Project Abstract
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Offshore faulting in the Continental Borderland poses a potential tsunami hazard in Southern California. Recent studies have shown the recurrence times for major earthquakes on the Ventura-Pitas Point system to be on the order of several hundred to several thousand years, within the range of engineering interest. We have computed the tsunami impact of several scenarios on the Southern California coast.
As expected, large events on this system cause significant inundation along the coast in Ventura and, to a lesser degree, Santa Barbara counties. While local bathymetry of the Continental Borderlands causes energy focusing within the Santa Barbara Channel, the tsunami outside of the Santa Barbara Channel attenuate rapidly. Details in the fault geometry and slip distribution are important for the tsunami simulations, and we have explored different models as well as events on the nearby Oak Ridge fault.
We present these results in the context of the existing and draft tsunami hazard maps from the California Geological Survey. Our results suggest that the hazard from the largest scenarios (M > 7.7) on the Ventura-Pitas Point structure in Ventura county is of the same order of magnitude as the existing tsunami hazard and evacuation maps and the upcoming 2500 year draft maps. A better understanding of the recurrence for this source is therefore essential in determining how these fault systems will add to the existing tsunami hazard models. Outside of Ventura County, the tsunami hazard from the Ventura-Pitas Point system is limited and unlikely to contribute to the hazard maps. |
