Lake Kivu
Lake Kivu is one of the Great Lakes of Africa. It lies on the border between the Democratic Republic of the Congo and Rwanda. Lake Kivu empties into the Ruzizi River, which flows southwards into Lake Tanganyika. It gained notoriety as a place where many of the victims of the 1994 Rwandan genocide were dumped into.
Geography
The lake covers a total surface area of some 2700 km² and stands at a height of 1460 metres above sea level. The first European to visit was German Count Adolf von Götzen in 1894. The lake bed sits upon a rift valley that is slowly being pulled apart, causing volcanic activity in the area.
A large island, Idjwi, lies in the lake, while settlements on its shore include Bukavu, Kabare, Kalehe, Saké and Goma in Congo and Gisenyi, Kibuye and Cyangugu in Rwanda.
Chemistry
Lake Kivu is one of three known exploding lakes, along with Cameroonian Lake Nyos and Lake Monoun, that experience lake overturns. Analysis of Lake Kivu's geological history indicates a periodic massive biological extinction about every 1,000 years. The trigger for lake overturns in Lake Kivu's case is unknown but periodic volcanic activity is suspected. The gasseous chemical composition of exploding lakes is unique to each lake; in Lake Kivu's case, methane and carbon dioxide due to lake water interaction with a volcano. The risk from a possible Lake Kivu overturn would be catastrophic, dwarfing other documented lake overturns at Lake Nyos, since approximately 2 million people live in the lake basin.
Scientists hypothesize that sufficient volcanic interaction with the lake's bottom water that has high gas concentrations would heat water, force the methane out of the water, spark a methane explosion, and trigger a nearly simultaneous release of carbon dioxide. The carbon dioxide would then suffocate large numbers of people in the lake basin as the gases roll off the lake surface. It is also possible that the lake could spawn lake tsunamis as gas explodes out of it.
The risk posed by Lake Kivu began to be understood during the analysis of more recent events at Lake Nyos. Lake Kivu's methane was only originally thought to be a cheap natural resource for export and the generation of cheap power. Once the mechanisms that caused lake overturns began to be understood, so did the risk the lake posed to the local population.
Scientists installed a vent pipe at Lake Nyos in 2001 to vent bottom water gases out of its waters, but such a solution for the much larger Lake Kivu would be extremely expensive, running into millions of dollars. No plan has been initiated to reduce the risk posed by Lake Kivu.