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Samuel Y Johnson

Seafloor Mapping - Geologic framework, hazards, and habitats

Sam Johnson is a Research Geologist in the U.S. Geological Survey Pacific Coastal and Marine Science Center (PCMSC), an organization of about 100 research and support staff based in Santa Cruz and Menlo Park, CA.  He served as PCMSC Center Director from 2003 to 2008. He currently designs, coordinates, and conducts research projects that focus on seafloor and benthic habitat mapping, coastal and marine geomorphology and geologic framework, coastal evolution, and coastal earthquake and tsunami hazards.  He helped plan and is the USGS lead for the multi-agency California Seafloor Mapping Program. His present research is focused on active tectonics and hazards offshore central California (Santa Barbara Channel to Cape Mendocino).

Professional Experience

  • 1982-1984 - Assistant Professor, Washington State University

  • 1984 to 2003 - Research Geologist, USGS Energy and Earthquake Hazards Programs

  • 2003 to 2008 - Center Director, USGS Pacific Coastal and Marine Science Center

  • 2008 to 2019 - Research Geologist, USGS Pacific Coastal and Marine Science Center

  • 2019 to present - Research Geologist Emeritus, USGS Pacific Coastal and Marine Science Center

Education and Certifications

  • B.A. (1975) University of California, Santa Cruz (Earth Sciences)

  • M.S. (1978) University of Washington (Geological Sciences)

  • Ph.D. (1982) University of Washington Geological Sciences

Affiliations and Memberships*

  • Geological Society of America (Fellow)

  • American Geophysical Union

  • Society for Sedimentary Geology

  • Seismological Society of America

Honors and Awards

  • Department of Interior Distinguished Service Award (2019)

Science and Products

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Fish on seafloor, Offshore Northern California

California Seafloor Mapping Program

The California Seafloor Mapping Program (CSMP) is a cooperative program to create a comprehensive coastal and marine geologic and habitat base map series for all of California's State waters.
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Coastal and Marine Hazards and Resources Program, Pacific Coastal and Marine Science Center, Big Sur Landslides, Deep Sea Exploration, Mapping and Characterization
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California Seafloor Mapping Program

The California Seafloor Mapping Program (CSMP) is a cooperative program to create a comprehensive coastal and marine geologic and habitat base map series for all of California's State waters.
Learn More
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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.
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Natural 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
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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.
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People wearing safety gear lean over the gunwale of a ship to help guide a large metal frame holding instruments.

California Seafloor Mapping Program data collection

Here we describe the data collection methods and techniques of the California Seaflor Mapping Program: mapping, video and photography ground-truthing, and seismic profiling data collection.
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Natural Hazards Mission Area, Coastal and Marine Hazards and Resources Program, Pacific Coastal and Marine Science Center
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California Seafloor Mapping Program data collection

Here we describe the data collection methods and techniques of the California Seaflor Mapping Program: mapping, video and photography ground-truthing, and seismic profiling data collection.
Learn More
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Seafloor image showing depth with lots of text of explanation.

California Seafloor Mapping Program map-set production

USGS and the California Ocean Protection Council (COPC) are supporting development of peer-reviewed map sets for California’s mainland State Waters.
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Natural Hazards Mission Area, Coastal and Marine Hazards and Resources Program, Pacific Coastal and Marine Science Center
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California Seafloor Mapping Program map-set production

USGS and the California Ocean Protection Council (COPC) are supporting development of peer-reviewed map sets for California’s mainland State Waters.
Learn More
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3-D angular view of a bay inlet with a bridge spanning the inlet, the floor of the bay is shown as if the water is drained out.

California Seafloor Mapping Program applications

California Seafloor Mapping Program data and map publications have and will be used for a large range of applications in coastal zone management and research.
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Coastal and Marine Hazards and Resources Program, Pacific Coastal and Marine Science Center
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California Seafloor Mapping Program applications

California Seafloor Mapping Program data and map publications have and will be used for a large range of applications in coastal zone management and research.
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Filter Total Items: 15

Chirp sub-bottom data of USGS field activity K0211PS collected in Puget Sound, Washington in April of 2011

High-resolution chirp sub-bottom data were collected by the U.S. Geological Survey in April 2011 south of Bainbridge Island and west of Seattle in Puget Sound, Washington. Data were collected aboard the R/V Karluk during field activity K0211PS using an Edgetech SB-512i sub-bottom profiler. Sub-bottom acoustic penetration spans several tens of meters and is variable by location.
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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 Mission Area, Coastal and Marine Hazards and Resources Program, Earthquake Hazards Program, Pacific Coastal and Marine Science Center

