HR: 1340h
AN: OS23D-1355    [Abstracts]
TI: Tsunami Inundation Mapping for Seward, Alaska: Tectonic and Landslide Sources
AU: * Suleimani, E
EM: elena@giseis.alaska.edu
AF: Geophysical Institute, University of Alaska Fairbanks, P.O. Box 757320, Fairbanks, AK 99775-7320 United States
AU: Beg\'{e}t, J
EM: ffjeb1@uaf.edu
AF: Department of Geology and Geophysics, University of Alaska Fairbanks, P.O. Box 755780, Fairbanks, AK 99775-5780 United States
AU: Hansen, R
EM: roger@giseis.alaska.edu
AF: Geophysical Institute, University of Alaska Fairbanks, P.O. Box 757320, Fairbanks, AK 99775-7320 United States
AU: Marriott, D
EM: duncan@giseis.alaska.edu
AF: Geophysical Institute, University of Alaska Fairbanks, P.O. Box 757320, Fairbanks, AK 99775-7320 United States
AB: The Alaska Tsunami Modeling Team participates in the National Tsunami Hazard Mitigation Program by evaluating and mapping potential tsunami inundation of coastal communities in Alaska. We address the problem of predicting runup of tsunami waves by solving nonlinear shallow-water equations with a finite-difference method. Embedded grids of different resolution are employed to increase spatial resolution in the shelf area. Numerical simulations yield runup heights, extent of maximum inundation for chosen tsunami scenarios, depths of inundation on dry land, and maximum velocity current distribution in inundation zones. Seward, a community in the Prince William Sound area, suffered an extensive damage and 12 fatalities during the 1964 tsunami. The 1964 Good Friday earthquake induced submarine landsliding in deltaic sediments underlying Seward. Local tsunami waves as much as 10 m high devastated Seward minutes later. Using high resolution bathymetric imagery we identified and mapped the extent of submarine landslides which originated near Seward, as well as multiple submarine landslides from other deltas around upper Resurrection Bay. Three distinct slides occurred at Seward, but only the largest slide produced subaerial failures in the delta fan, affecting 1250 m of the Seward waterfront. Estimated slide volumes, based on our imagery analysis and post-1964 coring studies, ranged from about 15,000,000 $m^3$ to 33,000,000 $m^3$. Previously unrecognized submarine landslides were also mapped at Fourth of July valley and other deltas in Resurrection Bay. These slides were smaller in volume then the slides from Seward itself. Some of these slides may predate the 1964 earthquake, and indicate repeated occurrences of submarine landslides and tsunamis following great earthquakes. We consider several tsunami scenarios for Seward inundation mapping that include both tectonic and landslide sources.
DE: 4255 Numerical modeling
DE: 4564 Tsunamis and storm surges
SC: Ocean Sciences [OS]
MN: 2004 AGU Fall Meeting