Incorporating anisotropic material properties into simulations of the earthquake cycle

Maricela Best Mckay, & Brittany A. Erickson

Published August 15, 2017, SCEC Contribution #7782, 2017 SCEC Annual Meeting Poster #176

We are developing a methodology for incorporating and studying the effects of anisotropy when simulating the full earthquake cycle. The method is developed for a vertical strike-slip fault in two-dimensions, with antiplane motion. Inertial terms are dropped from the elastic anisotropic wave equation to obtain a steady state problem. This resulting equilibrium equation is discretized with a finite difference method. A nonlinear rate-and-state friction law is enforced at the fault. Time stepping is adaptive to capture highly varying time scales, and as such is able to produce self-consistent initial conditions.

We are developing the method to create anisotropic layers in the material around a fault, particularly in layering strong anisotropy close to the fault with a transition to isotropy off fault. We are interested in whether anisotropy can be used to explain observed surface deformation or perhaps reconcile discrepancies in estimates of fault locking depth. Towards these goals, in this initial study we vary the degree of anisotropy relative to an isotropic reference case and look at the effect this has on the recurrence interval. We also study how this impacts surface displacement and velocities. Initial results suggest that increasing the degree of anisotropy extends the recurrence interval, relative to the isotropic reference, leading to larger amounts of slip per rupture.

Key Words
earthquake cycle, anisotropy, computational modeling

Citation
Best Mckay, M., & Erickson, B. A. (2017, 08). Incorporating anisotropic material properties into simulations of the earthquake cycle . Poster Presentation at 2017 SCEC Annual Meeting.

Related Projects & Working Groups
Fault and Rupture Mechanics (FARM)