Abstract: There is a growing interest in understanding how geologic faults respond to transient source of fluids, either as a natural process or induced by human activities. This issue has become a societal concern due to the increasing interest in geothermal energy, CO2 storage, or injection of fluids associated with hydraulic fracking. To this end, computational earth science often relies on modeling to understand complex physical systems which cannot be directly observed. In this seminar, I will present H-MECs (Hydro-Mechanical Earthquake Cycles), a newly-developed two-phase flow numerical framework — which couples solid rock deformation and pervasive fluid flow — to simulate how crustal stress and fluid pressure evolve during the earthquake cycle. This unified, continuum-based model, incorporates (in)elastic deformation, inertial wave-mediated effects, fully-coupled poroelastic response, and an adaptive time stepping to allow the correct resolution of both long- and short-time scales, ranging from years to milliseconds. I will present a set of different applications, from megathrust earthquakes to anthropogenic fluid injection experiments, and discuss how pore-fluid pressure evolution and the dynamic evolution of hydraulic properties on- and off-fault control sequences of seismic and aseismic slip.
Results show that the weakening phase is controlled by localized compaction of pores and dynamic self-pressurization of fluids inside the undrained fault zone, whereas the subsequent propagation of dynamic ruptures is driven by pore-pressure waves. These modeling results demonstrate that fault failure can occur due to poroelastic coupling on a finite-width shear zone, thus highlighting the importance of considering the realistic hydro-mechanical structure of faults to investigate fluid-driven seismic and aseismic slip.
You will find the complete schedule for Njord Seminar Series fall '22 here.
To get news, invitations to seminars and more from Njord, please go here to subscribe to our newsletter.