Studies of an opencast coalmine in western Germany indicate that opencast mining has triggered extensive ground subsidence in the surrounding area and reactivated dormant geological faults. Researchers from the GFZ Helmholtz Centre for Geosciences in Potsdam, Germany, examined satellite data and geological field measurements from the Rhenish coalfields, located between Aachen and Cologne.
Their findings, published in Engineering Geology, show that the significant volumes of groundwater extracted for safe mine operations led to a lowered water table. This resulted in widespread subsidence extending up to 20km from the mine's edge. The most affected locations were not random, but instead clustered and intensified along existing geological faults, which were re-awakened by the mining-induced subsidence.
The impact of this subsidence is evident in cracks found in local buildings and roads, including a school that has reportedly shifted by half a metre. As mining continues in the area, subsidence is expected to persist for decades. The researchers suggest that combining satellite monitoring with geological data could produce regional subsidence hazard maps, aiding communities in planning and developing more resilient infrastructure.