HR: 17:00h
AN: G44A-05    [Abstracts]
TI: Coseismic and Postseismic Slip of the 2004 Parkfield Earthquake from GPS and InSAR data
AU: * Johanson, I A
EM: ingrid@seismo.berkeley.edu
AF: UC Berkeley, Department of Earth and Planetary Science 307 McCone Hall, Berkeley, CA 94720 United States
AU: Fielding, E J
EM: Eric.J.Fielding@jpl.nasa.gov
AF: Jet Propulsion Laboratoty/Caltech, 4800 Oak Grove Drive, Pasadena, CA 91109 United States
AU: Rolandone, F
EM: frederique.rolandone@lgs.jussieu.fr
AF: Universite Pierre et Marie Curie, Laboratoire de Tectonique, UMR7072 Barre 46-45 Niveau 2 - Case 129 4, Place Jussieu, Paris Cedex 05, F-75252 France
AU: Bürgmann, R
EM: burgmann@seismo.berkeley.edu
AF: UC Berkeley, Department of Earth and Planetary Science 307 McCone Hall, Berkeley, CA 94720 United States
AB: We present the results of an inversion of space geodetic data for slip in the coseismic and postseismic periods of the 2004 Parkfield earthquake. The data is a combination of InSAR data from the ENVISAT and RADARSAT satellites, and campaign and continuous GPS measurements. The InSAR data consists of eight interferometric pairs spanning the earthquake and variable-length portions of the pre- and post-seismic periods. We fit a model including an interseismic slip rate, coseismic offsets from the San Simeon and Parkfield earthquakes and a post-Parkfield earthquake exponential decay to daily time series of the GPS-derived displacements. We use the results of the GPS time-series fit for the Parkfield coseismic offsets and amplitudes of the postseismic exponential decay in the joint inversion. The model used in the inversion assumes that slip in the postseismic period evolves as an exponential decay and we simultaneously solve for coseismic slip and the amplitude of the postseismic exponential. With this model formulation, the distribution of postseismic slip is not allowed to change with time, only its magnitude. The model resolves nearly equal amounts of slip for the coseismic and postseismic time periods. This result underlines the importance of aseismic slip in the slip budget for the Parkfield segment of the San Andreas fault. The two periods also show an inverse correspondence in their slip distributions. The coseismic rupture occurred mainly in two high-slip asperities; the smaller occurring near the hypocenter and the larger occurring 10-20 km north. Shallow postseismic slip took place mainly on the fault areas surrounding the coseismic rupture, including the rupture areas of two M_w5.0 aftershocks.
DE: 1207 Transient deformation (6924, 7230, 7240)
DE: 1209 Tectonic deformation (6924)
DE: 1240 Satellite geodesy: results (6929, 7215, 7230, 7240)
DE: 1242 Seismic cycle related deformations (6924, 7209, 7223, 7230)
DE: 6924 Interferometry (1207, 1209, 1242)
SC: Geodesy [G]
MN: Fall Meeting 2005