Mount Cameroon
Mount Cameroon is an active stratovolcano in the Southwest Region of Cameroon next to the city of Buea near the Gulf of Guinea. Mount Cameroon is also known as Cameroon Mountain or Fako or by its indigenous name Mongo ma Ndemi. Mount Cameroon is ranked 22nd by topographic isolation.
It is the highest point in sub-Saharan western and central Africa, the fourth-most prominent peak in Africa, and 31st-most prominent in the world.
The mountain is part of the area of volcanic activity known as the Cameroon Volcanic Line, which also includes Lake Nyos, the site of a disaster in 1986. The eruption of 28 April-June 1909 caused the German colonial government of Kamerun to temporarily move from Buea to Douala. The most recent eruption occurred on February 3, 2012.
Geology
Formation
Mount Cameroon lies on the Cameroon Volcanic Line, a 1,600 km NE–SW belt of oceanic and continental volcanoes stretching from Pagalu Island in the Gulf of Guinea to northern Cameroon. The volcano forms an elliptical stratovolcano about 50 km × 35 km with a volume of roughly 1,200 km3. It sits on a horst of Precambrian granite and gneiss overlain by Cretaceous to Quaternary sediments. The summit is cut by several tectonic axes, notably the Debundscha axis, Limbe axis and Batoke axis, inherited from basement shear zones. Gravity and wavelet-analysis studies reveal dense mantle intrusions rising into the crust and suggest that the Tiko and Ekona faults focus magma ascent to depths of at least 25 km. Differences in mantle signature between the eastern and western flanks of the volcano support a mantle origin for the Cameroon Volcanic Line.Age
of volcanoes along the Cameroon Volcanic Line shows ages ranging from about 51.8 million years to the present. Mount Cameroon is the youngest and only presently active volcano on the line. Historical records document major eruptions in 1909, 1922, 1925, 1954, 1959, 1982, 1999, 2000 and 2012. A 1922 flank eruption sent lava to the Atlantic coast and the 1999 eruption came within 200 m of the sea.Lava chemistry
Mount Cameroon erupts predominantly basanite and alkali basalt, with small amounts of hawaiite, mugearite and camptonite. Xenoliths of dunite, wehrlite and clinopyroxenite in some strombolian cones indicate additions from the mantle and lower crust. Petrographic studies of the 1999 and 2000 eruptions show that the lavas are basanites containing roughly 20–25 % phenocrysts of euhedral to sub‑hedral olivine, clinopyroxene and plagioclase. Olivine phenocrysts make up around 10 % of these lavas; clinopyroxenes classify as diopside, and plagioclase crystals range from bytownite to andesine. Compared with older Mount Cameroon lavas, the 1999 and 2000 basanites have elevated Nb and K2O contents and plot on a mixing trend with the 1959 and 1982 lavas.The February–March 1959 eruption produced basanite–hawaiite lava with a mean effusion rate of 13–18 m3 s-1 and a volume of about 3.4×107 m3. Geochemical analyses show early fractionation of olivine and diopside followed by Fe–Ti oxides and plagioclase, making the 1959 lavas the most fractionated of all 20th‑century Mount Cameroon lavas. Two distinct magma types were erupted from two different magma chambers. More evolved magma was erupted from vents at roughly 1,960 m elevation while more mafaic magma drained from lower vents around 1,500 m, so that the magmas did not mix.
Eruptive history
Mount Cameroon is among Africa’s most active volcanoes, with eight major eruptions during the twentieth century. The volcano has more than 100 cones and vents arranged along NE–SW fractures and experiences both sustained eruptions and brief eruptions. During in-active times, seismicity rarely exceeds magnitude 3 with depths around surface level to about 60 km. Seismic activity intensifies before eruptions and can involve deep swarms between 20 and 55 km.- 1959 eruption – The February–March 1959 eruption was centered at a NW–SE fissure on the north‑eastern flank and produced a compound lava flow about 7.75 km long. Two main channels and several smaller lava flows covered roughly 4.5×106 m2 with thicknesses of 5–12 m. The eruption lasted about 22–30 days. The eruption produced explosive cinder cones at higher elevations and quieter spatter cones at lower elevations.
- 1982 eruption – Although not described in detail, the 1982 eruption produced basanite similar to earlier lavas; geochemical data show that early more evolved lava gave way to less evolved lava over the course of the eruption.
- 1999 and 2000 eruptions – These flank eruptions were the most recent substantial events. The 1999 eruption and the 2000 eruption produced basanite lavas following the NE–SW fracture system and created more than 100 cones and vents. Thermobarometry suggests that magma was stored mainly between 20 and 39 km depth, corresponding to the crust–mantle boundary, with transient shallow pockets during the 1999 eruption. Short‑lived explosive outbursts occurred in 1989 and 2012 without lava emission, illustrating the complex behaviour of the magma plumbing system.
- 2012 eruption – On 3 February 2012 a brief eruption occurred at Mount Cameroon. Tourists on the mountain reported strong explosions followed by visible "flames" and ash from a vent. Cameroon state radio and television later reported that the blast lasted only a couple of seconds and lightly injured two porters and guides. The event did not produce significant lava flows. Independent petrological and geophysical work indicates magma storage mainly near the crust–mantle boundary along the Cameroon Volcanic Line, consistent with deep-sourced gas release during brief explosive episodes.
Flora
- Lowland rain forest predominates on the lower slopes, from sea level to elevation. The lowland forests are part of the Cross-Sanaga-Bioko coastal forests ecoregion. They are composed of evergreen trees with a dense canopy high, with taller emergent trees rising above the canopy. Many trees have buttress roots. The forests are diverse and species-rich, with numerous lianas. Much of the lowland forest has been converted to agriculture and agroforestry, including oil palm plantations.
- Lower montane forest, also known as submontane forest or cloud forest, grows between elevation. The lower montane forests are composed of evergreen trees, which form a canopy that is either closed or discontinuous. There are scattered areas of meadow and scrubland, with grasses, herbs, tall herbaceous plants, tree ferns, woody shrubs, and low trees. Frequent clouds and mists sustain profuse epiphytes, including mosses, ferns, and orchids. The lower montane forests are diverse and species-rich, with characteristic Afromontane plants and endemic species. Impatiens etindensis and I. grandisepala are herbaceous epiphytes endemic to the montane forests of Mount Cameroon. The lower montane forests, together with the higher-elevation forests, scrub, and grasslands, are part of the Mount Cameroon and Bioko montane forests ecoregion.
- Upper montane forest grows from elevation. Trees up to high form an open-canopied forest with numerous epiphytes. The upper montane forests are less species-rich than the lower-elevation forests, and fires are more frequent.
- Montane scrub grows between elevation. Low trees of form open-canopied forests, woodlands, and shrublands, with an understory of small shrubs, herbs, ferns, and climbers.
- Montane grassland occurs between elevation. The dominant vegetation is tussock grasses, with scattered fire-tolerant shrubs and low trees.
- Sub-alpine grassland is found at the highest elevations, from to over. Frost-tolerant tussock grasses, dwarf trees and shrubs, and crustose, foliose, and fruticose lichens predominate.
Fauna
Two species of birds are endemic to Mount Cameroon, Mount Cameroon spurfowl and Mount Cameroon speirops.