Oku Volcano | John Seach
Lake Nyos and Lake Monoun



6.44 N, 10.3 E
summit elevation 1080 m
Volcanic field

Oku Volcanic field is located in NW Cameroon. The region is part of the Cameroon line of volcanoes which runs from Annobon Island in the Atlantic Ocean to Oku in NW Cameroon. North of Oku the line splits north to the Biu Plateau in Nigeria, and eastwards to Ngaoundere plateau in eastern Cameroon.

Lake Nyos
Lake Nyos is a deep maar lake of explosive origin in NW Cameroon. The lake has an area of 1.49 sq km, 208 m deep, and a water volume of 132 million cubic m. The lake was formed by phreatomagmatic eruption several hundred years ago.

1986 Gas Release
In 1986 a gas cloud released from Lake Nyos killed 1746 people from Kam-Nyos, Subum, Cha, and other villages. The eruption was preceded on the same day by smoke or gas emission and a weak explosion. Between 9-10 pm on 21st August 1986 the main eruption of gas was accompanied by a tsunami with a wave height of about 20m. The release of carbon dioxide from the lake was caused by a phreatic explosion which mobilised accumulated gas at the bottom of the lake.

Lake Monoun
Lake Monoun is located in 10 km north of Foumbot, in the western highlands of Cameroon. The area is part of the Foumbot volcanic field, which consists of 34 craters, many of which contain lakes. The lake occupies a 96 m deep crater which contains a high concentration of dissolved carbon dioxide.

There are no local legends about eruptions at Lake Monoun, but the youthful volcanic topography indicated eruption within the past few hundred years.

1984 Gas Release
On 15th August 1984 a gas eruption from Lake Monoum killed 37 people. The
Lake Monoun event was not related to a volcanic explosion, but was caused by release of long term build up of carbon dioxide derived from soda springs or other carbon dioxide-rich groundwater flow into the submerged crater. Sudden degassing of the C02-rich waters was attributed to an upset of the density-stratification of the lake by a landslide from the crater's eastern rim.

Further reading
Halbwachs, M., Sabroux, J.C., Grangeon, J., Kayser, G., Tochon‐Danguy, J.C., Felix, A., B´ eard, J.C., Villevieille, A., Vitter, G., Richon, P. and Wüest, A., 2004. Degassing the “killer lakes” Nyos and Monoun, Cameroon. Eos, Transactions American Geophysical Union85(30), pp.281-285.

Cotel, A.J., 1999. A trigger mechanism for the Lake Nyos disaster. Journal of volcanology and geothermal research88(4), pp.343-347.

Evans, W.C., Kling, G.W., Tuttle, M.L., Tanyileke, G. and White, L.D., 1993. Gas buildup in Lake Nyos, Cameroon: the recharge process and its consequences. Applied Geochemistry8(3), pp.207-221.

Giggenbach, W.F., 1990. Water and gas chemistry of Lake Nyos and its bearing on the eruptive process. Journal of Volcanology and Geothermal Research42(4), pp.337-362.

Sigurdsson, H., Devine, J.D., Tchua, F.M., Presser, F.M., Pringle, M.K.W. and Evans, W.C., 1987. Origin of the lethal gas burst from Lake Monoun, Cameroun. Journal of Volcanology and Geothermal Research31(1-2), pp.1-16.

Baxter, P.J., Kapila, M. and Mfonfu, D., 1989. Lake Nyos disaster, Cameroon, 1986: the medical effects of large scale emission of carbon dioxide?. British Medical Journal298(6685), pp.1437-1441.

Kling, G.W., Clark, M.A., Wagner, G.N., Compton, H.R., Humphrey, A.M., Devine, J.D., Evans, W.C., Lockwood, J.P., Tuttle, M.L. and Koenigsberg, E.J., 1987. The 1986 lake nyos gas disaster in cameroon, west Africa. Science236(4798), pp.169-175.

Oku Volcano Eruptions

1986, 1984, 1550 ± 100