SANIRE2013 Symposium - “There is no limit”, 7-8 November 2013, Polokwane Durrheim et al. 1 Observational studies in South African mines to mitigate seismic risks: advances in rock engineering knowledge and technology R. J. Durrheim 1,2,3 , H. Ogasawara 1,4 , M. Nakatani 1,5 , Y. Yabe 1,6 , A.M. Milev 1,3 , A. Cichowicz 1,7 , H. Kawakata 1,6 , H. Moriya 1,6 , M. Naoi 1,5 , T. Kgarume 1,3 , O Murakami 1,4 and the SATREPS 1 Research Group 1. JST-JICA Science and Technology Research Partnership for Sustainable Development (SATREPS) 2. The University of the Witwatersrand, South Africa, Raymond.Durrheim@wits.ac.za 3. CSIR Centre for Mining Innovation, South Africa 4. Ritsumeikan University, Japan 5. Earthquake Research Institute of the University of Tokyo, Japan 6. Tohoku University, Japan 7. Council for Geoscience, South Africa, artur@geoscience.org.za INTRODUCTION Seismicity poses a serious risk to workers in deep and overstressed mines, such as the gold mines in the Witwatersrand basin of South Africa, as well as inhabitants of earthquake-prone regions such as Japan. A 5-year collaborative project entitled "Observational studies in South African mines to mitigate seismic risks" was launched in 2010 to address these risks, drawing on over a century of South African and Japanese research experience with respect to mining-related and tectonic earthquakes, respectively (Ogasawara et al., 2009; Durrheim, 2010 Durrheim et al., 2010; Utsu, 2003). The project has four main aims (see Figure 1): 1. To learn more about earthquake preparation and triggering mechanisms by deploying arrays of sensitive sensors within rock volumes where mining is likely to induce seismic activity. 2. To learn more about earthquake rupture and rockburst damage phenomena by deploying robust strong ground motion sensors close to potential fault zones and on stope hangingwalls. 3. To upgrade the South African surface national seismic network in the mining districts. 4. To develop human, technical and infrastructural capacity in South Africa. The knowledge gained during the course of the project and the new infrastructure installed will improve seismic hazard assessment methods in mines and mitigate the risk of rockbursts. It is also anticipated that new knowledge of earthquake physics will mitigate the risks posed by tectonic earthquakes. METHODOLOGY Research sites have been established at mines operated by Anglogold Ashanti (Moab-Khotsong) and Sibanye Gold (Hlanganani Shaft, Cooke #4 Shaft) (Durrheim et al., 2012). Boreholes were drilled to locate faults that are considered likely to become seismically active as a result of mining activity. Acoustic emission sensors, strain- and tilt meters, and controlled seismic sources were installed to monitor the deformation of the rock mass, the accumulation of damage during the earthquake preparation phase, and changes in dynamic stress produced by the propagation of the rupture front (see Figure 1). The suite of sensors has greater sensitivity and dynamic range than those typically used in civil or