A method to interpret induced seismicity clouds as a fracture network

Abstract

We use the three-point method for determining preferred directions or surfaces within a cloud of earthquakes and we extend this method by introducing weighting factors depending on inter-event distance and on event magnitude. Besides, a new method of statistical analysis of seismic clouds is developed to provide pseudo spatial probability of an event-driven fracture network. This method also applies distance and magnitude weighting, but additionally allows using focal mechanisms. Both methods are first tested and validated on synthetic data, and then applied to the seismicity induced in 2000 during the hydraulic stimulation of the well GPK2 of the Soultz-sous-Forêts geothermal site. The results obtained at Soultz are comparable to results from previous works.