Lake-killers – Rope around the Earth and other surprises of science
One August night in 1986 in villages near lake Nyos, located in a mountainous region of the African state of Cameroon, in the dream died just 1,700 people. The cause of their death was the lake, even though some unfortunates lived 25 kilometers from its shores. However, this distance was not enough to save them from a huge cloud of carbon dioxide that rose from the lake bottom and covered the neighboring hills and valleys, depriving oxygen all living beings on this territory and thereby causing them suffocation.
In this part of Africa there are three very unusual lake. One of them, Manon, two years before described the tragedy resulted in the deaths of 37 people, but the emission of gas from the bottom of Nyos was much worse. The third lake, Kivu, while never identified in the air is carbon dioxide, although in its waters this deadly gas dissolved, no less.
The hazardous nature of these lakes comes from their location — all they were formed in craters of volcanoes, and over the centuries carbon dioxide has leaked from the crater of the volcano and accumulated in bottom waters. In the other, smaller lakes gas in such cases due to the natural movement of water is distributed over the surface and then evaporates. But these three Cameroonian lakes of standing water and very deep, which creates increased pressure on underwater the gases and does not allow them to climb out, there is some sort of syphon soda. In fact, soda is carbon dioxide dissolved in the water. From time to time — usually after a storm or the landslide — a motionless layer of water with dissolved carbon dioxide is disturbed, and the lake at an alarming rate begins to emit gas; formed a giant bubble, which, when they reached the surface, turns into a cloud. First it rises a few tens of meters above the water, and then, being heavier than air, falls to the ground and spreads through the neighborhood. From lake Nyos was thrown into the air about cubic kilometers of gas (enough to fill 500 large stadiums), and spreading a cloud (or rather ran!) at a speed of 60 kilometers per hour. If lakeside were the sensors that feed an alarm, those of the dead who lived furthest away, would have been about fifteen minutes and some of them certainly have time to escape.
To avoid the repetition of disaster, the French scientists put into the lake two hundred meter plastic tube that reaches to the very bottom and removes carbon dioxide in the atmosphere, not allowing it to accumulate to a critical mass. Scientists from his laboratory in Paris watching the lake in satellite communications and in that case, if, despite precaution, the gas will approach the danger indicators could be used to open the pipe valves and vent the excess gas.
Unfortunately, a detailed examination of this strange lake has revealed another potential source of threat. On the North shore of the reservoir there is the old dam, a breakthrough which will cause flooding and the release of gas, which can choke up to ten thousand people.
Recent news is also not encouraging. Although the exhaust pipe and played a role, a team of scientists who visited lake Nyos in 2006, reported that the lake is still full of gas, representing for the local population in mortal danger, and he could erupt at any moment.