Lake Nyos: The 1986 gas eruption that killed thousands

Forty years after the catastrophic event at Lake Nyos in northwest Cameroon, the disaster remains the most prominent example of a limnic eruption. On the night of August 21, 1986, a massive release of dissolved carbon dioxide from the lake's depths killed approximately 1,700 to 2,000 people and numerous animals.

Scientific investigations suggest that the release was triggered by a landslide or a minor earthquake, which disrupted the lake's stratified layers. This caused the CO2-rich deep water to rise, reducing pressure and allowing the gas to escape in a self-sustaining process. The Smithsonian estimates that roughly one cubic kilometer of magmatic carbon dioxide was emitted.

Because the gas is denser than air, it flowed down valleys and slopes at speeds of 60 to 100 km/h, displacing oxygen and suffocating those in its path. The event fundamentally changed the scientific understanding of the risks posed by volcanic lakes that store large quantities of dissolved gases.