Gedamsa

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  • Country
  • Volcanic Region
  • Primary Volcano Type
  • Last Known Eruption
  • 8.35°N
  • 39.18°E

  • 1984 m
    6508 ft

  • 221230
  • Latitude
  • Longitude

  • Summit
    Elevation

  • Volcano
    Number

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.



Synonyms
Gadamsa Caldera | Gedemsa Caldera


Cones
Feature Name Feature Type Elevation Latitude Longitude
Ittisa Cone
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.).

Volcano Types

Caldera
Cinder cone(s)

Tectonic Setting

Rift zone
Continental crust (> 25 km)

Rock Types

Major
Rhyolite
Trachyte / Trachyandesite
Minor
Basalt / Picro-Basalt

Population

Within 5 km
Within 10 km
Within 30 km
Within 100 km
216,008
216,008
744,211
8,000,105

Affiliated Databases

Large Eruptions of Gedamsa Information about large Quaternary eruptions (VEI >= 4) is cataloged in the Large Magnitude Explosive Volcanic Eruptions (LaMEVE) database of the Volcano Global Risk Identification and Analysis Project (VOGRIPA).
WOVOdat WOVOdat is a database of volcanic unrest; instrumentally and visually recorded changes in seismicity, ground deformation, gas emission, and other parameters from their normal baselines. It is sponsored by the World Organization of Volcano Observatories (WOVO) and presently hosted at the Earth Observatory of Singapore.
EarthChem EarthChem develops and maintains databases, software, and services that support the preservation, discovery, access and analysis of geochemical data, and facilitate their integration with the broad array of other available earth science parameters. EarthChem is operated by a joint team of disciplinary scientists, data scientists, data managers and information technology developers who are part of the NSF-funded data facility Integrated Earth Data Applications (IEDA). IEDA is a collaborative effort of EarthChem and the Marine Geoscience Data System (MGDS).
Smithsonian Collections Search the Smithsonian's NMNH Department of Mineral Sciences collections database. Go to the "Search Rocks and Ores" tab and use the Volcano Name drop-down to find samples.