Perpustakaan Digital ITB

Underground mines face complex geotechnical challenges, particularly in understanding the role of shear zones on the stability of mining operations. Shear zones are generally formed by geologic-scale tectonic deformation and consist of weakened rock material. Mining activities can trigger stress redistribution that weakens these zones and increases the risk of collapse. This study applies the tomographic double-difference (tomoDD) method to model and analyze the structure of P-wave (Vp), S-wave (Vs), and Vp/Vs ratio in the “SEVERA” underground mine area. Seismic monitoring was conducted from January to May 2024 and recorded 288 seismic events with a total of 1979 P-wave phases and 1979 S-wave phases, with a moment magnitude range from -1.2 Mw to 0.9 Mw. These data were obtained from 34 seismic stations scattered around the study area and used in the tomographic inversion process. The inversion results reveal two main blocks with significant velocity contrasts, a high velocity anomaly block interpreted as massive and compact rocks, and a low velocity anomaly block associated with altered or fractured rocks. Interestingly, within the high velocity anomaly block there is a localized low velocity zone that may be related to the backfill zone which over time the energy released from this activity tends to migrate into the shear zone. The findings provide important insights for mine stability evaluation and geomechanical risk mitigation