On Friday night an earthquake of magnitude 3.3 occurred 28 km east of Viljoenskroon, Fezile Dabi District Municipality in the Free State.
According to the European-Mediterranean Seismological Centre (EMSC), the quake was located at a shallow depth of 10 km.
Cities and towns close to the epicentre may have experienced very weak shaking, said the EMSC. This would have included Vredefort (pop. 14 600), Viljoenskroon (pop. 55 000), and Parys (pop. 71 300).
The Free State tremor follows a series of small quakes recorded in other provinces in 2024. Honourable mentions are a magnitude 3.2 in Gauteng in February, and a mild magnitude 1.4 tremor in Cape Town in late March.
Mining activities in South Africa are often the underlying cause of the country’s tremors.
In the wake of the damaging magnitude 4.9 Orkney quake of 2014, Professor Andrzej Kijko of the University of Pretoria’s Natural Hazard Centre said that 95% of South Africa’s tremors were caused by mining – especially around the areas of Klerksdorp, Welkom and Carletonville.
South Africa’s strongest earthquakes and tremors
So far there has been no major incident or damage reported from Friday’s tremor in the Free State.
Not so for the earthquake of 1969 in the Western Cape, (which was nowhere near the mining belt).
Tulbagh – 1969 – Magnitude 6.3
At about 22:04 on 29 September 1969, the Boland farming towns of Tulbagh, Wolseley and Ceres experienced the most destructive earthquake in South African history.
The epicentre of the earthquake was situated in Saron – a region near Tulbagh. The earthquake measured a sizable 6.3 on the Richter scale, with tremors reported in the broader Cape region.
Many homes were destroyed and 12 people died – among them children at a local children’s home.
Thousands were left homeless and landslides set off wildfires. The aftershocks from the quakes continued and could be felt for several months.
The Ceres-Tulbagh earthquake is the strongest earthquake to shake South Africa since measurements began around 1900.
Orkney – 2014 – Magnitude 5.5
The 2014 Orkney earthquake occurred on 5 August, with the epicentre near Orkney – a gold-mining town in the North-West province of South Africa.
The shock measured a magnitude of 5.5 on the Richter scale by the Council for Geoscience (CGS) in South Africa. This made it the biggest earthquake in South Africa since the 1969 Tulbagh quake.
There was a single fatality in the Orkney quake. A 31-year-old man died when a wall of an old mining house collapsed on him. 34 trapped miners were eventually brought to the surface and treated for minor injuries, including lacerations, contusions and a broken leg.
Stilfontein – 2005 – Magnitude 5.3
On 9 March, 2005, a magnitude 5.3 earthquake struck 2 400 meters underground in Stilfontein in the North-West. Approximately 3 200 miners were underground when the quake hit, but by evening, 3 158 had been rescued.
A further 40 were eventually brought to surface, while two mineworkers lost their lives, making it one of South Africa’s major mine-related seismic tragedies in recent years.
The earthquake caused significant damage to buildings in Stilfontein, and structural damage that forced evacuations.
The tremor was blamed on deep gold mining activity in the Klerksdorp district.
Welkom – 1976 – Magnitude 5.2
Widespread damage occurred throughout the gold-mining hub of Welkom on 8 December 1976, when an earthquake measuring 5.2 on the Richter scale hit the Free State town.
Four miners died in the event, while a six-story block of flats completely collapsed.
Some sources suggest that this earthquake may have also been triggered by mining activity in the region.
Bela-Bela tremor – 2013 – Magnitude 4.8
On 2 December 2013, a seismic event struck near Bela-Bela (formerly Warmbaths) in Limpopo, registering a magnitude of 4.8.
The tremor was felt as far afield as Parkhurst and Randburg in Johannesburg.
No serious injuries, casualties nor major structural damage was recorded.
