Seismic hazard evaluation using apparent stress ratio for mining-induced seismic events

Abstract

This thesis investigates precursory trends in seismic data prior to the occurrence of large and potentially damaging seismic events at Agnico Eagle’s LaRonde mine. A variety of sample populations are selected to represent varying degrees of seismic hazard within a large area of interest at LaRonde. The main factor considered for hazard assessment is the local stress conditions within the rock mass, inferred from the apparent stress of seismic events. An alternative means of analyzing apparent stress measurements using a relative ratio, referred to as Apparent Stress Ratio (ASR), is presented. The use of a ratio eliminates the need for thresholds values to define high and abnormal apparent stress. ASR values are analyzed in reference to varying time frames, allowing for changes in stress conditions over time to be considered. Hazard maps created using ASR and peak ASR values correspond well to areas of elevated seismic hazard previously identified at LaRonde. For an area of interest at LaRonde, ASR as an alarm tool possesses a success rate of 68% with a false alarm ratio of 2:1.