HR: 1330h
AN: U53A-01    [Abstracts]
TI: Source mechanism of the Aceh Sumatra 2004 earthquake from very long period Earth free oscillations
AU: * Lambotte, S
EM: sophie.lambotte@eost.u-strasbg.fr
AF: EOST-IPGS, CNRS-ULP, 5, rue Ren‚ Descartes, Strasbourg, 67084 France
AU: Rivera, L
EM: luis@sismo.u-strasbg.fr
AF: EOST-IPGS, CNRS-ULP, 5, rue Ren‚ Descartes, Strasbourg, 67084 France
AU: Hinderer, J
EM: jacques.hinderer@eost.u-strasbg.fr
AF: EOST-IPGS, CNRS-ULP, 5, rue Ren‚ Descartes, Strasbourg, 67084 France
AB: The giant Aceh 2004 earthquake strongly excited the free oscillations of the earth, including some usually elusive very long period modes which are conspicous in the first calculated spectra. Several source models, published in the first days after the event, obtained from teleseismic body waves, show a rupture length of 400-500 km with a source duration of 200 sec approximately. On the other hand, the spatial distribution of aftershocks fills a much longer region, going further than 1000 km north of the epicenter, and some short period teleseismic observations suggest a source duration as long as 8 minutes. Both observations suggest a giant rupture, difficult to model with the standard teleseismic bodywave analysis du to overlapping of different phases. In order to gain some insight into the details of the rupture process, we model the very long period seismic and gravitational world wide records corresponding to this event. From the amplitude of the splitted singlets of the gravest free oscillations of the earth excited by the Aceh earthquake, we study its focal mechanism, seismic moment, depth, extent and history of the source.
DE: 1242 Seismic deformations (7205)
DE: 7209 Earthquake dynamics and mechanics
DE: 7215 Earthquake parameters
DE: 7255 Surface waves and free oscillations
DE: 7260 Theory and modeling
SC: Union [U]
MN: 2005 Joint Assembly