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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

  • Volcano

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.

Basic Data

Volcano Number

Last Known Eruption



Unknown - Evidence Credible

1984 m / 6508 ft


Volcano Types

Pyroclastic cone(s)

Rock Types

Trachyte / Trachyandesite
Basalt / Picro-Basalt

Tectonic Setting

Rift zone
Continental crust (> 25 km)


Within 5 km
Within 10 km
Within 30 km
Within 100 km

Geological Summary

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 following references have all been used during the compilation of data for this volcano, it is not a comprehensive bibliography.

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.).

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
Ittisa Cone

Photo Gallery

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).

Smithsonian Sample Collections Database

There are no samples for Gedamsa in the Smithsonian's NMNH Department of Mineral Sciences Rock and Ore collection.

Affiliated Sites

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).
MODVOLC - HIGP MODIS Thermal Alert System Using infrared satellite Moderate Resolution Imaging Spectroradiometer (MODIS) data, scientists at the Hawai'i Institute of Geophysics and Planetology, University of Hawai'i, developed an automated system called MODVOLC to map thermal hot-spots in near real time. For each MODIS image, the algorithm automatically scans each 1 km pixel within it to check for high-temperature hot-spots. When one is found the date, time, location, and intensity are recorded. MODIS looks at every square km of the Earth every 48 hours, once during the day and once during the night, and the presence of two MODIS sensors in space allows at least four hot-spot observations every two days. Each day updated global maps are compiled to display the locations of all hot spots detected in the previous 24 hours. There is a drop-down list with volcano names which allow users to 'zoom-in' and examine the distribution of hot-spots at a variety of spatial scales.
MIROVA Middle InfraRed Observation of Volcanic Activity (MIROVA) is a near real time volcanic hot-spot detection system based on the analysis of MODIS (Moderate Resolution Imaging Spectroradiometer) data. In particular, MIROVA uses the Middle InfraRed Radiation (MIR), measured over target volcanoes, in order to detect, locate and measure the heat radiation sourced from volcanic activity.