1,746 people suffocate in disaster caused by lake in Africa

Cameroon is a country located in central Africa. There are several lakes within its borders, among which the more famous ones are Lake Nios and Lake Monone.

In Africa, people like to build villages and tribes around lakes, because lakes can provide some convenient survival resources.

But what is interesting is that although these lakes in Cameroon have brought survival resources to nearby villages, there are also some deep-rooted fears for local residents.

There are often similar legends circulating in the villages around these lakes, which probably means that the legendary demon lives in the lake. inhabitants and livestock.

Many legends may not be groundless. On the night of August 21, 1986, the "devil" of Lake Nios in Cameroon really appeared, resulting in the death of 1,746 people and more than 3,500 livestock.

According to survivors' recollections, they heard a "rumbling" sound, and at the same time, a foam spurted out of the lake and gathered into a "white cloud" on the water, and the spray column stretched from the water to 100 height in meters.

This scene seems to be a bit similar to the scene in "Journey to the West" when the goblin appears.

Then, the "white clouds" began to sink and flowed into the residents' residences. Residents in the affected areas fell to the ground one after another, some at home, some on the road, and some in the wild...

The residents who fell to the ground lost consciousness almost instantly, or suffocated to death within a few minutes. What is even more frightening is that the area covered by the "clouds" extends to about 25 kilometers around the lake. Within the coverage area, there is almost no animal activity. sound.

The cloud and fog basically disappeared until August 23, and the silence was lifted. People in the surrounding areas also began to enter the valley to check. They found that the dead bodies of people and livestock were lying on the ground everywhere.

In addition, the people who came back also found that the calm lake surface, which was originally beautiful blue, turned deep red, as if it was dyed red by blood. At the same time, the lake surface dropped by about 1 meter, and the trees around the lake were also damaged. Knocked down, really like a monster crawling out of the bottom of the lake.

In this disaster, in addition to those who fled, there were some survivors who woke up after being in a coma for more than 36 hours, but their family members and neighbors were basically dead, and the disaster left them with some permanent disability , some people can no longer live a normal life afterwards.

So, what is the "devil" in Lake Nyos? Why is it possible to take people's lives quietly?

Survey Results: Higher is Safer

This kind of thing quickly attracted the attention of scientists. Biologists and geologists from many countries came here to conduct field investigations. They soon found that people and livestock died of suffocation, and the culprit was carbon dioxide.

If the clouds contained high levels of carbon dioxide, then that could explain what the local residents saw.

Because carbon dioxide is denser than air (1.5 times that of air), the clouds that are sprayed high into the sky begin to sink and dissolve into the surrounding air within 25 kilometers.

Of course, carbon dioxide is not toxic to people, but when the concentration of carbon dioxide in the air is higher than 15%, people will feel suffocated after taking a few more puffs, and gradually lose consciousness, and they will suffocate and die in a few minutes.

This is because carbon dioxide is the waste gas of our life activities, and when it is above a certain concentration, we cannot breathe.

To figure out why carbon dioxide leaked from the bottom of the lake, geologists probed the bottom of Lake Nios with instruments and found a layer of rock rich in carbon dioxide.

The gas content of this layer will gradually rise over time, and then slowly dissolve into the lake water. Since the depth of Lake Nios reaches at least 206 meters, the pressure of the bottom lake water is very high.

The solubility of carbon dioxide increases with pressure, and the deeper the lake, the more carbon dioxide the water at its bottom can dissolve.

One of the descriptions of the survivors caught the attention of scientists—the lake surface changed from blue to red. Through investigation, it was found that the source of the red color was that iron was oxidized to iron oxide (Fe2O3) in the air.

The bottom of Lake Nios is rich in iron, so this event is likely due to some external force that eventually caused the water at the bottom of the lake to overturn.

Moreover, the upturning of the water at the bottom of the lake also explains the source of carbon dioxide, because the water at the bottom of the lake that originally dissolved carbon dioxide loses pressure after the upturn, which will lead to the release of carbon dioxide supersaturation.

Through the descriptions of the survivors, scientists even restored the process of the event, including how much carbon dioxide was released in total by the event.

The entire process releases about 100,000 to 300,000 tons of carbon dioxide, which may initially rise at 100 kilometers per hour before sinking rapidly.

After reaching the lake, it spreads around at a speed of 20-50 kilometers per hour. That is, 5.6-13.9 m/s. It is estimated that it is difficult for ordinary people to run faster than the movement speed of carbon dioxide in this event.

However, the higher you stand, the safer it is, because the carbon dioxide is denser and it moves along the ground, so in fact more than 4,000 people in several villages in total were unharmed or fled in this incident.

The incident is very clear here. The "devil" in Lake Nios is carbon dioxide, which has been lurking at the bottom of the lake, but there are many theories about what external force caused the water originally at the bottom of the lake to overturn.

Why is the carbon dioxide dissolved at the bottom of the lake suddenly released?

A huge landslide on the edge of Lake Nios still caught the attention of scientists, and the "rumbling" heard by survivors may have been created by the landslide.

They speculate that the landslide likely created a wave more than 25 meters high on the lake, which pushed toward the lake and eventually knocked down trees along the lake.

In addition, the material that fell to the bottom of the lake turned the water upside down, eventually causing the carbon dioxide dissolved in the lake to leak and causing disaster.

But why do landslides happen for no reason?

There are now three views - rain, earthquakes and volcanic eruptions.

Of course, I personally prefer to believe it was a small volcanic eruption, because according to some survivors, they also smelled some pungent odors before losing consciousness, which are likely to be gases such as sulfur dioxide and hydrogen sulfide , and these gases are often accompanied by volcanic eruptions.

In addition, this also explains why the lake level drops by 1 meter, because the volcanic eruption can easily create a crack in the bottom of the lake, and the lake water will pour into it.

at last

Now this kind of natural disaster is called "lake eruption", the name is quite vivid, but it is very rare.

It is not an easy task to release the carbon dioxide dissolved in the high-pressure lake bottom water without pressure. It needs to meet many conditions. In addition, those lakes that are not very deep cannot cause such a disaster at all.

However, it is a bit surprising that a lake that was originally very calm and that the nearby residents depended on for survival can suddenly create a 100-meter-high spray column and then take lives silently.

This may be nature, and we need to have a basic sense of awe.