Lynch, RA 2017, 'Investigation of fracture zone properties using reflected seismic waves from passive microseismicity', in J Wesseloo (ed.), Deep Mining 2017: Proceedings of the Eighth International Conference on Deep and High Stress Mining
, Australian Centre for Geomechanics, Perth, pp. 529-536, https://doi.org/10.36487/ACG_rep/1704_35_lynch
A new method has been developed for imaging seismic reflectors using seismogram data recorded by a few standard triaxial geophones. A directional migration approach reduces imaging artefacts due to the low aperture of the sensor array. This is possible by measuring the polarisation in the seismogram coda and considering all four reflected body-waves: PP', PS', SP' and SS'.
This technique has been applied to seismograms recorded by deep borehole sensors at Williams mine, Canada, in order to invert for fracture zone properties surrounding the open pit. A fracture zone thickness of 20 m, with average rock quality designation (RQD) of 75%, best matches the seismic data, and is closely correlated to the mine's borehole core observations. This finding has useful implications for efforts to remove tunnel reflections from seismograms recorded by standard (short borehole) geophones underground. As such, it is a necessary first step before standard microseismic monitoring arrays can be used to image the rock mass beneath and ahead of a working underground mine using reflection seismology.
Keywords: seismic reflection imaging, underground seismic exploration
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