Nearly 1,700 people died in 1986 when Cameroon's Lake Nyos suddenly released deadly levels of carbon dioxide into the air, following a build-up of the gas in the lake. Another 10,000 people were uprooted and 3,000 heads of livestock were also lost.
"I lost more than 21 members of my family and all our cattle after the explosion," said 45-year old Che Ephraim, a resident of the area at the time.
The lake, located on the flank of an inactive volcano, sits above magma and leaks carbon-dioxide into the water.
With the longer-term aim of returning displaced communities to their land and rebuilding livelihoods around the lake, the United Nations Development Programme and partners have inserted two large-scale and open-ended pipes into the lake to allow controlled release of carbon dioxide into the atmosphere, a process called de-gassing.
The two columns add to a de-gassing pipe laid in 2001 as an experiment of Cameroon’s geological, mining and research community, with support from the Government of Cameroon and the European Union, who were seeking innovative ways reduce the occurrence of high levels of carbon dioxide in the 200-metre-deep lake that caused it to ‘explode’ 25 years ago.
Experts at the country’s Institute of Geological and Mining Research say the lake will be secure in two years, allowing former residents to return to their homes.
Authorities for the region of Menchum, the site of the lake, have also put in place emergency response measures, including a solar-powered alarm system triggered by excessive carbon dioxide levels, first aid training, and mapping of safe havens. A successful evacuation simulation was conducted in March 2011.
Lake Nyos is one of only three known ‘exploding lakes’ in the world, the others being Lake Monoun, also in Cameroon, and Lake Kivu in Rwanda.