The importance of earthquake interactions for injection-induced seismicity: Retrospective modeling of the Basel Enhanced Geothermal System

We explore the role of earthquake interactions during an injection-induced seismic sequence. We propose a model, which considers both a transient pressure and static stress redistribution due to event interactions as triggering mechanisms. By calibrating the model against observations at the Enhanced Geothermal System of Basel, Switzerland, we are able to reproduce the time behavior of the seismicity rate. We observe that considering earthquake interactions in the modeling leads to a larger number of expected seismic events (24% more) if compared to a pressure-induced seismicity only. The increase of the number of events is particularly evident after the end of the injection. We conclude that implementing a model for estimating the static stress changes due to mutual event interactions increases significantly the understanding of the process and the behavior of induced seismicity.