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Is California Overdue for Large Earthquakes?

Session: Overdue?

Type: Oral

Date: 4/21/2021

Presentation Time: 10:45 AM Pacific

Description: 

The question itself suggests a budget of some events that must be balanced over some time period. What could control such a budget? What sort of events should be counted? Over what time interval is the budget due? Suggestions that California or other regions are overdue generally come from comparisons of seismologically observed earthquake catalogs with rates estimated from paleo-seismic, geologic, and/or geodetic data. Estimates rely on many unverified assumptions, including steady rates of fault slip or seismic moment release, equivalence of seismic and tectonic moment release, and in some cases quasi-periodic earthquake recurrence. Here I compare inferences based on observed paleo-seismic events in California with cataloged "large" (m7+) earthquakes. The paleo-seismic data suggest we are now overdue because six events were reported from 1820 to 1920 but none from 1920 to 2020. However, the seismic catalog includes 8 large earthquakes in the first interval and 9 in the second. The paleo-seismic event data remain puzzling, but California does not appear overdue for actual large earthquakes.

Presenting Author: David D. Jackson

Student Presenter: No

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