SCEC Award Number 24120 View PDF
Proposal Category Individual Research Project (Single Investigator / Institution)
Proposal Title Statewide paleoseismic inter-event time statistics
Investigator(s)
Name Organization
Michael Oskin University of California, Davis
SCEC Milestones A1-3, A3-4 SCEC Groups Geology, EFP, FARM
Report Due Date 03/15/2025 Date Report Submitted 03/21/2025
Project Abstract
 Identifying the appropriate probability model for earthquake recurrence is essential for correctly forecasting seismic hazard and testing multi-cycle earthquake simulations. In my previous SCEC-supported effort, I showed that a Weibull model (Weibull, 1951), which yields a power-law increase in earthquake hazard with elapsed time since the previous event, proves superior for modeling long paleoseismic time series from the San Andreas, San Jacinto, and Alpine faults. In this work, I further test this model by combining shorter paleoseismic records available from across California. The intellectual merit of this research is that by constraining an appropriate statistical model for earthquake probability, we can better understand the physical processes setting the stage for the next large earthquake.
Intellectual Merit The intellectual merit of this research is that by constraining an appropriate statistical model for earthquake probability, we can better understand the physical processes setting the stage for the next large earthquake.
Broader Impacts The broader impact of this research is that competing statistical models produce meaningful differences in hazard over the time between events, especially early and late in the seismic cycle. Refining how statistical models are applied to paleoseismic data has the potential to transform how the community approaches seismic hazard.
Project Participants Evelyn Usher, UC Davis M.S. student.
Exemplary Figure Figure 3. Ratio-distribution analysis for four different subsets of active faults in California. The Hayward fault falls on the line for k = 1, similar to hazard exponents for isolated sections of the San Andreas fault along the north coast and Mojave section. A compilation of shorter records from the San Andreas fault defines a distribution like that constrained from individual long earthquake records. The lower two plots show results from three strike-slip faults in southern California (Garlock, Elsinore, and Rose Canyon), with a hazard exponent k ≈ 0.5. similar to the San Jacinto fault at Hog Lake and Mystic Lake.
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