HR: 0800h
AN: U51A-0009    [Abstracts]
TI: Status of GPS Based Investigations on the Recent Sequence of Earthquakes on the Sumatran Trench
AU: Hermawan, I
EM: hermawan@geologie.ens.fr
AF: Laboratoire de Geologie ENS/CNRS, 24, rue Lhomond, Paris, 75005, France
AU: Vigny, C
EM: vingy@geologie.ens.fr
AF: Laboratoire de Geologie ENS/CNRS, 24, rue Lhomond, Paris, 75005, France
AU: * Cattin, R
EM: cattin@geologie.ens.fr
AF: Laboratoire de Geologie ENS/CNRS, 24, rue Lhomond, Paris, 75005, France
AU: Chamot-Rooke, N
EM: rooke@geologie.ens.fr
AF: Laboratoire de Geologie ENS/CNRS, 24, rue Lhomond, Paris, 75005, France
AB: Within only a few years, almost all the length of the Sumatran trench accommodating the Indo- Australian/Sundaland convergence ruptured. After the giant earthquake of December,26 2004 and the march, 28 Nias earthquake, the last sequence of earthquakes along the Mentawai Islands (12 september) broke the remaining gap. According to the distribution of aftershocks, it is not completely clear whether the last sequence of earthquakes reproduced the 1833 rupture (Sieh, 2006), i.e. leaving an untouched section of 100-200 km roughly in front of the Siberut Island and city of the Padang (capital of west Sumatra). Immediately after 09/12, we re- occupied with GPS a network of 30 benchmarks we had installed in the Padang area and surveyed initially in June 2007. From these measurements, we expect to be able to constrain the rupture of the earthquake, and especially to quantify the co-seismic slip near the northern end of the rupture. We also installed 4 cGPS stations along the Sumatran coast around Padang to monitor post-seismic deformation in this area, and help determine if this area slipped or is still accumulating strain for a future earthquake. Along with GPS results, we will show the role played by Coulomb stress, shear stress and normal stress increase, as well as pore pressure modification, on past and future earthquake triggering; on the trench itself and on the Great Sumatra Fault, the continental structure that accommodates the strike-slip component of the oblique plate convergence behind the trench.
DE: 1240 Satellite geodesy: results (6929, 7215, 7230, 7240)
DE: 7215 Earthquake source observations (1240)
DE: 7230 Seismicity and tectonics (1207, 1217, 1240, 1242)
DE: 7240 Subduction zones (1207, 1219, 1240)
SC: Union [U]
MN: 2007 Fall Meeting