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

Sławomir Siwek

doi:10.46873/2300-3960.1325

Abstract

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 10E+09J 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 litosphere 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 north-eastern part of the Rydułtowy I mining area, whose mining user is PGG S.A. KWK ROW 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 Mine Ignacy 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 litosphere tides.

Highlights

U nderground hard coal mining with longwall systems in the Upper Silesian Coal Basin in Poland generates a system of forces in Carboniferous rocks that exceed their mechanical strength
Times of occurrence of induced seismic tremors were superimposed on obtained real changes of acceleration of gravity which are visible in raw gravity data obtained from recordings made with the gPhoneX-155 tidal gravimeter at the site in the Industrial Cultural Centre of the Ignacy Mine in Rybnik Niewiadom
Following the launch of the European Plate Observing System e Poland project in the Upper Silesian region, continuous measurements of changes in gravity acceleration via tidal gravimeters have become possible. These refers to changes in the short term, caused by nearby mining tremors or distant strong earthquakes, and in the long term, caused by the gravitational interaction of the celestial bodies of the solar system with the Earth, commonly referred to as tides

Summary

Introduction

U nderground hard coal mining with longwall systems in the Upper Silesian Coal Basin in Poland generates a system of forces in Carboniferous rocks that exceed their mechanical strength. One of the elements that act as a catalyst for the occurrence of a seismic tremor is considered to be the slow-periodic changes in the gravitational loading of the rock mass resulting from the interaction between the Earth and the surrounding celestial bodies. These interactions are commonly referred to as lithospheric tides. The aim of this paper is to verify whether it is possible to determine extent slow-variable tidal gravity loads are the direct catalyst for tremors induced by mining longwall exploitation. The existence of a periodicity in the sub-catalog of the most energetically strong tremors (Eþ05JeEþ06J) for periods corresponding to the main lithospheric tidal waves was investigated

Observations of tidal changes of gravity

Mining tremors in the area of longwall VIII E-E1

Data analysis

Conclusions

Findings

Funding body