Video: 'The Lake Nyos Disaster: The Silent Death That Killed Hundreds'

(Thursday, August 21, 1986, 9:30 p.m. West Africa Time) — A sudden release of carbon dioxide from Lake Nyos in northwestern Cameroon killed 1,746 people and about 3,500 livestock tonight in one of the deadliest natural disasters in the country’s history.

The disaster occurred when an estimated 100,000 to 300,000 tons of carbon dioxide erupted from the volcanic lake in what scientists call a limnic eruption.

The gas initially surged from the lake at an estimated 62 mph before spreading across the surrounding countryside. Because carbon dioxide is heavier than air, the cloud settled over nearby villages, displacing oxygen and suffocating people and animals as far as 16 miles from the lake.

Many victims died in their homes or while sleeping, with entire communities affected by the otherwise invisible gas.

Scientists later determined that carbon dioxide had accumulated in the deep waters of Lake Nyos over years, dissolved under pressure from volcanic activity beneath the lake. The sudden release turned the normally placid lake into the source of a massive, deadly gas cloud.

A similar disaster had occurred two years earlier at Lake Monoun, also in Cameroon.

Following the Lake Nyos disaster, authorities and scientists installed a degassing system designed to gradually release carbon dioxide from the lake’s deep waters and reduce the risk of another catastrophic eruption.

The Lake Nyos and Lake Monoun disasters remain the only two recorded limnic eruptions in modern history.