Grobbelaar, MRG, Birch, D & Cichowicz, A 2017, 'Comparison of data from complementary seismograph networks in a mining district', in J Wesseloo (ed.), Proceedings of the Eighth International Conference on Deep and High Stress Mining
, Australian Centre for Geomechanics, Perth, pp. 117-124.
South Africa has embarked on the installation of dense local surface networks within a number of mining regions in order to create a unique situation where data from an event can be recorded by three separate networks; at distances of: 500 km by the national seismograph network, 4 km by the local network and 100 m by the mining networks. The data can be used for hazard at the stope and hazard within the region and, thus, trends can be identified in order to assist in the investigation and mitigation of seismic related accidents. This is a first for the country.
The ML5.5 earthquake on 5 August 2014, provided an ideal opportunity for collaboration and comparison between the local surface and mining networks, especially since each network has its own unique challenges due to equipment specifications and capabilities. Thus, such a comparison would help quantify these differences.
The locations of the earthquakes, as well as other spectral parameters, obtained by each network were investigated. Many of the parameters were very similar, such as the estimated Mw magnitudes from both the networks. Similarly, the scalar seismic moments offered by both networks are comparable, but with a tendency to underestimate by the mining network in comparison to the local surface network. In addition, the radiated seismic energy estimated by both networks follow the same trend, however, significant scattering of the estimated energy is observed at small values.
The spatial patterns of seismicity associated with the aftershocks of the ML5.5 earthquake were compared and both networks reveal a very similar pattern, however, the mining network delineated the fault with a higher accuracy than the local surface network.
Keywords: comparison, spectral parameters, mining, seismograph networks
Antelope 2014, Antelope Version 5.4, Environmental Monitoring Software, viewed 23 August 2016, www.kinemetrics.com
Brune, JN 1970, ‘Tectonic stress and the spectra of seismic shear waves from earthquakes’, Journal of Geophysical Research, vol. 75, pp. 4997–5009.
Brune, JN 1971, ‘Correction’, Journal of Geophysical Research, vol. 76, p. 5002.
Cichowicz, A 2001, ‘Quantification of complex seismic sources’, Proceedings of the 5th International Symposium on Rockbursts and Seismicity in Mines (RaSiM5), Southern African Institute of Mining and Metallurgy, Johannesburg, pp. 91–97.
Cichowicz, A & Birch, D 2012, Enabling output 2: Estimation of Seismic Source Parameters part of the project: Fluid-Induced Seismicity in the Central Basin Area: Ground Motion Prediction and the Development of an Early Warning System for Risk Reduction, commissioned by the Mine Health and Safety Council, project number, SIM 11-02-01.
Cichowicz, A, Kgaswane, E, van Aswegen, G, Adamos, P, Birch, D, Jele, V, Kometsi, R, Prasad, K, Saunders, I, Strasser, F, Tabane, L & Zulu, B 2010, Monitoring Seismicity in the Central Rand and East Rand Goldfield – Mine-Flooding Induced Seismicity, report no. 2010-0056, part of the Strategic Water Management Project commissioned by the Department of Mineral Resources of South Africa.
Hanks, T & Kanamori, H 1979, ‘A moment magnitude scale’, Journal of Geophysical Research, vol. 84, no.B5, pp. 2348–2350.
Keilis-Borok, V 1959, ‘On estimation of the displacement in an earthquake source and of source dimension, Annals of geophysics, vol. 12, pp. 205–214.
Kinemetrics Inc.© 2016, viewed 23 August 2016, www.kinemetrics.com
Madariaga, R 1976, ‘Dynamics of an expanding circular fault’, Bulletin of the Seismological Society of America, vol. 66, pp. 639–666.
Madariaga, R 1979, ‘On the relation between seismic moment and stress drop in the presence of stress and strength heterogeneity’, Journal of Geophysical Research, vol. 84, pp. 2243–2250.
Saunders, I, Brandt, MBC, Steyn, J, Roblin, DL & Kijko, A 2008, ‘The South African National Seismograph Network’, Seismological Research Letters, vol. 79, no. 2, pp. 203–210.