O'a Caldera

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  • Country
  • Volcanic Region
  • Primary Volcano Type
  • Last Known Eruption
  • 7.47°N
  • 38.58°E

  • 2075 m
    6806 ft

  • 221280
  • Latitude
  • Longitude

  • Summit
    Elevation

  • Volcano
    Number

The Global Volcanism Program has no activity reports for O'a Caldera.

The Global Volcanism Program has no Weekly Reports available for O'a Caldera.

The Global Volcanism Program has no Bulletin Reports available for O'a Caldera.

Basic Data

Volcano Number

Last Known Eruption

Elevation

Latitude
Longitude
221280

Unknown - Evidence Credible

2075 m / 6806 ft

7.47°N
38.58°E

Volcano Types

Caldera
Pyroclastic cone(s)

Rock Types

Major
Rhyolite
Trachyte / Trachyandesite
Minor
Basalt / Picro-Basalt

Tectonic Setting

Rift zone
Continental crust (> 25 km)

Population

Within 5 km
Within 10 km
Within 30 km
Within 100 km
148,588
148,588
477,361
8,808,566

Geological Summary

O'a caldera along the central Ethiopian Rift is the country's largest rift-valley caldera. The caldera forms the eastern portion of the 15 x 25 km dumbbell-shaped Lake O'a (also known as Lake Shalla). Formation of the caldera about 240,000 years ago was accompanied by the eruption of two ignimbrite deposits, the first of which was strongly welded. The only post-caldera activity consists of two pyroclastic cones north of the caldera, one silicic and the other basaltic, and a group of tuff rings, spatter cones, and lava flows of Holocene (perhaps as young as prehistorical) age near the SW shore of the lake. These were erupted along the Corbetti-Shalla segment of the Wonji Fault Belt, which extends north from Corbetti caldera. Fumarolic activity continues on all sides of the lake.

References

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

Di Paola G M, 1972. The Ethiopian Rift Valley (between 7° 00' and 8° 40' lat north). Bull Volc, 36: 517-560.

IAVCEI, 1973-80. Post-Miocene Volcanoes of the World. IAVCEI Data Sheets, Rome: Internatl Assoc Volc Chemistry Earth's Interior..

Mohr P A, Mitchell J G, Raynolds R G H, 1980. Quaternary volcanism and faulting at O'a caldera, central Ethiopian Rift. Bull Volc, 43: 173-190.

Mohr P A, Wood C A, 1976. Volcano Spacings and Lithospheric Attenuation in the Eastern Rift of Africa. Earth Planet Sci Lett, 33: 126-144.

The Global Volcanism Program is not aware of any Holocene eruptions from O'a Caldera. If this volcano has had large eruptions (VEI >= 4) prior to 10,000 years ago, information might be found on the O'a Caldera 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

Shalla | Shala

Cones

Feature Name Feature Type Elevation Latitude Longitude
Tulu Billa Pyroclastic cone
Tulu Fike Pyroclastic cone

Craters

Feature Name Feature Type Elevation Latitude Longitude
Chitu Maar

Photo Gallery


The eastern (right) side of dumbbell-shaped Lake O'a (Lake Shalla) forms the 17-km-wide O'a caldera. Greenish-colored Lake Kunni (Lake Abiata) at the upper right lies NE of the Pleistocene caldera. Post-caldera activity produced pyroclastic cones north of the caldera. The small greenish Chitu maar on the SW side of the lake was erupted in an area of Holocene vents along the Corbetti-Shalla fissure system extending north from Corbetti caldera. Fumarolic activity continues on the southern and eastern shores of the lake.

NASA Space Shuttle image ISS001-363-7, 2001 (http://eol.jsc.nasa.gov/).

Smithsonian Sample Collections Database


A listing of samples from the Smithsonian collections will be available soon.

Affiliated Sites

Large Eruptions of O'a Caldera 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.