I study seafloor geology along the West Coast of the U.S. using various types of geophysical surveys to map the seafloor and image sub-seafloor strata. The purpose of this work is to help understand the hazards posed to coastal communities and infrastructure by offshore active faults and submarine landslides.
I received a Bachelors Degree in Earth Science from U.C. Berkeley in 1981, and a Masters Degree in Geology from San Jose State University in 1993. I have worked at the USGS since 1981, first in the Minerals Program, where I worked to assess the potential for undiscovered mineral deposits in the western U.S., and used Argon geochronology to date mineral deposits and related igneous rocks. In 1995, I joined the Pacific Coastal and Marine Science Center, where I study marine geologic hazards such as earthquakes on offshore faults and tsunamis generated by submarine landslides.
Science and Products
U.S. West Coast and Alaska Marine Geohazards
Digital maps of submarine landslides and mass wasting features offshore of southern California
Methane seep locations derived from water-column acoustic backscatter data collected along Cascadia Margin offshore Oregon and Northern California, 2018-2021
Multichannel sparker and chirp seismic reflection data collected offshore South East Alaska during USGS Field Activity 2017-621-FA
Geophysical and core sample data collected offshore central California, during field activity 2019-651-FA (ver 2.0, August 2023)
Composite multibeam bathymetry surface and data sources of the southern Cascadia Margin offshore Oregon and northern California
Geophysical and core sample data collected offshore San Francisco, California, during field activity 2019-649-FA from 2019-10-11 to 2019-10-18
Geophysical and core sample data collected offshore Oceanside to San Diego, southern California, during field activity 2018-638-FA from 2018-05-21 to 2018-05-26
Geophysical and sampling data collected offshore Oceanside, southern California during field activity 2017-686-FA from 2017-10-23 to 2017-10-31
Quaternary faults offshore of California
Multichannel minisparker and chirp seismic reflection data of USGS field activity 2016-616-FA collected in the Catalina Basin offshore southern California in February 2016
Minisparker and chirp seismic-reflection data of field activity 2014-645-FA collected in the outer Santa Barbara Channel, California, between 2014-11-12 to 2014-11-25 (ver. 2.0, March 2020)
Multibeam bathymetry and acoustic-backscatter data collected in 2016 in Catalina Basin, southern California and merged multibeam bathymetry datasets of the northern portion of the Southern California Continental Borderland
Colored shaded-relief bathymetry, acoustic backscatter, and selected perspective views of the northern part of the California Continental Borderland, southern California
Colored shaded-relief bathymetry, acoustic backscatter, and selected perspective views of the Inner Continental Borderland, southern California
California State Waters Map Series: offshore of Refugio Beach, California
California State Waters Map Series: Offshore of Refugio Beach, California
California State Waters Map Series: offshore of Coal Oil Point, California
California State Waters Map Series: Offshore of Coal Oil Point, California
California State Waters Map Series: offshore of Santa Barbara, California
California State Waters Map Series: Offshore of Santa Barbara, California
Onshore and offshore geologic map of the Coal Oil Point area, southern California
Onshore and offshore geologic map of the Coal Oil Point area, southern California
Geologic map of the Cerro Gordo Peak 7.5' Quadrangle, Inyo County, California
Diving deeper into seep distribution along the Cascadia Convergent Margin, USA
Subaqueous clinoforms created by sandy wave-supported gravity flows: Lessons from the central California shelf
Assessment of significant sand resources in Federal and California State Waters of the San Francisco, Oceanside, and Silver Strand littoral cell study areas along the continental shelf of California
Compilation of existing data for sand resource studies in Federal and California State Waters of the San Francisco, Oceanside, and Silver Strand littoral cell study areas along the continental shelf of California—Strategy for field studies and sand resour
Focused fluid flow and methane venting along the Queen Charlotte fault, offshore Alaska (USA) and British Columbia (Canada)
Morphology, structure, and kinematics of the San Clemente and Catalina faults based on high-resolution marine geophysical data, southern California Inner Continental Borderland
