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.

Mining operations cause negative changes in the environment. Therefore, such areas require constant monitoring, which can benefit from remote sensing data. In this article, research was carried out on the environmental impact of underground hard coal mining in the Bogdanka mine, located in the southeastern Poland. For this purpose, spectral indexes, satellite radar interferometry, Geographic Information System (GIS) tools and machine learning algorithms were utilized. Based on optical, radar, geological, hydrological and meteorological data, a spatial model was developed to determine the statistical significance of the selected factors’ individual impact on the occurrence of wetlands. Obtained results show that Normalized Difference Vegetation Index (NDVI) change, terrain height, groundwater level and terrain displacement had a considerable influence on the occurrence of wetlands in the research area. Moreover, the machine learning model developed using the Random Forest algorithm allowed for an efficient determination of potential flooding zones based on a set of spatial variables, correctly detecting 76% area of wetlands. Finally, the GWR (Geographically Weighted Regression (GWR) modelling enabled identification of local anomalies of selected factors’ influence on the occurrence of wetlands, which in turn helped to understand the causes of wetland formation.

Abstract. Induced seismicity by human operations such as mining is usually unpredictable due to the sudden and unexpected character of this phenomenon. The effects of seismic events on the surface, i.e. ground deformation had been difficult to measure with traditional geodetic methods, which are based on discrete point observations and are carried out at temporal intervals and in fixed locations (e.g. levelling lines). Development of radar remote sensing (InSAR) techniques and proliferation of open satellite radar data such as Sentinel- 1 mission provides means that can now be successfully applied to investigate areas and ground movements affected by seismicity induced by mining. In this paper four induced seismic events with magnitudes from 4.5 to 4.8 that occurred between 16 December 2016 and 15 September 2018 in the Rudna underground copper mine area in SW Poland have been investigated with differential satellite radar interferometry (DInSAR). Based on the results of processing of 37 pairs of Sentinel-1 data captured before and after each of these events, deformation areas have been spatially localised and vertical displacement and extent of deformation have been calculated. The mean maximum vertical displacements range from −70 mm for the 4.5 magnitude tremor to −94 mm for the 4.8 magnitude event. Whereas, mean extent ranges from 1.5 km to 1.9 km in the W-E direction and from 1.8 km to 2.1 km in the N-S direction. A linear relation between magnitude of induced tremor and increase in vertical displacement and extent of the ground deformation has been established. Moreover, the results of this study indicate that InSAR is adequately accurate technique to analyse ground displacements caused by mining induced tremors and provides continuous field data on the geometry of the resulting deformation areas.

The paper describes the main development trends of methods for determining surface displacements (deformations) resulting from the phenomenon of induced seismicity by mining operations. Due to the unpredictable and sudden nature of induced seismicity, it is difficult to make measurements of displacements by traditional geodetic methods. In order to determine the methods used to determine surface displacements, an extensive review of current scientific literature was carried out. The scope of the analysis included methods for measuring deformations in mining areas during and after mining. Based on the review of over a dozen research papers, geodetic and remote sensing methods are presented, which are used to determine surface displacements at a lower or higher intensity. The analysis of the methods concerned in particular: leveling, Global Navigation Satellite System (GNSS), satellite radar interferometry, airborne LiDAR and aerial photogrammetry. As a result of the analysis, it was found that the satellite radar interferometry is presently the predominant displacement detection technique.

Induced seismicity is one of the negative phenomena caused by anthropogenic activities that include mining of minerals. This phenomenon manifests itself as sudden and unpredictable shocks of rock mass, which can cause surface deformation and damage to ground infrastructure. Until the advent of satellite radar interferometry that enables analysis of historical events, the characteristics of these unexpected surface deformations were difficult to assess. The main aim of the research was the spatial analysis of the geometry of surface displacements caused by eight induced tremors in the Rudna copper mine (SW Poland) and the dependence of deformation characteristics (vertical displacements, extent) on the induced shock energy. For this purpose, Sentinel-1 satellite imagery, the differential radar satellite interferometry (DInSAR) method and geographic information systems (GIS) based spatial statistics were used. Vertical displacements were mapped on the basis of 37 calculated interferograms. Spatial statistics on the pixel-to-pixel level were performed in the GIS Map Algebra environment. In the result, descriptive and spatial statistics characterizing deformations caused by individual shocks were calculated. The average values of vertical displacements ranged from −44 to −119 mm. Strong, statistical correlation between the extent, maximum vertical displacement, and energy values was determined. In addition, geometries of the formed deformation areas were analyzed and presented graphically. The results obtained in this research constitute development of a knowledge base on surface displacements caused by induced tremors in underground copper mining.

