3D Finite element modeling of stress interaction: an application to Landers and Hector Mine fault systems

We model the coseismic and postseismic stress changes and the surface deformation caused by earthquake dislocations through a three-dimensional (3-D) finite element numerical procedure applied to the 1992 Landers and the 1999 Hector Mine earthquakes. Our goal is to investigate the stress interaction between these complex nonplanar fault systems. The modeling strategy proposed in this study allows the calculation of elastic deformation and Coulomb stress changes either by imposing the slip distribution as a boundary condition along assigned faults or by retrieving the slip pattern on preexisting faults imposing the regional stress field. We study how different initial stress conditions ( including the depth dependence of isotropic components of the regional stress), different values of Coulomb friction coefficient, and the 1-D rigidity layering can affect the slip pattern on assumed faults and the resulting Coulomb stress changes. We propose here an original approach to simultaneously model slip distribution, surface deformation, and stress perturbations consistently with the rheological parameters of the lithosphere and its state of stress