The California Geological Survey Response to the 20 December 2022 Magnitude m6.4 Ferndale Earthquake Sequence
Description:
Seismic hazard in coastal northern California (CA) has an annualized earthquake loss of over $30 million USD. While the two largest contributors to seismic hazard in CA are the San Andreas and Cascadia subduction zone fault systems, Gorda intraplate earthquakes are the largest source of annual seismicity in CA. In the Mendocino triple junction (MTJ) region, these two overlapping fault systems interact in ways that we are only beginning to understand. Based on seismicity, the 20 December 2022 magnitude M6.4 earthquake ruptured 40-50 km of a N70E striking intraplate fault zone within the subducted Gorda plate.
Understanding the potential impact from future earthquakes supports community preparedness and mitigation to protect lives and reduce potential damage to infrastructure. An essential part for estimating hazards from future earthquakes is the documentation of ground deformation following earthquakes to better develop relations between earthquake source parameters and the occurrence of surface effects caused by shaking and surface rupture.
The California Geological Survey (CGS) and U.S. Geological Survey (USGS) operate an earthquake field response program designed to collect field observations of fragile and perishable geologic evidence for earthquakes that impact the state. The CGS, with Federal, State, and non-profit partners, coordinates earthquake field investigations through the CA Earthquake Clearinghouse (CEQCH). The CEQCH activated a virtual clearinghouse following the M6.4 earthquake to support coordination and documentation of multi-agency field observations.
The CGS and the USGS have been collaborating closely since the 2019 Ridgecrest Earthquake to develop a data acquisition schema to collect ephemeral data and to create a field data acquisition system which can be deployed within 15 minutes for post-earthquake investigations. Field observations include landslides and cracks in sand dunes and road fill, though there was no evidence for liquefaction.
Session: Constraining Seismic Hazard in the Cascadia Subduction Zone [Poster]
Type: Poster
Date: 4/20/2023
Presentation Time: 08:00 AM (local time)
Presenting Author: Jason R. Patton
Student Presenter: No
Invited Presentation:
Authors
Jason Patton Presenting Author Corresponding Author jrp2@humboldt.edu California Geological Survey |
Timothy Dawson tim.dawson@conservation.ca.gov California Geological Survey |
Michael Falsetto michael.falsetto@conservation.ca.gov California Geological Survey |
Sara Gallagher sara.gallagher@conservation.ca.gov California Geological Survey |
John Oswald john.oswald@conservation.ca.gov California Geological Survey |
Cynthia Pridmore cynthia.pridmore@conservation.ca.gov California Geological Survey |
Kate Thomas kate.thomas@conservation.ca.gov California Geological Survey |
Spencer Watkins spencer.watkins@conservation.ca.gov California Geological Survey |
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The California Geological Survey Response to the 20 December 2022 Magnitude m6.4 Ferndale Earthquake Sequence
Category
Constraining Seismic Hazard in the Cascadia Subduction Zone