HR: 09:45h
AN: U51A-06    [Abstracts]
TI: GPS Measurements of Coseismic and Postseismic Deformation for the Mw 9.0 2004 Sumatra Earhquake: Constraints on Seismographic Inversions of the Earthquake Source and Tsunami Models
AU: Subarya, C
EM: csubarya@bakosurtanal.go.id
AF: BAKOSURTANAL, Indonesia National Coordination Agency for Surveying and Mapping, Jl. Raya Jakarta Bogor km 46, Cibinong, Indonesia
AU: * Bock, Y
EM: ybock@ucsd.edu
AF: Scripps Institution of Oceanography, 9500 Gilman Drive, Institute of Geophysics and Planetary Physics, La Jolla, CA 92093 United States
AU: Prawirodirdjo, L
EM: linette@gpsmail.ucsd.edu
AF: Scripps Institution of Oceanography, 9500 Gilman Drive, Institute of Geophysics and Planetary Physics, La Jolla, CA 92093 United States
AU: McCaffrey, R
EM: mccafr@rpi.edu
AF: Rensselaer Ploytechnic Institute, Department of Earth and Environmental Sciences, Troy, NY 12180 United States
AU: Sieh, K
EM: sieh@gps.caltech.edu
AF: Califorrnia Institute of Technology, Geological and Planetary Sciences, Mail code 100-23 , Pasadena, CA 91125 United States
AU: Natawidjaja, D
EM: danny@gps.caltech.edu
AF: Califorrnia Institute of Technology, Geological and Planetary Sciences, Mail code 100-23 , Pasadena, CA 91125 United States
AU: Galetzka, J
EM: galetzka@gps.caltech.edu
AF: Califorrnia Institute of Technology, Geological and Planetary Sciences, Mail code 100-23 , Pasadena, CA 91125 United States
AB: The active tectonics of western Indonesia is dominated by convergence of the Australia plate with Sumatra and Java. Along Sumatra the direction of convergence is highly oblique to the trench strike, and is partitioned into nearly arc-perpendicular thrusting at the trench and arc-parallel, right-lateral slip at the Sumatran fault (SF). Both faults are the source of strong and frequent earthquake activity. Two great (M > 8-9) subduction earthquakes occurred in 1833 and 1861, and several large (M > 7) strike-slip events are centered on or near the SF. We present coseismic and postseismic deformations for the devastating Mw 9.0 Sumatra earthquake of 26 December 2004, which ruptured to the NW of the 1861 rupture zone. We are currently performing resurveys with GPS of a network of tens of monuments established and surveyed repeatedly in Northern Sumatra, Banda Aceh, and the Mentawai Islands in the period 1989-2001, to study the mechanics of strain partitioning at this oblique subduction zone. The monuments have expected coseismic displacements ranging up to a few meters, and include stations within 100 km of the earthquake's epicenter, and within the zone of greatest destruction in Banda Aceh. A resurvey of these points is the best way to recover the permanent deformation of the Aceh and North Sumatra regions associated with the earthquake, and to monitor the subsequent postseismic deformation with good spatial resolution. We also present results from a continuous GPS network in North Sumatra and the Mentawai Islands, operating for nearly two years. Together, the resurveyed monuments and the continuous GPS stations will provide important constraints on seismographic inversions of the earthquake source and tsunami models, which up until now have had very little geodetic input. The repeat measurements will provide critical information on segmentation of the great earthquake rupture zones and their boundaries. Furthermore, we will be able to determine the wavelength of deformation that will be important for quantifying and understanding the (expected large) time dependent deformation. We also postulate the impact that a high-rate real-time GPS network would have had on mitigating the loss of human life resulting from this event, and present plans for such a network in Sumatra.
DE: 1243 Space geodetic surveys
DE: 7205 Continental crust (1242)
DE: 8155 Plate motions--general
SC: Union [U]
MN: 2005 Joint Assembly