Abstract
Numerical simulations of Sequences of Earthquakes and Aseismic Slip
(SEAS) have rapidly progressed to address fundamental problems in fault
mechanics and provide self-consistent, physics-based frameworks to
interpret and predict geophysical observations across spatial and
temporal scales. To advance SEAS simulations with rigor and
reproducibility, we pursue community efforts to verify numerical codes
in an expanding suite of benchmarks. Here we present code comparison
results from a new set of benchmark problems BP6-QD-A/S/C that consider
a single aseismic slip transient induced by changes in pore fluid
pressure consistent with fluid injection and diffusion in fault models
with different treatments of fault friction. Ten modeling groups
participated in problems BP6-QD-A and BP6-QD-S considering
rate-and-state fault models using the aging and slip law formulations
for frictional state evolution, respectively, allowing us to explore
these ingredients across multiple codes and better understand how
various computational factors affect the simulated evolution of pore
pressure and aseismic slip. Comparisons of problems using the aging
versus slip law illustrate how models of aseismic slip can differ in the
timing and amount of slip achieved with different treatments of fault
friction given the same perturbations in pore fluid pressure. We achieve
excellent quantitative agreement across participating codes, with
further agreement being found by ensuring sufficiently fine
time-stepping and consistent treatment of remote boundary conditions.
Our benchmark efforts offer a community-based example to reveal
sensitivities of numerical modeling results, which is essential for
advancing multi-physics SEAS models to better understand and construct
reliable predictive models of fault dynamics.