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
Modeling of depth to base of Last Glacial Maximum and seafloor sediment thickness for the California State Waters Map Series, eastern Santa Barbara Channel, California
Influence of fault trend, bends, and convergence on shallow structure and geomorphology of the Hosgri strike-slip fault, offshore central California
U.S. Geological Survey (USGS) Western Region; Santa Barbara Channel Coastal and Ocean Science
High-Resolution Seismic-Reflection and Marine Magnetic Data Along the Hosgri Fault Zone, Central California
Crustal structure and earthquake hazards of the subduction zone in southwestern British Columbia and western Washington
Map and data for Quaternary faults and folds in Washington state
Evidence for Late Holocene earthquakes on the Utsalady Point fault, Northern Puget Lowland, Washington
Active shortening of the Cascadia forearc and implications for seismic hazards of the Puget Lowland
Late Holocene earthquakes on the Toe Jam Hill fault, Seattle fault zone, Bainbridge Island, Washington
Hydrothermal and tectonic activity in northern Yellowstone Lake, Wyoming
Field and laboratory data from an earthquake history study of the Toe Jam Hill Fault, Bainbridge Island, Washington
Location, structure, and seismicity of the Seattle fault zone, Washington: Evidence from aeromagnetic anomalies, geologic mapping, and seismic-reflection data
Science and Products
- Science
- Data
Filter Total Items: 19No Result Found
- Maps
- Multimedia
- Publications
Filter Total Items: 64
Modeling of depth to base of Last Glacial Maximum and seafloor sediment thickness for the California State Waters Map Series, eastern Santa Barbara Channel, California
Models of the depth to the base of Last Glacial Maximum and sediment thickness over the base of Last Glacial Maximum for the eastern Santa Barbara Channel are a key part of the maps of shallow subsurface geology and structure for offshore Refugio to Hueneme Canyon, California, in the California State Waters Map Series. A satisfactory interpolation of the two datasets that accounted for regional geAuthorsFlorence L. Wong, Eleyne L. Phillips, Samuel Y. Johnson, Ray W. SliterInfluence of fault trend, bends, and convergence on shallow structure and geomorphology of the Hosgri strike-slip fault, offshore central California
We mapped an ∼94-km-long portion of the right-lateral Hosgri fault zone in offshore central California using a dense network of high-resolution seismic reflection profiles, marine magnetic data, and multibeam bathymetry. These data document the location, length, and continuity of multiple fault strands, highlight fault-zone heterogeneity, and demonstrate the importance of fault trend, fault bends,AuthorsSamuel Y. Johnson, Janet Tilden WattU.S. Geological Survey (USGS) Western Region; Santa Barbara Channel Coastal and Ocean Science
USGS coastal and ocean science in the Western United States and the Pacific integrates scientific expertise in geology, water resources, biology, and geography. Operating from 10 major science centers in the Western Region, the USGS is addressing a broad geographic and thematic range of important coastal and marine issues. In California, the Santa Barbara Channel represents one area of focus.AuthorsSamuel Y. JohnsonHigh-Resolution Seismic-Reflection and Marine Magnetic Data Along the Hosgri Fault Zone, Central California
The U.S. Geological Survey (USGS) collected high-resolution shallow seismic-reflection and marine magnetic data in June 2008 in the offshore areas between the towns of Cayucos and Pismo Beach, Calif., from the nearshore (~6-m depth) to just west of the Hosgri Fault Zone (~200-m depth). These data are in support of the California State Waters Mapping Program and the Cooperative Research and DevelopAuthorsRay W. Sliter, Peter J. Triezenberg, Patrick E. Hart, Janet T. Watt, Samuel Y. Johnson, Daniel S. ScheirerCrustal structure and earthquake hazards of the subduction zone in southwestern British Columbia and western Washington
