station CE.57213. The seismic data wHigh-resolution seismic data acquired at northern Ano Nuevo, California
The U.S. Geological Survey acquired high-resolution P- and S-wave seismic data across the Frijoles Fault strand of the San Gregorio Fault Zone (SGFZ) at northern Ano Nuevo, California in 2012. SGFZ is a right-lateral fault system that is mainly offshore, and prior studies provide highly variable slip estimates, which indicates uncertainty about the seismic hazard it poses. Therefore, the primary gHigh-resolution seismic data acquired at six Southern California Seismic Network (SCSN) recording stations in 2017
In August 2017, the U.S. Geological Survey acquired high-resolution P- and S-wave seismic data near six Southern California Seismic Network (SCSN) recording stations in southern California: CI.OLI Olinda; CI.SRN Serrano; CI.MUR Murrieta; CI.LCG La Cienega; CI.RUS Rush; and CI.STC Santa Clara (Figure 1). These strong-motion recording stations are located inside Southern California Edison electricalHigh-resolution seismic data acquired at six seismic network recording stations in San Bernardino County, California in 2019
In May 2019, the U.S. Geological Survey acquired high resolution P- and S-wave seismic data near six seismic network recording stations in San Bernardino County, California: Southern California Seismic Network CI.CLT Calelectic, CI.MLS Mira Loma, CI.CJM Cajon Mountain and CI.HLN Highland; California Strong Motion Instrumentation Program station CE.23542; and US National Strong-Motion Network statiData Release for a 2020 High-Resolution Seismic Survey across Northeastern Edwards Air Force Base, Kern County, California
In June of 2020, the U.S. Geological Survey conducted a high-resolution seismic survey at Edwards Air Force Base in Kern County, California. Seismic data were acquired using a DTCC SmartSolo 3-component nodal seismometer system ("node"), which continuously recorded at 2000 samples per second. Nodes were deployed 5 meters apart along a southwest-northeast trend to create an approximately 3-km-longData Release for the 2016 East Bay Seismic Imaging Investigation of the Hayward Fault Zone
In October 2016, we acquired an approximately 15-km-long seismic profile along a linear transect across the East Bay region of the San Francisco Bay area. Our goal was to image previously unknown strands of the Hayward Fault zone and to better delineate the structure and geometry of the main trace of the Hayward Fault. Our profile started near the southern border of San Leandro, California at theData Release for the 2018 U.S. Geological Survey - California Geological Survey Fault-Imaging Surveys Across the Hollywood and Santa Monica Faults, Los Angeles County, California
We acquired multiple types of controlled-source seismic data across the Hollywood Fault in Hollywood, Calif., and the Santa Monica Fault in Beverly Hills, Calif., in May and June of 2018. We acquired two separate profiles across the Hollywood Fault, and from those data we can evaluate multiple seismic datasets and calculate seismic models including guided-wave data, tomographic VP data, tomographiData report for line 8 of the 2011 USGS seismic imaging survey at San Andreas Lake, San Mateo County, California
In June of 2011, the U.S. Geological Survey acquired high-resolution P- and S-wave seismic data across the mapped (Schussler, 1906) trace of the San Andreas Fault zone at San Andreas Lake in unincorporated San Mateo County, California. Our seismic survey consisted of seismic reflection, refraction, and guided-wave data along a 60-m-long profile. To acquire the reflection and refraction data we co-Data Report for Nodal Seismograph Recording at the Byerly Seismographic Vault, University of California, Berkeley, California
In September and October 2019, the USGS and UC Berkeley (UCB) deployed two nodal seismographs at the Byerly Seismographic Vault (station BRK), east of the UCB campus. One of the nodes was located immediately outside the vault, and the other was located within the vault, adjacent to a broadband seismometer. The objective of this deployment was to compare recordings of local earthquakes and ambient2017b high resolution seismic imaging of the West Napa Fault Zone, St. Helena, California
In September 2017, the U.S. Geological Survey acquired high resolution P- and S-wave seismic data across the suspected trace of the West Napa Fault zone in St. Helena, California, approximately 70 m north of the previous seismic survey conducted in April 2017 (Chan et al., 2018). We acquired seismic reflection, refraction, and guided-wave data along a 75-m-long profile across the expected trend of2017 U.S. Geological Survey/BC Hydro seismic data recorded at three dam sites on Vancouver Island, British Columbia, Canada
In May 2017, we acquired high-resolution seismic profiles near three dam sites (Strathcona, Laodre and John Hart dams) located on Vancouver Island, British Columbia, Canada. Our goal was to measure seismic velocities (particularly Vs) at each dam site using body and surface waves. The data were analyzed using refraction tomography and multi-channel analysis of surface waves (MASW), especially in t2015 high resolution seismic acquisition at Dos Palmas Preserve, Mecca, California
In March 2015, the U.S. Geological Survey acquired seismic reflection and refraction data along an approximately 2.8-km-long profile across northwest-trending San Andreas Fault splays located at the Dos Palmas Preserve east of Salton Sea. To acquire the reflection and refraction data, we collocated shots and geophones, spaced every 3 m along the profile. We used 933 SercelTM L40A P-wave (40-Hz ver - Publications
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Evidence of active Quaternary deformation on the Great Valley fault system near Winters, northern California
The Great Valley fault system defines the tectonic boundary between the Coast Ranges and the Central Valley in California, is active throughout the Quaternary, and has been the source of several significant (M > 6) historic earthquakes, including the 1983 M 6.5 Coalinga earthquake and the 1892 Vacaville–Winters earthquake sequence. However, the locations and geometries of individual faults in the2018 U.S. Geological Survey–California Geological Survey fault-imaging surveys across the Hollywood and Santa Monica Faults, Los Angeles County, California
