No abstract

Physical processes occurring in the focus of tremor can be identified by solving a focal mechanism via the seismic moment tensor inversion method. In this article the estimation of focal mechanisms of strong mining tremors (according to Polish law tremors of energy higher or equal 1·105 J), which occurred during longwall mining of coal seam no. 507 in one of the hard coal mines in the Polish part of Upper Silesian Coal Basin was performed. Totally 7 strong mining tremors with the local magnitude from 1.84 to 2.52 were analysed. The most probable geomechanical processes in the foci of these tremors have been reconstructed. An attempt to determine the correlation between the edges of overlying seams no. 502, 504 or 506 and strong mining tremors occurrence has been made. The strike of determined nodal planes is in accordance with the azimuth of mentioned edges. The difference between them (absolute value) varies from 0.3° to 34.1° (on average approximately 19°).

Measurements of vibrations induced by blasting works in mining plants are one of the possibilities of controlling the operations of open-pit facilities by supervisory authorities. As part of these works, impact of vibrations surveys on buildings within the range of harmful impacts zone of seismic vibrations are carried out to guarantee the safety and protection of their residents. The article presents the possibilities of using digital apparatus for recording and processing vibrations induced by blasting works used during supervisory activities in open-pit mines from 2015 to 2017. Recording and size of events depends on mining conditions and geological structure of the exploited deposit and is closely related to detonation of explosive. The use of dynamic impacts SWD scale against the backdrop of the current norm no PN-B-02170:2016-12 are discussed and examples of assessments of harmfulness of vibrations transmitted by the ground to buildings are presented. It was found that bigger and bigger number of monitoring measurements is performed every year, causes reducing the number of complaints and incriminating letters on mine companies receive in effects of impact of vibrations.