Mapping, exploration, and characterization of the California continental margin and associated features from the California-Oregon border to Ensenada, Mexico
Commentary: Variability in shelf sedimentation in response to fluvial sediment supply and coastal erosion over the past 1,000 Years in Monterey Bay, CA, United States
The Santa Cruz Basin submarine landslide complex, southern California: Repeated failure of uplifted basin sediment
The Santa Cruz Basin (SCB) is one of several fault-bounded basins within the California Continental Borderland that has drawn interest over the years for its role in the tectonic evolution of the region, but also because it contains a record of a variety of modes of sedimentary mass transport (i.e., open slope vs. canyon-confined systems). Here, we present a suite of new high-resolution marine geo
Faunal and stable isotopic analyses of benthic foraminifera from the Southeast Seep on Kimki Ridge offshore southern California, USA
Slope failure and mass transport processes along the Queen Charlotte Fault Zone, western British Columbia
Multibeam echosounder (MBES) images, 3.5 kHz seismic-reflection profiles and piston cores obtained along the southern Queen Charlotte Fault Zone are used to map and date mass-wasting events at this transform margin – a seismically active boundary that separates the Pacific Plate from the North American Plate. Whereas the upper continental slope adjacent to and east (upslope) of the fault zone offs
Slope failure and mass transport processes along the Queen Charlotte Fault, southeastern Alaska
The Queen Charlotte Fault defines the Pacific–North America transform plate boundary in western Canada and southeastern Alaska for c. 900 km. The entire length of the fault is submerged along a continental margin dominated by Quaternary glacial processes, yet the geomorphology along the margin has never been systematically examined due to the absence of high-resolution seafloor mapping data. Hence
Science and Products
- Science
U.S. West Coast and Alaska Marine Geohazards
Marine geohazards are sudden and extreme events beneath the ocean that threaten coastal populations. Such underwater hazards include earthquakes, volcanic eruptions, landslides, and tsunamis.ByNatural Hazards Mission Area, Coastal and Marine Hazards and Resources Program, Pacific Coastal and Marine Science Center, 3-D CT Core Imaging Laboratory, Core Preparation and Analysis Laboratory and Sample Repositories, Big Sur Landslides, Deep Sea Exploration, Mapping and Characterization, Subduction Zone Science - Data
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Digital maps of submarine landslides and mass wasting features offshore of southern California
This data release provides the locations and certain key metrics of landslide features offshore southern California, including landslide perimeters, scarps, evacuation zones, debris aprons, and slide-prone areas in geographic information system (GIS) shapefile format. The offshore region of southern California is a tectonically active area that includes more than 20 fault-bounded basins and ridgesMethane seep locations derived from water-column acoustic backscatter data collected along Cascadia Margin offshore Oregon and Northern California, 2018-2021
Between 2018-2021, the U.S. Geological Survey cooperated with NOAA to conduct multibeam echo-sounding surveys to map the seafloor along the Cascadia convergent margin, collecting acoustic bathymetry, backscatter and water column data. Rising bubbles emitted from methane cold seeps on the seafloor can be detected acoustically with this multibeam echo-sounding sonar, and this dataset contains the loMultichannel sparker and chirp seismic reflection data collected offshore South East Alaska during USGS Field Activity 2017-621-FA
High-resolution multichannel seismic reflection data and chirp sub-bottom data were collected by the U.S. Geological Survey in July and August 2017 offshore southeast Alaska to expand data coverage along the Queen Charlotte Fault system. Data were acquired to study earthquake hazards, fault mechanics and submarine mass wasting processes along the Queen Charlotte fault system, a 1200 km long transfGeophysical and core sample data collected offshore central California, during field activity 2019-651-FA (ver 2.0, August 2023)
