Seismicity-Permeability Relationships Through Fluid Injection Fault Reactivation Laboratory Experiments

Included are results from shear reactivation experiments on laboratory faults pre-loaded close to failure and reactivated by the injection of fluid into the fault. The sample comprises a single-inclined-fracture (SIF) transecting a cylindrical sample of Westerly and granitoid granite.Experiments were conducted with the zero load point displacement (ZD) boundary condition or constant shear stress condition. Upstream pore pressures are incremented (0.5 MPa per 3-5-minute step) to reactivate the fault while holding downstream pressure constant or holding constant pressure differences between upstream and downstream. Fluid (DI water) flows along the fault with the upstream pressure stepwise incremented to trigger fault reactivation (MEQs) and establish a new steady state flow regime where the updated permeability is measured. Fault shear displacement was measured together with acoustic emissions (AE) from the calibrated PZT sensors located at the sample end. Passive AE signals were recorded downstream in this study.