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Lake Nyos

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Overview


Situated in Cameroon, Lake Nyos is a carbon-dioxide saturated lake as a result of the magma which lies beneath it. In 1986, the lake released a horrific amount of carbon dioxide and suffocated 1800 people along with livestock from the villages which surround it.

Background


Lake Nyos is a crater lake in the Northwest Province of Cameroon. It sits high on the side of an inactive volcano near Mount Oku. Directly underneath the lake lies !Lake_nyos.jpg|align=right,thumbnail!a large pocket of Carbon Dioxide (CO2) that continually seeps into the lake, saturating it with the gas.

The area is has an extensive volcanic history though it has been dormant for around 400 years ago, when the hole was created that was eventually filled by what is today known as Lake Nyos. Old lava flows ring the lake essentially creating a natural dam of volcanic rock.

Lake Nyos is thermally stratified, with layers of warm, less dense water near the surface floating on the colder, denser water layers near the lake's bottom. Over long periods, carbon dioxide gas seeping into the cold water at the lake's bottom is dissolved in great amounts.

Most of the time, the lake is stable and the CO2 remains in solution in the lower layers. However, over time the water becomes supersaturated, and if an event such as an earthquake or volcanic eruption occurs, large amounts of CO2 may suddenly come out of solution.

 

1986 Event


On August 21, 1986 a limnic eruption - occurs when CO2 suddenly erupts from deep lake water - occurred and triggered the release of about 1.6 million tonnes of CO2. Around a cubic kilometer of gas flowed from the mountain down into the two populated valleys below. The gas displaced all the air, suffocating 1800 people and 3500 livestock. Of the additional 4000 inhabitants who fled the valleys, many developed respiratory problems, burns and even paralysis from the gas.

The cause of the disaster is still debated between geologists. Most geologists suspect a landslide while some believe that there was a small volcanic eruption at the base of the lake. Others still believe that cool rainwater that fell on one side of the lake triggered the overrun of the water. Whatever the cause of the dislocation, the gas-laden water of the bottom of the lake with the upper layers, where the reduced pressure allowed the gas to seep out.

References


Lake Nyos - wikipedia

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