A.N.T.S

Limnic Eruption

The threat level for limnic eruptions is low, they can only occur in deep, stable, tropical, volcanic lakes such as Lake Nyos in Cameroon Africa.

<---Back to Index

A limnic eruption, also referred to as a lake overturn, is a rare type of natural disaster in which carbon dioxide (CO₂) suddenly erupts from deep lake water, suffocating wildlife, livestock and humans. Such an eruption may also cause tsunamis in the lake as the rising CO₂displaces water.

Scientists believe landslides, volcanic activity, or explosions can trigger such an eruption. Lakes in which such activity occurs may be known as limnically active lakes or exploding lakes.

Limnic eruptions can cause the following:

Asphyxiation

May also cause:

Lake Tsunami

After the eruption you will be faced with the rule of 3's basic survival skills

Protect yourself

Limnic eruptions only occur in deep, stable, tropical, volcanic 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

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 37 people living nearby. A second, deadlier eruption happened at neighboring Lake Nyos in 1986, this time releasing over 80 million cubic meters of CO₂ and killing between 1,700 and 1,800 people.

For a limnic eruption to occur, the lake must be nearly saturated with gas.

In the two known cases, the major component was CO₂, however, in Lake Kivu, scientists are concerned about the concentrations of methane gas as well.

The gas may come from

CO₂ may come from volcanic gas emitted from under the lake or from decomposition of organic material.

Once the lake is saturated with CO₂It is very unstable. A trigger is all that is needed to set off an eruption. In the case of the 1986 eruption at Lake Nyos, landslides were the suspected triggers, but an actual volcanic eruption, an earthquake, or even wind and storms are other possible triggers. In any case, the trigger pushes some of the saturated water higher in the lake, where the pressure is insufficient to keep the CO₂ in solution. Bubbles start forming and the water is lifted even higher in the lake, where even more of the CO₂ comes out of solution. This process forms a column of gas. At this point the water at the bottom of this column is pulled up by suction, and it too loses its CO₂ in a runaway process. This eruption pours CO₂ into the air and can also displace water to form a tsunami.

There are several reasons this type of eruption is very rare.

First, there must be a source of the CO₂, so only regions with volcanic activity are at risk.

Second, temperature lakes, such as North America's Great Lakes, turn over each spring and fall as a result of seasonal air temperature changes, mixing water from the bottom and top of the lake, so CO ₂ that builds up at the bottom of the lake is brought to the top where the pressure is too low for it to stay in solution and it escapes into the atmosphere.

Finally, a lake must be quite deep to have enough pressure to dissolve large volumes of CO ₂. So only in deep, stable, tropical, volcanic lakes such as Lake Nyos are limnic eruptions possible.

A.N.T.S

Main Navigation