A Lake that Killed 1,700 People and 3500 livestocks overnight, and the reason still unknown


 

                                                                                            Photo courtesy U S. Geological Survey

Lake Nyos is a crater lake in the northwest region of Cameroon, located about 315 km northwest of Yaounde, the capital. On 21 August  night, 1986, one of the strangest and most mysterious natural disasters in history took place at Lake Nyos. The lake released thousands of tonnes of  carbon dioxide gas that spread out over the area choking to death around 1700 humans and 3500 livestocks within minutes. Many people were silently asphyxiated in their sleep. When few survivors woke up from suffocating, they found only dead bodies of their kith and kin. 


    Photo courtesy BBC UK

Scientists explain that probably a limnic eruption has occurred on that night in Lake Nyos. limnic eruption is a rare type of natural disaster in which carbon dioxide dissolved in the deep lake waters suddenly erupts and forms a gas cloud over the area suffocating people and animals. 


Usually, tonnes of carbon dioxide are contained in the lake in its deepest waters. However, on that fatal night, something at around 9 pm  activated the release  of an enormous amount of CO2 and because CO2 is heavier than the surrounding air, it quickly sunk into the valleys below, blanketing everything in the sheet of toxic gas. It is one of the most tragic natural events  recorded, and scientists still could not explicate what precipitated it. The trigger could have been an earthquake, a landslide, or a volcanic eruption.

To prevent these limnic eruptions in future, in 2001,  pipes were installed in the lake so that CO2 emanating from the lake bed could be released into the air gradually.

Again in 2011, more pipes were installed after scientists warned of a probable gas burst that could be bigger than the earlier disaster.

Later researchers found that the natural wall surrounding Lake Nyos has started to weaken causing concern to people of another disaster.  A dam has since been built around the wall of Lake Nyos to protect it. Despite these preventive measures, the lake is still considered by many experts as dangerous.

 





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