Coastal and Marine Geohazards of the U.S. West Coast and Alaska Active
Coastal and marine geohazards are sudden and extreme events beneath the ocean that threaten coastal populations. Such underwater hazards include earthquakes, volcanic eruptions, landslides, and tsunamis.
Southern California
USGS aims to boost knowledge about the threat of earthquakes and underwater landslides in Southern California with modern, high-resolution seafloor imaging.
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. People living near coastlines may think “out of sight, out of mind” when it comes to underwater dangers. But in tectonically active regions, such as the west coast of the Americas, the potential lurks for sudden seafloor movement to cause great damage to coastal communities. Using the power of modern mapping and seismic technology to gather detailed seafloor data can directly impact human life and cities by improving earthquake and tsunami forecasts.
For many people who live near the coastlines, underwater dangers are “out of sight, out of mind.” But in tectonically active regions, such as the west coast of the Americas, the potential lurks for a surge of underwater motion that could disrupt many communities along the coast.
The 2011 Tohoku earthquake and tsunami were vivid reminders that remote disasters can affect an entire ocean basin. Understanding how and what regions might be affected by faraway disasters is an important, yet complex problem.
In addition to remote threats, local hazards lie just off the shores of the western U.S. Such hazards include shaking by large earthquakes in subduction zones, where one tectonic plate compresses another (Cascadia, Aleutian Trench); or on strike-slip faults, where one tectonic plate moves horizontally past another (central and southern California). Related hazards include tsunamis generated by shifts in the seafloor or by underwater landslides that occur during earthquakes. Landslides can also threaten equipment on the ocean floor such as pipelines, communication cables, and oil platforms.
One barrier to measuring the true seismic risk has been the scarcity of high-resolution maps of the ocean floor. The technology for mapping large parts of the ocean floor with enough detail needed to study offshore faults has only been available for about the last 20 years, long after coastal areas had been densely developed. The USGS Coastal and Marine Geohazards team applies this technology to the seafloor off several urban regions along the west coast. For example, the San Francisco Bay Area has the highest density of active faults of any urban area in the nation; the densely populated expanse (approximately 20 million people) in southern California is threatened by the nation’s highest level of earthquake risk; and Alaska has had more large earthquakes than the rest of the U.S. combined. In addition, detailed imaging of the ocean bottom has uncovered new evidence of submarine landslides. Creating three-dimensional views of the seafloor down to depths of 12 kilometers has given scientists remarkable ways to examine how a fault works, or how fluids may follow underground paths and possibly trigger landslides.
It’s challenging to know how a fault will behave without seeing its detailed structure: its bends, connections, and branches. To discover a fault’s structure, scientists go to sea to collect streams of data that they turn into comprehensive underwater maps. This type of imaging, along with knowing the age of sediment along faults and measuring other factors such as magnetics and density, can help tell the story of when the fault last ruptured or how fast it’s moving. Since these details are seldom known or easy to calculate for offshore faults, it’s challenging to incorporate these faults into earthquake models and estimate their actual hazard risk.
Reassessing the threat of earthquake, tsunami, and landslide hazards to ports and nuclear power plants on the U.S. west coast can directly impact facility management, emergency-management planning, and plant re-licensing. The data can also affect building codes, the design of highways, bridges, and other large structures, as well as earthquake insurance rates.
Below are the current studies of the “U.S. West Coast and Alaska Marine Geohazards” Project.
Below are datsets associated with this project.
Below are publications associated with this project.
Magnetic map of the Irish Hills and surrounding areas, San Luis Obispo County, central California
Tsunami hazards to U.S. coasts from giant earthquakes in Alaska
Slip rate on the San Diego trough fault zone, inner California Borderland, and the 1986 Oceanside earthquake swarm revisited
Influence of fault trend, bends, and convergence on shallow structure and geomorphology of the Hosgri strike-slip fault, offshore central California
The elusive character of discontinuous deep-water channels: New insights from Lucia Chica channel system, offshore California
Late Quaternary sediment-accumulation rates within the inner basins of the California Continental Borderland in support of geologic hazard evaluation
Recent faulting in the Gulf of Santa Catalina: San Diego to Dana Point
Recent developments in understanding the tectonic evolution of the Southern California offshore area: Implications for earthquake-hazard analysis
Submarine landslides of the Southern California Borderland
Potential earthquake faults offshore Southern California, from the eastern Santa Barbara Channel south to Dana Point
Submarine landslides in the Santa Barbara Channel as potential tsunami sources
Multichannel seismic-reflection data acquired off the coast of southern California -- Part A 1997, 1998, 1999, and 2000
Below are news stories associated with this project.
