Badda And Sagatu (Gara Badda)
Badda is a large volcano lying immediately east of, and overlapping, Chilallo (No. 42). Like Chilallo it appears to be formed predominantly of alkaline trachyte lava flows.
The 'Main Ethiopian Rift' extends for some 600 km from the Afar Depression south-southwestwards to the Kenya border. Centred on the rift and the adjacent rift shoulders are numerous volcanoes that are mainly alkaline, many being composed predominantly of peralkaline silicic rocks. Descriptions of these centres follow (Nos 054-00-033-054-00-053). Much of the rift floor is covered by welded to unwelded ash-flow and pumice deposits of peralkaline rhyolitic composition which were probably erupted from fissures (Merla et al., 1979), although some may have emanated from the central volcanoes. There are few detailed descriptions of these deposits but information on the central part of the rift will be found in Di Paola (1973) and on the evolution of the northern part of the rift in Kazmin et al. (1980). A general account of the relationships between tectonics and volcanism is that of Mohr (1983) who has collected together chemical data (Mohr, 1962a). Some 77 K-Ar dates for volcanic rocks within the rift and for volcanoes of the rift shoulders will be found in Woldegabriel et al. (1990).
Badda is a large volcano lying immediately east of, and overlapping, Chilallo (No. 42). Like Chilallo it appears to be formed predominantly of alkaline trachyte lava flows.
The Alutu volcanic centre lies immediately south of Lake Zwai (Ziway), covers some 90 km2 and rises 650 m above the surrounding lake deposits and tuffs.
O'a is the largest of the calderas in the Ethiopian rift valley with a longer axis of 17 km. It lies beneath the eastern half of Lake Shalla (Hora O'a), parts of which are some 250 m deep.
The Baltata volcano is located immediately northwest of Cacca (No. 47). No details of the petrology have been found but Baltata is shown on an unpublished map of Di Paola (1976) as including pantellerites and alkali trachytes.
On the key of an unpublished map of Di Paola (1976) this volcano, covering about 18x12 km, is shown as comprising "..pantelleritic ignimbrites associated with mugearitic-alkali and peralkaline trachytic central volcanoes." It has a radial dyke swarm (Mohr, 1980).
The Corbetti volcanic complex consists of the Corbetti caldera, which has a diameter of 12 km, and the younger volcanoes of Urji, which is located in the centre of the caldera, and Chabbi, which overlaps the eastern caldera margin (Di Paola, 1972).
No details have been traced but this occurrence is shown on an unpublished map of Di Paola (1976) and Di Paola (1973) as being pantelleritic.
No details traced but shown on unpublished map of Di Paola (1976) as being pantelleritic.
No details traced but shown on unpublished maps of Di Paola (1976 and 1973) as being pantelleritic.
The denuded remnants of an ignimbrite sheet which is reported to be comenditic, and originally covering at least 300 km2, are found around Lake Chamo and on islands in Lake Abaya (Levitte et al., 1974).