How a lake in Africa killed 1,746 people in a matter of minutes (and how it could happen again)
The night of August 21, 1986, passed like any other around Lake Nyos, a volcanic crater lake located. On the flank of a dormant volcano near Mount Oku in northwestern Cameroon. Some local village residents huddled around cooking fires, enjoying a late supper. Many others, tired from a busy day at the market, were already sleeping in their humble huts.
Around 9:30 pm, those who remained awake heard something similar to an explosion coming from Lake Nyos. Within minutes, nearly 1,800 people would be dead.
That night, Lake Nyos ejected a jet of water more than 90 meters high. At the same time releasing carbon dioxide that had accumulated in the lake for years. A cloud of gas rose into the sky before descending over the hills and heading towards the unsuspecting villagers. There was little chance of escape with about 1 km³ of gas traveling at almost 50 km/h. The hot cloud of carbon dioxide displaced the air as it passed the cabins. Suffocating almost everyone it contacted until it finally dissipated.
Locals knew lake Nyos as “the good lake” for its clean drinking water. But that night in 1986, he was responsible for one of the deadliest natural disasters in African history.
A rare natural phenomenon
Nyos, the town closest to the lake, was the most affected. The next day, a man who traveled to Nyos on his motorcycle found. The town littered with the corpses of people and animals. He couldn’t find anyone alive.
Some people lay unconscious for two days, only to find their entire family dead.
As word of the disaster spread, scientists flocked to Cameroon to understand what had happened. Testing the water soon revealed that the lake had unusually high carbon dioxide levels. These were so high that when the scientists tried to bring the water samples to the surface. The pressure of the gas caused the containers to burst.
They theorized that carbon dioxide had accumulated at the bottom of Lake Nyos until something disturbed it. That disturbance set off a chain reaction that forced gas out of the lake bottom into the atmosphere. Therefore, In a rare natural phenomenon called a limnic eruption.
In the months that followed, American chemists investigating the phenomenon found carbon dioxide levels. So Lake Nyos was rising at an alarming rate.
Geologists from Cameroon’s Ministry of Mines, Water, and Energy have proposed installing a system of pipes. The lake, is designed to allow the controlled release of carbon dioxide from its bed to the surface. Starting with small pipes about the diameter of a garden hose, scientists began testing the idea in 1990. Switching to progressively larger pipes in subsequent years. Their villages has destroyed to prevent them from returning.
Although the pipes provided a temporary solution, 5,500 tons of carbon dioxide is still accumulating each year. In Lake Nyos from the magma chamber far below the volcanic line where the lake’s crater is located. Finally secured funding to install the first permanent pipeline in 2001, followed by two additional pipelines in 2011. It took another five years for carbon dioxide to reach levels safe enough. For villagers to return and rebuild their communities, three decades. after the disaster.
The threat of killer lakes
It is unknown what caused the limnic eruption of Lake Nyos. It could have been something as small as a rock falling into the water. Or even a strong gust of wind. Once scientists began to figure out what might have caused the disaster, they began looking for cases of similar eruptions. It didn’t take them long to find one.
Just two years earlier, at Lake Mimony, about 150 kilometers from Lake Nyos, nearby villagers heard a loud crash. In the hours that followed, 37 people mysteriously died. Until then, the strange occurrence had not attracted much attention. But in light of the Lake Nyos disaster, the problem was more significant than anticipate.
Scientists now believe that only three lakes in the world accumulate. such lethal levels of carbon dioxide in their depths. Nyos, Mimony, and Lake Kivu in Congo and Rwanda.
While Lake Nyos and Lake Mimony have declare safe, the same cannot be said for Lake Kivu. About 2 million people live in the lake’s valleys, 1,700 times larger than Lake Nyos and twice as deep. Although Rwanda has begun to use methane from Lake Kivu as a source of energy. Large-scale efforts to remove the gas from the lake altogether have not yet been made. Until that happens, history threatens to repeat itself as danger quietly bubbles under the surface.