A GPS study of land subsidence in the Petrosani (Romania) coal mining area

The Petrosani basin is a large and important coal mining zone in the South Carpathians area of Romania. In recent times, most mines have been closed, but an extensive and dense network of galleries still exists. Most of the abandoned ones were not filled in with mine tailings. There is strong concern and evidence that the old galleries are collapsing and/or filling up with water, leading to significant surface deformation and potential hazards, especially for the local communities. We present an analysis of GPS data from nineteen (19) campaign sites spanning the period 2007-2012. Our results are quite consistent and show significant horizontal and vertical surface motions. The horizontal velocities range from 0 to 260 mm/year (mainly in WSW direction), while the vertical velocities range from +39 (uplift) to -263 (subsidence) mm/year. The largest motions appear to be associated with the central (oldest) sector of the mining area. The pattern of vertical motions suggests that the peripheral area is affected by slight uplift in response to the subsidence of the central sector.