Reactivation of Fault Zones due to Thermo-Poroelastic Stress Changes

This work investigates numerically by means of the Finite Element Method (FEM) the influence of a) homogeneous poroelastic medium, b) a heterogeneous poroelastic medium containing small-sized defects, and c) a hydraulic fracture within a poroelastic medium on the stability of a fault system during simultaneous depletion and injection.

Since the mechanism of fault slip are a matter of research, this modelling campaign aims at investigating the size of a possible reactivated area on the fault system. The size of the reactivation is related to Amonton’s law that governs fault reactivation as soon as the ratio of the shear (⊤) to normal (σn) stress acting on a fault exceeds the friction coefficient (µ) of the fault (see for example Moeck and Backers 2011 ). The size of the reactivated area can then be related to moment magnitudes through empirical correlation (e.g., Wells and Coppersmith 1994 ). This approach assures a conservative measure of possible earthquake magnitudes by employing numerical methods linked with statistics.