Correlation of Permeability Evolution With Frequency‐Magnitude Distributions for Injection‐Induced Seismicity Under Varying Initial Stress States

Abstract The initial stress state on faults exerts fundamental control on both the magnitude of induced seismicity and the dynamic response of permeability evolution. We report fluid injection experiments with permeability measurement on smooth and rough faults under varied initial stress states. The proximity of the initial stress state to instability governs the intensity and failure mode of their seismic response during reactivation. High‐resolution spatiotemporal mapping of acoustic emission (AE) hypocenters revealed the progressive localization and evolution of rupture processes. We show that initial stress state drives a gradual transformation in failure mechanism from progressive failure to laboratory‐scale dynamic instability. We show that b ‐value increases/decreases as permeability increment decreases/increases. Based on these findings, we construct a permeability model based on the Gutenberg–Richter law and maximum likelihood estimation, to quantitatively describe the dependence between the permeability and the b ‐value for micro‐earthquakes. We apply this correlation to invert for the evolution of permeability with observed seismicity and to illuminate the mechanisms of the coupled seismic‐hydrological behavior accompanying injection‐induced seismicity.