It sounds like a bad horror movie: exploding killer lakes. But such lakes are a reality in Cameroon, Africa. Scientists there are developing a solution, however, to stop the natural hazard.
In 1986, Lake Nyos in Cameroon exploded with a deadly cloud of carbon dioxide. Since then, researchers have been working to lower the carbon dioxide concentration in the lake by running an exhaust pipe 24 hours a day, expunging the lake of its extra gas, like the uncorking of a champagne bottle. Image courtesy of George Kling.
In 1984 and 1986, volcanic lakes Monoun and Nyos, respectively, silently erupted poisonous columns of carbon dioxide that swept out of their craters and into the valleys below — asphyxiating thousands of animals and 1,800 people along the way. “It came as a total surprise to everyone,” says Johan Varekamp, a geologist at Wesleyan University in Middletown, Conn. “Exploding lakes were a hazard we didn’t even know about,” he says. Since then, scientists have found only one other lake with similarly high concentrations of carbon dioxide and methane: Lake Kivu, also in Africa, may have similarly burst in the past several thousand years.
The carbon dioxide and methane in Monoun and Nyos, which have reached saturation levels of 97 percent, originate from magma deep beneath the lakes. The lakes are layered, with heavy carbon dioxide-laden waters at depth, topped by distinct layers of successively less concentrated waters. The climate in the area is not conducive for mixing, so the lakes stay layered unless something disturbs them, as happened in the 1980s (though scientists still do not know the exact cause of that disturbance).