Induced seismicity in the Changning salt mining zone, China, could be driven by the pore-pressure diffusion

Abstract

The detailed mechanism of induced seismicity associated with salt mining remains elusive. Herein we compile the geological, industrial data, and seismic records within the Changning salt mining zone, China, and simulate the changes in crustal stresses and seismicity rate based on the physics-based poroelastic model and rate-and-state earthquake nucleation model. Our models reveal that the regional induced seismicity, including the 2019 Ms. 6.0 Changning earthquake, which might be one of the largest induced events by industrial exploitation ever recorded, is mainly driven by the pore-pressure diffusion, but suppressed by pumping operations. Motivated by the injection-extraction scenario, we further investigate the effect of wells' locations on stress changes, which could be potentially used for well site optimization to minimize the poroelastic response. A simple mode of setting extraction wells around the injection well could reduce the seismicity rate by a factor of two. These results collectively advance the understanding of physics and hazards associated with injection-extraction-induced earthquakes, and help design or guide industrial well deployment.