We acquired multiple types of seismic data across the Hollywood Fault in Hollywood, Calif., and the Santa Monica Fault in Beverly Hills, Calif., in May and June 2018. On the basis of our data, we infer near-surface locations of various traces of these faults.From two separate profiles across the Hollywood Fault, we evaluated multiple seismic datasets and models, including guided-wave data, tomograMechanics of near-field deformation during co- and post-seismic shallow fault slip
Poor knowledge of how faults slip and distribute deformation in the shallow crust hinders efforts to mitigate hazards where faults increasingly intersect with the expanding global population at Earth’s surface. Here we analyze two study sites along the 2014 M 6.0 South Napa, California, earthquake rupture, each dominated by either co- or post-seismic shallow fault slip. We combine mobile laser scaSeismic evaluation of shallow-depth structure, faulting, and groundwater variations across the Dos Palmas Preserve, Riverside County, California
IntroductionDos Palmas Preserve is a Colorado Desert oasis and wetland in Riverside County, California, located near the base of the Orocopia Mountains and northeast of the Salton Sea. The original source of water for the oasis was artesian springs that developed at the base of the Orocopia Mountains, but more abundant water supplies were later provided to Dos Palmas Preserve when the Coachella CaThree-dimensional basin and fault structure from a detailed seismic velocity model of Coachella Valley, Southern California
The Coachella Valley in the northern Salton Trough is known to produce destructive earthquakes, making it a high seismic hazard area. Knowledge of the seismic velocity structure and geometry of the sedimentary basins and fault zones is required to improve earthquake hazard estimates in this region. We simultaneously inverted first P wave travel times from the Southern California Seismic Network (3Two-dimensional seismic velocities and structural variations at three British Columbia Hydro and Power Authority (BC Hydro) dam sites, Vancouver Island, British Columbia, Canada
SummaryIn June, 2017, we acquired seismic data along five linear profiles at three British Columbia Hydro and Power Authority (BC Hydro, a Canadian provincial Crown Corporation) dam sites (John Hart, Ladore, and Strathcona Dams) on Vancouver Island, British Columbia, Canada. We also attempted to acquire linear seismic profiles at two additional BC Hydro dam sites (Ruskin Dam and Stave Falls Dam) eVS30 at three strong-motion recording stations in Napa and Solano Counties, California — Lovall Valley Road, Broadway Street and Sereno Drive in Vallejo, and Vallejo Fire Station — Calculations determined from S-wave refraction tomography and multichannel
The August 24, 2014, moment magnitude (Mw) 6.0 South Napa earthquake caused an estimated $400 million in structural damage to the City of Napa, California. In 2015, we acquired high-resolution P- and S-wave seismic data near three strong-motion recording stations in Napa and Solano Counties where high peak ground accelerations (PGAs) were recorded during the South Napa earthquake. In this report,VS30 at three strong-motion recording stations in Napa and Napa County, California — Main Street in downtown Napa, Napa fire station number 3, and Kreuzer Lane — Calculations determined from s-wave refraction tomography and multichannel analysis of surfac
The August 24, 2014, moment magnitude (Mw) 6.0 South Napa earthquake caused an estimated $400 million in structural damage to the City of Napa, California. In 2015, we acquired high-resolution P- and S-wave seismic data near three strong-motion recording stations in Napa County where high peak ground accelerations (PGAs) were recorded during the South Napa earthquake. In this report, we present reSubsurface geometry of the San Andreas fault in southern California: Results from the Salton Seismic Imaging Project (SSIP) and strong ground motion expectations
The San Andreas fault (SAF) is one of the most studied strike‐slip faults in the world; yet its subsurface geometry is still uncertain in most locations. The Salton Seismic Imaging Project (SSIP) was undertaken to image the structure surrounding the SAF and also its subsurface geometry. We present SSIP studies at two locations in the Coachella Valley of the northern Salton trough. On our line 4, aShallow-depth location and geometry of the Piedmont Reverse splay of the Hayward Fault, Oakland, California
The Piedmont Thrust Fault, herein referred to as the Piedmont Reverse Fault (PRF), is a splay of the Hayward Fault that trends through a highly populated area of the City of Oakland, California (fig. 1A). Although the PRF is unlikely to generate a large-magnitude earthquake, slip on the PRF or high-amplitude seismic energy traveling along the PRF may cause considerable damage during a large earthqSubsurface fault damage zone of the 2014 Mw 6.0 South Napa, California, earthquake viewed from fault‐zone trapped waves
The aftershocks of the 24 August 2014 Mw 6.0 South Napa earthquake generated prominent fault‐zone trapped waves (FZTWs) that were recorded on two 1.9‐km‐long seismic arrays deployed across the northern projection (array 1, A1) and the southern part (A2) of the surface rupture of the West Napa fault zone (WNFZ). We also observed FZTWs on an array (A3) deployed across the intersection of the FrankliReply to “Comment on ‘Near-surface location, geometry, and velocities of the Santa Monica fault zone, Los Angeles, California’ by R. D. Catchings, G. Gandhok, M. R. Goldman, D. Okaya, M. J. Rymer, and G. W. Bawden” by T. L. Pratt and J. F. Dolan
In a comment on our 2008 paper (Catchings, Gandhok, et al., 2008) on the Santa Monica fault in Los Angeles, California, Pratt and Dolan (2010) (herein referred to as P&D) cite numerous objections to our work, inferring that our study is flawed. However, as shown in our reply, their objections contradict their own published works, published works of others, and proven seismic methodologies. Rather