Passive seismic tomography for three-dimensional time-lapse imaging of mining-induced rock mass changes

Progression of an immature block cave in proximity to a mature sublevel cave was monitored over an 18-month period using double-difference tomography. This method utilizes existing microseismic data to generate time-lapse images of seismic wave velocity changes within the rock mass. The velocity changes are caused by damage zones forming or local high-stress concentrations. In this study, images were generated on monthly intervals. An average of 2000 microseismic events recorded by 25 stations were used to generate each image. Results showed a development of the initial undercut followed by the growing cave and interaction with the adjacent sublevel cave. The goal of the research is to provide a tool that can augment both numerical modeling results and underground geotechnical measurements to allow the mine operator to produce in the safest and most efficient manner possible.