Inferring Hydraulic Pressure Changes from Induced Seismicity Observations: Three Showcases from Geothermal Reservoirs

Figure 1

(a) Time-encoded relative hypocentre locations in perspective view with best-fitting plane determined by linear regression. Trajectory of St. Gallen GT-1 is indicated by a black line. Red shaded area denotes presumably falsely located event cluster (see Induced Seismicity above). Coordinates are given with respect to the top of GT-1 (47.415200°N 9.328801°E). (b) The structural model of St. Gallen displaying the well path of the geothermal well (black line), top Palaeozoic (violet) and faults (as interpreted from the 3D seismic survey [9]) as well as hypocentres of the induced seismicity (from the Swiss Seismological Service (SED), red dots). View from northeast. (c) Earthquake source-centred, stereographic projection (lower hemisphere) of -wave polarity data for all 347 events. The beachball indicates the compound fault plane solution and is approximately similar to the largest event ( 3.5) determined by Diehl et al. [16] with strike/dip/rake-values of 124°/72°/174°, respectively.

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