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James Conrad

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.

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A building after an earthquake has crumbled the roof and brick walls, the interior is now visible.

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. Devastating earthquakes in Japan (2011) and Chile (2010) that spawned pan-oceanic tsunamis sent a sobering reminder that U.S. coastlines are also vulnerable to natural disasters that originate in the ocean...
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Natural Hazards, 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
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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. Devastating earthquakes in Japan (2011) and Chile (2010) that spawned pan-oceanic tsunamis sent a sobering reminder that U.S. coastlines are also vulnerable to natural disasters that originate in the ocean...
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Composite 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 3
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Natural Hazards, Coastal and Marine Hazards and Resources Program, Pacific Coastal and Marine Science Center

Geophysical 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. Thi
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Natural Hazards, Coastal and Marine Hazards and Resources Program, Pacific Coastal and Marine Science Center

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

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 be
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Natural Hazards, Coastal and Marine Hazards and Resources Program, Pacific Coastal and Marine Science Center

Geophysical 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 unconsol
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Natural Hazards, Coastal and Marine Hazards and Resources Program, Pacific Coastal and Marine Science Center

Quaternary 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 da
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Natural Hazards, Coastal and Marine Hazards and Resources Program, Pacific Coastal and Marine Science Center

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

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 T
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Coastal and Marine Hazards and Resources Program, Pacific Coastal and Marine Science Center

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)

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. Dat
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Natural Hazards, Coastal and Marine Hazards and Resources Program, Pacific Coastal and Marine Science Center

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

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
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Coastal and Marine Hazards and Resources Program, Pacific Coastal and Marine Science Center

Multichannel minisparker and chirp seismic-reflection data of field activity 2015-651-FA; Chatham Strait and Cross Sound, southeastern Alaska from 2015-08-03 to 2015-08-21

High-resolution multichannel minisparker and chirp seismic-reflection data were collected in August of 2015 to explore marine geologic hazards of inland waterways of southeastern Alaska. Sub-bottom profiles were acquired in the inland waters between Glacier Bay and Juneau, including Cross Sound and Chatham Strait. High-resolution seismic-reflection profiles were acquired to assess evidence for act
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Coastal and Marine Hazards and Resources Program, Pacific Coastal and Marine Science Center

Chirp seismic-reflection data collected offshore of San Diego and Los Angeles Counties, southern California, from 2011-06-08 to 2011-06-22 (USGS field activity S-7-11-SC)

This dataset includes raw and processed, high-resolution seismic-reflection data collected in 2011 to collect information on active offshore faults. The survey area is offshore southern California between Long Beach and San Diego. The data were collected aboard the U.S. Geological Survey R/V Parke Snavely. The seismic-reflection data were acquired using an EdgeTech 512 subbottom profiler. Subbotto
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Natural Hazards, Coastal and Marine Hazards and Resources Program, Pacific Coastal and Marine Science Center

Chirp seismic-reflection data collected between Oceanside and La Jolla, offshore of southern California, from 2010-06-01 to 2010-06-12 (USGS field activity S-12-10-SC)

This dataset includes raw and processed, high-resolution seismic-reflection data collected in 2010 to collect information on active offshore faults. The survey is area is offshore southern California between Oceanside and La Jolla. The data were collected aboard the U.S. Geological Survey R/V Parke Snavely. The seismic-reflection data were acquired using an EdgeTech 512 chirp subbottom profiler. S
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Natural Hazards, Coastal and Marine Hazards and Resources Program, Pacific Coastal and Marine Science Center

Minisparker seismic-reflection data collected offshore of San Diego and Los Angeles Counties, southern California, from 2011-06-08 to 2011-06-22 (USGS field activity S-7-11-SC)

This dataset includes raw and processed, high-resolution seismic-reflection data collected in 2011 to collect information on active offshore faults. The survey area is offshore southern California between Long Beach and San Diego. The data were collected aboard the U.S. Geological Survey R/V Parke Snavely. The seismic-reflection data were acquired using a SIG 2mille minisparker and an Edgetech 512
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Natural Hazards, Coastal and Marine Hazards and Resources Program, Pacific Coastal and Marine Science Center

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 i
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Natural Hazards, Coastal and Marine Hazards and Resources Program, Pacific Coastal and Marine Science Center

