Duff, DJ, Valley,B, Milkereit, B & McGaughey, J 2011, 'Rock mass response to deep mining induced stress—research and tools development at the CEMI, Canada', in Y Potvin (ed.), Strategic versus Tactical 2011: Proceedings of the Fourth International Seminar on Strategic versus Tactical Approaches in Mining, Australian Centre for Geomechanics, Perth, pp. 73-84, https://doi.org/10.36487/ACG_rep/1108_07_Duff (https://papers.acg.uwa.edu.au/p/1108_07_Duff/) Abstract: Mining deeper is needed in order to sustain production in many established camps worldwide, but this comes with elevated risk due to, among other things, high stresses. In these conditions, the interactions between stress and structure become critical, as does the state of the rock mass itself and how it’s impacted by the process of mining. Research leading to optimised mine designs and an improved geomechanics outcome is needed. Specifically, rock mass system stiffness and its effect on the stability of structures, the performance of our ground support, and thereby the vulnerability of our excavations is critical to consider, but is not easily measured or understood. This is despite its fundamental importance. At a strategic level, work needs to focus on an integrated approach comprised of enhanced early site characterisation techniques/procedures coupled with rock mass behaviour monitoring in response to the mining process itself. Recognition of the inherently dynamic, rather than static, conditions which prevail in deep mines is essential to ensuring that strategic goals are met through employment of appropriate tactics. This paper will discuss the difficulties and hazards associated with unpredictable rock mass behaviour in deep mines and examine in some detail various tactical research and tool development approaches being undertaken to lower the risk associated with them.