Lake Pavin in the Puy-de-Dôme department is under close surveillance because of its resemblance to Lake Nyos. In August 1986, this Cameroonian lake caused the death by asphyxiation of more than 1,700 people following the brutal liberation of a huge volume of carbon dioxide. The gas either has been gradually accumulated in the depths of the lake following a slow but continuous volcanic degassing, or it is linked to a phreatomagmatic eruption of a particular type. In any case, the carbon dioxide content of the bottom of Lake Pavin seems far too low to cause such an explosion.