3D geomechanical modelling of induced seismicity: finite source wavefield simulation to moment tensor inversion

Abstract

Geomechanical modelling is generally used to simulate the nucleation of induce d earthquakes in, for instance the Groningen gas field. We apply quasi static simulation to investigate the stress changes from gas production. When a fault reaches a critical state, dynamic simulation provides information on the dynamic rupture during ea rthqu ake nucleation and the resulting wavefield . With the use of geomechanical modelling, it is possible to investigate the effects of the model parameters, e.g., depletion pattern and friction parameters. I n the modelling, the dynamic rupture at a finite fault is simulated both in space and time. The generated seismic wavefield from such a finite source is considered to be more realistic than the resulting wavefield from a point source. T he latter is often assumed in previous studies on the inversion of in duced earthquake data in the Groningen area. To link the wavefield generated by a geomechanically simulated finite source to the field seismic data for an earlier earthquake, we apply the same full moment tensor inversion to the waveform of a finite and of a point source . The inverted moment tensor from the field seismic observation provides a constraint to our geomechanical simulation. This allows us to perform a more realistic simulation of an induced earthquake.