A limnic eruption (also called Lake Overturn) is a very rare natural phenomenon. It occurs when a large bubble of carbon dioxide suddenly erupts from the bottom of deep lakes. Such an explosion may also cause tsunamis. The suffocating and inflammable gases kill everything in that area?people, animals and plants.

Only two Lake Overturns have been recorded to date. The first occurred 28 years ago in Cameroon at Lake Monoun. The massive quantities of carbon dioxide killed 37 people. A second overturn took place in 1986 at Lake Nyos. Over 80 million cubic meters of carbon dioxide were released, this time killing 1,800 residents and 3,500 livestock. This tragic event was the first known large-scale asphyxiation generated by a natural phenomenon.

Lake Kivu, one of the Great African Lakes, is not only 1,000 times larger than Lake Nyos – it is also situated in a far more densely populated area. The lake?s surrounds are home to millions of people. This is for sure one of the most dangerous place to live! Volcanic or landslide activity could trigger a limnic explosion at Lake Kivu.

Today, the lake Nyos also poses a threat because its natural wall is weakening. A geological tremor could cause this natural dike to give way, allowing water to rush into downstream villages all the way into Nigeria and allowing much carbon dioxide to escape.

Source :http://www.askipedia.com/8-unusual-lakes-that-will-blow-your-mind/