HR: 0800h
AN: U51A-0001    [Abstracts]
TI: Slip distributions of the southern Sumatra earthquake doublet of September 12, 2007 estimated from teleseismic inversion
AU: * Baba, T
EM: babat@jamstec.go.jp
AF: IFREE/JAMSTEC, 3173-25 Showa-machi, Kanazawa-ku, Yokohama, 2360001, Japan
AU: Cummins, P R
EM: phil.cummins@ga.gov.au
AF: Geoscience Australia, GPO Box 378, Canberra, ACT 2601, Australia
AU: Thio, H K
EM: Hong_Kie_Thio@URSCorp.com
AF: URS Group Inc., 556 El Dorado Street, Pasedena, CA 91101, United States
AB: The great earthquake of 26 December, 2004, ruptured the plate boundary offshore the Andaman and northern Sumatra Islands. This earthquake and the following tsunami had a devastating impact throughout the Indian Ocean. The Nias earthquake occurred on 28 March, 2005, rupturing the next plate boundary to the south of the 2004 Sumatra earthquake. Recently, a pair of magnitude 8.4 and 7.9 interplate earthquakes occurred on 12 September, 2007, in a region south of the 2005 Nias earthquake. We investigated the slip distributions of the 2007 Sumatra sequential earthquakes by inverting teleseimic body and surface waves. The slip model of the magnitude 8.4 earthquake showed a large slip zone of up to 7m about 100km northwest of the epicenter. The moment magnitude was estimated to be 8.47 which was very similar to that obtained by U.S. Geological Survey. In the magnitude 7.9 earthquake model, a significant slip patch of about 3m was imaged at the northern end of the slip region of the magnitude 8.4 earthquake. The magnitude 7.9 slip area did not reach the southern end of the plate boundary ruptured by the 2005 Nias earthquake. This indicates that there may be a seismic gap of about 120km between the 2005 Nias and the 2007 sequence. The total slip zone of these models was consistent with the 1833 rupture zone estimated by using coral data, which extended from approximately Eggano Island to the southern portion of Siberut Island. However, the amount of slip of the pair of the 2007 earthquakes was slightly smaller than that of the 1833 model.
DE: 7209 Earthquake dynamics (1242)
DE: 7230 Seismicity and tectonics (1207, 1217, 1240, 1242)
DE: 7240 Subduction zones (1207, 1219, 1240)
SC: Union [U]
MN: 2007 Fall Meeting