In-mine Underground Tunnel Seismic Experiment, using High-resolution Reflection Seismic Method at Maseve Mine, Rustenburg, South Africa.

Summary The in-mine underground seismic experiment has been successfully conducted and the preliminary results of line 1 and 3 are presented in this paper. The data was acquired 550 m below the surface, on the Merensky Reef development that is actively mining for PGEs and chromitites minerals. The aim was to delineate and obtain a high-resolution image of the underlying UG2 complex geological structures for optimum mineral exploitation. We used 10 kg sledgehammer source and 24 stations landstreamer system connected with 4.5 Hz and 100 Hz geophones, 1-5 m station separation and 250 ms sampling interval. The data analysis revealed several seismic events (such as airwave, P- and S-wave arrivals) in the raw shot gathers. The P-wave arrivals include the reflected events, which were interpreted as reflections from the underlying UG2 pyroxenite-chromitite contact and interbedded chromitite seams. The estimated first arrival P-wave velocity ranges from 6250 – 7000 m/s and the depth to the top of UG2 in the area is approximately 30 – 50 m. Possible fault and pothole features were observed. This study thus buttresses the undeniable advantage of high-resolution reflection seismic method and its application in underground tunnel seismic investigation for mineral exploration and resource optimization.