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Strong Ground Motions From Large Earthquakes on the Creeping Hayward, Rodgers Creek and Calaveras Faults, California

Description: 

Large earthquakes have a high likelihood of occurring in California in the next 30 years. Most of the faults these earthquakes may rupture are locked during the times between large events, but some creep, slowly slipping much of the time. In the San Francisco Bay area, significant creeping faults include the Hayward fault and its connected companions to the north and the south, the Rodgers Creek and Calaveras faults, respectively. These three faults have the highest probabilities of producing a large earthquake in this region, and because these faults occur in a densely populated area, they also pose significant seismic risk. We used the dynamic rupture method, as implemented in the finite-element software FaultMod (https://code.usgs.gov/esc/faultmod), and assumed the 3D San Francisco Bay area velocity model with elastic rock properties, slip-weakening friction, and initial stress conditions based on where the faults are creeping versus locked, to simulate 3 seconds and longer-period strong ground motions from large (M7) scenario earthquakes on these faults. The lowest shear-wave velocity we assigned to the rock properties in our models is 1950 m/s, so we used the Boore et al. (Earthquake Spectra, 2014) ground motion model with Vs30 set equal to 1950 m/s as a comparison. We show that our dynamic rupture simulation results produce reasonable agreement with the Boore et al. (2014) empirical relations.

Session: Accuracy and Variability of Physics-based Ground Motion Modeling [Poster]

Type: Poster

Date: 4/15/2025

Presentation Time: 08:00 AM (local time)

Presenting Author: Grace

Student Presenter: No

Invited Presentation: 

Poster Number: 84

Authors