Did you know that lakes can literally explode? A limnic eruption, also known 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 capable of suffocating wildlife, livestock, and humans.
A limnic eruption may also cause tsunamis as the rising CO2 displaces water. Scientists believe earthquakes, volcanic activity, and other explosive events can serve as triggers for limnic eruptions. Lakes in which such activity occurs are referred to as limnically active lakes or exploding lakes. Some features of limnically active lakes include:
- CO2-saturated incoming water
- A cool lake bottom indicating an absence of direct volcanic interaction with lake waters
- An upper and lower thermal layer with differing CO2 saturations
- Proximity to areas with volcanic activity
Investigations of the Lake Monoun and Lake Nyos casualties led scientists to classify limnic eruptions as a distinct type of disaster event, even though they can be indirectly linked to volcanic eruptions.
Due to the largely invisible nature of the underlying cause (CO2 gas) behind limnic eruptions, it is difficult to determine to what extent eruptions have occurred in the past. In recent history, this phenomenon has been observed twice. The first recorded limnic eruption occurred in Cameroon at Lake Monoun in 1984, causing asphyxiation and death of 37 people living nearby. A second, deadlier eruption happened at neighboring Lake Nyos in 1986, this time releasing over 80 million m3 of CO2, killing around 1,700 people and 3,500 livestock, again by asphyxiation.
A third lake, Lake Kivu, rests on the border between the Democratic Republic of the Congo and Rwanda, and contains massive amounts of dissolved CO2. Sediment samples from the lake taken showed an event caused living creatures in the lake to go extinct around every 1000 years, and caused nearby vegetation to be swept back into the lake. Limnic eruptions can be detected and quantified on a CO2 concentration scale by taking air samples of the affected region.
The Messel pit fossil deposits of Messel, Germany, show evidence of a limnic eruption there in the early Eocene. Among the victims are perfectly preserved insects, frogs, turtles, crocodiles, birds, anteaters, insectivores, early primates, and paleotheres.
