By Lehlohonolo Lehana.
The Council for Geoscience (CGS) confirmed that an earthquake occurred on Saturday evening, 22 July 2023, at around 18:46.
“The earthquake registered a local magnitude of approximately 2.98, as recorded by the South African National Seismograph Network (SANS). The epicentre was located south of Johannesburg, 2 kilometres south of Harmony Doornkop Gold Mine, “the council said.
In June, South Africans were awoken to a powerful 4.4 magnitude earthquake which was felt across large parts of Gauteng.
The earthquake hit the Gauteng province at approximately 2:38am early on Sunday morning 10 June 2023 causing homes and buildings to shake.
The National Council for Geoscience said Sunday morning’s tremor in Gauteng measured a magnitude of 4.4.
Two weeks later, Johannesburg residents were shaken awake by the 2.2 magnitude earthquake originating in Soweto.
CGS believes Gauteng is more stable in terms of its tectonic activity than KwaZulu-Natal or even Cape Town but this is not cast in stone.
Being a mining city, Johannesburg is no stranger to tremors which is why many residents thought the shaking felt on Saturday was probably just one of them.
A normal assumption would be that the size of the earthquake determines the damage it does. But this is not true. According to Durrheim: “Earthquakes don’t kill people; buildings do. “Often, it is infrastructure that is not equipped to deal with earthquakes which falls and causes deaths.
Africa is not known to have big earthquakes. There have only been four that have measured above 7.0, including a 7.3 event that hit Tanzania in 1910. Algeria and Morocco are high on the risk list, as well as countries on the East African rift.
An example of a mid-sized earthquake that caused widespread damage was one that struck in Morocco in 1960. It measured at 5.7 but killed about 13 000 people, making it the deadliest quake to hit Africa and one of the deadliest globally in terms of lives lost.