No abstract available.AuthorsMichael A. Fisher, Roy D. Hyndman, Samuel Y. Johnson, Thomas M. Brocher, Robert S. Crosson, Ray E. Wells, Andrew J. Calvert, Uri S. ten BrinkMap and data for Quaternary faults and folds in Washington state
The map shows faults and folds in Washington State that exhibit evidence of Quaternary deformation and includes data on timing of most recent movement, sense of movement, slip rate, and continuity of surface expression.AuthorsDavid J. Lidke, Samuel Y. Johnson, Patricia A. McCrory, Stephen F. Personius, Alan R. Nelson, Richard L. Dart, Lee-Ann Bradley, Kathleen M. Haller, Michael N. MachetteEvidence for Late Holocene earthquakes on the Utsalady Point fault, Northern Puget Lowland, Washington
Trenches across the Utsalady Point fault in the northern Puget Lowland of Washington reveal evidence of at least one and probably two late Holocene earthquakes. The "Teeka" and "Duffers" trenches were located along a 1.4-km-long, 1-to 4-m-high, northwest-trending, southwest-facing, topographic scarp recognized from Airborne Laser Swath Mapping. Glaciomarine drift exposed in the trenches reveals evAuthorsS. Y. Johnson, A. R. Nelson, S. F. Personius, R. E. Wells, H.M. Kelsey, B.L. Sherrod, K. Okumura, R. Koehler, Robert C. Witter, L. A. Bradley, D.J. HardingActive shortening of the Cascadia forearc and implications for seismic hazards of the Puget Lowland
Margin-parallel shortening of the Cascadia forearc is a consequence of oblique subduction of the Juan de Fuca plate beneath North America. Strike-slip, thrust, and oblique crustal faults beneath the densely populated Puget Lowland accommodate much of this north-south compression, resulting in large crustal earthquakes. To better understand this forearc deformation and improve earthquake hazard, asAuthorsS. Y. Johnson, R. J. Blakely, W. J. Stephenson, S.V. Dadisman, M. A. FisherLate Holocene earthquakes on the Toe Jam Hill fault, Seattle fault zone, Bainbridge Island, Washington
Five trenches across a Holocene fault scarp yield the first radiocarbon-measured earthquake recurrence intervals for a crustal fault in western Washington. The scarp, the first to be revealed by laser imagery, marks the Toe Jam Hill fault, a north-dipping backthrust to the Seattle fault. Folded and faulted strata, liquefaction features, and forest soil A horizons buried by hanging-wall-collapse coAuthorsA. R. Nelson, S. Y. Johnson, H.M. Kelsey, R. E. Wells, B.L. Sherrod, S.K. Pezzopane, L. A. Bradley, R. D. Koehler, R.C. BucknamHydrothermal and tectonic activity in northern Yellowstone Lake, Wyoming
Yellowstone National Park is the site of one of the world's largest calderas. The abundance of geothermal and tectonic activity in and around the caldera, including historic uplift and subsidence, makes it necessary to understand active geologic processes and their associated hazards. To that end, we here use an extensive grid of high-resolution seismic reflection profiles (∼450 km) to document hyAuthorsS. Y. Johnson, W. J. Stephenson, L. A. Morgan, Wayne C. Shanks, K. L. PierceField and laboratory data from an earthquake history study of the Toe Jam Hill Fault, Bainbridge Island, Washington
No abstract available.AuthorsAlan R. Nelson, Samuel Y. Johnson, Ray E. Wells, Silvio K. Pezzopane, Harvey M. Kelsey, Brian L. Sherrod, Lee-Ann Bradley, Rick D. Koehler, Robert C. Bucknam, Ralph Haugerud, William T. LapradeLocation, structure, and seismicity of the Seattle fault zone, Washington: Evidence from aeromagnetic anomalies, geologic mapping, and seismic-reflection data
A high-resolution aeromagnetic survey of the Puget Lowland shows details of the Seattle fault zone, an active but largely concealed east-trending zone of reverse faulting at the southern margin of the Seattle basin. Three elongate, east-trending magnetic anomalies are associated with north-dipping Tertiary strata exposed in the hanging wall; the magnetic anomalies indicate where these strata contiAuthorsR. J. Blakely, R. E. Wells, C. S. Weaver, S. Y. Johnson - News
*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