Volcano Journal Entry

Gas Released from Volcanic Lake (February 24, 2003)

Scientists recently began siphoning off potentially deadly carbon dioxide gas from volcanic Lake Monoun in northwestern Cameroon. They set up a fountain that lets the gas bubble up from the depths of the lake.

The project will release gas that has built up in the lake since a deadly explosion of carbon dioxide nearly twenty years ago. A similar project is underway at nearby Lake Nyos (in photo at right), another volcanic lake in Cameroon.

Carbon dioxide gas suddenly exploded from Lake Monoun in 1984, sending out a cloud of poisonous fumes that killed thirty-seven people in a nearby village. Two years later, an even more deadly explosion of carbon dioxide erupted from Lake Nyos. About 1,700 people were killed in that blast.

In normal concentrations, carbon dioxide is harmless. But huge, highly concentrated clouds of the gas shot from the lakes in the 1984 and 1986 explosions. Because carbon dioxide is denser than air, the gigantic clouds of gas settled like dense fog over populated valleys in the surrounding area. The thick layers of gas killed people by suffocation.

A chain of dormant, flooded volcanoes runs from the Atlantic Ocean to the border between Cameroon and Nigeria. Carbon dioxide from magma eventually seeps into the volcanic lakes and builds to high concentrations. The gas is suddenly released when the waters are stirred. This can happen from an event such as a landslide or an earthquake. The effect is similar to what happens when a soda bottle is shaken.

Both Monoun and Nyos formed about 400 years ago as rising plumes of hot magma collided with groundwater and triggered violent steam explosions. This formed craters that later filled to become lakes.