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Constraining the Stability of a Rate-and-State Fault Subjected to Fluid Injection

Fluid injections are ubiquitous in the exploitation of geoenergy resources but can cause nearby faults to slip. This reactivation is often attributed to the reduced frictional resistance accompanying an increase in fault zone fluid pressure. Once a fault has been reactivated, however, it is still unclear what controls the stability and spatial extent of the ensuing slip. Here, we investigate these questions with a fully-dynamic model of a rate-and-state fault subjected to fluid injection. We first apply our model to a fluid-injection experiment on a well-instrumented natural fault and demonstrate how such field experiments can help constrain frictional parameters and hence fault stability. In particular, considering the fault response to a decrease in injection pressure allows us to discriminate between different frictional scenarios with indistinguishable slip signature at the injection site during pressurization but diverging spatial behavior and propensity to large run-away earthquakes with continued injection. Starting from this constrained parameter regime, we then explore how fluid injections and the associated pore pressure diffusion affect earthquake nucleation processes on a rate-and-state fault. Our findings indicate that avoiding injection near low-residual-friction faults and depressurizing upon slip acceleration could help prevent large-scale earthquakes.

Presenting Author: Stacy Larochelle

Student Presenter: Yes

Day: 4/19/2021

Time: 2:00 PM - 3:15 PM Pacific

Additional Authors