Beware of the Broken Faults!

Session: Numerical Modeling of Rupture Dynamics, Earthquake Ground Motion and Seismic Noise
Type: Oral
Date: 4/29/2020
Time: 03:30 PM
Room: 230 + 235
Description: 

Recent advancement in seismic imaging and data analysis techniques have enabled the discovery of an incredible level of complexity in faults geometry and stress variations in the crust. An enduring computational challenge is to incorporate these complexities to unravel their implications on earthquake processes at different scales. In this presentation, I will focus on some recent efforts from my group in developing a computational algorithm for modeling earthquake ruptures with high resolution fault zone physics. I will present a hybrid method that combines Finite element method (FEM) and Spectral boundary integral (SBI) equation through the consistent exchange of displacement and traction boundary conditions, thereby benefiting from the flexibility of FEM in handling problems with nonlinearities or small-scale heterogeneities and from the superior performance and accuracy of SBI. I will demonstrate the capability and computational efficiency of this hybrid scheme for resolving small scale fault zone complexities using a model of a fault zone with explicit representation of small scale secondary faults and branches enabling new insights into earthquake rupture dynamics that may not be realizable in homogenized isotropic plasticity or damage models. Specifically, I show that secondary faults may not only act as energy sinks but they could also be energy sources promoting transient accelerations of rupture propagation speed and slip rate on the main fault. I also show that these secondary features significantly affect the stress state on the main fault and contribute to the enhanced generation of high frequency radiation and may even lead to rupture transition to the supershear mode under conditions deemed unfavorable in the planar fault case. These results suggest that small scale geological complexities may play an important role in seismic hazard even if their contribution to the overall slip budget is not large.

Presenting Author: Ahmed Elbanna

Authors