Volcanoes in the Sea Near Nigeria: An Overview of the Cameroon Volcanic Line

The Cameroon line is a 1,600 km (1,000 mi) long chain of volcanoes that includes islands in the Gulf of Guinea and mountains on the African mainland, from Mount Cameroon on the coast towards Lake Chad on the northeast. They form a natural border between eastern Nigeria and the West Region of Cameroon.

Cameroon Volcanic Line Map

The islands, which span the equator, have tropical climates and are home to many unique plant and bird species. The mainland mountain regions are much cooler than the surrounding lowlands, and also contain unique and ecologically important environments.

Geological Features

The Cameroon volcanic line is geologically unusual in extending through both the ocean and the continental crust. In the Gulf of Guinea, the Cameroon line consists of six offshore volcanic swells that have formed islands or seamounts. From the southwest to the northeast the island groups are Annobón (or Pagalu), São Tomé, Príncipe and Bioko.

On the mainland, the line starts with Mount Cameroon and extends northeast in a range known as the Western High Plateau, home to the Cameroonian Highlands forests.

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Island Volcanoes

  • Annobón (Pagalu): The southernmost island in the chain, with an area of about 17.5 km2 (6.8 sq mi). It is an extinct volcano that rises from deep water to 598 m (1,962 ft) above sea level.
  • São Tomé: An island of 854 km2 (330 sq mi), lying almost on the equator. The entire island is a massive shield volcano which rises from the floor of the Atlantic Ocean, over 3,000 m (10,000 ft) below sea level, and reaches 2,024 m (6,640 ft) above sea level in the Pico de São Tomé. Most of the lava that has erupted over the last million years has been basalt.
  • Príncipe: The smaller of the two major islands of São Tomé and Príncipe, with an area of 136 km2 (53 sq mi). Volcanic activity stopped around 15.7 million years ago, and the island has been deeply eroded apart from spectacular towers of phonolite.
  • Bioko: Located just 32 km (20 mi) off the coast of Cameroon, on the continental shelf. Bioko has three basaltic shield volcanoes, joining at the lower levels: San Carlos, Santa Isabel, and San Joaquin.

Bioko has exceptional numbers of endemic species of flora and fauna, partly due to the great range of altitudes, particularly birdlife. The montane forest is protected by the 330 km2 (130 sq mi) Basilé National Park and the 510 km2 (200 sq mi) Luba Crater Scientific Reserve. Bioko is a part of Equatorial Guinea.

Bioko Island

Mainland Volcanoes

The Western High Plateau, also called the Western Highlands or the Bamenda Grassfields, continues the Cameroon line into the mainland of Cameroon. The plateau rises in steps from the west. The region has cool temperatures, heavy rainfall, and savanna vegetation. Volcanism has created fertile black and brown soils.

Geologists disagree over which volcanic regions should be included in the Cameroon volcanic line. All definitions include the islands and the continental stretch up to Oku.

Volcanic Activity in Nigeria

The Jos and Biu Plateaux volcanic provinces occupy the northeastern half of Nigeria bordering the Cameroon Volcanic Line, dotted with conspicuously visible number of dormant volcanoes with no reported activity. These dormant volcanoes represent potential future eruption sites.

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The volcanoes are represented by well-preserved cones and lava flows. In places the lava flows have been lateritized and eroded leaving remnants of weathered basalt boulders and a number of plugs and dome-like outcrops lacking any preserved cones.

Jos Plateau

Field investigations have revealed the existence of about 22 dormant volcanoes on the Jos Plateau region alone and are generally aligned in series of NNW-SSE trend. None of these volcanoes have record of any activity in recent past. They are composed mainly of basaltic scoria and pyroclastic materials.

The Ganawuri line comprises from the north to south of the Bum, Jal, and Kwakwi volcanoes. The Hoss volcanic line consists of two volcanoes; Miango in the north and Hoss volcano in the south. The Southern-most end members are namely the Panyam and Gu volcanic lines.

Biu Plateau

The Biu Plateau in NE Nigeria is composed of basaltic lava flows. A large number of recent cinder cones with well-defined craters are aligned in a NNW-SSE direction. Cinder cones and lava flows of the Biu Plateau often contain abundant peridotite xenoliths.

Lake Nyos Disaster

Lake Nyos sits high in a volcanic plain amidst the Cameroon line of volcanoes, which stretches into the Gulf of Guinea. The lake itself fills a circular maar, formed when groundwater meets hot lava or magma and explodes. The hole from the eruption eventually fills with water, forming a crater lake.

