HR: 1400h
AN: G43B-02    [Abstracts]
TI: Semi-analytic Models of Deformation in Heterogeneous Media With Nonlinear Visco-elastic Rheologies.
AU: * Barbot, S D
EM: sbarbot@ucsd.edu
AF: Institute of Geophysics and Planetary Physics, Scripps Institution of Oceanography, University of California San Diego, 9500 Gilman Dr. 0225, La Jolla, CA 92093, United States
AU: Fialko, Y
EM: yfialko@ucsd.edu
AF: Institute of Geophysics and Planetary Physics, Scripps Institution of Oceanography, University of California San Diego, 9500 Gilman Dr. 0225, La Jolla, CA 92093, United States
AB: Elastic properties of rocks may vary substantially (generally, in 3-D) in the seismogenic zone, and rheologic behavior of rocks below the brittle-ductile transition may be highly non-linear. Such variations present a considerable challenge for the accurate modeling of the response of the lithosphere to the co-seismic excitation. We develop a methodology to compute the time-dependent response of the lithosphere after the occurrence of an earthquake in the case of an arbitrarily heterogeneous and anisotropic upper crust underlain by a visco-elastic substrate obeying the power-law rheology. The time evolution of the deformation is approximated by a finite difference scheme involving purely elastic solutions for equivalent body forces that account for variations in the effective viscosity. It follows, for instance, that Green's functions such as the Okada's solution for a homogeneous half-space can be used to model the time-dependent deformation of a visco-elastic body with an arbitrarily varying nonlinear viscosity structure. We treat the case of an anti-plane screw dislocation for which we derive a new iterative spectral scheme based on Fredholm integrals. The static two-dimensional numerical solution is benchmarked with several analytical or semi-analytical formulations in the cases of full relaxation of a horizontal viscous substrate, and anisotropic or elastic heterogeneities across the fault. The time dependent deformation in the case of linear visco-elasticity favorably compares to the propagator matrix semi-analytical solution. We apply the Fredholm solver to compute the surface deformation following the healing of a damage zone in the vicinity of an earthquake rupture and assess a potential bias in slip inversions that results from the neglect of a fault damage zone. Finally, we show that the same methodology can be applied in three dimensions.
DE: 1240 Satellite geodesy: results (6929, 7215, 7230, 7240)
DE: 1241 Satellite geodesy: technical issues (6994, 7969)
DE: 1295 Integrations of techniques
DE: 1299 General or miscellaneous (1709)
SC: Geodesy [G]
MN: 2007 Joint Assembly