Mining-triggered seismicity governed by a fold hinge zone: The Upper Silesian Coal Basin, Poland

• Published in: Engineering geology 2020-09, Vol.274, p.105728, Article 105728
• Main Authors: Mendecki, Maciej Jan, Szczygieł, Jacek, Lizurek, Grzegorz, Teper, Lesław
• Format: Article
• Language: English
• Subjects: Focal mechanisms; IS-EPOS Platform; Stress inversion; Triggered seismicity; Upper Silesian Coal Basin
• ISSN: 0013-7952; 1872-6917
• DOI: 10.1016/j.enggeo.2020.105728

Mining tremor mechanisms and principal stress directions were analysed in order to compare characteristics of seismic events and stress regimes with tectonic settings in the Bytom Syncline, located in the Upper Silesian Coal Basin. The results of seismic moment tensor inversion calculated for 41 events with magnitudes > M2.0 were used to trace changes in types of mechanism (normal, strike-slip, reverse) with the progress of mining from Panel 3, coal seam 503, Bobrek Mine. The data was sourced from the IS-EPOS Platform, an open data infrastructure for the study of anthropogenic hazards linked to georesource exploitation. The foci were located below the seam and followed a longwall excavation. The computed mechanisms and distribution of spatial-temporal events enabled three clusters representing three different stages of stress regimes to be distinguished. The calculated principal stress axes indicated the main stress directions present in the studied area, enabling a local model of the derivative pattern of neotectonic deformation to be described. The regime changed from horizontal extension in the syncline limb (first cluster) to transpression (second cluster) to dominating compression in the hinge (third cluster), resulting in reverse fault production. Finally, the results revealed the causes of seismicity in the studied area and showed that the studied events had been mostly triggered. •A seismic moment tensor was used to trace changes in mechanism with the progress of exploitation.•The stress path from the coal seam to its hinge via syncline limb was deciphered.•In the syncline hinge, compression produced reverse mechanisms activated by mining.•The study presents the novel teamwork features of the IS-EPOS Platform.