## 4 In Situ AE Monitoring in Gold Mines
### Gold Mine Mponeng in South Africa  
The joint Japanese-German Underground Acoustic Emission Research project (JAGUARS) (see Table 3) in South Africa measures AE events in the frequency range from 700 Hz to 200 kHz. In the JAGUARS project [73] conducted in Mponeng Gold Mine in Carltonville in South Africa in 3.3 km depth the full evolution of a rock burst with moment magnitude \(M_{W}=1.9\) could be monitored using an in situ AE monitoring network. The JAGUARS network was installed in spring 2007. The gold is mined from the Witwatersrand formation. The gold-carrying sedimentary layer (Ventersdorp Contact Reef) is embedded in a thick series of quartzite, dipping with 26.5\({}^{\circ}\) toward the south-east, and reaches a thickness of 0.5 to 1 m. The JAGUARS network is located approximately 90 m below the reef, next to a gabroic dike (Pink-Green (PG) Mike, Figure 16). This dominant geological feature is 30 m wide and dips nearly vertically. It cuts through the reef and serves as a support pillar for the exploitation. [PERSON] et al. [99] estimated the seismic velocities of rock types in the vicinity of the network from velocity tomography using AE transmission measurements. For the quartzite host rock, [PERSON] et al. [99] estimated seismic velocities of \(v_{p}=6.2\) km/s for P waves and \(v_{S}=3.8\) km/s for S waves. The velocities within the pink-green dike were found to be slightly higher, with \(v_{P}=6.9\) km/s and \(v_{S}=3.9\) km/s. Mining in the vicinity of the JAGUARS network (Figure 16) started in early 2007. The network focuses on the dike-host rock contact close to the mining front, where larger events with magnitudes \begin{table}
\begin{tabular}{c c} \hline
**Institute** & **Main Contributors** \\ \hline
**Japan** & - \\ Earthquake Research Institute of the University of Tokyo & [PERSON], [PERSON]; \\ Tohoku University & [PERSON] \\ Ritsumeikan University & [PERSON] \\ \hline
**Germany** & - \\ GFZ: German Research Centre for Geosciences Potsdam & [PERSON], [PERSON], [PERSON], [PERSON] \\ GMuG mpH, Bad Nauheim & [PERSON] \\ \hline
**South Africa** & - \\ Seismogen CC, Carletonville & \\ AngloGoldAsnith Ltd. & \\ Institute of Mine Seismology (IMS), Stellenbosch & [PERSON], [PERSON] \\ Council for Scientific and Industrial Research (CSIR), & [PERSON], [PERSON], [PERSON] \\ Johannesburg & [PERSON], [PERSON] \\ \hline \end{tabular}
\end{table} 
Table 3: Group members of the joint Japanese-German Underground Acoustic Emission Research in South Africa (JAGUARS) project [36; 73]. up to \(M_{W}=3.0\) were expected due to stress concentration induced by mining (personal conversation with [PERSON], 2009). The seismic network is consisting of 8 borehole AE sensors and one triaxial accelerometer. All sensors were installed in short boreholes of 6 m to 15 m length. The data were recorded in trigger-mode recording. The stress changes owing to the approaching mining front on the PG dyke are modeled by [PERSON] [77]. A main shock with magnitude of \(M_{W}=1.9\) occurred on 27 December 2007 in the center of the AE monitoring network [33; 36; 74]. [PERSON] et al. [74] manually picked P- and S-wave arrival times to locate more than 20,000 AE events, that occurred within 150 hours, following the main shock. The location error for events within a radius of about 40 m of the center of the AE network was less than 1 m. Most of the AE events from this period occurred within 50 m to 100 m of the network, where the spatial coverage of the network is best. The events contain signals with a broad range of high frequencies, which allowed the sensitivity of the network toward very high frequencies above 25 kHz to be analysed in greater detail [36; 52]. Owing to the resulting excellent recording of the aftershock AE event sequence with most AE events after the main shock, the rupture process and the rupture plane could be studied in great detail. The spatial distribution of 9,444 aftershocks is shown in map view in Figure 17a. The main shock hypocenter is shown by a grey star.