Analysis and interpretation of clusters of seismic events in mines

Spatial clustering of seismic events in mines has been widely reported in literature. Despite obvious visual correlations between spatial clusters of seismic events and geomechanical structures in mines (such as pillars, dykes and faults), very limited research has been undertaken to utilise this information to filter seismic data. A linkage between spatial seismic event clusters and discrete rockmass failure mechanisms is tenuous and not well established using current seismic analysis techniques. A seismic event clustering methodology is proposed. The first component of the methodology uses a complete-linkage (CLINK) clustering routine to identify relatively compact clusters of seismic events. The CLINK clusters are then subjected to a singlelink clustering process, which uses spatial location and seismic source parameters as similarity measures. The resultant "Comprehensive Seismic Event Clustering" (CSEC) methodology can be used to identify individual seismic sources and rockmass failure mechanisms within a broad population of events. The CSEC methodology incorporates the vast majority of events within a population, such that the resultant clusters are a good representation of the entire seismic data set. Within bounds, the clusters of seismic events identified in the CSEC methodology exhibit self-similar characteristics. Based on this clustering process a "Local Rockmass Seismic Source Model" is proposed. The model suggests that seismic events are primarily generated by local rockmass failure mechanisms. The local rockmass failure is a result of a combination of mining-induced stresses, geological features, rockmass conditions