Around 17 employees of AngloGold Ashanti's Great Noligwa and Moab Khotsong mines at Vaal River have been injured in a 5.3-magnitude earthquake that shook central South Africa.
According to the US Geological Survey, the earthquake hit at a depth of around 8km near Orkney, an area having many gold mining operations.
AngloGold said in a statement: "Power to our Vaal River mines was temporarily interrupted and has since been mostly restored.
"We are in the process of establishing telephonic contact with all mining crews, in line with our safety protocols.
"Our priority is the safe passage of our employees from underground. Again, in line with safety protocols, engineers are inspecting shaft infrastructure, and at those shafts where this work is complete, hoisting of people to surface has already begun."
Meanwhile, officials at AngloGold Ashanti, Harmony Gold, Gold Fields and Sibanye Gold were quoted by Reuters as saying that they had felt the tremors in their headquarters but had so far received no reports of anything untoward in their mines.
AngloGold said that its West Wits operations, including Mponeng and Tau Tona mines, were not affected by the natural disaster.
Sibanye Gold corporate affairs senior vice-president James Wellsted told Mining Weekly Online that there had been no fall-of-ground at its operation in the area, but confirmed that the miners below ground had felt the tremor.
"The miners will be ending their shift shortly and we'll warn the shift replacing them that they should be careful, but we've had no injuries."
Private emergency medical service ER24 spokeswoman Luyanda Majija said: "There are no entrapments.
"Most miners working in various mines have been brought out.
"Most shafts have been evacuated."
Image: Moab Khotsong is one of the two mines of AngloGold Ashanti that felt the tremors. Photo: courtesy of AngloGold Ashanti.