Mining Seismology

Institute of Ural Branch of Russian Academy of Sciences Cover: Evolution of the sinkhole in Berezniki-1 potash mine (Perm region, Russia) and associated seismicity Backcover: Cross-section of fossilized Permian tree conserved in salt layer Printed by Inter-YES ltd, Perm, Russia SEISMICITY ASSOCIATED WITH KARST IN FLOODED SALT MINES -511 -

Cover: Evolution of the sinkhole in Berezniki-1 potash mine (Perm region, Russia) and associated seismicity Backcover: Cross-section of fossilized Permian tree conserved in salt layer Verkhnekamskoye potash deposit (VPD) is the only exploited potash deposit in Russia. It is second in the world on reserves after the Saskatchewan deposit in Canada. The first mine at the VPD was brought into production in 1933. Intensive mining began in the middle of the 1980s, when 6 mines were in operation. Ores are extracted from potash beds at the depths of 200-400 meters below surface. There is no evidence of any natural seismic activity in the vicinity of the potash mines prior to the beginning of mining. Large induced seismic events with magnitudes 2.6-4.7 that were felt by residents appeared in the 1990s. The epicentres of these earthquakes were within the VPD boundaries. Since 1995 underground monitoring systems were installed in all 6 working potash mines. Fifteen years of monitoring enabled accurate observation of induced seismicity at mines.

In October 2006 a serious accident happened in Berezniki-1 mine of the world’s second largest Verkhnekamskoye potash deposit. The integrity of the waterproof stratum which separates mine workings from aquifers was broken and an uncontrolled flooding of the mine had began. The accident resulted in the appearance of several potential problems associated with karst processes in the rock mass above the mine, i.e. hazardous subsidence of the earth’s surface and formation of a sinkhole. The exact position of the water inflow zone was unknown due the inaccessibility of the excavations within the problematic part of the mine. This aggravated the situation seriously. The applied complex of geophysical and geotechnical methods made it possible to localize the inflow zone, to estimate the size of the expected sinkhole and to monitor its development in time. Seismic monitoring played an essential role in these investigations. This paper summarizes the details of the seismological observations i...

In October 2006 a serious accident happened in Berezniki-1 mine of the world's second largest Verkhnekamskoye potash deposit. The integrity of the waterproof stratum which separates mine workings from aquifers was broken and an uncontrolled flooding of the mine had begun. The accident resulted in the appearance of several potential problems associated with karst processes in the rock mass above the mine, i.e. hazardous subsidence of the earth's surface and formation of a sinkhole. The exact position of the water inflow zone was unknown due the inaccessibility of the excavations within the problematic part of the mine. This aggravated the situation seriously. The applied complex of geophysical and geotechnical methods made it possible to localize the inflow zone, to estimate the size of the expected sinkhole and to monitor its development in time. Seismic monitoring played an essential role in these investigations. This paper summarizes the details of the seismological observations in Berezniki-1 mine and the main results thereof.