HR: 0800h
AN: S31C-0568    [Abstracts]
TI: HYDRODYNAMIC SIMULATIONS OF FAR-FIELD TSUNAMI RISK IN THE INDIAN OCEAN, WITH SPECIAL EMPHASIS ON AFRICA
AU: * Synolakis, C E
EM: costas@usc.edu
AF: University of, Southern California, Los Angeles, CA 90089, United States
AU: Okal, E A
EM: emile@earth.northwestern.edu
AF: Northwestern, University, Evanston, IL 60208, United States
AU: Hartnady, C J
EM: chris@umvoto.com
AF: UMVOTO, P.O. Box 61, Muizenberg, 7950, South Africa
AB: We evaluate far-field tsunami risk in the Indian Ocean Basin based on hydrodymanic simulations of eight case studies of possible mega earthquakes at the major seismic zones surrounding the basin. They represent worst-case scenarios of seismic rupture along the full extent of seismogenic faults having supported large earthquakes in the historical record. We consider seismic sources located at the extremities of the 2004 Sumatra-Andaman rupture, namely along the Southern coast of Sumatra and in the Andaman-Myanmar province; along the Makran coast of Pakistan and Iran; and also along the Southern coast of Java, where the possibility of a large interplate thrust earthquake cannot be entirely dismissed. Following Ando's [1975] remark concerning the capricious character of segmentation during repeated mega-earthquakes at subduction zones, we consider events even bigger than identified in the historical record, especially in Southern Sumatra. We also envision risk to South Africa from a potential mega-event in the South Sandwich Islands. The results of our hydrodynamic simulations indicate that the distribution of maximum amplitudes in the Indian Ocean Basin is primarily controlled by the classical effect of source directivity, and additionally by refraction and focusing along bathymetric features. As a result, many provinces in the basin could be threatened by higher tsunami amplitudes than in 2004. This pattern is particularly important along the coast of East Africa, from Somalia to and including South Africa, in Madagascar and the Mascarene Islands, especially under a South Sumatra scenario involving an earthquake comparable to, or even possibly larger than, the 1833 event, whose epicentral area is widely believed to be under enhanced seismic risk as a result of stress transfer from the 2004 and 2005 ruptures to the Northwest.
DE: 4564 Tsunamis and storm surges
DE: 7230 Seismicity and tectonics (1207, 1217, 1240, 1242)
SC: Seismology [S]
MN: 2007 Fall Meeting