There Is a Lake That Explodes

Deep volcanic crater lakes can act like massive, naturally occurring soda bottles. Far below the surface of Lake Nyos, a pocket of magma steadily released carbon dioxide directly into the lake's bottom layers. For centuries, the immense pressure of the water (Review) above kept this gas dissolved and trapped. The lake’s water remained stratified, with a cold, dense, gas-rich layer at the bottom and a lighter, fresher layer on top, preventing the gas from escaping. This delicate balance, however, was a disaster waiting to happen.

On August 21, 1986, a trigger—likely a landslide or a small volcanic tremor—disrupted these layers. This event violently "uncapped" the lake, causing the dissolved CO2 to erupt out of the water in a massive, effervescent explosion. The resulting cloud, estimated to be over 100 meters thick, was heavier than air. It silently swept down the surrounding valleys at nearly 100 kilometers per hour, displacing oxygen. With no warning, the invisible gas suffocated thousands of people and animals in their homes and fields.

To prevent a recurrence, scientists have since installed large pipes in Lake Nyos to continuously and safely siphon the gas-rich water from the bottom to the surface. This allows the CO2 to be released in small, harmless amounts, averting the buildup that led to the 1986 catastrophe. The event served as a stark warning, as other lakes around the world, like the much larger Lake Kivu, pose a similar and even greater threat.