The first application of AMR approach to non-mining induced seismicity: A case study from water injection boreholes and water reservoirs

Critical-point-like models can be used for the examination of seismic activity and attempts to forecast seismic events. One such model is the Accelerated Moment Release (AMR), based on cumulative seismic moment. While this method is commonly used in studying natural seismicity, it has yet to be thoroughly tested for areas with induced seismicity, where it may yield better results. This paper aimed to examine the potential application of AMR for three datasets related to hydraulic injections (Soultz data collected in: 2000, 2003, 2004) and three artificial water reservoirs (Czorsztyn, Monteynard, Val D'Agri). We determined the types of seismic energy release for each area. Furthermore, we compared them with injection rates and wellhead pressures in the research boreholes for the Soultz episodes and water level fluctuations in the reservoirs. The final results demonstrated increased seismic activity related to water and brine injection into the rock mass, manifested in accelerated-like AMR curves. However, no correlation was observed between water levels in artificial reservoirs and the rate of seismic energy release. Additionally, we analysed the distribution of seismic events focusing on participating in the main earthquake nucleation process, and the observations were related to geological-tectonic conditions. Finally, we created a model of the relationship between the rate of M₀ release and wellhead pressure over a one-day interval. Comparing it with the AMR models enabled a better understanding of how the rock mass releases seismic energy. The final conclusion of the research confirms the usefulness of using AMR for seismicity caused by injections.