Acoustic monitoring of laboratory induced fault reactivation

The risk of induced seismicity is increasing, due to the increasing human activities in the subsurface, such as gas extraction, geothermal energy production, or CO2 storage. To mitigate the seismic hazard and limit the risk, monitoring and forecasting are essential. We performed stress-driven and fluid-injection-driven fault reactivation on saw-cut faulted sandstone samples. Simultaneously to the fault reactivation, active acoustic transmission measurements were performed. The transmission data was analyzed using transmissivity, Coda Wave Interferometry and Decorrelation. They show clear changes in their signal before fault reactivation. This is attributed to the pre-slip, therefore these acoustic parameters are precursory signals to the imminent fault slip and can be used to forecast the upcoming seismicity. They provide a potential method for monitoring and forecasting to minimize the risk of natural and induced earthquakes.