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.
Shelf evolution along a transpressive transform margin, Santa Barbara Channel, California
The transtensional offshore portion of the northern San Andreas fault: Fault zone geometry, late Pleistocene to Holocene sediment deposition, shallow deformation patterns, and asymmetric basin growth
Investigation of late Pleistocene and Holocene activity in the San Gregorio fault zone on the continental slope north of Monterey Canyon, offshore central California
Reducing risk where tectonic plates collide—U.S. Geological Survey subduction zone science plan
Geologic controls on submarine slope failure along the central U.S. Atlantic margin: Insights from the Currituck Slide Complex
High-resolution seismic-reflection data from offshore northern California — Bolinas to Sea Ranch
Missing link between the Hayward and Rodgers Creek faults
Seismic attribute detection of faults and fluid pathways within an active strike-slip shear zone: New insights from high-resolution 3D P-Cable™ seismic data along the Hosgri Fault, offshore California
A submarine landslide source for the devastating 1964 Chenega tsunami, southern Alaska
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
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
Quaternary tephrochronology and deposition in the subsurface Sacramento–San Joaquin Delta, California, U.S.A.
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: 68Shelf evolution along a transpressive transform margin, Santa Barbara Channel, California
High-resolution bathymetric and seismic reflection data provide new insights for understanding the post–Last Glacial Maximum (LGM, ca. 21 ka) evolution of the ∼120-km-long Santa Barbara shelf, located within a transpressive segment of the transform continental margin of western North America. The goal is to determine how rising sea level, sediment supply, and tectonics combine to control shelf geoAuthorsSamuel Y. Johnson, Stephen Hartwell, Christopher C. Sorlien, Peter Dartnell, Andrew C. RitchieThe transtensional offshore portion of the northern San Andreas fault: Fault zone geometry, late Pleistocene to Holocene sediment deposition, shallow deformation patterns, and asymmetric basin growth
We mapped an ~120 km offshore portion of the northern San Andreas fault (SAF) between Point Arena and Point Delgada using closely spaced seismic reflection profiles (1605 km), high-resolution multibeam bathymetry (~1600 km2), and marine magnetic data. This new data set documents SAF location and continuity, associated tectonic geomorphology, shallow stratigraphy, and deformation. Variable deformatAuthorsJeffrey W. Beeson, Samuel Y. Johnson, Chris GoldfingerInvestigation of late Pleistocene and Holocene activity in the San Gregorio fault zone on the continental slope north of Monterey Canyon, offshore central California
We provide an extensive high‐resolution geophysical, sediment core, and radiocarbon dataset to address late Pleistocene and Holocene fault activity of the San Gregorio fault zone (SGFZ), offshore central California. The SGFZ occurs primarily offshore in the San Andreas fault system and has been accommodating dextral strike‐slip motion between the Pacific and North American plates since the mid‐MioAuthorsKatherine L. Maier, Charles K. Paull, Daniel S. Brothers, David W. Caress, Mary McGann, Eve M. Lundsten, Krystle Anderson, Roberto GwiazdaReducing risk where tectonic plates collide—U.S. Geological Survey subduction zone science plan
The U.S. Geological Survey (USGS) serves the Nation by providing reliable scientific information and tools to build resilience in communities exposed to subduction zone earthquakes, tsunamis, landslides, and volcanic eruptions. Improving the application of USGS science to successfully reduce risk from these events relies on whole community efforts, with continuing partnerships among scientists andAuthorsJoan S. Gomberg, K. A. Ludwig, Barbara Bekins, Thomas M. Brocher, John Brock, Daniel S. Brothers, Jason D. Chaytor, Arthur Frankel, Eric L. Geist, Matthew M. Haney, Stephen H. Hickman, William S. Leith, Evelyn A. Roeloffs, William H. Schulz, Thomas W. Sisson, Kristi L. Wallace, Janet Watt, Anne M. WeinGeologic controls on submarine slope failure along the central U.S. Atlantic margin: Insights from the Currituck Slide Complex
