HR: 1340h
AN: S53A-1017    [Abstracts]
TI: Understanding Landslide Tsunami Hazard in Alaska Fjords for Tsunami Inundation Mapping
AU: * Suleimani, E
EM: elena@gi.alaska.edu
AF: Geophysical Institute University of Alaska Fairbanks, 903 Koyukuk Dr. P.O.BOX 757320, Fairbanks, AK 99775-7320, United States
AU: Hansen, R
EM: roger@giseis.alaska.edu
AF: Geophysical Institute University of Alaska Fairbanks, 903 Koyukuk Dr. P.O.BOX 757320, Fairbanks, AK 99775-7320, United States
AB: Several communities of the southern coast of Alaska are located in glacial fjords, which are fed by major rivers and creeks draining nearby glaciers and depositing sediments into the bays at a high rate. Sediment accumulation on the steep underwater slopes contributes to the landslide tsunami hazard in these communities. During the Great Alaska Earthquake of 1964, the majority of tsunami-related deaths was due to local landslide tsunamis that occurred almost immediately after the initial shaking, and without any warning signs. In these coastal communities, tsunami potential from tectonic and submarine landslide sources must be evaluated for comprehensive mapping of areas that are at risk for inundation. We are creating tsunami inundation maps for Seward, Alaska, in the scope of the National Tsunami Hazard Mitigation Program. Seward is a community located at the head of Resurrection Bay, which was hit hard by both tectonic and landslide-generated tsunami waves during the 1964 earthquake. The purpose of the project is long- term prediction of potential landslide-generated tsunamis in Resurrection Bay, and public education on landslide-related tsunami hazard. In order to construct tsunami inundation maps for Seward, we use an approach that combines modeling of the historical tsunami events of 1964 in Resurrection Bay for model verification, and assessing the landslide tsunami hazard by simulating hypothetical landslide scenarios and performing sensitivity analysis. To reconstruct the sequence of waves observed at Seward on March 27, 1964, we model tsunami waves caused by superposition of the local landslide-generated tsunamis and the major tectonic tsunami. Next we create hypothetical landslide scenarios that are based on the underwater sediment accumulation areas derived from the bathymetry difference maps. 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. We deliver modeling results to the community for local tsunami hazard planning and construction of evacuation maps.
DE: 3285 Wave propagation (0689, 2487, 4275, 4455, 6934)
DE: 4534 Hydrodynamic modeling
DE: 4564 Tsunamis and storm surges
SC: Seismology [S]
MN: 2007 Fall Meeting