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Country: | Ethiopia | |
| Subregion Name: | Northeastern Africa | ||
| Volcano Number: | 0201-23- | ||
| Volcano Type: | Caldera | ||
| Volcano Status: | Holocene | ||
| Last Known Eruption: | Unknown | ||
| Summit Elevation: | 1984 m | 6,509 feet | |
| Latitude: | 8.35°N | 8°21'0"N | |
| Longitude: | 39.18°E | 39°11'0"E | |
| 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. | |||
