Limnic eruption

A limnic eruption, also referred to as a lake overturn, is a rare type of natural disaster in which dissolved carbon dioxide (CO₂) suddenly erupts from deep lake waters, forming a gas cloud that can suffocate wildlife, livestock, and humans. Such an eruption may also cause tsunamis in the lake as the rising CO₂ displaces water. Scientists believe earthquakes, volcanic activity, or explosions can be a trigger for such phenomenon. Lakes in which such activity occurs may be known as limnically active lakes or exploding lakes. Some features of limnically active lakes include:

Scientists have recently determined, from investigations into the mass casualties in the 1980s at Lake Monoun and Lake Nyos, that although limnic eruptions can be indirectly related to volcanic eruptions, they are actually separate types of disaster events.

To date, this phenomenon has been observed only twice. The first was in Cameroon at Lake Monoun in 1984, causing the asphyxiation and death of 38 people living nearby. A second, deadlier eruption happened at neighbouring Lake Nyos in 1986, this time releasing over 80 million cubic metres of CO₂ and killing around 1,700 people and 3,500 livestock, again by asphyxiation.

Due to the nature of the event, it is hard to determine if limnic eruptions have happened elsewhere. A third lake, Lake Kivu, exists on the border between the Democratic Republic of the Congo and Rwanda, and contains massive amounts of dissolved CO₂. Sample sediments from the lake were taken by professor Robert Hecky from the University of Michigan, which showed that an event caused living creatures in the lake to go extinct approximately every thousand years, and caused nearby vegetation to be swept back into the lake. Limnic eruptions can be measured on a scale using the concentration of CO₂ in the surrounding area.

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