Study of the relationship of tidal changes in gravity with the time of mining tremors in the area of the mining longwall in a coal mine – case study in USCB, Poland

Deep mining of coal deposits in Upper Silesia Coal Basin in Poland over several hundred years has led to disturbances in the natural state of equilibrium. As a result of changes in stress distribution, mass distribution (changes in gravity forces) and deformation of the rock mass, seismic tremors with energy reaching up to 10Eþ09J are generated. In this paper, the time of mining tremors occurrence is linked with changes in the gravitational load of the rock mass caused by lithosphere tides, which are considered to be one of the factors leading to occurrence of natural seismic tremors. The analysis used data on tremors in the immediate vicinity of the longwall VIII E-E1 in seam 703/1 located in the northeastern part of the Rydułtowy I mining area, whose mining user is ROW Mine Mining Plant Rydułtowy. These data was compared with data recorded by gPhoneX-155 tidal gravimeter which measures changes in gravity acceleration. Gravimeter gPhoneX-155 is installed on the stand in the Industrial Cultural Center of Ignacy Mine in Rybnik-Niewiadom, within a few hundred meters of the longwall VIII E-E1. The results obtained in the paper indicate a relationship between changes in gravitational load known as lithosphere tides and the time of longwall mining-induced tremors. At the same time, no periodicity was found in the tremors catalog allowing to link them directly to lithosphere