Social media is buzzing after an earth tremor was felt early this morning on the West Rand, specifically in the North West province, with many residents reporting on it.
Data from the United States Geological Survey (USGS) has confirmed that the tremor’s epicentre was just outside Stilfontein. It was one of the most severe tremors ever reported in the area, with residents from Mohlakeng and Khutsong commenting about it.
Other areas where the tremor was felt include Parys, Krugersdorp, Orkney and Potchefstroom.
Also read: Roodepoort residents off to a shaky start
Tremors such as this one raise the question of what impact South Africa’s mining activity has on the stability of the earth’s crust. In 2010, the South African Weather and Disaster Observation Service (SAWDOS) took a closer look at mining-induced earthquakes in South Africa.
An earthquake is a convulsion of the earth – a sudden release of energy, normally caused by movement along a fault plane, or by volcanic activity, which generates potentially destructive seismic waves.
The rate of seismic activity in South Africa’s gold mining districts is higher than elsewhere in the world (even than California and Japan, which are renowned for earthquakes).
Tremors are a constant challenge because of the ever-increasing depths at which gold and platinum are mined. Each working day, as many as 300 000 miners go underground to drill and blast out the rock containing South Africa’s rich metal and mineral deposits. South Africa has the deepest mines in the world, with some going nearly four kilometers underground.
According to Lindsay Linzer (from the University of the Witwatersrand) and Ray Durrheim (from the University of the Witwatersrand and the CSIR) and the Council for Geoscience, the excavations created by miners and the enormous weight of the overlying rock cause high stresses which can trigger sudden ‘slips’ along weak zones, or even cause intact rock to rip and tear, creating (or ‘inducing’) potentially devastating mining-related earthquakes.
Also read: Krugersdorpers wake up to earth sahking event
The consequences of a tremor can be catastrophic for mineworkers, as the sudden rupture creates seismic waves, which travel through the earth at tremendous speeds, violently shaking the excavations and sometimes ejecting rock fragments.
South Africa’s most severe tremor to date shook the Klerksdorp district on 9 March 2005 and registered 5.3 on the Richter scale. It damaged buildings and injured 58 people in nearby Stilfontein. Two miners were killed and
3 200 others had to be evacuated. The mine was closed for several months, with serious consequences for mineworkers and Stilfontein residents.
Following this incident, the Chief Inspector of Mines commissioned a comprehensive investigation into the risks to miners, mines, and the public, posed by large seismic events in the country’s gold mining districts. It was found that such events can be expected in these areas as long as the current rate of deep mining continues.
Sources: University of Witwatersrand, SAWDOS, Facebook, USGS
Do you perhaps have more information pertaining to this story? Email us at randfonteinherald@caxton.co.za (please remember to include your contact details in the email) or phone us on 011 693 3671.
For free daily local news on the West Rand, also visit our sister newspaper websites
Remember to visit our Facebook, Twitter and Instagram pages to let your voice be heard!