Below are partners associated with this project.
- Overview
Coastal and marine geohazards are sudden and extreme events beneath the ocean that threaten coastal populations. Such underwater hazards include earthquakes, volcanic eruptions, landslides, and tsunamis.
Southern CaliforniaUSGS aims to boost knowledge about the threat of earthquakes and underwater landslides in Southern California with modern, high-resolution seafloor imaging.
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. People living near coastlines may think “out of sight, out of mind” when it comes to underwater dangers. But in tectonically active regions, such as the west coast of the Americas, the potential lurks for sudden seafloor movement to cause great damage to coastal communities. Using the power of modern mapping and seismic technology to gather detailed seafloor data can directly impact human life and cities by improving earthquake and tsunami forecasts.
For many people who live near the coastlines, underwater dangers are “out of sight, out of mind.” But in tectonically active regions, such as the west coast of the Americas, the potential lurks for a surge of underwater motion that could disrupt many communities along the coast.
The 2011 Tohoku earthquake and tsunami were vivid reminders that remote disasters can affect an entire ocean basin. Understanding how and what regions might be affected by faraway disasters is an important, yet complex problem.
In addition to remote threats, local hazards lie just off the shores of the western U.S. Such hazards include shaking by large earthquakes in subduction zones, where one tectonic plate compresses another (Cascadia, Aleutian Trench); or on strike-slip faults, where one tectonic plate moves horizontally past another (central and southern California). Related hazards include tsunamis generated by shifts in the seafloor or by underwater landslides that occur during earthquakes. Landslides can also threaten equipment on the ocean floor such as pipelines, communication cables, and oil platforms.
One barrier to measuring the true seismic risk has been the scarcity of high-resolution maps of the ocean floor. The technology for mapping large parts of the ocean floor with enough detail needed to study offshore faults has only been available for about the last 20 years, long after coastal areas had been densely developed. The USGS Coastal and Marine Geohazards team applies this technology to the seafloor off several urban regions along the west coast. For example, the San Francisco Bay Area has the highest density of active faults of any urban area in the nation; the densely populated expanse (approximately 20 million people) in southern California is threatened by the nation’s highest level of earthquake risk; and Alaska has had more large earthquakes than the rest of the U.S. combined. In addition, detailed imaging of the ocean bottom has uncovered new evidence of submarine landslides. Creating three-dimensional views of the seafloor down to depths of 12 kilometers has given scientists remarkable ways to examine how a fault works, or how fluids may follow underground paths and possibly trigger landslides.
It’s challenging to know how a fault will behave without seeing its detailed structure: its bends, connections, and branches. To discover a fault’s structure, scientists go to sea to collect streams of data that they turn into comprehensive underwater maps. This type of imaging, along with knowing the age of sediment along faults and measuring other factors such as magnetics and density, can help tell the story of when the fault last ruptured or how fast it’s moving. Since these details are seldom known or easy to calculate for offshore faults, it’s challenging to incorporate these faults into earthquake models and estimate their actual hazard risk.
Reassessing the threat of earthquake, tsunami, and landslide hazards to ports and nuclear power plants on the U.S. west coast can directly impact facility management, emergency-management planning, and plant re-licensing. The data can also affect building codes, the design of highways, bridges, and other large structures, as well as earthquake insurance rates.
- Science
Below are the current studies of the “U.S. West Coast and Alaska Marine Geohazards” Project.
- Data
Below are datsets associated with this project.
Filter Total Items: 22No Result Found - Publications
Below are publications associated with this project.
