HR: 1340h
AN: G13A-0794    [Abstracts]
TI: Models of Afterslip and Viscoelastic Response following the Landers and Hector Mine Ruptures
AU: * Luttrell, K M
EM: kmobley@ucsd.edu
AF: Scripps Institution of Oceanography, 9500 Gilman Dr. MC 0224, La Jolla, CA 92093-0225 United States
AU: Smith, B R
EM: brsmith@ucsd.edu
AF: Scripps Institution of Oceanography, 9500 Gilman Dr. MC 0224, La Jolla, CA 92093-0225 United States
AU: Sandwell, D T
EM: dsandwell@ucsd.edu
AF: Scripps Institution of Oceanography, 9500 Gilman Dr. MC 0224, La Jolla, CA 92093-0225 United States
AU: Fialko, Y
EM: fialko@radar.ucsd.edu
AF: Scripps Institution of Oceanography, 9500 Gilman Dr. MC 0224, La Jolla, CA 92093-0225 United States
AB: We evaluate the postseismic deformation following the 1992 {\it M}$_{w}$ 7.3 Landers and 1999 {\it M}$_{w}$ 7.1 Hector Mine earthquakes using a fault slip distribution that includes both strike-slip and dip-slip. Observations of coseismic slip show significant vertical deformation that has not yet been included in models of postseismic activity. The rheological models include both deep afterslip and the viscoelastic response of a half space beneath an elastic layer. We simulate the complex geometries of the ruptures using hundreds of vertical fault patches as constrained by the surface rupture and aftershock studies. The viscoelastic response is modeled using a 3-D coseismic slip model obtained from inversions of InSAR and GPS observations [{\it Simmons et al.}, 2002; {\it Fialko}, 2004]. The post-seismic afterslip models which include strike-slip, dip-slip, and shallow fault-normal displacement are developed using the coseismic rupture geometry. The 3-D deformation is computed at a 500-m grid spacing and compared with available postseismic interferograms in both the near field and far field allowing us to consider both long wavelength and short wavelength behavior. The objective of the analysis is to evaluate the relative importance of afterslip and viscoelastic response and to determine whether a model with a thick elastic plate ($\sim$50 km) and moderate mantle viscosity (10$^{19}$ Pa s) is compatible with geodetic observations.
UR: http://topex.ucsd.edu
DE: 8010 Fractures and faults
DE: 8040 Remote sensing
DE: 8164 Stresses--crust and lithosphere
DE: 1206 Crustal movements--interplate (8155)
DE: 1242 Seismic deformations (7205)
SC: Geodesy [G]
MN: 2004 AGU Fall Meeting