Constraining Fault Friction and Stability With Fluid?Injection Field Experiments

While the notion that injecting fluids into subsurface can reactivate faults by reducing frictional resistance is well established, ensuing evolution of slip still poorly understood. What controls whether induced remains stable and confined to fluid-affected zone or accelerates a runaway earthquake? Are there observable indicators propensity earthquakes before they happen? Here, we investigate these questions modeling unique fluid-injection experiment on natural fault with laboratory-derived friction laws. We show range models diverging stability sustained injection reproduce measured during pressurization. Upon depressurization, however, most unstable scenario departs from observations, suggesting relatively stable. The could be further distinguished optimized depressurization tests spatially distributed monitoring. Our findings indicate avoiding near low-residual-friction depressurizing acceleration help prevent large-scale earthquakes.