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On the evening of August 21, 1986, a silent, invisible killer raced down the hills around Lake Nyos, taking the lives of nearly everything in its path. Scientists would discover months later, after much research, that a cloud of carbon dioxide rose out of the lake and rolled into a valley below at more than 100 kilometers (60 miles) per hour. The suffocating gas killed nearly 1,800 people, 3,500 livestock, and countless birds and insects.

Lake Nyos

The unpredictable and dangerous nature of the lake led scientists from around the world to propose solutions that would prevent another carbon dioxide eruption. In 2001, French scientists installed a degassing instrument-mostly a pipe and fountain that allows gas to escape at a consistent rate. Two more pipes were installed in 2011.

The Lake Nyos Disaster - Africa's Killer Lake - A Short Documentary

Volcanic Hazard Assessment

This work focuses on the need to assess the hazard level of some of these volcanoes for effective monitoring, disaster preparedness and land use planning as more people live and farm in these potentially endangered volcanic prone areas, unaware of the inherent risk.

Records of gas emissions at Lakes Monoun and Nyos in Cameroon Republic in 1984 and 1986 respectively destroyed lives and properties within 14 km radius to a large extent, affected some communities in Nigeria (Mambilla Plateau and Katsina-Ala River banks).

Inventory of Volcanoes on the Jos Plateau, Nigeria

The following table presents an inventory of the volcanoes of the Jos Plateau, Nigeria, including their coordinates, estimated population at risk, type of volcano, diameter of crater, elevation, and materials deposited.

S. No. Name/locality Coordinates Estimated population of people at risk Type of volcano Diameter of crater Elevation (ASL) Materials deposited
1 Bum 200,000 Cone Basaltic
2 Jal 150,000 Cone Basaltic
3 Kwakwi 250,000 Cone Basaltic
4 Miango volcano I N09°51′.365″; E008°43′.961″ 250,000 Cone 350 m 1297 m Scoraceous basalt/pyoclastics
5 Miango volcano II N09 51. 000′; E008 44″. 191′ Cone 650 m 1303 m ‘’
6 Kassa volcanoes Highest Peak: N09°36′.119″; E008°53′.521″ 100,000 Cluster (6 overlapping volcanoes) Average 300 m Average 1342 m Olivine basalt, scoria, tuff, breccia/volcanic bomb
7 Sha 1 N09° 10′. 543″;E008° 47′. 955″; 20,000 Dome 200 m 1310 m Pyroclastics (granite fragments/lava)
8 Sha 2 N09°10′. 846″;E008° 48′. 05″; 10,000 Dome 200 m 1294 m Weathered basaltic materials capped by iron concretions
9 Passakai N09° 10′. 543″;E008° 47′. 955″ 10,000 Dome 300 m 1375 m Lateritized
10 Wushik (Lakas) volcano N09° 24′ 165″; E009° 10′ 554″ 10,500 Cone 250 m 1300 m Scoria/pyroclastics
11 Kogul (Nyeis) volcano N09° 22′ 573″;E009° 11′ 068″ 80,000 Cone 250 m 1250 m Scoria/pyroclastics
12 Kerang I N09° 20′ 286″;E009° 11′ 643″; 200,000 Cone 600 m 1400 m Scoria/basaltic rocks with large phenocrysts of olivine, garnet and pyroxene
13 Kerang II N09° 20′ 392″;E009° 11′ 502″; Cinder Cone 1000 m 1450 m Scoria/basaltic rocks with large phenocrysts of olivine, garnet and pyroxene
14 Kerang III volcano (Swan junction) N09° 20′ 306″;E009° 10′ 561″ Cone 1000 m 1486 m Scoria/pyroclastics
15 Kerang IV N09° 11′ 283″;E008° 12′ 547″ Cluster (with 2 craters) 1.5 km 1372 m Pulverised basement and lava
16 Pidong volcano N09° 17′ 650″;E009° 12′ 312″ 50,000 Crater Lake 700 m 1378 m Scoria/pyroclastics
17 Jiblik volcano N09° 16′ 591″;E009° 16′ 890″ 100,000 Cinder Cone 1 km 1228 m Scoraceous basalt +garnet/pyroclastics
18 Kagu volcano N09° 13′ 901″; 008° 16′ 383″ 50,000 Cone 1 km 1060 m Scoraceous basalt/pyroclastics
19 Katul volcano N09° 11′ 264″;E009° 15′ 795″ 5000 Cone 700 m 976 m Scoraceous basalt/pyroclastics
20 Lakdak 7000 cone Scoraceous basalt/pyroclastics

Understanding the Cameroon Volcanic Line and its associated volcanic features is crucial for assessing potential hazards and ensuring the safety of the communities living in these regions.

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