The April 2001 issue of Earth Pages News (Taming Lake Nyos, Cameroon) announced attempts to release CO2-rich water from the bottom of the notorious Lake Nyos, by setting in motion a sort of soda siphon. A massive discharge of gas from Lake Nyos in 1986 killed 1700 local people, possibly after a small earthquake and landslide disturbed the bottom water. Nearby Lake Monoun had already asphyxiated 37 people two years previously. Both lakes are stagnant, and carbon dioxide released by exhalation from deep magma chambers dissolves under pressure in their deepest levels. If the water rises, then it belches out dissolved gas, with potentially disastrous results. Taming these killer lakes by bringing gas-rich water up pipes works because as the gas bubbles out of solution it rushes up the pipe dragging water with it, to create a fountain. This is slowly relieving the danger of Lake Nyos, and there have been no problems caused by disturbing the deep water by the pipe’s presence, so far. A French team from the University of Savoie is now installing a similar device in Lake Monoun, which poses a greater threat than Nyos, because the gas-rich water is only 60 metres down. Potentially far more dangerous are the lakes of the East African Rift system, where magma exhalation is far more widespread and seismicity more common. Lake Kivu, near Goma on the border between Rwanda and the Democratic Republic of Congo, threatens far more people with a massively greater threat, which also includes huge volumes of buried methane. Luckily, the lava flow there during early 2002 did not reach the gas-rich level. The experience from Cameroon promises an eventually easing of the dangers elsewhere.
Source: Krajick, K. 2003. Efforts to tame second African “killer lake” begin. Science, v. 299, p. 805.