Focal mechanism solutions for roof collapse in deep mine

Microseismic monitoring is an effective means of forecasting instabilities in ruptured rock masses during deep mining. Based on the complex geological conditions of a mine in Southwest China, a digital 24–channel microseismic monitoring system was established to monitor microseismic events during deep mining. In the monitoring period, the focal mechanism solutions of roof collapse accidents were analysed using a double couple model. The results show that the focal mechanism solutions of the double couple model can be used to explain roof ruptures and instabilities. Two seismic source events were located at the F4 active fault, and the other seismic source event was located at the rock stratums demarcation line between little eighth orebody and C1b stratum. It was concluded that the active microseismic events were caused by deep mining. The method can be used to forecast roof collapse.