This dataset includes sub-bottom seismic and sediment core data collected during USGS field activity 2019-651-FA. Data were collected aboard the M/V Bold Horizon in October 2019 offshore central California in the vicinity of Morro Bay. Sub-bottom data include multichannel sparker and CHIRP seismic in SEG-Y format with associated navigation tracklines. Core data include photo and computed tomographComposite multibeam bathymetry surface and data sources of the southern Cascadia Margin offshore Oregon and northern California
Bathymetry data from various sources, including newly released 2018 and 2019 multibeam data collected by the National Oceanic and Atmospheric Administration (NOAA) and the U.S. Geological Survey (USGS), were combined to create a composite 30-m resolution multibeam bathymetry surface of the southern Cascadia Margin offshore of Oregon and northern California. The bathymetry data are available as a 3Geophysical and core sample data collected offshore San Francisco, California, during field activity 2019-649-FA from 2019-10-11 to 2019-10-18
The U.S. Geological Survey (USGS) collected geophysical and core sample data aboard the R/V Bold Horizon in 2019 on cruise 2019-649-FA offshore San Francisco, California. The data were collected to assess sand and gravel resources in Federal and State waters for potential use in future beach nourishment projects along stretches of the coast where critical erosion hotspots have been identified. ThiGeophysical and core sample data collected offshore Oceanside to San Diego, southern California, during field activity 2018-638-FA from 2018-05-21 to 2018-05-26
The U.S. Geological Survey (USGS) collected geophysical and core sample data aboard the R/V Bold Horizon in 2018 on cruise 2018-638-FA offshore Oceanside to San Diego, southern California. The data were collected to assess sand and gravel resources in Federal and State waters for potential use in future beach nourishment projects along stretches of the coast where critical erosion hotspots have beGeophysical and sampling data collected offshore Oceanside, southern California during field activity 2017-686-FA from 2017-10-23 to 2017-10-31
This data release contains geophysical and sediment sample data that were collected aboard the R/V Snavely in 2017 on U.S. Geological Survey cruise 2017-686-FA offshore Oceanside, southern California. The goal of the survey was to provide high-resolution imaging, magnetic anomaly profiles and sediment analysis to characterize the surface and subsurface properties of the study area such as unconsolQuaternary faults offshore of California
A comprehensive map of Quaternary faults has been generated for offshore of California. The Quaternary fault map includes mapped geometries and attribute information for offshore fault systems located in California State and Federal waters. The polyline shapefile and matching KML file have been compiled from previously published mapping where relatively dense, high-resolution marine geophysical daMultichannel minisparker and chirp seismic reflection data of USGS field activity 2016-616-FA collected in the Catalina Basin offshore southern California in February 2016
This data release contains 25 multichannel minisparker seismic reflection (MCS) profiles and 41 chirp sub-bottom profiles that were collected in February of 2016 from the Catalina Basin offshore southern California by the U.S. Geological Survey Pacific and Coastal Marine Science Center in cooperation with the University of Washington. Data were collected aboard the University of Washington's R/V TMinisparker and chirp seismic-reflection data of field activity 2014-645-FA collected in the outer Santa Barbara Channel, California, between 2014-11-12 to 2014-11-25 (ver. 2.0, March 2020)
The U.S. Geological Survey (USGS) collected high-resolution multichannel sparker, minisparker and chirp seismic-reflection data in November 2014, from offshore Catalina and Santa Cruz basins. The survey was designed to image faults and folds associated with movement on the faults in offshore southern California, including the Catalina, Catalina Ridge, San Clemente, and San Diego Trough faults. DatMultibeam bathymetry and acoustic-backscatter data collected in 2016 in Catalina Basin, southern California and merged multibeam bathymetry datasets of the northern portion of the Southern California Continental Borderland
In February 2016 the University of Washington in cooperation with the U.S. Geological Survey, Pacific Coastal and Marine Science Center (USGS, PCMSC) collected multibeam bathymetry and acoustic-backscatter data in and near the Catalina Basin, southern California aboard the University of Washington's Research Vessel Thomas G. Thompson. Data was collected using a Kongsberg EM300 multibeam echosounde - Maps
