Once upon a time
One of the horrible and mysterious natural disasters in history happened at Lake Nyos on 21 August 1986. The strange thing is, the real cause behind that disaster remaining unexplained till now.
There was a small lake in Nyos- a village in the north-west region of Cameroon, which atop a volcanic crater. On 21 august 1986, the lake released thousands of tonnes of toxic carbon dioxide ranging from 300,000 up to 1.6 million without any natural warning. This silent death cloud spread all over the countryside at nearly 100 km/h.
How horrible was the plague?
It’s one of the most gut-wrenching natural events in recorded history. The effect was as devastating and swift. It killed locals and wildlife by eliminating oxygen from air within a 25-km radius of the lake. Many people from the villages of Cha, Nyos, and Subum were silently asphyxiated in their sleep. Some were found with blood around their noses and mouths. It suffocated an estimate of 1,746 people and more than 3,500 livestock within minutes. The trigger was silent, but the effects were catastrophic.
When the few remaining survivors woke up, they found no disturbances, no violence, just corpses. Even the flies had dropped dead. Reporters in the area described that it looks like an aftermath of a neutron bomb.
Joseph Nkwain, who woke up 3 hours after the cloud hit, recounted the experience to researchers. “I could not speak. I became unconscious. I could not open my mouth because then I smelled something terrible. I heard my daughter snoring in a terrible way, very abnormal. When crossing to my daughter’s bed … I collapsed and fell. My arms had some wounds; I didn’t really know how I got those wounds. I wanted to speak, but my breath would not come out… My daughter was already dead.”
What do we know?
At the time, researchers determined that Lake Nyos had released a massive amount of CO2 at around 9 pm. Since CO2 is heavier than the surrounding air, it quickly sunk into the valleys below, blanketing everything in a sheet of toxic gas 50 meters thick. Volcanic gases emanating from the ground below the lake dissolve and become concentrated in its deepest waters, and the tropical temperatures form a sort of ‘cap’ of warm water above this cooler water. It’s not clear what ‘broke the seal’ and allowed the deep, contaminated water to rise. But it could have been an earthquake, a landslide, or a volcanic eruption, or even something as simple as heavy runs muddling the water levels.
In the absence of a scientific explanation, conspiracy theories reared their inevitable heads, with some locals convincing themselves that the eruption had been triggered by an undisclosed bomb test, carried out by the Israeli and Cameroon governments.
The current problem
The natural wall surrounding Lake Nyos started to weaken. A dam has since been built around the wall to protect it. But researchers think that in future, a lake overflow may happen and it can cause instant disaster.