Cameroon’s Mysterious Crater Lakes

(Photo credit: Harri's Photography/Flickr Open/Getty Images)

Though picturesque, some crater lakes hide a deadly secret. (Photo credit: Harri’s Photography/Flickr Open/Getty Images)

August 21, 1986 started out as a normal day near Cameroon’s Lake Nyos. By the end of the day, however, 1746 people and 3500 livestock in the area would be dead. The cause of the catastrophe was, of all things, an exploding lake. But what caused the lake to explode? More importantly, could it happen again?

Lake Nyos, located in northwestern Cameroon, is a crater lake formed by subterranean volcanic activity. As a result of its origins, hot magma lies fifty miles beneath it. This hot magma releases carbon dioxide (CO2) and other gases. These gases flow upward into the natural spring waters that feed the lake. The CO2 is absorbed by the cold water that sinks to the lake’s bottom. In normal lakes, this carbon dioxide would be released as the lake water turns over as a result of seasonal temperature changes. The steady temperatures of Cameroon’s tropical climate, however, do not promote lake turnover. The result is that, over time, more and more carbon dioxide becomes saturated in the lake’s deep water. (The amount of CO2 that can dissolve in water is dependent on temperature and pressure.) Estimates show that more than five gallons of carbon dioxide were dissolved in every gallon of water in Lake Nyos back in 1986.

According to eyewitnesses to the event in1986, the normally clear waters of Lake Nyos turned a reddish-brown and a sudden wind arose that stirred up giant waves. An unknown trigger – possibly a landslide, small volcanic eruption, or cold rain – caused a limnic (lake) explosion. A fountain of water exploded 300 feet into the air as hundreds of thousands of tons of carbon dioxide escaped the lake at a speed of 60 miles per hour. This cloud of carbon dioxide suffocated living things located within a 15-mile radius of the lake. While carbon dioxide makes up 0.03 percent of the air we breathe, at concentrations greater than 10 percent, it can be fatal.

A similar event happened two years prior at another crater lake in Cameroon called Lake Monoun. Thirty-seven people died from the toxic gases during that limnic explosion.

To prevent a similar catastrophe from happening again, French scientists put into operation a plan to de-gas Lake Nyos. In 2001, the scientists installed a pipe that reaches to the lake bottom and lets gas escape at a regular rate, rather than allowing it to accumulate in the water. Ten years later, in 2011, scientists installed two additional pipes. In addition to the pipes, they also set up a solar-powered alarm system to monitor the carbon dioxide levels in the lake. If the levels exceed a certain amount, an alarm sounds to warn nearby villagers that they need to escape to higher ground. A similar venting pipe system was installed in Lake Monoun in 2003. While these measures may not totally eliminate the dangers that arise from carbon dioxide buildup, they at least heighten awareness, allowing residents to take the actions they feel necessary.

Country: Cameroon

Location: Cameroon is located in central Africa and is located between Equatorial Guinea and Nigeria.

Area: 475,440 sq km (land and water) (slightly larger than California)

Climate: The climate of Cameroon varies with its terrain; it is tropical along the coast and semiarid and hot in the north.

Terrain: The terrain of Norway includes mountains, plains, and coastal plains.

Natural Resources: Bauxite, hydropower, iron ore, petroleum, timber

Economics: $53.16 billion (est. 2013)

Environmental Issues: Waterborne diseases, desertification, poaching, overfishing, overgrazing, deforestation.

Source: CIA – The World Factbook (https://www.cia.gov/library/publications/the-world-factbook/geos/cm.html)

 

This article was originally published on EcoZine in November 2014.

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