Colored shaded-relief bathymetry, acoustic backscatter, and selected perspective views of the northern part of the California Continental Borderland, southern California
The California Continental Borderland is the complex continental margin in southern California that extends from Point Conception southward into northern Baja California (Fisher and others, 2009). This colored shaded-relief bathymetry map of the northern continental borderland in southern California was generated primarily from multibeam-echosounder data collected by the University of Washington iColored shaded-relief bathymetry, acoustic backscatter, and selected perspective views of the Inner Continental Borderland, southern California
In late 2013, Scripps Institution of Oceanography collected multibeam bathymetry and acoustic-backscatter data of the Inner Continental Borderland Region, Southern California. The U.S. Geological Survey Pacific Coastal and Marine Science Center processed these data, and this report provides the data in a number of different formats in addition to a set of map sheets. The data catalog provides theCalifornia State Waters Map Series: offshore of Refugio Beach, California
In 2007, the California Ocean Protection Council initiated the California Seafloor Mapping Program (CSMP), designed to create a comprehensive seafloor map of high-resolution bathymetry, marine benthic habitats, and geology within California’s State Waters. The CSMP approach is to create highly detailed seafloor maps through collection, integration, interpretation, and visualization of swath sonarCalifornia State Waters Map Series: Offshore of Refugio Beach, California
In 2007, the California Ocean Protection Council initiated the California Seafloor Mapping Program (CSMP), designed to create a comprehensive seafloor map of high-resolution bathymetry, marine benthic habitats, and geology within California’s State Waters. The CSMP approach is to create highly detailed seafloor maps through collection, integration, interpretation, and visualization of swath sonarCalifornia State Waters Map Series: offshore of Coal Oil Point, California
In 2007, the California Ocean Protection Council initiated the California Seafloor Mapping Program (CSMP), designed to create a comprehensive seafloor map of high-resolution bathymetry, marine benthic habitats, and geology within the 3-nautical-mile limit of California’s State Waters. The CSMP approach is to create highly detailed seafloor maps through collection, integration, interpretation, andCalifornia State Waters Map Series: Offshore of Coal Oil Point, California
In 2007, the California Ocean Protection Council initiated the California Seafloor Mapping Program (CSMP), designed to create a comprehensive seafloor map of high-resolution bathymetry, marine benthic habitats, and geology within the 3-nautical-mile limit of California’s State Waters. The CSMP approach is to create highly detailed seafloor maps through collection, integration, interpretation, andCalifornia State Waters Map Series: offshore of Santa Barbara, California
In 2007, the California Ocean Protection Council initiated the California Seafloor Mapping Program (CSMP), designed to create a comprehensive seafloor map of high-resolution bathymetry, marine benthic habitats, and geology within the 3-nautical-mile limit of California’s State Waters. The CSMP approach is to create highly detailed seafloor maps through collection, integration, interpretation, andCalifornia State Waters Map Series: Offshore of Santa Barbara, California
In 2007, the California Ocean Protection Council initiated the California Seafloor Mapping Program (CSMP), designed to create a comprehensive seafloor map of high-resolution bathymetry, marine benthic habitats, and geology within the 3-nautical-mile limit of California’s State Waters. The CSMP approach is to create highly detailed seafloor maps through collection, integration, interpretation, andOnshore and offshore geologic map of the Coal Oil Point area, southern California
Geologic maps that span the shoreline and include both onshore and offshore areas are potentially valuable tools that can lead to a more in depth understanding of coastal environments. Such maps can contribute to the understanding of shoreline change, geologic hazards, both offshore and along-shore sediment and pollutant transport. They are also useful in assessing geologic and biologic resources.Onshore and offshore geologic map of the Coal Oil Point area, southern California
