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The Global Volcanism Program has no activity reports for Gedamsa.
The Global Volcanism Program has no Weekly Reports available for Gedamsa.
The Global Volcanism Program has no Bulletin Reports available for Gedamsa.
The Gedamsa caldera is located along the Main Ethiopian Rift east of Lake Koka and SW of the Wonji Sugar Estate Farm. The 7 x 9 km wide caldera (also spelled Gadamsa or Gedemsa) is cut by many NNE-SSW-trending regional faults of the Ethiopian Rift, particularly on the east side of the caldera. The caldera is steep-sided, with 100-200 m high walls whose upper part consists primarily of rhyolitic lava flows, and formed as a result of the eruption of a series of trachytic ignimbrites. Late-Pleistocene to Holocene volcanics form a chain of rhyolitic lava flows and pumice deposits, known as Ittisa, that rises about 200-250 m above the floor of the caldera. A large 1-km-wide crater is located at the eastern part of the chain. A Holocene lava dome or flow is found on the SW flank of the volcano. Regional faults have truncated the volcano, and small basaltic spatter cones have formed inside the caldera rim. Weak fumarolic activity was reported at two locations at Gedamsa.
The Global Volcanism Program is not aware of any Holocene eruptions from Gedamsa. If this volcano has had large eruptions (VEI >= 4) prior to 10,000 years ago, information might be found on the Gedamsa page in the LaMEVE (Large Magnitude Explosive Volcanic Eruptions) database, a part of the Volcano Global Risk Identification and Analysis Project (VOGRIPA).
This compilation of synonyms and subsidiary features may not be comprehensive. Features are organized into four major categories: Cones, Craters, Domes, and Thermal Features. Synonyms of features appear indented below the primary name. In some cases additional feature type, elevation, or location details are provided.
|Gadamsa Caldera | Gedemsa Caldera|
|Feature Name||Feature Type||Elevation||Latitude||Longitude|
|Gedamsa caldera is located along the Main Ethiopian Rift east of Lake Koka (left) and SW of the Wonji Sugar Estate Farm (upper right). The 7 x 9 km wide caldera (also spelled Gadamsa or Gedemsa) is cut by many NNE-SSW-trending regional faults of the Ethiopian Rift. A chain of rhyolitic lava flows and a large 1-km-wide crater occupies the caldera floor. A young lava dome and flow is found on the SW flank of the volcano (lower left).
NASA Landsat image, 1999 (courtesy of Hawaii Synergy Project, Univ. of Hawaii Institute of Geophysics & Planetology).
The following references have all been used during the compilation of data for this volcano, it is not a comprehensive bibliography. Discussion of another volcano or eruption (sometimes far from the one that is the subject of the manuscript) may produce a citation that is not at all apparent from the title.
Acocella V, Korme T, Salvini F, Funiciello R, 2003. Elliptic calderas in the Ethiopian Rift: control of pre-existing structures. J Volc Geotherm Res, 119: 189-203.
Berhe S M, 1978. Geological map of the Nazret area. Ethiopian Mapping Agency, 1:250,000.
Di Paola G M, 1972. The Ethiopian Rift Valley (between 7° 00' and 8° 40' lat north). Bull Volc, 36: 517-560.
Peccerillo A, Barberio M R, Yirgu G, Ayalew D, Barbieri M, Wu T W, 2003. Relationships betweem mafic and peralkaline silicic magmatism in continental rift settings: a petrological, geochemical and isotopic study of the Gedemsa volcano, Central Ethiopian Rift. J Petr, 44: 2003-2032.
WoldeGabriel G, 1987. . (pers. comm.).