The Occurrence Of Large Earth Tremors In The Gold Mining Districts Of South Africa

In recent years some gold mining areas have experienced a relatively high level of seismicity with some seismic events exceeding 4 on the local Richter magnitude scale. In this report the largest individual earthquakes from 1971 to 1992 (magnitude 4,0 and above) are compared by considering their energy release. It is found that the present energy release rate deviates around<br>the derived mean and that there is no indication of an abnormal stress build-up.