Multiple styles of failure, ranging from densely spaced, mass transport driven canyons to the large, slab-type slope failure of the Currituck Slide, characterize adjacent sections of the central U.S. Atlantic margin that appear to be defined by variations in geologic framework. Here we use regionally extensive, deep penetration multichannel seismic (MCS) profiles to reconstruct the influence of thAuthorsJenna C. Hill, Daniel S. Brothers, Bradley K. Craig, Uri S. ten Brink, Jason D. Chaytor, Claudia FloresHigh-resolution seismic-reflection data from offshore northern California — Bolinas to Sea Ranch
The U.S. Geological Survey collected high-resolution seismic-reflection data in September 2009, on survey S-8-09-NC, offshore of northern California between Bolinas and Sea Ranch.The survey area spans about 125 km of California’s coast and extends around Point Reyes. Data were collected aboard the U.S. Geological Survey R/V Parke Snavely. Cumulatively, ~1,150 km of seismic-reflection data were acqAuthorsRay W. Sliter, Samuel Y. Johnson, John L. Chin, Parker Allwardt, Jeffrey Beeson, Peter J. TriezenbergMissing link between the Hayward and Rodgers Creek faults
The next major earthquake to strike the ~7 million residents of the San Francisco Bay Area will most likely result from rupture of the Hayward or Rodgers Creek faults. Until now, the relationship between these two faults beneath San Pablo Bay has been a mystery. Detailed subsurface imaging provides definitive evidence of active faulting along the Hayward fault as it traverses San Pablo Bay and benAuthorsJanet Watt, David A. Ponce, Thomas E. Parsons, Patrick E. HartSeismic attribute detection of faults and fluid pathways within an active strike-slip shear zone: New insights from high-resolution 3D P-Cable™ seismic data along the Hosgri Fault, offshore California
Poststack data conditioning and neural-network seismic attribute workflows are used to detect and visualize faulting and fluid migration pathways within a 13.7 km2 13.7 km2 3D P-Cable™ seismic volume located along the Hosgri Fault Zone offshore central California. The high-resolution 3D volume used in this study was collected in 2012 as part of Pacific Gas and Electric’s Central California SeismicAuthorsJared W. Kluesner, Daniel S. BrothersA submarine landslide source for the devastating 1964 Chenega tsunami, southern Alaska
During the 1964 Great Alaska earthquake (Mw 9.2), several fjords, straits, and bays throughout southern Alaska experienced significant tsunami runup of localized, but unexplained origin. Dangerous Passage is a glacimarine fjord in western Prince William Sound, which experienced a tsunami that devastated the village of Chenega where 23 of 75 inhabitants were lost – the highest relative loss of aAuthorsDaniel S. Brothers, Peter J. Haeussler, Lee Liberty, David Finlayson, Eric L. Geist, Keith A. Labay, Michael ByerlyRecords 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, cAuthorsKatherine L. Maier, Daniel S. Brothers, Charles K. Paull, Mary McGann, David W. Caress, James E. ConradThe 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 chirpAuthorsDaniel S. Brothers, James E. Conrad, Katherine L. Maier, Charles K. Paull, Mary L. McGann, David W. CaressQuaternary tephrochronology and deposition in the subsurface Sacramento–San Joaquin Delta, California, U.S.A.
We document characteristics of tephra, including facies and geochemistry, from 27 subsurface sites in the Sacramento-San Joaquin Delta, California, to obtain stratigraphic constraints in a complex setting. Analyzed discrete tephra deposits are correlative with: 1) an unnamed tephra from the Carlotta Formation near Ferndale, California, herein informally named the ash of Wildcat Grade (<~1.450 - >~AuthorsKatherine L. Maier, Emma Gatti, Elmira Wan, Daniel J. Ponti, Mark Pagenkopp, Scott W. Starratt, Holly A. Olson, John Tinsley - 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