Naked Science Forum
Non Life Sciences => Geology, Palaeontology & Archaeology => Topic started by: chris on 16/05/2017 08:10:41
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Sebastian says:
I am researching a project for school and I want to find out how does an earthquake epicentre form far away from a plate boundary? Specifically Moijabana, central Botswana.
Can you help?
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A good place to start looking for a particular earthquake is the US Geological Survey:
https://earthquake.usgs.gov/earthquakes/eventpage/us10008e3k#executive
In particular, this map (https://earthquake.usgs.gov/earthquakes/map/#%7B%22autoUpdate%22%3A%5B%5D%2C%22basemap%22%3A%22terrain%22%2C%22feed%22%3A%22us10008e3k%22%2C%22listFormat%22%3A%22default%22%2C%22mapposition%22%3A%5B%5B-24.1367281697474%2C22.362670898437496%5D%2C%5B-21.24330241973194%2C27.9437255859375%5D%5D%2C%22overlays%22%3A%5B%22plates%22%5D%2C%22restrictListToMap%22%3A%5B%22restrictListToMap%22%5D%2C%22search%22%3A%7B%22id%22%3A%22us10008e3k%22%2C%22isSearch%22%3Atrue%2C%22name%22%3A%22Search%20Results%22%2C%22params%22%3A%7B%22endtime%22%3A%222017-04-24T17%3A40%3A18.560Z%22%2C%22latitude%22%3A-22.6784%2C%22longitude%22%3A25.1558%2C%22maxradiuskm%22%3A250%2C%22minmagnitude%22%3A3%2C%22starttime%22%3A%222017-03-13T17%3A40%3A18.560Z%22%7D%7D%2C%22sort%22%3A%22newest%22%2C%22timezone%22%3A%22utc%22%2C%22viewModes%22%3A%5B%22list%22%2C%22map%22%5D%2C%22event%22%3Anull%7D) shows that there have been 8 earthquakes in this region - but mostly around 5 on the Richter scale.
Wikipedia says the causes are poorly understood: https://en.wikipedia.org/wiki/Intraplate_earthquake
Although Botswana is far from a plate boundary, the great rift valley (https://en.wikipedia.org/wiki/Great_Rift_Valley) is slowly tearing Africa apart as far south as Mozambique, and this must cause rock stresses on other parts of Africa. These stresses could be relieved by intraplate quakes.