One of only two recorded limnic eruptions in history, killing 1,746 people via a sudden CO2 release from Lake Nyos in Cameroon.
Key Facts
- Deaths
- 1,746 people killed
- Livestock killed
- 3,500
- CO2 released
- 100,000–300,000 tons
- Gas cloud initial speed
- ~100 km/h
- Lethal radius
- 25 km
- Date
- 21 August 1986
By the Numbers
Location
Cause → Event → Consequence
Lake Nyos, a crater lake in northwestern Cameroon, had accumulated dangerously high concentrations of dissolved CO2 in its deep waters over time. A limnic eruption—a sudden overturn of the lake—triggered the explosive release of this gas. The exact initiating mechanism, whether a landslide, volcanic activity, or other disturbance, remains uncertain.
On 21 August 1986, Lake Nyos underwent a limnic eruption, releasing an estimated 100,000–300,000 tons of CO2 in a sudden burst. The gas cloud rose at nearly 100 km/h before descending onto surrounding villages, suffocating people and livestock within a 25-kilometre radius due to CO2 being heavier than air.
The disaster killed 1,746 people and 3,500 livestock in nearby villages. In response, authorities installed a degassing system at Lake Nyos to gradually reduce dissolved CO2 levels and lower the risk of future eruptions. The event, alongside the 1984 Lake Monoun disaster, prompted scientific study of limnic eruptions as a distinct natural hazard.
Human Cost
Each dot represents approximately 10,000 deaths. Total estimated: 1,746 (other)