The initiation of Gondwana breakup, and transform faulting along the Davie Fracture Zone, occurred in the Toarcian (about 182 million years ago) following the eruption of the Bouvet (Karoo) mantle plume.
It contains part of the East African Orogen, which formed in the Neoproterozoic to Cambrian assembly of the Gondwana.
[6] The first rifting event, separation from Somalia and the rest of Africa, caused displacement along the Davie Ridge, in the Mozambique Channel to the west of the islands, a now extinct transform.
The rifting is also associated with extensive deformation as well as volcanism in the late Cretaceous and Cenozoic (Eocene to Miocene).
The most seismically active area is beneath the Ankaratra Plateau in the centre of the island, which experienced magnitude 5.2 and 5.5 earthquakes in 1985 and 1991.
To the northwest, there are the recently active Comoro Islands, which are hypothesized to be related to a hot spot.