Another volcano in Tibesti is Emi Koussi, which is the highest mountain of the Tibesti and of the entire Sahara region. The volcano Tarso Toh lies northwest of Toussidé, the Botoum and Botoudoma/Petit Botoum rhyolite extrusions are located south of Trou au Natron. The origin of volcanism in Tibesti is unclear; both a hotspot-related mechanism and tectonic effects of the collision between the African Plate and the Eurasian Plate have been proposed.