A serene lake in Africa turned blood orange before it tragically killed nearly 1,800 people.
Lake Nyos, located in northwest Cameroon, became infamous for a tragic event in 1986, when a massive release of toxic carbon dioxide (CO₂) gas from the lake killed nearly 1,800 people and thousands of livestock in nearby villages.
This natural disaster, known as a limnic eruption, is one of the only known occurrences of its kind and highlights a rare but deadly phenomenon in certain volcanic lakes.
On the night of August 21, 1986, a sudden disturbance in Lake Nyos (possibly a landslide, volcanic activity, or gradual CO₂ saturation) caused the gas-rich deep water to rapidly rise to the surface.
This triggered a violent release of approximately 100,000 to 300,000 tons of CO₂ in a massive gas cloud that spilt over the lake’s edges and descended into the valleys below.
The gas cloud travelled down into the valleys below, suffocating people and animals over a 25-kilometer (15-mile) radius.
Survivors reported hearing a loud rumbling before losing consciousness or waking to find others dead.
Eyewitnesses recounted how the lake turned a blood-red colour as a sudden wind swept through, stirring up massive waves.
The colour change occurred when iron-rich water rose to the surface and oxidised upon contact with the air.
According to the witnesses, most people heard nothing apart from a smell of foul odour when the incident happened, reports The Sun.
One of the survivors, Joseph Nkwain from Subum, said: “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.”
Mr Nkwain tried to reach his daughter’s bed, but he collapsed and fell. He woke up the next morning when his friend came and knocked at his door.
He continued: “I opened the door. I wanted to speak, my breath would not come out. I went into my daughter’s bed, thinking that she was still sleeping My daughter was already dead.”
After the disaster, scientists from around the world began studying Lake Nyos to understand the cause and prevent future eruptions. They identified high CO₂ concentrations in the lake’s lower layers due to volcanic activity beneath the lakebed.
In response, degassing pipes were installed in the lake in 2001. These pipes allow for the controlled release of CO₂ from the lake’s depths to the surface, reducing the buildup of gas and the risk of another eruption.
The degassing efforts have continued, with more pipes installed over time to ensure the lake remains safe for nearby communities.
Besides the risk of another CO₂ eruption, Lake Nyos poses another danger: the natural volcanic dam that holds back its waters.
This dam is vulnerable to collapse, especially in the event of seismic activity or further erosion, which could lead to catastrophic flooding in downstream areas.
Efforts have been made to reinforce the dam and monitor its stability as part of a broader disaster-prevention strategy.