ABSTRACT
As a consequence of geomechanical and geotechnical conditions, as well as anthropogenic activities, in the mines of the Ostrava-Karviná coal basin (Czech Republic), rockbursts have been recognized to be a serious seismic risk. Therefore, local as well as regional monitoring arrays were deployed there in order to investigate the actual seismic activity on a continuous basis. The particle velocity of P- and S-waves was one of the essential parameters that was investigated on the seismograms recorded at the seismic stations placed in situ. This paper summarises the results of underground seismic measurements conducted between 1993 and 2013, and seeks to identify some empirical dependencies by determining the decay of particle velocity according to the scaled distance from the foci of the rockbursts. The scaling distance r* is defined for rockbursts by the formula r* = d/√E (m.J−1/2), while for explosions the formula r* = d/ 3√Q (m.kg−1/3) is usually used. The seismic energy, local magnitude and focus coordinates of the rockbursts, as well as positions where damage to workings occurred, were employed as additional inputs. Furthermore, the degree of this damage was tested, based on the particle velocity value generated by rockbursts occurring during exploitation of the longwalls. We tried to estimate the manifestations of individual rockbursts by the length of the damaged workings, specifically the roads, affected by the respective, and anomalous, geomechanical event. At the same time, a complex elaboration of the state of the workings following each rockburst has been carried out after the inspection conducted by the professionals of the Regional Mining Authority who determine the further progress of mining activities in the affected locality.
