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Characterisation of Mining-induced and Natural Seismicity
- Publisher: European Association of Geoscientists & Engineers
- Source: Conference Proceedings, 6th SAGA Biennial Conference and Exhibition, Sep 1999, cp-221-00012
Abstract
Preliminary analyses of seismic records of mining-induced earthquakes from the<br>Kaapvaal Craton experiment indicate that these data are of sufficiently high quality<br>and large quantity to enable significant improvements of the crustal velocity structure<br>of southern Africa through the routine identification of seismic phases. Principal<br>event parameters, such as origin time, location, depth and local magnitude, are<br>collated from the bulletins published by the Council for Geoscience (Graham et al.,<br>1997) and from individual mine databases from gold mining companies throughout<br>South Africa. The waveform data for events with a magnitude greater than 2.0 are<br>extracted from the Kaapvaal database. This database was acquired through the<br>deployment of a 54-station, SO-site network of broadband seismic stations distributed<br>across the southern African region. as part of the multinational project “The anatomy<br>of an Archean craton” (Carlson et al., 1996). The restricted time of this deployment<br>is from April 1997 until June 1999. Careful identification of phases across and<br>around Kaapvaal craton are fundamental in deriving more representative velocity<br>models of the crust and upper mantle of the southern African region. Results from<br>other current seismic research, including receiver function and two-station surface<br>wave dispersion studies, will also be used to assist refinement of the S wave velocity<br>models for the crust and upper mantle (James et al, 1998). The event location data<br>provided by the mines are accurate to a few hundred meters, providing a unique<br>opportunity of combining very accurate locations with waveform data from the<br>regional Kaapvaal network. This will enable an improved velocity model of the crust<br>and upper mantle to be calculated and used in the future for locating events.