The issue of monitoring surface motions in post-mining areas in Europe is important due to the fact that a significant number of post-mining areas lie in highly-urbanized and densely-populated regions. Examples can be found in: Belgium, the Czech Republic, France, Germany, the Netherlands, Spain, the United Kingdom, as well as the subject of this study, the Polish Walbrzych Hard Coal Basin. Studies of abandoned coal fields show that surface deformations in post-mining areas occur even several dozen years after the end of underground coal extraction, posing a threat to new development of these areas. In the case of the Walbrzych area, fragmentary, geodetic measurements indicate activity of the surface in the post-mining period (from 1995 onward). In this work, we aimed at determining the evolution of surface deformations in time during the first 15 years after the end of mining, i.e., the 1995–2010 period using ERS 1/2 and Envisat satellite radar data. Satellite radar data from European Space Agency missions are the only source of information on historical surface movements and provide spatial coverage of the entirety of the coal fields. In addition, we attempted to analyze the relationship of the ground deformations with hydrogeological changes and geological and mining data. Three distinct stages of ground movements were identified in the study. The ground motions (LOS (Line Of Sight)) determined with the PSInSAR (Persistent Scatterer Interferometry) method indicate uplift of the surface of up to +8 mm/a in the first period (until 2002). The extent and rate of this motion was congruent with the process of underground water table restoration in separate water basins associated with three neighboring coal fields. In the second period, after the stabilization of the underground water table, the surface remained active, as indicated by local subsidence (up to −5 mm/a) and uplift (up to +5 mm/a) zones. We hypothesize that this surface activity is the result of ground reaction disturbed by long-term shallow and deep mining. The third stage is characterized by gradual stabilization and decreasing deformations of the surface. The results accentuate the complexity of ground motion processes in post-mining areas, the advantages of the satellite radar technique for historical studies, and provide information for authorities responsible for new development of such areas, e.g., regarding potential flood zones caused by restoration of groundwater table in subsided areas.

The study presents results of surface displacements calculated with the PSInSAR technique for the area of the former Wałbrzych Hard Coal Basin (WHCB) in SW Poland. Underground mining of hard coal took place there until the late 90'ties of the 20 th Century. In accordance with the present state of knowledge, secondary deformations are a common phenomenon on post-mining areas. The chosen monitoring technique has provided data and has allowed study surface movements in Wałbrzych in the post mining period, for which no other, conventional surveys were available. In the analysis radar images acquired by the ENVISAT satellite for the 458 track and for the 2002-2009 period have been used. The results of PSInSAR data processing indicate elevation of the surface within the boundaries of former mining areas, reaching up to +6 mm/yr and on average +4 mm/yr. We assume that the end of mine water drainage and restoration of Carboniferous ground water table is the main factor responsible for this process and observe delayed response of the rock mass.

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The article presents an attempt at using synthetic aperture radar interferometry to determine surface displacement in a region affected by a strong earthquake induced by underground mining operations. It was assumed that the satellite radar data obtained from the Sentinel 1A/B satellites may be used to monitor induced seismicity, i.e. mining tremors. Such seismic activity is observed at much shallower depths, and the surface area affected by such activity is much more limited than in the case of natural seismic events. Research was performed in a region located in the southwest part of Poland, where copper ore is extracted using underground methods. The geological structure of the selected area increases the likelihood of induced seismic events. Moreover, the area is one of the most seismically active regions in this part of Europe. The tremor analysed in this paper occurred on November 29, 2016, and had a magnitude of M w 4.2. Calculations showed that the seismic event resulted in the creation of a 2.7 km x 2.5 km subsidence basin. The paper demonstrates that it is possible to use data provided by the Sentinel 1A/B satellites to detect surface displacements caused by a mining tremor.