HR: 13:40h
AN: U13A-01 INVITED     [Abstracts]
TI: Tsunami Generation from the 2004 Sumatra-Andaman Earthquake
AU: * Satake, K
EM: kenji.satake@aist.go.jp
AF: Geological Survey of Japan, AIST, 1-1-1 Higashi, site C7, Tsukuba, 305-8567 Japan
AB: The tsunami caused by the December 26, 2004, Sumatra earthquake (Mw 9.1) propagated across the Indian Ocean and caused the worst tsunami disaster. Factors contributed to the tragedy include the giant size of the earthquake, absence of both tsunami warning system and long-term forecast of future earthquakes in the Indian Ocean. Seismological developments since 1960, when the Chilean earthquake (Mw 9.5) caused Pacific-wide tsunami damage, make it possible to estimate the earthquake source parameters within minutes after the occurrence and utilize it for the tsunami warning purposes. The length of the tsunami source of the December Sumatra-Andaman earthquake is enigmatic. The aftershock zone extended from west of Sumatra through Nicobar Islands all the way to Andaman Islands; the total length is over 1,200 km. The seismic wave analyses indicate the southern half ruptured in rather rapidly while the northern half did slowly. Sea level changes in Andaman and Nicobar Islands indicate that the coseismic crustal deformation extended to Andaman Islands. The tsunami source size was estimated to be about 700 km long from the tsunami arrival times recorded on tide gauges, but the northern end was not well constrained. The tsunami heights in Indian Ocean, captured by Jason-1 and other satellites, support that the tsunami source was about 1,100 km long. For more accurate tsunami computations requires detailed shallow bathymetry data. To document the 2004 tsunami, many scientists from all over the world visited the affected coasts. From Japan alone, several survey teams visited coasts of Indonesia, Thailand, Myanmar, India and Sri Lanka, with collaborators in each country. The tsunami heights in Sumatra Island, particularly around Band Aceh, were mostly larger than 20 m with the maximum of 30 m. The tsunami heights along the Andaman Sea coast were highly variable; they were 5 to 15 m in Thailand but less than 3 m in Myanmar. In fact, the tsunami damage and casualties, reportedly 61, were much slighter in Myanmar than other countries. The tsunami heights were also up to 5 m on India_fs Andaman Islands. In Sri Lanka, the tsunami heights were 5 to 15 m. The tsunami height distribution is consistent with the damage distribution, and supports that the tsunami source was concentrated in the southern 700 km section of the aftershock zone.
DE: 3060 Subduction zone processes (1031, 3613, 8170, 8413)
DE: 4564 Tsunamis and storm surges
DE: 7215 Earthquake source observations (1240)
DE: 7221 Paleoseismology (8036)
SC: Union [U]
MN: Fall Meeting 2005