Towards a poroelastodynamics framework for induced earthquakes

Abstract

Earthquakes can be triggered after pore pressure perturbations activate critically stressed seismogenic faults, where the perturbations can originate from natural causes like earth tides, rainfall, snowfall or anthropogenic causes like wastewater disposal, CO$_2$ injection, oil production, or groundwater extraction. As the faults slip under the action of the induced stress field, seismic waves are spawned from the hypocenter location. The waves propagate through the domain with a velocity that evolves with the evolving pressure and stress fields. The effect of these waves on the surrounding rock and the seismic velocity recorded on the seismograph can be modeled accurately only by incorporating elastodynamics in the deformation model coupled with flow-induced pressure perturbations. Hitherto, most of the literature in the realm has been limited to elastostatics coupled with flow within a prescribed/kinematic or quasi-dynamic fault slip framework. In this work, we provide a framework for coupling of wave propagation with pore pressure perturbations using one-way coupled poroelastodynamics in the presence of faults in which the pore pressure is specified apriori as a spatiotemporal function.We present results from analysis of displacement and velocity fields in the domain and tractions and slip evolution on the fault. The rendition of two-way coupled poroelastodynamics in which the flow problem is also solved is proposed as future work.