Posted for Anjali Nayar
Volcanoes in Eastern Democratic Republic of Congo could erupt “any day now,” razing the city of Goma with lava and poisoning the air with methane and carbon dioxide, says Dieudonné Wafula, the head scientist at Goma’s Volcano Observatory (OVG).
In the last few weeks, the OVG has recorded a sharp increase in the activity of the Nyamuragira and Nyiragongo volcanoes (see USGS map), including increased local temperatures, tremors and larger than usual plumes of gas and volcanic dust.
The Nyamuragira and Nyiragongo volcanoes last erupted in 2002, forcing 300,000 people to flee lava flows in central Goma city, says Michel Halbwachs, a volcanologist from the University of Savoie, in an official report on the eruptions.
But the real worry is that an eruption could destabilize the deep waters of Lake Kivu, 18 km away on DRC’s border with Rwanda, releasing lethal doses of carbon dioxide and methane gas.
Bathymetric surveys by engineering consultancy LAHMEYER International in 1998 showed Lake Kivu contains roughly 255 billion cubic metres of carbon dioxide and 55 billion cubic metres of methane, according to the government of Rwanda.
The gasses are dissolved under pressure at the bottom of the lake; the gas concentrations are highest around 250-280m and are fairly protected from the lake’s surface mixing, which reaches a depth of about 50m.
But according to Wafula, the gas-rich layers could be destabilized and released by seismic activity or if enough lava flowed into the lake’s depths, warming and mixing the water.
It’s not the first time something like this has happened – a sudden release of 80 million cubic metres carbon dioxide from Lake Nyos in Cameroon in 1986, possibly because of a landslide, asphyxiated at least 1,700 people and 3,500 livestock in surrounding villages. Two years earlier in the same remote area of Cameroon, a lethal cloud of carbon dioxide gas erupted out of Lake Monoun, killing 37 people, according to Halbwachs, who headed a project that attempted to degas the “killer lakes. ”
The sediment record in Lake Kivu suggests massive extinctions of lake life occurred roughly every 1,000 years, possibly because of degassing events, according to work by Robert Hecky from the University of Waterloo.
This March, US energy company ContourGlobal signed a $325 million deal with neighbouring Rwanda to extract methane from the depths of lake Kivu, providing the region with 100 MW of gas-powered electricity.
The project could help reduce the risk of an eruption of toxic gasses from the lake, but the project is not expected to become operational until 2010 (see the press release).
Image: Nyiragongo on 1 April 2009 / OVG