CHARACTERISTICS OF THE PROCESSES TAKING PLACE AT THE SOURCES OF HIGH ENERGY TREMORS OCCURRING IN THE UPPER SILESIAN COAL BASIN IN POLAND-REGIONAL CHARACTER OF THE PHENOMENON

摘要

Seismic observations in the Upper Silesian Coal Basin carried out by the Upper Silesian Regional Seismic Network of Central Mining Institute date back to the 1950s. More than 61 000 mine tremors of energy E ＞ 105 J (local magnitude Mt ＞ 1,6) occurred over the period of 1974 to 2008. From the analysis of the seismic source location relative to mine faces and from the analysis of the tectonic structures location, two types of seismicity have been distinguished. These are called respectively mining and regional types of seismicity. The former one is strongly associated with the mining activity and seismic events that occur in the vicinity of active mining excavations. These events are, as a rule, energetically relatively weak. The latter one results from the interaction between mining and tectonic factors. These seismic events appear to be located in tectonically disturbed zones (faults) and the sources are visibly more energetic. They can also be intensely felt on the surface.