HR: 0830h
AN: G21B-0272    [PDF]
TI: Observations of Surface Deformation Following the 1992 M7.3 Landers Earthquake, Southern California: Robust Test of the Post-Seismic Relaxation Models.
AU: * Fialko, Y
EM: fialko@radar.ucsd.edu
AF: IGPP/SIO, University of California San Diego, IGPP-225 UCSD, La Jolla, CA 92093
AB: The co- and post-seismic deformation due to the 1992 $M_w7.3$ Landers earthquake is investigated using the entire catalog of the ERS Synthetic Apetrure Radar (SAR) data, and GPS measurements made between 1992 and 1999. The co-seismic stress perturbations due to the Landers earthquake are computed using a slip model derived from inversions of the SAR data from the ascending and descending orbits. These stress perturbations are then used to predict the visco-elastic and poro-elastic response of the Earth's crust within a few hundred kilometers from the earthquake rupture. Calculations are performed for both the homogeneous and layered half-space models. The predicted surface deformation is compared to the Interferometric SAR and GPS data. The stacked InSAR data spanning the time period between 1992 and 1999 reveal a transient post-seismic deformation with a characteristic decay time of several years. The observed deformation pattern cannot be readily explained by any single mechanism. In particular, the data exhibit high strains across the Landers rupture, inconsistent with visco-elasic models of relaxation in the lower crust or upper mantle. The poro-elastic model quite well predicts the InSAR signal, assuming that the pore fluid flow extends to the middle crust (down to about 15 km), but it underpredicts the far-field GPS data. We demonstrate that a combination of poro-elastic relaxation above the brittle-ductile transition, and afterslip on the Landers rupture is required to satisfactory explain both the InSAR and GPS data.
UR: http://igpp.ucsd.edu/~fialko/res_land.html
DE: 1208 Crustal movements--intraplate (8110)
DE: 1242 Seismic deformations (7205)
DE: 1243 Space geodetic surveys
DE: 7205 Continental crust (1242)
DE: 7260 Theory and modeling
SC: Geodesy [G]
MN: 2003 Fall Meeting