A forward model for earthquake generation on interacting faults including tectonics, fluids, and stress transfer

We present a forward model of interacting faults for systems of any geometr y. The model generalizes that of Miller et al. [1996,1999] to a fully three -dimensional model where faults of any strike and geometry interact through an elastic matrix using the general solutions of Okada [1992]. The model i ncludes large-scale plate motion loading and increasing pore pressures from a source term, undrained poroelastic effects, large coseismic hydraulic pr operty changes, and porosity creation through dilatant slip. To illustrate the basic behavior and utility of the model, results are presented of the l ong-term evolution (approximate to 9300 years) for a generic case of a blin d, dipping fault and a subvertical strike-slip fault in a transpressional e nvironment. We show the stress state evolution along both faults, seismicit y time lines, quasi-static rupture propagation including rake angle changes , local and regional stress buildup and rotations, static and dynamic fault interactions, and Delta CFS (changes in Coulomb Failure Stress) within the fault system. Large compartments of varying overpressure result on both fa ults from coseismic pore pressure changes and contribute to the complexity of the stress state. For the considered case, we find that the poroelastic effects on the receiver fault are about twice the change in the shear stres s, providing a significant contribution to the Delta CFS. Regional stress r otations in response to the model seismicity indicate that further model de velopments must include dynamic generation of new faults in response to the evolving tectonic regime.