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Dynamic models of an earthquake and tsunami offshore Ventura, California

David D. Oglesby, Michael Barall, Eric L. Geist, & Kenny J. Ryan

Published August 18, 2015, SCEC Contribution #6251

The Ventura basin in Southern California includes coastal dip-slip faults that can likely produce earthquakes of magnitude 7 or greater and significant local tsunamis. We construct a 3-D dynamic rupture model of an earthquake on the Pitas Point and Lower Red Mountain faults to model low-frequency ground motion and the resulting tsunami, with a goal of elucidating the seismic and tsunami hazard in this area. Our model results in an average stress drop of 6 MPa, an average fault slip of 7.4 m, and a moment magnitude of 7.7, consistent with regional paleoseismic data. Our corresponding tsunami model uses final seafloor displacement from the rupture model as initial conditions to compute local propagation and inundation, resulting in large peak tsunami amplitudes northward and eastward due to site and path effects. Modeled inundation in the Ventura area is significantly greater than that indicated by state of California's current reference inundation line.

Oglesby, D. D., Barall, M., Geist, E. L., & Ryan, K. J. (2015). Dynamic models of an earthquake and tsunami offshore Ventura, California. Geophysical Research Letters, 42(16), 6599-6606. doi: 10.1002/2015GL064507.