NWD/Floods/Lake Nyos Disaster
Floods Dec.09.2020 78

Lake Nyos Disaster

Expeditions of scientists complete the investigation of the case that occurred on August 21, 1985. This day, a cloud of asphyxiant gas passed over the northern shores of Lake Nios in western Cameroon, and the lake Nyos explosion happened, leaving 1746 dead. There were almost no residents left in the village of Nyos, Subum, Cha, and Fang, and all livestock, poultry, and even insects were killed.

Since this lake is located in the crater of the volcano, which was thought to be asleep, many researchers who came here soon after the tragedy suggested that the volcano came alive and the poison gas released by the eruption and poisoned all living things in its path.

Surveys conducted by expeditions from Italy, France, Japan, Nigeria, Switzerland, the USA, and Great Britain found that vegetation along the shores of the lake was affected. In some places, the leaves turned black and faded away like during the cold. The conclusion was made: this is a consequence of the lake Nyos limnic eruption, gas expanding, cooled down, and froze the leaves.

It is known that the release of dissolved in water carbon dioxide CO2 goes with the absorption of energy and, accordingly, causes cooling. In this case, the cooling may have been 10 degrees. The first attempts to take chemical samples of deep water turned out to be unsuccessful: while lifting vessels exploded due to the high pressure of gases contained in them. It was only possible to do so with the slower lifting of vessels with an open valve. The on-site analysis showed that 99.6 percent of dissolved gases represented carbon dioxide, besides, the samples contained methane and a small amount of helium.

The analysis carried out in laboratory conditions by German scientists allowed us to conclude: immediately after the catastrophe, the lake waters contained about 250 million cubic meters of CO2. The isotopic composition of oxygen and carbon confirms that the gases arrived here, seeping from the depths of the earth. New measurements made in April 1992 say that CO2 continues to enter the lake – about five million cubic meters a year.

All this contradicts the testimony of survivors, who claim that at the time of the disaster, they smelled rotten eggs or powder and allegedly heard the sound of an explosion. Such phenomena could have been accompanied by an explosive volcanic eruption. But it would inevitably disrupt a powerful layer of sedimentary bedrock, which is deposited very slowly. At the same time, none of the taken water samples contained sediments, and there were no sulfur gases.

Carbon dioxide is believed to be odorless but has a mild acidic taste because it forms carbon dioxide in the mouth. English researchers note that there are no separate words for “smell” and “taste in all six languages spoken by the inhabitants of the Lake Nios neighborhood. Therefore, these sensations could be transmitted by the same word “smell” when translated. Also, it is difficult to explain why some residents of Subum village, located 10.4 kilometers from the lake, claim to have simultaneously heard the rumble of an explosion and felt the “bad smell,” although the gas cloud could travel this distance in half an hour and the sound in 32 seconds.

Limnic eruption Nyos victims went quickly in mass graves, without carrying out an autopsy. Doctors, even the native Cameroonians living in the capital of the country, do not speak local languages, and symptoms of those who suffered the tragedy are described only approximately. It is noted, however, that some of the victims had blisters on their bodies. Volcanologists took this as evidence of exposure to hot or acid gases released by the eruption. But in living, they were only superficial and healed quickly.

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