WASHINGTON -- A gigantic cloud of carbon dioxide that bubbled out of a mountain lake and flowed into neighboring villages caused 1,700 deaths in Cameroon last August, a final report on the disaster said Wednesday.
The report, by a U.S. team of medical, geological and chemical specialists, said the unusual combination of physical characteristics in about 40 similar lakes in the northern part of the African nation means similar disasters could occur again -- and probably happened before.
About 1,700 people in the area of Lake Nyos were found dead Aug. 21, 1986, their sprawled bodies bearing no evident signs of violence or a death struggle. Interspersed with the human bodies were the carcasses of herds of cattle, dogs and even insects.
The report said those people who survived tended to be at a slightly higher elevation than those who died. The patients on the second floor of a maternity hospital survived, while those on the first floor perished. Some people asleep in beds were unharmed, while those lying in the same house on floor mats died.
Evidence indicates carbon dioxide seeped out of molten volcanic rock deep in the earth and bubbled up through the earth's crust. The bubbles normally seep harmlessly into the air, but in this case some of the carbon dioxide apparently was bottled up by Lake Nyos' deep waters.
For some unknown reason, a monster bubble of carbon dioxide belched out of the bottom of the lake -- possibly triggered by a summer rain storm.
Survivors who were at a higher elevation than the lake said they recall hearing a rumbling sound, seeing a large wave wash across the water and seeing a white cloud rise from the lake.
The report said the vast bubble of carbon dioxide, probably the equivalent of a cubic kilometer, flowed into valleys and villages.
Survivors described a warm sensation, the smell of rotten eggs and loss of consciousness. Such symptoms are consistent with a cloud of carbon dioxide, the report said.
The report said the waters of Lake Nyos and several other similar volcanic lakes in the region have a high concentration of carbon dioxide building up in their bottom waters. Nearby springs also showed a high level of carbon dioxide.
The report, assembled by the State Department's Office of Foreign Disaster Assistance, recommended that a series of pipes could be run to the bottom of such lakes as part of a circulation system that could bring the bottom waters to the surface, safely reducing the concentration of carbon dioxide found at the lower depths of the lake.