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Killer lakes of Africa

Lakes can explode releasing deadly clouds of volcanic gases.

After a busy market day, on August 21, 1986, the people of the village of Lower Nyos (Cameroon) went to bed early. In the night there was a strange sound, like a distant explosion. More than 1.700 people died that night. Unharmed corpses of people and animals were lying everywhere. Not even insects had been spared.  In the first days after the catastrophe, everybody struggled to understand what had happened. Rumors of secret government experiments, strange invisible superweapons and stories of atomic bombs soon started to circulate.

Survivors later reported the stench of an unusual smell and seeing a white-translucent cloud. The killer was a strange volcanic phenomenum. When the cold, gas-rich water, from the bottom of the lake, reached the surface an explosive degassing of 1.6 million tons of carbon-dioxide occurred, forming a 160 feet high cloud. The invisible and odorless carbon dioxide was heavier than normal air and the cloud descended quickly from the slopes of Nyos, filling the surrounding valleys and covering the villages with an asphyxiating blanket of carbon dioxide.

Lake Nyos is located in the Cameroon Volcanic Line, a 950 mile long chain of volcanoes and crater lakes extending from the Gulf of Guinea into Cameroon and Nigeria. Lake Nyos is one of three deadly lakes that lies on the  border of Rwanda and the Democratic Republic of the Congo. In that chain is also Lake Monoun and Lake Kivu.

All three crater lakes sit above volcanic earth. Magma below the surface releases carbon dioxide into the lakes, resulting in a deep, carbon dioxide-rich layer right above the lakebed. That carbon dioxide can be released in an explosion, asphyxiating any passersby.

The origin of this unusual collection of gasses is not completely understood. It’s possible that during the beginning breakup of Africa from South America a third rift zone started to develop, with some volcanic activity in it, but in the end failed to become a real rift and oceanic basin like the Atlantic Ocean. There is still a large magma chamber to be found in a depth of 50 miles under most of the Cameroon Volcanic Line. From this magma chamber large quantities of gas are released.

It is unknown when the next erruption will occur.

 

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