People of Cameroon, especially those who live along the shores of Lake Nyos know very well the story of an evil spirit which emerged from the lake killing all those who lived near it.
While this was a legend shared and passed across from one generation to another, the truth of the matter was, “the Bad Lake” was in actual fact a killer lake that at one point in its wake, killed more than 1, 700 people and animals around the lake.
On August 21, 1986, Lake Nyos experienced one of the strangest natural disasters in history, from which over 1,746 people suffocated in one night.
How did this happen?
Scientific reports connote that Lake Nyos was formed in a volcanic crater created about 400 years ago. Crater lakes normally contain high levels of carbon dioxide (CO2) formed by the volcanic activity happening miles beneath them. Under normal circumstances, this gas is released over time as the lake turns over.
That is not how Lake Nyos worked, however: instead of releasing the gas, the lake was storing it, dissolving the CO2 in the calm waters. Pressurized to the physical limit, Lake Nyos was a bomb in waiting.
On a fateful night, something triggered a commotion in the lake. It is not known what the prompt was- landslide, small volcanic eruption, or small cold rain falling on an edge of the lake. Whatever the cause, the effect was catastrophic.
The lake exploded like a bomb it was, sending a fountain of water over 300 feet into the air creating a mini-tsunami. Although the water was lethal, more fatal was the gas that masked the countryside. This kind of explosion is known as a Limnic Eruption.
In about 20 seconds, some 1.2 cubic kilometers of carbon dioxide was released into the atmosphere. The result was instant death as oxygen was squeezed out of the affected areas. The wave of the poisonous gas spread in the villages around the lake. All fire and flames were immediately extinguished spelling doom in the area.
In a matter of minutes, people and animals perished. The villages of Nyos, Kam, Cha and Subum were wiped out. In a nearby village, out of 800 people only six survived, and according to a report, those who did survive, escaped to higher ground on motorcycles.
Many people died in their sleep without ever knowing what hit them. Others met their death at their doorsteps, on their way out to find out the cause of the loud sound they had earlier heard.
In that period, the normally calm and clear blue waters turned into a deep red as if symbolizing the number of people and animals it had swallowed in the violence. Science, however, explains that the deep red color was a result of iron stirred up from the bottom.
Efforts to degas the lake to avert future disasters
In a bid to avert future explosions, the lake needed to be degassed especially because deeper studies of the lake revealed that there was more CO2 forming at the depth in the lake that could react again.
In 2001, an electronic pump that would simulate an eruption was sunk in an effort to degas the lake. A pipe has been installed in Lake Nyos that runs vertically between the lake bottom and the surface. The pipe allows the gas to escape at a regular rate. Due to the pressurized nature of the gas, the water comes out of the vent in a rather lovely CO2- powered jet of water.
While this has been working over the years, there is a need to do more because according to reports, the CO2 saturation in the lake has gone high again. If it exploded, it would cause a double disaster of both flooding and gassing simultaneously.
Lake Kivu in Rwanda, which also happens to be created through volcanic explosions just like Lake Monoun (Cameroon) has been shown to have a historical record of causing creatures in the lake to go extinct approximately every a thousand years. According to scientists, a volcanic disturbance on the lake could cause much more harm and destruction than witnessed in Nyos.
But the Rwandan government with support from foreign organizations are exploiting the lake’s underneath resources such as methane to produce electricity. By so doing, Rwanda is reducing the pressure from below the lake with an aim of reducing the risk of a catastrophic event. If an explosion ever happened at Lake Kivu, more than 2 million that live along the shores would succumb to the deadly gasses.
For now, the three lakes are still and nobody knows when the disaster will strike again. Governments and foreign organizations are however employing every effort necessary to avert the calamities that could be brought about by explosions in the volcanic lakes.
Image credit USGS