'An invisible avalanche': what happened in Cameroon's 1986 Lake Nyos disaster?

On 21 August, 1986, 1,746 people died from carbon dioxide poisoning after gas escaped overnight from the bottom of Lake Nyos in Cameroon. RFI examines what happened in the world's deadliest "limnic eruption" and how, 40 years later, our understanding of the danger posed by volcanic lakes is still evolving.

By RFI