Chirp and minisparker seismic-reflection data of field activity F-02-07-NC collected offshore Ano Nuevo to San Francisco, San Mateo County California from 2007-03-22 to 2007-04-06

High-resolution single-channel Chirp and minisparker seismic-reflection data were collected by the U.S. Geological Survey in March and April 2007, offshore San Mateo County, California. Data were collected aboard the R/V Fulmar during field activity F-02-07-NC. Chirp data were collected using an EdgeTech 512 chirp subbottom system and were recorded with a Triton SB-Logger. Minisparker data were co
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Natural Hazards Mission Area, Coastal and Marine Hazards and Resources Program, Pacific Coastal and Marine Science Center

California State Waters Map Series Data Catalog--Punta Gorda to Point Arena

As part of the USGS's California State Waters Mapping Project, a 50-m grid of sediment thickness for the seafloor within the 3-nautical mile limit between Punta Gorda and Point Arena was generated from seismic-reflection data collected between 2010 and 2012, and supplemented with geologic structure (fault) information following the methodology of Wong (2012). Water depths determined from bathymetr
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Natural Hazards Mission Area, Coastal and Marine Hazards and Resources Program, Pacific Coastal and Marine Science Center

California State Waters Map Series Data Catalog--Point Sur to Point Arguello

As part of the USGS's California State Waters Mapping Project, a 50-m grid of sediment thickness for the seafloor within the 3-nautical mile limit between Point Sur and Point Arguello was generated from seismic-reflection data collected between 2008 and 2014, and supplemented with geologic structure (fault and fold) information following the methodology of Wong (2012). Water depths determined from
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Natural Hazards Mission Area, Coastal and Marine Hazards and Resources Program, Pacific Coastal and Marine Science Center

Multichannel minisparker seismic-reflection data of field activity 2015-617-FA; Monterey Bay, offshore central California from 2015-02-23 to 2015-03-06

This data release contains approximately 190 line-kilometers of processed, high-resolution multichannel seismic-reflection (MCS) profiles that were collected aboard the R/V Snavely in 2015 on U.S. Geological Survey cruise 2015-617-FA in Monterey Bay, offshore central California. The majority of MCS profiles collected are oriented north-south across the Monterey Canyon head to address marine geohaz
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Natural Hazards Mission Area, Coastal and Marine Hazards and Resources Program, Pacific Coastal and Marine Science Center

Marine magnetic data from Point Sur to Piedras Blancas, central California, 2011

This dataset includes marine magnetic data collected by the U.S. Geological Survey (USGS) in 2011 during field activity B-05-11-CC between Point Sur and Piedras Blancas, central California.
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Natural Hazards Mission Area, Coastal and Marine Hazards and Resources Program, Pacific Coastal and Marine Science Center, Big Sur Landslides

Marine geophysical data - Point Sal to Refugio State Beach, southern California

This data release includes approximately 1,032 km of marine single-channel seismic-reflection data collected by the U.S. Geological Survey on a research cruise (USGS survey 2014-632-FA) in July and August, 2014, between Point Sal and Refugio State Beach. The dataset includes 168 profiles, most of which were collected on tracklines roughly perpendicular to the coast at 1 km line spacing; additional
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Pacific Coastal and Marine Science Center

California State Waters Map Series Data Catalog--Pigeon Point to Monterey, California

Data catalog for California State Waters Map Series--Pigeon Point to Monterey, California.
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Pacific Coastal and Marine Science Center

California State Waters Map Series Data Catalog--Offshore of Monterey, California

Data catalog for California State Waters Map Series--Offshore of Santa Cruz, California.
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Natural Hazards Mission Area, Coastal and Marine Hazards and Resources Program, Pacific Coastal and Marine Science Center

California State Waters Map Series Data Catalog--Monterey Canyon and Vicinity, California

Data Catalog for California State Waters, Monterey Canyon and Vicinity, California
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Pacific Coastal and Marine Science Center

California State Waters Map Series Data Catalog--Offshore of Aptos, California

Data catalog for California State Waters Map Series--Offshore of Aptos, California.
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Natural Hazards Mission Area, Coastal and Marine Hazards and Resources Program, Pacific Coastal and Marine Science Center
Filter Total Items: 18

Geologic and geophysical maps of the Santa Maria and part of the Point Conception 30'×60' quadrangles, California

This report presents digital geologic, gravity, and aeromagnetic maps for the onshore parts of the Santa Maria and Point Conception 30'x60' quadrangles at a compilation scale of 1:100,000. The map depicts the distribution of bedrock units, surficial deposits, paleontological data, geophysical data and structural features in the Santa Maria basin and the Santa Ynez Mountains to the south, an area c
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Natural Hazards Mission Area, Coastal and Marine Hazards and Resources Program, Energy Resources Program, National Cooperative Geologic Mapping Program, Central Energy Resources Science Center, Geology, Minerals, Energy, and Geophysics Science Center, Geosciences and Environmental Change Science Center, Pacific Coastal and Marine Science Center

