FloodRisk: Earthquakes, uplift, and long-term liabilities – risks minimisation during mine flooding

After the cessation of coal mining in Germany, mine drainage in the abandoned mines is subject to changes. Subsequent to the cessation of deep mine drainage, mine waters are ascending above a higher, regionally predefined level flooding former extraction areas. Mine water ascent is associated with stress changes in the subsurface rocks, which may induce local ground movements and activation of mining-related and natural fault zones. This may result in seismic events, which may be sensed on the surface as tremors.

Within the scope of this project, ground movements and seismic events will be quantified and discussed for selected localities in the Saar and Ruhr area. In particular, this project will improve the understanding how surface deformation and stress changes in the geological subsurface due to mine water ascent are geomechanically coupled. For this purpose, a multidisciplinary approach consisting of geodetic, geophysical, geomechanical, and geological methods will be applied. Furthermore, this project draws on a variety of geological and geodetic data acquired in the course of centuries-long mining activity. The aim is an advanced understanding of the processes that result from mine flooding in order to enable an estimation on seismicity in critical areas.

Geodetic methods will be used to detect ground motions in the Saar and Ruhr area. Based on geophysical measurements, induced seismicity will be monitored in selected areas. By means of drill cores and representative rock outcrops, rock parameters will be determined, geological structures characterised, and three-dimensional subsurface models created. Moreover, this project aims to develop economic sensors to detect gas leakage. The results of these studies will be the basis for an interdisciplinary, conceptual model on flood-induced ground movements and seismicity. This enables the deduction of operations for future mine flooding and the establishment of an optimised reservoir management.