Gravity field changes during deep exploitation of the coal longwall and their relation to stress distribution and seismic activity

Mining operations cause volumetric deformations within the rock mass and changes in its density, to which gravimetric method is sensitive. These are particularly well seen periodic measurements of local gravity field. The paper analyses relationship between movement a longwall coal seam change distribution field time space observed on ground surface. Relative were carried out six series 2018 2020; before start extraction, with progress after cessation mining. Collected data allowed differential maps be plotted. Differential anomalies subsequent measurement series, reference one then analysed. temporal variations suggest density medium overburden, stress state caused by passage front. An attempt was made relate variability stresses overburden intensity seismic tremors energy > 10E4 J accompanying exploitation.