2 December 2020
Gamsberg mine in South Africa: when is a landslide a geotechnical failure?
Gamsberg mine is a comparatively new open cast pit in the Northern Cape, South Africa. Operated by Vedanta Zinc International, it currently produces 400,000 tonnes of ore per month. Once full production capacity is reached Gamsberg is expected to produce 4 000,000 tonnes of ore and 250,000 tonnes of zinc-in-concentrate per year. The current reserve and resource is 214 million tonnes, and operations are estimated to last about 30 years.
On 17 November at about 1:15 am Gamsberg suffered what its owners are describing as a “geotechnical failure” that was sufficiently large to require that the company release a formal statement. The failure occurred in a high wall excavation known at a part of the mine known as the South Pit. At the time of the failure there were ten members of staff at the bottom of the pit. Eight were rescued, but it appears that the other two were killed.
The failure is sufficiently large that it is clearly visible on the daily Planet Labs imagery. The images below show the South Pit; the left image was captured on 14 November, before the landslide, and the image on the right was captured after the event on 17 November.
Images of the landslide at Gamsberg mine have also been posted to Reddit. This image provides an overview of the landslide itself:-
Whilst this image shows the damage caused by the landslide:-
There is very little additional information about this very large mining landslide. The impact on the workers in the mine and to the equipment above suggests that it might not have been anticipated. As high wall mines often have sophisticated monitoring of their slopes, it is increasingly unusual for the operators to be taken by surprise by such events.
Reference and acknowledgement
Planet Team (2020). Planet Application Program Interface: In Space for Life on Earth. San Francisco, CA. https://www.planet.com/