It’s thought that up to two million people living on the banks of Lake Kivu in central Africa are at risk of being asphyxiated by gases, as CO2 and methane are believed to have built up beneath its surface.

It’s estimated that the lake, which straddles the borders of the Democratic Republic of Congo and Rwanda, now contains 300 cubic kilometres of carbon dioxide and 60 cubic kilometres of methane

The gases are thought to have bubbled into the Kivu from volcanic vents, while CO2 sequestration is currently seen by some sources as a possible solution.

Intense water pressures have trapped the gases in layers 80 metres below the lake’s surface, but reports are suggesting that geological or volcanic events could disturb these waters and release the gases – potentially fatally.

Disturbing waters saturated with carbon dioxide could cause a huge cloud of carbon dioxide to bubble up from the depths and smother everything in its path. Some 1,700 people were suffocated by such an occurrence at Lake Nyos in Cameroon, West Africa, in 1986.

With the region spanning Africa’s Great Rift Valley, it’s something of a centre for volcanic activity and so, is at risk of disturbing the trapped gases. At the same time, engineers are reportedly trying to tap Kivu’s rich supplies of methane by lowering pipes down to its holding layers and siphoning off the gas.

While this could then be burnt and used as a source of industrial and domestic energy, it also carries the risk of tampering with the lake’s gases and triggering a disaster.

Sam Rushing, President of Advanced Cryogenics Ltd and resident gasworld Technical Writer, is keen to point out that while this isn’t necessarily an immediate threat, it can’t be entirely ruled out either.

“It is impossible to say that such an explosive and deadly event is imminent – however it is possible.”

“The positive side of the CH4 concentration in lake Kivu has produced a new natural gas source, for domestic and industrial energy demands in this region.”