The majority of seismic hazard assessment tools are solely based on statistical analyses of several seismic source parameters such as event rate and time, and seismic moment. These analyses are often applied to the entire mining area which can impact the accuracy and reliability of the hazard assessment tool in each zone. Experience has shown that mining geomechanical risk is complex and its mitigation needs a broad understanding of other geotechnical factors such as rock mass properties, geological structures, mining method, stress regime, etc. Since all the contributing parameters and their impact are not entirely understood, it is critical to apply a range of geotechnical/geomechanical analyses in correlation to each other and quantify the changes in the rock mass behaviour. The goal of this paper is to develop a seismic hazard assessment tool calibrated for each geotechnical domain within the mine. To develop the tool, we incorporated mine geotechnical and geological data, seismic source parameters, and tomography analyses from a hard rock underground mine in North America. There exist several sub-vertical faults and one horizontal structure in the mine which create clear contrasts in rock mass behaviour across the structure. The results show good correlation among the different datasets, and a calibrated seismic hazard tool has been developed that provides ongoing updates to the mine operation.
Exposure to seismic hazard in mines is controlled through various evacuation, exclusion and re-entry procedures. The aim of exposure management procedures is to tactically reduce the safety risk by removing personnel from work areas during periods of elevated seismic hazard. Given that risk assessment is based on exposure, the design of exposure management procedures must also be risk-based. In practice, the decision to re-enter a workplace after an exclusion is generally only made based on an assessment of the seismic hazard, often using previously defined levels of tolerable seismic activity rates. The definition of tolerable seismic hazard, in the context of re-entry, is seldom quantitatively assessed based on risk. In order to move towards a comprehensive seismic risk management strategy, design methodologies must be able to quantify the impact of different exclusion and re-entry practices on risk. The appropriate reentry practice can then be selected given the defined risk-based design acceptance criteria. There is still a long way to go before the risk-based design framework for exposure management procedures is complete. This paper reviews the current state of design of exposure management controls in the context of risk and discusses several important areas for further research.