Colored 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 the
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Pacific Coastal and Marine Science Center

California 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 sonar
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Pacific Coastal and Marine Science Center

California 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, and
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Pacific Coastal and Marine Science Center

California 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, and
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Natural Hazards, Coastal and Marine Hazards and Resources Program, Pacific Coastal and Marine Science Center

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.
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Pacific Coastal and Marine Science Center

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
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Focused 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 B
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Natural Hazards, Coastal and Marine Hazards and Resources Program, Pacific Coastal and Marine Science Center

Morphology, 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 hal
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Natural Hazards, Coastal and Marine Hazards and Resources Program, Pacific Coastal and Marine Science Center

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

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.2019.00113
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Natural Hazards, Coastal and Marine Hazards and Resources Program, Pacific Coastal and Marine Science Center

The tectonically controlled San Gabriel Channel–Lobe Transition Zone, Catalina Basin, Southern California Borderland

High-resolution geophysical data across the Catalina Basin, offshore southern California, USA, reveal a complex channel–lobe transition zone (CLTZ) and provide an opportunity to characterize an entire seafloor CLTZ in a tectonically active and confined-basin setting. The seafloor morphology, distribution of depositional and erosional features, and location of depocenters in the CLTZ are controlled
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Pacific Coastal and Marine Science Center

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
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Ecosystems, Natural Hazards, Coastal and Marine Hazards and Resources Program, Pacific Coastal and Marine Science Center, Wetland and Aquatic Research Center , Woods Hole Coastal and Marine Science Center

Faunal 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 publish
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Natural Hazards, Coastal and Marine Hazards and Resources Program, Pacific Coastal and Marine Science Center

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
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Pacific Coastal and Marine Science Center

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
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Natural Hazards, Coastal and Marine Hazards and Resources Program, Pacific Coastal and Marine Science Center, Woods Hole Coastal and Marine Science Center

Strain partitioning in southeastern Alaska: Is the Chatham Strait Fault active?

A 1200 km-long transform plate boundary passes through southeastern Alaska and northwestern British Columbia and represents one of the most seismically active, but poorly understood continental margins of North America. Although most of the plate motion is accommodated by the right-lateral Queen Charlotte–Fairweather Fault (QCFF) System, which has produced at least six M > 7 earthquakes since 1920
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Pacific Coastal and Marine Science Center

Seafloor fluid seeps on Kimki Ridge, offshore southern California: Links to active strike-slip faulting

The Kimki Ridge fluid seeps are located in western Catalina Basin about 60 km southwest of the southern California mainland and at a water depth of approximately 1100 m. Multichannel seismic reflection profiles collected by the U.S. Geological Survey (USGS) in 2014 show acoustic transparency within the Kimki Ridge, suggesting the possibility of fluid seeps and possible sub-seafloor fluid pathways.
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Natural Hazards, Coastal and Marine Hazards and Resources Program, Pacific Coastal and Marine Science Center

Records of continental slope sediment flow morphodynamic responses to gradient and active faulting from integrated AUV and ROV data, offshore Palos Verdes, southern California Borderland

Variations in seabed gradient are widely acknowledged to influence deep-water deposition, but are often difficult to measure in sufficient detail from both modern and ancient examples. On the continental slope offshore Los Angeles, California, autonomous underwater vehicle, remotely operated vehicle, and shipboard methods were used to collect a dense grid of high-resolution multibeam bathymetry, c
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Natural Hazards, Coastal and Marine Hazards and Resources Program, Pacific Coastal and Marine Science Center

The Palos Verdes Fault offshore southern California: late Pleistocene to present tectonic geomorphology, seascape evolution and slip rate estimate based on AUV and ROV surveys

The Palos Verdes Fault (PVF) is one of few active faults in Southern California that crosses the shoreline and can be studied using both terrestrial and subaqueous methodologies. To characterize the near-seafloor fault morphology, tectonic influences on continental slope sedimentary processes and late Pleistocene to present slip rate, a grid of high-resolution multibeam bathymetric data, and chirp
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Pacific Coastal and Marine Science Center
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Expedition along a Hazardous, Fast-Moving Fault off Southeast Alaska—the Queen Charlotte-Fairweather Fault

USGS scientists hope to learn more about the earthquake hazards that this large, fast-moving fault poses to communities and tourists in Alaska and...

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