Offshore geology and geomorphology from Point Piedras Blancas to Pismo Beach, San Luis Obispo County, California

Marine geology and geomorphology were mapped along the continental shelf and upper slope between Point Piedras Blancas and Pismo Beach, California. The map area is divided into the following three (smaller) map areas, listed from north to south: San Simeon, Morro Bay, and Point San Luis. Each smaller map area consists of a geologic map and the corresponding geophysical data that support the geolog

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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 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 San Gregorio, 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 San Gregorio, 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 San Gregorio, 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 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 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 Mission Area, Coastal and Marine Hazards and Resources Program, Pacific Coastal and Marine Science Center

California State Waters Map Series: offshore of Carpinteria, 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 Carpinteria, 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
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Filter Total Items: 64

High-resolution geophysical and geochronological analysis of a relict shoreface deposit offshore central California: Implications for slip rate along the Hosgri fault

The Cross-Hosgri slope is a bathymetric lineament that crosses the main strand of the Hosgri fault offshore Point Estero, central California. Recently collected chirp seismic reflection profiles and sediment cores provide the basis for a reassessment of Cross-Hosgri slope origin and the lateral slip rate of the Hosgri fault based on offset of the lower slope break of the Cross-Hosgri slope. The Cr
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Jared W. Kluesner, Samuel Y. Johnson, Stuart P. Nishenko, Elisa Medri, Alex Simms, Gary Greene, Harrison J. Gray, Shannon A. Mahan, Jason Scott Padgett, Emma Taylor Krolczyk, Daniel S. Brothers, James E. Conrad
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Geosciences and Environmental Change Science Center, Pacific Coastal and Marine Science Center

Subaqueous 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. T
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Elisa Medri, Alexander R. Simms, Jared W. Kluesner, Samuel Y. Johnson, Stuart P. Nishenko, H. Gary Greene, James E. Conrad
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Pacific Coastal and Marine Science Center

Deepwater debrites and linked megaturbidites in confined basins: An example from the Onnuri Basin, East Sea of Korea

We analyzed data from seven piston cores, multi-channel seismic-reflection (MCS) and chirp profiles, and multibeam echosounder (MBES) data to study the distribution, emplacement time, sedimentary facies, and depositional processes of sediment-gravity-flow deposits in the Onnuri Basin, a confined basin in the East Sea. These data reveal that debris flows have traveled ca. 30 km downslope, forming a
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Deniz Cukur, In-Kwon Um, Jong-Hwa Chun, Gwang-Soo Lee, Gee-Too Kong, Samuel Y. Johnson, Senay Horozal
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Natural Hazards Mission Area, Coastal and Marine Hazards and Resources Program, Pacific Coastal and Marine Science Center

Structural controls on slope failure within the western Santa Barbara Channel based on 2D and 3D seismic imaging

The Santa Barbara Channel, offshore California, contains several submarine landslides and ample evidence for incipient failure. This region hosts active thrust and reverse faults that accommodate several mm/yr of convergence, yet the relationships between tectonic deformation and slope failure remain unclear. We present 3‐D and 2‐D multichannel seismic reflection (MCS) data sets, multibeam bathyme
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Jared W. Kluesner, Daniel S. Brothers, Alexis L Wright, Samuel Y. Johnson
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Natural Hazards Mission Area, Coastal and Marine Hazards and Resources Program, Pacific Coastal and Marine Science Center, Deep Sea Exploration, Mapping and Characterization

Controls on sediment distribution in the coastal zone of the central California transform continental margin, USA

We use >10,000 km of high-resolution seismic-reflection data together with multibeam bathymetry to document complex and highly variable post-Last Glacial Maximum (LGM) sediment distribution and thickness in the coastal zone (~10 m isobath to 5.6 km offshore) along a ~800 km section of central California's transform continental margin. Sediment thickness ranges from 0 (seafloor bedrock) to 64 m wit
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Samuel Y. Johnson, Jeffrey W. Beeson, Janet Watt, Ray Sliter, Antoinette Papesh
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Natural Hazards Mission Area, Coastal and Marine Hazards and Resources Program, Pacific Coastal and Marine Science Center, Big Sur Landslides

Offshore shallow structure and sediment distribution, Punta Gorda to Point Arena, Northern California

This publication consists of two map sheets that display shallow geologic structure, along with sediment distribution and thickness, for an approximately 150-km-long offshore section of the northern California coast between Punta Gorda and Point Arena. Each map sheet includes three maps at scales of either 1:100,000 or 1:200,000, and together the sheets include 30 figures that contain representati

