Slip tendency of faults and pore pressure evolution in the “Wasserprovinz Haus Aden” – Ruhr area

Mining has required pumping in a wide area of the Ruhr region. In part, this leads to subsidence of more than 10 m. The matrix permeability of the rocks in the underground is rather low. Therefore, fracture fluid flows are assumed to contribute significantly to the groundwater flow. Our study area is the area between Dortmund and Hamm. It includes a number of major faults (in general, one set of faults is NE-SW oriented thrust faults, the other set of faults can be described as NW-SE mainly normal faults) that potentially subdivide the area into compartments with different hydraulic behavior. The dilation tendency is important for migration pathways. We present the dilation tendency based on the contemporary tectonic stress field. Furthermore, the slip tendency is presented for different water levels in comparison to the observed seismicity. The slip tendency shows how changes in effective stress (and thus changes in pore pressure and water level) modify the tendency of a fault to slip (see also other FLOODRisk contributions). In addition, we use a generic numerical model within the compartment "Haus Aden Shaft 2" to simulate the change in reactivation potential of the bounding faults for water level changes due to activities in a nearby "generic" mine.