Southern California Earthquake Hazards Active
Southern California has the highest level of earthquake risk in the United States, with half of the expected financial losses from earthquakes in the Nation expected to occur in southern California. Sitting astride the Pacific - North American plate boundary at the Big Bend of the San Andreas Fault, Southern California has over 300 faults capable of producing magnitude 6 and larger earthquakes. Affecting the more than 20 million inhabitants of the Los Angeles and San Diego metropolitan areas, this complex set of faults presents the greatest urban risk in the United States.
The high level of earthquake activity in a complex tectonic regime provides a unique natural laboratory for the study of the physics of earthquakes. This, along with the intricately detailed data that are available, allows us to develop the best methods for estimating earthquake hazards from geologic, seismologic, and geodetic information.
This project focuses on collaborative research concerning the occurrence of earthquakes on the geologically complex structures of southern California. The effect of three-dimensional geological complexities on the earthquake process complicates our attempts to understand and predict all aspects of the process, from earthquake sources and triggering through rupture initiation and propagation, to the effects of shaking.
We study the dynamics of fault rupture in southern California through analysis of unique data from state-of-the-art monitoring networks, with an emphasis on understanding strong ground motions in heterogeneous materials.
We study fault interaction by relating fault system behavior to analogous cases of great strike-slip earthquakes elsewhere, to provide insight into possible past and future earthquakes in the region.
We study the behavior of fault systems through analysis of these data and geologic field investigations, with an emphasis on the thrust faults of the Transverse Ranges and the San Andreas Fault system.
We use statistical analyses of earthquakes to develop operational earthquake forecasts.
We use technologic advancements in imagery to monitor afterslip hazard following large earthquakes.
Investigations into source characteristics, wave propagation effects, and site response variability will eventually lead to the capability to produce suites of site-specific ground motions from likely earthquake sources. This can lead directly to reduced earthquake losses as the earthquake hazard is better characterized. We continue to evaluate earthquake processes and understand earthquake repeat models by utilizing paleoseismic sites with long earthquake histories, such as at Wrightwood, which records 30 past earthquakes. With the Southern California Earthquake Center, we compile data sets of the Quaternary faults in southern California, a velocity map of current deformation from GPS, and a moment tensor catalog of the M>5 earthquakes in the last century. These will be definitive compilations of the earthquake history of southern California to be used in any future seismic hazard analysis of the region.
- Overview
Southern California has the highest level of earthquake risk in the United States, with half of the expected financial losses from earthquakes in the Nation expected to occur in southern California. Sitting astride the Pacific - North American plate boundary at the Big Bend of the San Andreas Fault, Southern California has over 300 faults capable of producing magnitude 6 and larger earthquakes. Affecting the more than 20 million inhabitants of the Los Angeles and San Diego metropolitan areas, this complex set of faults presents the greatest urban risk in the United States.
Sources/Usage: Public Domain. View Media DetailsMoletrack crossing China Lake dry lake bed after Ridgecrest earthquake in July of 2019. The high level of earthquake activity in a complex tectonic regime provides a unique natural laboratory for the study of the physics of earthquakes. This, along with the intricately detailed data that are available, allows us to develop the best methods for estimating earthquake hazards from geologic, seismologic, and geodetic information.
This project focuses on collaborative research concerning the occurrence of earthquakes on the geologically complex structures of southern California. The effect of three-dimensional geological complexities on the earthquake process complicates our attempts to understand and predict all aspects of the process, from earthquake sources and triggering through rupture initiation and propagation, to the effects of shaking.
We study the dynamics of fault rupture in southern California through analysis of unique data from state-of-the-art monitoring networks, with an emphasis on understanding strong ground motions in heterogeneous materials.
We study fault interaction by relating fault system behavior to analogous cases of great strike-slip earthquakes elsewhere, to provide insight into possible past and future earthquakes in the region.
We study the behavior of fault systems through analysis of these data and geologic field investigations, with an emphasis on the thrust faults of the Transverse Ranges and the San Andreas Fault system.
We use statistical analyses of earthquakes to develop operational earthquake forecasts.
We use technologic advancements in imagery to monitor afterslip hazard following large earthquakes.
Investigations into source characteristics, wave propagation effects, and site response variability will eventually lead to the capability to produce suites of site-specific ground motions from likely earthquake sources. This can lead directly to reduced earthquake losses as the earthquake hazard is better characterized. We continue to evaluate earthquake processes and understand earthquake repeat models by utilizing paleoseismic sites with long earthquake histories, such as at Wrightwood, which records 30 past earthquakes. With the Southern California Earthquake Center, we compile data sets of the Quaternary faults in southern California, a velocity map of current deformation from GPS, and a moment tensor catalog of the M>5 earthquakes in the last century. These will be definitive compilations of the earthquake history of southern California to be used in any future seismic hazard analysis of the region.
Sources/Usage: Public Domain. View Media DetailsUSGS Geophysicists Elizabeth Cochran and Nicholas Van der Elst install a seismometer on the base. Photo credit: Ben Brooks, USGS
Sources/Usage: Public Domain. View Media DetailsGeologists with USGS, the California Geological Survey (CGS) and Naval Air Weapons Station China Lake (NAWS) worked together in response to the Ridgecrest earthquake sequence in California that occurred July 4-6, 2019. Photo credit: Katherine Kendrick, USGS
Sources/Usage: Public Domain. View Media DetailsUSGS Pasadena Earthquake Response Coordinator Sue Hough surveys displaced rocks near the southern end of the surface rupture of the 5 July 2019 M7.1 Ridgecrest earthquake. Photo credit: Sue Hough, USGS - Publications
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