The distance analysis of a mine scale event

Abstract

Mining induced seismic events greater then Nuttli Magnitude 3.0 are difficult to understand, have high potential consequences and are becoming increasingly common in Canada. The term mine scale event (MSE) is used to describe a seismic event in which the mechanisms and processes involved take place on a scale similar to that of the mine. A MSE from Nickel Rim South Mine was investigated using seismic data to explain its time, location and large magnitude. A novel tool, Time Distance Analysis was developed to identify spatial-temporal trends in seismicity around the MSE. Guidelines were developed to account for the unknown spatial and temporal extent of the processes that led to and were affected by the MSE. The results showed that preceding seismicity tended to coalesce around the eventual hypocenter of the MSE while subsequent seismicity migrated away. The coalescence was interpreted to represent the deterioration of a fault asperity, leading to an eventual rupture. After the MSE occurred, the dispersion of seismicity was interpreted to represent an unloading of the source region.