Sunday 15 June 2014

Magnitude 4.9 Earthquake in northern Free State, South Africa.

The United States Geological Survey recorded a Magnitude 4.9 Earthquake at a depth of 5 km close to Klerksdorp in northern Free State, South Africa, slightly after 4.15 pm local time (slightly after 2.15 pm GMT) on Sunday 15 June 2014. This is a large Earthquake by South African standards, and was felt across much of northern Free State and southern North West Province, an area where quakes are particularly dangerous due to the large number of mines, although on this occasion there are no reports of any damage or casualties.

The approximate location of the 15 June 2014 Free State Earthquake. Google Maps.

Earthquakes are rare in South Africa, with only 10 Earthquakes exceeding Magnitude 4.5 recorded since 1966 (when instrumental records begin in the country) making this one of the largest Earthquakes ever recorded in South Africa. 

Because of this rarity it is hard to make precise judgements about the cause of quakes in South Africa, due to a paucity of data. Northwestern South Africa is close the southern end of the Great Rift Valley exits the continent and passes out under the Indian Ocean. The Great Rift Valley is slowly splitting the African Plate in two allow a line from the Red Sea through Ethiopia, and which includes the great lakes and volcanoes of east-central Africa. This has the potential to open into a new ocean over the next few tens of millions of years, splitting Africa into two new, smaller, continents; Nubia to the west and Somalia to the east.

Witness statements can help geologists to understand Earthquakes and the geological processes that cause them; if you felt this quake (or if you were in the area but did not, which is also useful information) you can report it to the South African Council for Geoscience here.

See also...

Most accounts of the history of seismology in South Africa relate the earliest recorded Earthquake in the country as having occurred on 7 April 1620, as recorded by the French explorer Augustin de Beaulieu, who was becalmed near Robben Island, prior to reaching Table Bay on 15 April. De Beaulieu recorded hearing a pair of ‘startling thunderclaps like cannon shots’, which have subsequently...

A Magnitude 4.7 Earthquake was recorded at a depth of 5.0 km...

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