<p>Human activity, in particular mining operations are the cause of terrain changes, manifesting on the terrain surface in form of subsidence troughs. Presence of subsidence troughs in inhabited areas may be the cause of significant damage to the structure of buildings, roads and other man-made objects. Both vertical and horizontal terrain displacements occuring inside the trough could be the reason for deterioration of mentioned objects. Hence the need to measure the impact of mining activity on the terrain surface. Current measurement techniques used to determine terrain displacements include GNSS, leveling and SAR interferometry. One of the limitations of interferometric measurements is that displacement values are in the satellites Line-of-Sight (LOS). The fact that the values are only quasi-vertical causes an ambiguity when it comes to determining whether the dominating component of displacement is vertical or horizontal. Projecting the one-dimentional LOS motion to the vertical direction using only the incidence angle can cause significant errors if the magnitude of horizontal motion is considerable. However, the specific 3-dimentional diplacement components can be derived using different acquisition geometries. In order to determine all 3 components (horizontal North-South, East-West and vertical Up-Down), 3 different viewing geometries have to be used so that the equation can be solved. However, the North-South component can be neglected due to low sensitivity of Sentinel-1 SAR instrument to displacement in that direction. Following that, 2 different viewing geometries can be sufficient to derive the East-West and vertical components.</p><p>The aim of the study is to determine how mining activity affects the surface in terms of both horizontal and vertical displacements. Radar pairs from Sentinel-1 ascending and descending orbit were used to create interferograms, based on which LOS displacement fields were calculated. The North-South and East-West components of displacement were solved through the inversion of the linear equation system based on incidence angles, headings and LOS displacements of ascending and descending radar pairs.</p><p>The horizontal and vertical components were determined for differential interferograms obtained with the DInSAR method using Sentinel-1 imagery, as well as for time series displacement fields derived from the Small Baseline Subset (SBAS) approach over selected mining areas in Poland. The results have shown that data from ascending and descending orbits can be successfully merged in order to obtain both the horizontal (East-West) and vertical components of displacement over mining areas. Obtained values of displacements from both DInSAR and SBAS have confirmed that areas affected by mining activity are under the influence of changes in height, as well as shifts in horizontal direction. Thus it is important to take into consideration multiple acquisition geometries when it comes to studying deformations over mining areas.</p>

The North Anatolian Fault situated in Turkey is one of the longest and most active tectonic faults in the world. The paper presents an analysis of tectonic activity in its area based on the method of Small Baseline Synthetic Aperture Radar Interferometry. For this purpose 73 satellite SAR images and specialized software GMT5SAR were used with implement the SBAS algorithm. In addition, the most important aspects of data processing and their final products were presented, which determined the surface displacements occurring in the surveyed area from 1 January 2014 to 1 March 2017. The displacements of the SBAS surface area ranged from -10 cm to +10 cm. Based on the obtained results and their analysis, the author also assessed the suitability of SBInSAR technology for areas of land displacement.

<p>InSAR become more and more popular technique for monitoring mining excavation influence on terrain surface. Nowadays, research on the accuracy of InSAR measurements focuses on impact of external factors on SAR signal and process of phase unwrapping. SAR interferogram include information about a displacement in wrapped form – modulo 2π. Demodulation of phase (phase unwrapping) enable to restore true phase values and then correct interpretation of acquired information. Poor quality of data (low coherency) and large surface deformations cause phase discontinuities that make unwrapping process difficult and may generate incorrect results. Underground mining excavation, especially shallow or inducing seismic activity, may lead to large and abrupt surface displacements. Majority of unwrapping algorithms assume that the difference between any two adjacent samples in the continuous phase signal should not exceed a value of π. However, this assumption may be incorrect for large and abrupt surface displacements and lead to errors in the phase unwrapping and then to determination of incorrect values of surface displacements. Studies were conducted for areas where both natural and mining-induced seismic shocks occurred. DInSAR technique was used to create interferograms. Phase unwrapping processes were performed using Statistical-Cost, Network-Flow Algorithm for Phase Unwrapping (SNAPHU) for conventional parameters, modified discontinuity parameters and taking into account theoretical shock models (Mogi model). Research allowed to determine the impact of abrupt, large displacements on the phase unwrapping process.</p>