Beyond coloured balls ‒ making sense of large volumes of microseismic data with diverse source mechanisms

Authors: de Beer, W; Ardito, JA; Mercier, J-P; Falmagne, V Download Paper

DOI https://doi.org/10.36487/ACG_rep/1201_10_debeer

Cite As:
de Beer, W, Ardito, JA, Mercier, J-P & Falmagne, V 2012, 'Beyond coloured balls ‒ making sense of large volumes of microseismic data with diverse source mechanisms', in Y Potvin (ed.), Deep Mining 2012: Proceedings of the Sixth International Seminar on Deep and High Stress Mining, Australian Centre for Geomechanics, Perth, pp. 149-159, https://doi.org/10.36487/ACG_rep/1201_10_debeer



Abstract:
The central theme of this analysis is the study of seismic response of the rock mass before and after the occurrence of a moment magnitude 2.0 seismic event that occurred in December 2010 at the San Rafael Mine sublevel open stoping operation located in Peru. A microseismic data set acquired by the mine microseismic monitoring system is analysed using a range of methodologies, including passive source tomography imaging, focal mechanism inversion, as well as deterministic and probabilistic approaches. P- and S-wave velocity models, calculated for three time periods, using a passive source tomography algorithm developed by Advanced GeoScience Imaging Solutions (AGSIS), was applied to the data set to image the evolution of the rock mass. The models show variations in the seismic velocity before and after the event that may relate to the distribution and redistribution of stresses in the rock mass. Probable focal mechanisms, exploration of the spatial geometry of seismic event distributions (using singular value decomposition and clustering) as well as rapid separation of populations of events which are generated by different source mechanisms were also used to illuminate different aspects of the seismic response to mining at that time. We note that the separation of populations serves only to provide consistent and unique distributions to use in the assessment of hazard due to particular types of activity. The complete dataset (with the possible exception of blasts and ore pass noise) is required for modelling velocity structures and understanding stress transfer mechanisms in the rock mass.

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