In 1986, a crater lake released a toxic gas that killed thousands of people. Experts believe this disaster can happen again as danger bubbles silently beneath the surface.
What Happened in Lake Nyos?
On the night of August 21, 1986, a rumbling noise was heard at Lake Nyos in Northwest Cameroon in central Africa. The following morning, 1,746 people and more than 3,500 livestock within 16 miles (25 kilometers) of the lake were found dead.
According to Ephriam Che, a farmer who lived in a nearby house on a cliff, he heard the strange sound at around 9 p.m. When he awoke the following day, he decided to go to a waterfall and discovered that it was strangely dry. The entire place was also eerily quiet, with no sounds from birds, animals, or even birds.
Che's attention was desperately called by a cowherd named Halima Suley. Around her were 31 members of her family and 400 cattle, all dead. As described by Che, there were no flies on the dead bodies because the flies were also dead.
Other members of the village had similar stories. What makes it weirder is that no sign of struggle was found among the residents. The only clue was the smell of rotten eggs and odd marks like burns on the bodies of both the dead and the living.
It was not clear what had happened. Some people believe the disaster was due to chemical attacks and other superstitious explanations. Others recalled seeing a cloud of gas rolling out from the lake at a tremendous speed.
Lake Nyos is a deep crater lake located on the slopes of the Massif du Mbam mountain range. It was known by local residents as the "good" lake because it provides clean drinking water. However, on that catastrophic night, Lake Nyos was responsible for one of the deadliest natural disasters in the history of Africa.
Read also: Lake Karachay Contamination: How Dangerous Is the Most Radioactively Polluted Place on Earth?
What Caused the Deadly Eruption?
Scientists went to Nyos to investigate the event. They did not only find bodies strewn everywhere, but they also noticed that the lake had changed color from blue to red. Those who survived suffered from diarrhea, vomiting, and hallucinations, all of which were symptoms of carbon dioxide poisoning.
Samples from the lake confirmed the real cause of the incident. Lake Nyos is a crater lake located along the Cameroon line of volcanic activity. Since it lies on a pocket of magma, its water is highly acidic due to CO2 spewing from the magma layer below.
Although the lake lies within an extinct volcano, magma still flows beneath it. The leaking CO2 from the magma layers is first dissolved in the natural springs and then mixed with the lake waters to form carbonic acid.
About 90 million tons of carbon dioxide is charged into the lake water from the magma layer. A natural dam holds the water of Lake Nyos in place. The wall is composed of volcanic rocks and measures 130 feet (40 meters) high and 148 feet (45 meters) wide.
It is not exactly known what disturbed Lake Nyos that day. Some experts claim that it was due to a landslide in the region, while others suspect a small volcanic activity below the lake.
The people and animals living around the lake are still not safe. Experts believe that outgassing events can happen every 10 to 30 years. Some also suggest an even earlier accident because the rapidly eroding natural dam might lead to reduced water pressure and a release of carbon dioxide.
Read also: Lake Abraham's Frozen Bubbles: How Did the Pockets of Methane Form and What Makes Them Deadly?
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