Zoning of foci of seismic tremors in division G-23, KGHM Polska Miedź SA

Abstract

The rock mass disturbed by mining activities in a copper ore mine has a structure consisting of thick layers of predominantly high mechanical parameters. The layers, due to their strength properties and dimensions, have low deformability which influences a vast area in the form of increased stresses. This area is a part of a rock massif where dynamic destruction periodically occurs in particular fragments as the post-mining cavity expands. The size of such an identified fragment of the rock mass depends on the extent of goafs and the distance between them and mining operations as well as inhomogeneities and confinement in the rock massif. The specific structure of the overlying layers, especially their mechanical properties, determine, to a vast extent, the cracks of anthropogenic influence in the rock massif, which result in foci of seismic tremors often recorded far from the areas of conducted mining activities. A selection of seismic tremors for their spatial location, related to the conducted mining operations and the time of their occurrence, can be useful for forecasting areas which determine seismic hazards in the area of mining operations. The aspect of the analysis of seismic tremors recorded in Division G-23 may indicate the location of the areas of the rock mass which remains in a state of boundary energy balance until another portion of seismic energy is released ‘stabilizing’ the area containing this rock mass. The article presents results of the analysis of a set of tremors between 2013 and 2015, induced by mining activities in Division G-23, in order to forecast areas of seismic activity in the rock mass disturbed by mining operations.