Mechanical and Civil Engineering Seminar
Earthquake sequence simulations with fault zone fluid flow, pore pressure evolution, and viscoelasticity
Mechanical and Civil Engineering Seminar Series
Abstract: Earthquakes and aseismic slip are typically modeled by coupling elasticity and fault friction, but here we describe the rich set of behaviors that arise when accounting for additional processes. We account for fault zone fluid flow and permeability evolution from healing and sealing processes in the hundreds of years between earthquakes and cracking during earthquakes. Even with steady fluid input into the system, this leads to fault valving, the cyclic build-up and release of fluid overpressure (and consequent changes in fault strength), which influence earthquake nucleation and rupture propagation. We also show how fluids ascending from the base of faults can drive aseismic slip transients. Additionally, we explore the transition from localized frictional sliding in the upper crust to distributed viscous flow in the lower crust, examining the role of shear heating and changes in effective viscosity and their influence on earthquake behavior. Accounting for these additional processes brings earthquake simulations much closer to reality, allowing greater consistency with experimental and geologic constraints on fault zone structure and dynamics.
Bio: Eric M. Dunham is an Associate Professor in the Department of Geophysics at Stanford University and an affiliated faculty member with Stanford's Institute for Computational and Mathematical Engineering. His research explores the physics of natural hazards like earthquakes, volcanoes, and tsunamis; and more generally, computational physics-based modeling of hazards and wave propagation in solids and fluids. He received his PhD in Physics from the University of California, Santa Barbara, in 2005, with support of a National Defense Science and Engineering Graduate Fellowship, before moving to Harvard University as a Reginald A. Daly postdoctoral fellow and later as a Lecturer on Applied Math. He is an Alfred P. Sloan Fellow in Physics and a recipient of the National Science Foundation CAREER award and the Stanford School of Earth Sciences Excellence in Teaching Award. He teaches classes at Stanford on earthquake processes, wave propagation in solids and fluids, and scientific computing.
NOTE: At this time, in-person Mechanical and Civil Engineering Lectures are open to all Caltech students/staff/faculty/visitors with a valid Caltech ID. Outside community members are welcome to join our online webinar.
Zoom link: https://caltech.zoom.us/j/81450495702?pwd=VTNKbDM2Tno1ZlNjMDY2V1Q0U3NWdz09