Relation of coal mining to induced seismic activity

Seismic activity induced by longwall mining has been monitored and analyzed in order to clarify the relationship between the seismic energy release and the extracted deposit volume. From the total number of seismic events of (1937) 96 were felt at the surface, too. During the time period August 1987-June 1990, 6 rockbursts appeared which caused devastations in the mine. The localized foci of low energetic seismic events ( E = 10 2 -10 3 J) cluster the active coal face while the more intensive seismic events originate in the ‘higher’ roof. The deterioration of mining conditions when passing under a coal pillar or proceeding the edges of mined out coal seams in the roof was observed. The seismic energy release and extracted deposit volume are in good correlation when comparing their cumulative graphs. A certain delay between the beginning of coal extraction and increase of seismic activity is observed.