HR: 1340h
AN: S53A-1012    [Abstracts]
TI: Tsunami Hazard in Crescent City, California from Kuril Islands earthquakes
AU: * Dengler, L
EM: lad1@humboldt.edu
AF: Humboldt State University, #1 Harpst St, Arcata, CA 95521, United States
AU: Uslu, B
EM: bbuslu@yahoo.com
AF: University of Southern California, University of Southern California, Los Angeles, CA 90089- 2531, United States
AU: Barberopoulou, A
EM: aggeliki.barberopoulou@gmail.com
AF: University of Southern California, University of Southern California, Los Angeles, CA 90089- 2531, United States
AB: On November 15, Crescent City in Del Norte County, California was hit by a series of tsunami surges generated by the M = 8.3 Kuril Islands earthquake causing an estimated 9.7 million (US dollars) in damages to the small boat basin. This was the first significant tsunami loss on US territory since the 1964 Alaska tsunami. The damage occurred nearly 8 hours after the official tsunami alert bulletins had been cancelled. The tsunami caused no flooding and did not exceed the ambient high tide level. All of the damage was caused by strong currents, estimated at 12 to 15 knots, causing the floating docks to be pinned against the pilings and water to flow over them. The event highlighted problems in warning criteria and communications for a marginal event with the potential for only localized impacts, the vulnerability of harbors from a relatively modest tsunami, and the particular exposure of the Crescent City harbor area to tsunamis. It also illustrated the poor understanding of local officials of the duration of tsunami hazard. As a result of the November tsunami, interim changes were made by WCATWC to address localized hazards in areas like Crescent City. On January 13, 2007 when a M = 8.1 earthquake occurred in the Kuril Islands, a formal procedure was in place for hourly conference calls between WCATWC, California State Office of Emergency Services officials, local weather Service Offices and local emergency officials, significantly improving the decision making process and the communication among the federal, state and local officials. Kuril Island tsunamis are relatively common at Crescent City. Since 1963, five tsunamis generated by Kuril Island earthquakes have been recorded on the Crescent City tide gauge, two with amplitudes greater than 0.5 m. We use the MOST model to simulate the 2006, 2007 and 1994 events and to examine the difference between damaging and non-damaging events at Crescent City. Small changes in the angle of the rupture zone results can result in a half meter difference in water heights. We also look at the contribution of fault segments along the Kuril subduction zone using the FACTS server to look at the potentially most damaging source regions for Crescent City. A similar-sized rupture as the November 15 event located further south along the Hokkaido – Honshu area of the subduction zone, is likely to produce a slightly larger amplitude signal with and even greater delay between the first wave arrivals and the largest waves.
DE: 6309 Decision making under uncertainty
SC: Seismology [S]
MN: 2007 Fall Meeting