Filter Total Items: 68Magnetic map of the Irish Hills and surrounding areas, San Luis Obispo County, central California
A magnetic map of the Irish Hills and surrounding areas was created as part of a cooperative research and development agreement with the Pacific Gas and Electric Company and is intended to promote further understanding of the areal geology and structure by serving as a basis for geophysical interpretations and by supporting geological mapping, mineral and water resource investigations, and other tAuthorsV. E. Langenheim, J. T. Watt, K.M. DentonTsunami hazards to U.S. coasts from giant earthquakes in Alaska
In the aftermath of Japan's devastating 11 March 2011Mw 9.0 Tohoku earthquake and tsunami, scientists are considering whether and how a similar tsunami could be generated along the Alaskan-Aleutian subduction zone (AASZ). A tsunami triggered by an earthquake along the AASZ would cross the Pacific Ocean and cause extensive damage along highly populated U.S. coasts, with ports being particularly vulAuthorsHolly F. Ryan, Roland E. von Huene, Dave Scholl, Stephen KirbySlip rate on the San Diego trough fault zone, inner California Borderland, and the 1986 Oceanside earthquake swarm revisited
The San Diego trough fault zone (SDTFZ) is part of a 90-km-wide zone of faults within the inner California Borderland that accommodates motion between the Pacific and North American plates. Along with most faults offshore southern California, the slip rate and paleoseismic history of the SDTFZ are unknown. We present new seismic reflection data that show that the fault zone steps across a 5-km-widAuthorsHolly F. Ryan, James E. Conrad, C. K. Paull, Mary McGannInfluence 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 WattThe elusive character of discontinuous deep-water channels: New insights from Lucia Chica channel system, offshore California
New high-resolution autonomous underwater vehicle (AUV) seafloor images, with 1 m lateral resolution and 0.3 m vertical resolution, reveal unexpected seafloor rugosity and low-relief (<10 m), discontinuous conduits over ∼70 km2. Continuous channel thalwegs were interpreted originally from lower-resolution images, but newly acquired AUV data indicate that a single sinuous channel fed a series of diAuthorsK.L. Maier, A. Fildani, C. K. Paull, S.A. Graham, T.R. McHargue, D.W. Caress, Mary McGannLate Quaternary sediment-accumulation rates within the inner basins of the California Continental Borderland in support of geologic hazard evaluation
An evaluation of the geologic hazards of the inner California Borderland requires determination of the timing for faulting and mass-movement episodes during the Holocene. Our effort focused on basin slopes and turbidite systems on the basin floors for the area between Santa Barbara and San Diego, California. Dating condensed sections on slopes adjacent to fault zones provides better control on fauAuthorsW. R. Normark, M. McGann, R. W. SliterRecent faulting in the Gulf of Santa Catalina: San Diego to Dana Point
We interpret seismic-reflection profiles to determine the location and offset mode of Quaternary offshore faults beneath the Gulf of Santa Catalina in the inner California Continental Borderland. These faults are primarily northwest-trending, right-lateral, strike-slip faults, and are in the offshore Rose Canyon-Newport-Inglewood, Coronado Bank, Palos Verdes, and San Diego Trough fault zones. In aAuthorsH. F. Ryan, M.R. Legg, J. E. Conrad, R. W. SliterRecent developments in understanding the tectonic evolution of the Southern California offshore area: Implications for earthquake-hazard analysis
During late Mesozoic and Cenozoic time, three main tectonic episodes affected the Southern California offshore area. Each episode imposed its unique structural imprint such that early-formed structures controlled or at least influenced the location and development of later ones. This cascaded structural inheritance greatly complicates analysis of the extent, orientation, and activity of modern fauAuthorsM. A. Fisher, V. E. Langenheim, C. Nicholson, H. F. Ryan, R. W. SliterSubmarine landslides of the Southern California Borderland
Conventional bathymetry, sidescan-sonar and seismic-reflection data, and recent, multibeam surveys of large parts of the Southern California Borderland disclose the presence of numerous submarine landslides. Most of these features are fairly small, with lateral dimensions less than ??2 km. In areas where multibeam surveys are available, only two large landslide complexes were identified on the maiAuthorsH. J. Lee, H. Gary Greene, B. D. Edwards, M. A. Fisher, W. R. NormarkPotential earthquake faults offshore Southern California, from the eastern Santa Barbara Channel south to Dana Point
Urban areas in Southern California are at risk from major earthquakes, not only quakes generated by long-recognized onshore faults but also ones that occur along poorly understood offshore faults. We summarize recent research findings concerning these lesser known faults. Research by the U.S. Geological Survey during the past five years indicates that these faults from the eastern Santa Barbara ChAuthorsM. A. Fisher, C.C. Sorlien, R. W. SliterSubmarine landslides in the Santa Barbara Channel as potential tsunami sources
Recent investigations using the Monterey Bay Aquarium Research Institutes (MBARI) Remotely Operated Vehicles (ROVs) "Ventana" and "Tiburon" and interpretation of MBARI's EM 300 30 kHz multibeam bathymetric data show that the northern flank of the Santa Barbara Basin has experienced massive slope failures. Of particular concern is the large (130 km2) Goleta landslide complex located off Coal Oil PoAuthorsH. Gary Greene, L.Y. Murai, P. Watts, N.A. Maher, M. A. Fisher, C.E. Paull, P. EichhublMultichannel seismic-reflection data acquired off the coast of southern California -- Part A 1997, 1998, 1999, and 2000
No abstract available.AuthorsRay W. Sliter, William R. Normark, Christina E. Gutmacher - News
Below are news stories associated with this project.
Filter Total Items: 20 - Partners
Below are partners associated with this project.
Filter Total Items: 13