Cameroon

Cameroon presents an unusual seismic and volcanic setting characterised by the Cameroon Volcanic Line, a chain of volcanoes and volcanic massifs that extends roughly 1,600 kilometres from the island of Bioko (Equatorial Guinea) in the Gulf of Guinea northeast across the continent to the Adamawa Plateau and the Mandara Mountains. This volcanic chain does not follow a traditional plate boundary but instead lies within the African plate interior, probably above a linear zone of mantle upwelling or a series of hotspot tracks.

The most seismically significant feature along the Cameroon Volcanic Line is Mount Cameroon (4,095 m), an active stratovolcano and the highest peak in sub-Saharan West Africa. Eruptions in 1959, 1982, 1999, 2000, and 2012 were each accompanied by earthquake swarms as magma migrated through the volcanic plumbing system. The 1999 eruption was particularly well studied and showed a clear escalation of [[seismic-wave]] activity in the days before lava emerged on the flanks. The Limbe area at the foot of the volcano has experienced locally damaging earthquake shaking associated with intrusive events.

Lake Nyos, a crater lake in northwestern Cameroon, became tragically famous on 21 August 1986 when it released a massive cloud of carbon dioxide that asphyxiated approximately 1,700 to 1,800 people and thousands of livestock in surrounding villages. While not a conventional earthquake, the limnic eruption was preceded by minor seismic activity and involved the explosive release of CO₂ that had accumulated in CO₂-saturated bottom waters of the crater lake. A similar but smaller event killed 37 people at nearby Lake Monoun in 1984.

The tectonic setting of Cameroon beyond the volcanic line is dominated by the stable Congo craton in the south and the old basement of the Pan-African orogenic belt. Occasional [[fault]]-related earthquakes have been recorded in the Cameroon Highlands, the Adamawa Plateau, and near the border with Nigeria, where ancient basement faults can be reactivated by regional stress. [[magnitude]] events above 5.0 are rare but not unknown in northern Cameroon, where the influence of the distant East African Rift stress field is faintly detectable.