Geologic maps that span the shoreline and include both onshore and offshore areas are potentially valuable tools that can lead to a more in depth understanding of coastal environments. Such maps can contribute to the understanding of shoreline change, geologic hazards, both offshore and along-shore sediment and pollutant transport. They are also useful in assessing geologic and biologic resources.Geologic map of the Cerro Gordo Peak 7.5' Quadrangle, Inyo County, California
This digital map database, compiled from new mapping by the authors, represents the general distribution of bedrock and surficial deposits in the mapped area. Together with the accompanying pamphlet, it provides current information on the geologic structure and stratigraphy of the area covered. The database delineates map units that are identified by general age and lithology following the strat - Multimedia
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Filter Total Items: 38
Diving deeper into seep distribution along the Cascadia Convergent Margin, USA
Previous margin-wide studies of methane seep distribution along the Cascadia Subduction Zone indicate peaks in seep density within the landward limit of the of gas hydrate stability zone (GHSZ; ≤500 m depth), suggesting a link between current ocean warming, acceleration of hydrate dissociated, and methane emissions. This inferred connection, however, may not account for regional geologic and/or stAuthorsJane A. Rudebusch, Nancy G. Prouty, James E. Conrad, Janet Watt, Jared W. Kluesner, Jenna C. Hill, Nathaniel C. Miller, Sally J. Watson, Jess I.T. HillmanSubaqueous clinoforms created by sandy wave-supported gravity flows: Lessons from the central California shelf
Subaqueous clinoforms are an important yet underappreciated shelf feature. Their origins are typically associated with subaerial deltas but recent work has identified similar features in settings without a significant fluvial source. These other studies have shown that such subaqueous clinoforms, also known as infralittoral prograding wedges (IPWs), are created largely by wave-induced processes. TAuthorsElisa Medri, Alexander R. Simms, Jared W. Kluesner, Samuel Y. Johnson, Stuart P. Nishenko, H. Gary Greene, James E. ConradAssessment of significant sand resources in Federal and California State Waters of the San Francisco, Oceanside, and Silver Strand littoral cell study areas along the continental shelf of California
Executive SummaryThe Sand Resources Project was established through collaborative agreements between the U.S. Geological Survey (USGS), the Bureau of Ocean Energy Management (BOEM), and the California Ocean Protection Council (OPC) with the purpose of evaluating sand and gravel resources in Federal and California State Waters for potential use in future beach-nourishment projects. Project partnersAuthorsJonathan A. Warrick, James E. Conrad, Antoinette Papesh, Tom Lorenson, Ray SliterCompilation of existing data for sand resource studies in Federal and California State Waters of the San Francisco, Oceanside, and Silver Strand littoral cell study areas along the continental shelf of California—Strategy for field studies and sand resour
Executive SummaryThe Sand Resources Project was established through collaborative agreements between the U.S. Geological Survey (USGS), the Bureau of Ocean Energy Management (BOEM), and the California Ocean Protection Council (OPC) with the purpose of evaluating sand and gravel resources in Federal and California State Waters for potential use in future beach-nourishment projects. Project partnersAuthorsJonathan A. Warrick, James E. Conrad, Antoinette Papesh, Tom Lorenson, Ray SliterFocused fluid flow and methane venting along the Queen Charlotte fault, offshore Alaska (USA) and British Columbia (Canada)
Fluid seepage along obliquely deforming plate boundaries can be an important indicator of crustal permeability and influence on fault-zone mechanics and hydrocarbon migration. The ~850-km-long Queen Charlotte fault (QCF) is the dominant structure along the right-lateral transform boundary that separates the Pacific and North American tectonic plates offshore southeastern Alaska (USA) and western BAuthorsNancy G. Prouty, Daniel S. Brothers, Jared W. Kluesner, J. Vaughn Barrie, Brian D. Andrews, Rachel Lauer, Gary Greene, James E. Conrad, Thomas Lorenson, Michael D. Law, Diana Sahy, Kim Conway, Mary McGann, Peter DartnellMorphology, structure, and kinematics of the San Clemente and Catalina faults based on high-resolution marine geophysical data, southern California Inner Continental Borderland
