Lake-killer Nyos

Lake Nyos (also Nyos) is located in Cameroon (Central Africa), near the border with Nigeria. The depth of the lake is quite impressive-209 meters, and its area is about 1.6 square kilometers.

As the researchers suggest, this high-altitude lake was formed in the collapsed crater of an extinct volcano, which was filled with surface and underground water about 400 years ago. It is with the volcanic origin of the lake that the terrible events that led to the death of more than 1,700 people and several thousand animals are connected.

This event, later called the limnological disaster of Lake Nyos, occurred on August 21, 1986. Then, in one night, most of the population of the nearby villages of Nyos, Subum, Cha and Fang died. 1746 people did not wake up on that fateful August morning, and about 1000 Cameroonians sought medical help. All domestic animals, birds and even insects in the vicinity of the lake were killed.

The cause of death of people and birds was the reservoir, or rather what was hidden under it. The thing is that the volcano went out only on the surface. But in the depths, under Lake Nyos, there is a hotbed of volcanic activity that produces a huge amount of carbon dioxide-CO2. The resulting gas is constantly rising up through the pores in the igneous rock. Then it meets with ground water, dissolves in them and enters the reservoir.

Toxic gases accumulate in the bottom layers of Lake Nyos, which for some reason do not mix with the upper layers. The gas continues to saturate the deep layers of water until some external event disturbs this delicate balance.

On that dreadful evening, something disturbed the peace of Lake Nyos. It was an earthquake or a strong gust of wind, it is now difficult to say, but the bottom layers of water, saturated with deadly carbon dioxide, rose to the top.

The gas that burst to the surface in giant bubbles created powerful waves that flooded the lowlands on the southern coast. According to the researchers, carbon dioxide and the accompanying moisture turned into a fine mist that formed a cold aerosol. A toxic cloud of carbon dioxide, which is heavier than air, began to drain into the valleys surrounding the lake, killing all living things along the way. Some experts note that, in addition to carbon dioxide, the toxic cloud could contain sulfur and hydrogen.

Immediately after the tragedy, the waters of the lake turned red-brown.

After the incident, several expeditions with scientists from different countries arrived at Lake Nyos. As a result of research conducted immediately after the tragedy, it was possible to establish that in addition to people and animals, vegetation along the shores of the lake also suffered. The foliage had darkened and shrunk, as it does when exposed to low temperatures. Based on this, it was concluded that the gas released from the depths of the lake, during expansion, cooled and froze the foliage.

It is known that the release of carbon dioxide is accompanied by the absorption of energy and, accordingly, causes cooling. According to scientists, the air temperature around the lake could drop to 10 degrees in a short period of time.

Having appreciated the horror of what happened, the Cameroonian authorities took care to prevent similar disasters in the future.

It is interesting that in addition to Lake Nyos in this country there is another similar reservoir, also of volcanic origin, called Manun. On it, a few years before the tragedy on Lake Nyos, a similar case occurred, which claimed the lives of 37 people.