Downsizing an overcoring diameter to 60 mm (BX), the Compact Conical-ended Borehole Overcoring technique (BX CCBO) proved suitable for adverse conditions and difficult access from surface in deep levels South African gold mines. BX CCBO in-situ stress measurements have been carried out at seven sites at depths of 1.0 to 3.4 km, the measured maximum principal stresses, a ranging between 76 and 146 MPa. In South African gold mines, such a number of in-situ stress measurements have never been camed out previously in the σ1 and depth ranges relevant to the described studies. The in-situ stress measurements allowed us to confirm that an assumption on far-field (initial) stress gradient was acceptable with only slight modifications. An improved assumption on far-field stress gradient allowed us to better constrain both the stress and strength on the M>2 earthquake faults with σ1 ranging between 100 and 177 MPa. The stress range was also confirmed by analyzing breakouts and core discings ins hole drilled through a M12.1 hypocenter. At one site where σ1 was 100 11 OMPa, a BX CCBO was compared with a CSIRO cell in a good agreement, although some issues were found to address regarding BX CCBO measurements.