HR: 1330h
AN: U53A-10    [Abstracts]
TI: Rupture Process of the December 26, 2004 M_w = 9.0 Sumatra Earthquake
AU: * Robinson, D P
EM: davidr@earth.ox.ac.uk
AF: Univesity of Oxford, Department of Earth Sciences Parks Road, Oxford, OX1 3PR United Kingdom
AU: Das, S
EM: das@earth.ox.ac.uk
AF: Univesity of Oxford, Department of Earth Sciences Parks Road, Oxford, OX1 3PR United Kingdom
AB: We use primarily SH-wave data from 20 seismic stations at distances between ~40° and 85° to investigate the rupture history of this earthquake. The aftershocks define a 1200 km long zone along the Indo-Eurasian plate boundary. We use the aftershocks to identify the fault plane and the initial rupture area. We invert seismograms using the method of Das and Kostrov (JGR, 1990; PEPI, 1994) which uses constraints such as positivity of the slip rate at each time step, constraint on total moment, etc. to stabilize the solution. The mechanism of the Harvard CMT solution for this earthquake is used as the starting solution, but we search for alternate solutions with different strike, dip and rake as part of our inversion. We use only pure SH- and P-waves, that is, we terminate the seismograms when unmodelled phases such as ScS or PcP arrive, so we are able to study only about the first three minutes of the rupture process. The faulting process was found to be very heterogeneous. Details of faulting process, including moment distribution history, peak slip, peak slip rates, and average stress drops on different portion of the fault will be presented.
DE: 4564 Tsunamis and storm surges
DE: 7207 Core and mantle
DE: 7215 Earthquake parameters
DE: 7230 Seismicity and seismotectonics
SC: Union [U]
MN: 2005 Joint Assembly