The Comoros volcanic archipelago is located midway between the west coast Madagascar and the African east coast, at the northern extremity of the Mozambique Channel, between Lat. S 11-13° and Long. N 43-46°. It covers a total area of 2033 km² including four mean islands. The westernmost island of Grande Comore is geologically the most recent [most of the rocks have less than 1 Ma], the largest [1024 km²] and the highest [2361 m]. The volcanism is still active at the Karthala Volcano [2361 m].
The island is mainly composed of two recent shield volcanoes of dominant basaltic type: (1) the massif of La Grille [1087 m], which covers the northern half part of the island, is of intermediate age [Middle Pleistocene], with a morphology characterised by gentle slopes and scattered by several cinder cones; (2) the massif of the Karthala, which covers a surface of about two thirds of the island in its centre, is an active shield volcano [Quaternary] characterized by a near-absence of weatheri
The island is mainly composed of two recent shield volcanoes of dominant basaltic type: (1) the massif of La Grille [1087 m], which covers the northern half part of the island, is of intermediate age [Middle Pleistocene], with a morphology characterised by gentle slopes and scattered by several cinder cones; (2) the massif of the Karthala, which covers a surface of about two thirds of the island in its centre, is an active shield volcano [Quaternary] characterized by a near-absence of weatheri