Catalina Basin, located within the southern California Inner Continental Borderland (ICB), is traversed by two active submerged fault systems that are part of the broader North America-Pacific plate boundary: the San Clemente fault (along with a prominent splay, the Kimki fault) and the Catalina fault. Previous studies have suggested that the San Clemente fault (SCF) may be accommodating up to halAuthorsMaureen A. L. Walton, Daniel S. Brothers, James E. Conrad, Katherine L. Maier, Emily C. Roland, Jared W. Kluesner, Peter DartnellMapping, exploration, and characterization of the California continental margin and associated features from the California-Oregon border to Ensenada, Mexico
Priority Geographic Area: Both within and outside US Exclusive Economic Zone (EEZ). California continental margin. This area includes and continues south of the geographic area captured in the Watt et al. white paper. Description of Priority Area: The California continental margin, from the narrow shelf to abyssal depths, contains diverse seafloor features that influence benthic community types, bAuthorsAmanda Demopoulos, Nancy G. Prouty, Daniel S. Brothers, Janet Watt, James E. Conrad, Jason Chaytor, Chris CaldowCommentary: Variability in shelf sedimentation in response to fluvial sediment supply and coastal erosion over the past 1,000 Years in Monterey Bay, CA, United States
A commentary on: Variability in Shelf Sedimentation in Response to Fluvial Sediment Supply and Coastal Erosion Over the Past 1,000 Years in Monterey Bay, CA, United States. by Carlin J., Addison J., Wagner A., Schwartz V., Hayward J., Severin V. (2019) Front. Earth Sci., 7:113. doi: 10.3389/feart.2019.00113AuthorsJonathan Warrick, Amy E. East, Curt D. Storlazzi, James E. ConradThe Santa Cruz Basin submarine landslide complex, southern California: Repeated failure of uplifted basin sediment
The Santa Cruz Basin (SCB) is one of several fault-bounded basins within the California Continental Borderland that has drawn interest over the years for its role in the tectonic evolution of the region, but also because it contains a record of a variety of modes of sedimentary mass transport (i.e., open slope vs. canyon-confined systems). Here, we present a suite of new high-resolution marine geo
AuthorsDaniel S. Brothers, Katherine L. Maier, Jared W. Kluesner, James E. Conrad, Jason ChaytorFaunal and stable isotopic analyses of benthic foraminifera from the Southeast Seep on Kimki Ridge offshore southern California, USA
We investigated the benthic foraminiferal faunal and stable carbon and oxygen isotopic composition of a 15-cm push core (NA075-092b) obtained on a Telepresence-Enabled cruise to the Southeast Seep on Kimki Ridge offshore southern California. The seep core was taken at a depth of 973 m in the vicinity of a Beggiatoa bacterial mat and vesicomyid clams (Calyptogena) and compared to previously publishAuthorsMary McGann, James E. ConradSlope failure and mass transport processes along the Queen Charlotte Fault Zone, western British Columbia
Multibeam echosounder (MBES) images, 3.5 kHz seismic-reflection profiles and piston cores obtained along the southern Queen Charlotte Fault Zone are used to map and date mass-wasting events at this transform margin – a seismically active boundary that separates the Pacific Plate from the North American Plate. Whereas the upper continental slope adjacent to and east (upslope) of the fault zone offs
AuthorsH. G. Greene, J. Vaughn Barrie, Daniel S. Brothers, James E. Conrad, Kim Conway, Amy E. East, Randolph J. Enkin, Katherine L. Maier, Maureen A. L. Walton, K .M. M. RohrSlope failure and mass transport processes along the Queen Charlotte Fault, southeastern Alaska
The Queen Charlotte Fault defines the Pacific–North America transform plate boundary in western Canada and southeastern Alaska for c. 900 km. The entire length of the fault is submerged along a continental margin dominated by Quaternary glacial processes, yet the geomorphology along the margin has never been systematically examined due to the absence of high-resolution seafloor mapping data. Hence
AuthorsDaniel Brothers, Brian D. Andrews, Maureen A. L. Walton, H. Gary Greene, J. Vaughn Barrie, Nathaniel C. Miller, Uri S. ten Brink, Amy E. East, Peter J. Haeussler, Jared W. Kluesner, James E. Conrad - News