Tuesday 12 May 2020

Four miners thought to have died after collapse at Liberian gold mine.

Four miners are thought to have died, and ten more may be trapped below ground following a landslide at a gold mine in Bong County, Liberia, on Friday 8 May 2020. The landslide is thought to have been triggered by heavy rains in the area rather than the activities of the miners themselves, and to have covered the entrance to the mine. Landslides are a common problem after severe weather events, as excess pore water pressure can overcome cohesion in soil and sediments, allowing them to flow like liquids. The miners are thought to have been working at depth of about 20 m below ground, at an artisanal mine (mine dug by local people using traditional methods) located in the village of Camp Jackson. The alarm was raised by two miners who managed to escape from the pit.

The entrance to an artisanal gold mine in Bong County, Liberia, which was covered by a landslide on 9 May 2020. Front Page Africa.

Artisanal mining is widespread in Liberia and Sierra Leone. It is often referred to as 'illicit', though in an area with little formal employment this is somewhat unfair, with local people viewing small scale mining as a traditional way of gaining some hard cash. The area is covered by poorly consolidated alluvial (river) sediments, washed out from the mineral rich Fouta Djallon Highlands, in neighbouring Guinea, since the last ice age. These loose sediments can be excavated and panned to produce small amounts of gold and diamonds. This can be a dangerous task, as sediments close to the surface are likely to have been worked by previous generations of villagers, requiring deeper pits to be dug into the, often waterlogged, sediments, with the accompanying risk of pit collapses.

 The approximate location of the Camp Jackson gold mine. Google Maps.

West Africa has a distinct two season climatic cycle, with a cool dry season during the northern winter when prevalent winds blow from the Sahara to the northeast, and a warm rainy season during the northern summer when prevalent winds blow from the Atlantic Ocean to the southwest. These warm winds from the Atlantic are laden with moisture, which can be lost rapidly when the air encounters cooler conditions, such as when it is pushed up to higher altitudes by the Futa Jallon Mountains of Guinea, Sierra Leone and Liberia.

Rainfall and prevalent winds during the West African dry and rainy seasons. Encyclopedia Britanica.

See also...

https://sciencythoughts.blogspot.com/2020/05/collapse-at-mine-kills-at-least-two-in.htmlhttps://sciencythoughts.blogspot.com/2020/02/collapse-at-gold-mine-kills-at-least.html
https://sciencythoughts.blogspot.com/2019/02/collapse-at-gold-mine-feared-to-have.htmlhttps://sciencythoughts.blogspot.com/2018/06/flooding-kills-at-least-eighteen-in.html
https://sciencythoughts.blogspot.com/2017/10/unsustainable-chocolate-production.htmlhttps://sciencythoughts.blogspot.com/2017/08/hundreds-dead-after-mudslide-in-sierra.html
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