Authors
Jeffrey W. Beeson, Samuel Y. Johnson
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Natural Hazards Mission Area, Coastal and Marine Hazards and Resources Program, Pacific Coastal and Marine Science Center

Offshore shallow structure and sediment distribution, Point Sur to Point Arguello, central California

This publication consists of three map sheets that display shallow geologic structure, along with sediment distribution and thickness, for an about 225-km-long offshore section of the central California coast between Point Sur and Point Arguello. Each map sheet includes three maps, at scales of either 1:150,000 or 1:200,000, as well as a set of figures that contain representative high-resolution s
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Samuel Y. Johnson, Stephen R. Hartwell, Janet T. Watt, Jeffrey W. Beeson, Peter Dartnell
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Natural Hazards Mission Area, Coastal and Marine Hazards and Resources Program, Pacific Coastal and Marine Science Center, Big Sur Landslides

Shallow structure and geomorphology along the offshore northern San Andreas Fault, Tomales Point to Fort Ross, California

We mapped a poorly documented 35-km-long section of the northern San Andreas fault zone (NSAF) between Tomales Point and Fort Ross, California. Mapping is largely based on high-resolution seismic-reflection profiles (38 fault crossings), multibeam bathymetry, and onshore geology. NSAF strike in this section is nearly parallel to plate motion, characterized by a slight (~2°) northerly (transtension

Authors
Samuel Johnson, Beeson Jeffrey W.
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Natural Hazards Mission Area, Coastal and Marine Hazards and Resources Program, Pacific Coastal and Marine Science Center

Controls on submarine canyon head evolution: Monterey Canyon, offshore central California

The Monterey submarine canyon, incised across the continental shelf in Monterey Bay, California, provides a record of the link between onshore tectonism, fluvial transport, and deep-marine deposition. High-resolution seismic-reflection imaging in Monterey Bay reveals an extensive paleocanyon unit buried below the seafloor of the continental shelf around Monterey and Soquel canyon heads. Paleocanyo
Authors
Katherine L. Maier, Samuel Y. Johnson, Patrick E. Hart
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Natural Hazards Mission Area, Coastal and Marine Hazards and Resources Program, Pacific Coastal and Marine Science Center

Neotectonics of the Big Sur Bend, San Gregorio‐Hosgri fault system, central California

The right‐lateral San Gregorio‐Hosgri fault system (SGHF) extends mainly offshore for about 400 km along the central California coast and is a major structure in the distributed transform margin of western North America. We mapped a poorly known 64‐km‐long section of the SGHF offshore Big Sur between Piedras Blancas and Point Sur using high‐resolution bathymetry, seismic reflection, and marine mag
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Samuel Y. Johnson, Janet Watt, Stephen Hartwell, Jared W. Kluesner
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Coastal and Marine Hazards and Resources Program, Pacific Coastal and Marine Science Center

California State Waters Map Series — Offshore of Point Conception, California

IntroductionIn 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, interpre
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Samuel Y. Johnson, Peter Dartnell, Guy R. Cochrane, Stephen R. Hartwell, Nadine E. Golden, Rikk Kvitek, Clifton W. Davenport
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Pacific Coastal and Marine Science Center

California State Waters Map Series — Offshore of Gaviota, California

IntroductionIn 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, interpre
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Samuel Y. Johnson, Peter Dartnell, Guy R. Cochrane, Stephen R. Hartwell, Nadine E. Golden, Rikk Kvitek, Clifton W. Davenport
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Pacific Coastal and Marine Science Center
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A Research Retrospective: Offshore Fault Mapping of the San Andreas

Study of New Offshore Fault Mapping Related to the 1906 San Francisco Earthquake:  In 2019, for the first time ever, scientists comprehensively mapped...

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Signs of 1906 Earthquake in Offshore Map of Northern San Andreas

Read the news release from the Seismological Society of America, March 27, 2019

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USGS Seafloor-Mapping Expert Visits Korea Institute of Geology and Mineral Industries in South Korea

USGS research geologist Sam Johnson was invited visit to the Korea Institute of Geoscience and Mineral Industries to present USGS expertise on...

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USGS Seafloor-Mapping Expert Sam Johnson is Keynote Speaker at Geological Conference in South Africa

The geological survey of South Africa invited research geologist Sam Johnson of the USGS PCMSC to participate in a workshop, and conference, held in...

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Science and Products

*Disclaimer: Listing outside positions with professional scientific organizations on this Staff Profile are for informational purposes only and do not constitute an endorsement of those professional scientific organizations or their activities by the USGS, Department of the Interior, or U.S. Government