Seismic hazard assessment using apparent stress ratio

Abstract

Seismically active operations require special considerations for design and mining practices in order to mitigate the risk associated with large and potentially damaging seismic events. When detailed knowledge of the local rock mass conditions and the historical seismic response is considered during mine design, costly rehabilitation and time delays can be minimised. High apparent stress is an indicator of increasing stress within the rock mass. Apparent stress ratio (ASR) is a new and innovative way of quantifying apparent stress for a given seismic population. A high ASR value suggests that local stress conditions are high and increasing. Analysis of seismic event data from LaRonde Mine, Canada, suggests that the ASR is strongly correlated with the occurrence of large events — high seismic hazard. This paper presents the use of ASR as a precursory trend to large seismic events for both intermediate and long term seismic hazard. Practical examples are provided from LaRonde Mine.