Tsunami

There has been increasing public attention given to tsunamis since 2004 when the Indian Ocean Tsunami killed more than 230,000 people. Attention increased even further following the 2011 East Japan Tsunami, which killed more than 18,000 people and caused enormous economic damage, including devastating nuclear disaster at the Fukushima Dai-ichi Nuclear Power Plant. The U.S. Pacific Northwest (Washington, Oregon, and Northern California) is vulnerable to similar local tsunamis generated by a Cascadia subduction zone earthquake. In Southern California, there is a tsunami threat that could be triggered by a submarine landslide off the Santa Barbara or Los Angeles Basin.

Based on the directivity characteristics of tsunami energy propagation, the entire U.S. West Coast is vulnerable to distant tsunamis originated in the eastern end of the Aleutian (Alaska) and also Philippine Main. The extreme scenario would be strong, long-duration earthquake ground shaking associated with the subduction fault rupture, followed by large tsunami inundation. Such a scenario is not an exception, but rather a common occurrence in the continental margin where major geologic subduction processes occur. Substantial structural damage caused by tsunamis in Japan underscores the urgency of re-examining the present engineering design practice for the multiple-hazard scenario.