O'a Caldera

Shala

Caldera · Ethiopia · 2075m

The eastern (right) side of the darker Lake O'a (Lake Shalla) forms the 17-km-wide O'a caldera. Post-caldera activity produced cones N of the caldera. The small light blue-green Chitu maar on the W side of the lake was erupted in an area of Holocene vents along the Corbetti-Shalla fissure system extending N from Corbetti caldera. Fumarolic activity continues along the S and E shores. · Photo: NASA International Space Station image ISS001-363-7, 2001 (http://eol.jsc.nasa.gov/). · Wikimedia Commons

Type: Caldera
Country: Ethiopia
Region: Eastern Africa / Main Ethiopian Rift Volcanic Province
Elevation: 2075m
Coordinates: 7.457, 38.557
Last eruption: Unknown
Tectonic setting: Rift zone / Continental crust (> 25 km)
Landform: Caldera
Major rock type: Rhyolite

Geological summary

The Shala (also known as O'a) caldera along the central Main Ethiopian Rift forms the eastern portion of the 15 x 25 km Lake Shala. 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 to the N, one silicic and the other basaltic, and a group of tuff rings, spatter cones, and lava flows of Holocene age near the SW shore of the lake. These were erupted along the Corbetti-Shalla segment of the Wonji Fault Belt, which extends N from Corbetti caldera. Fumarolic activity continues on all sides of the lake.

O'a Caldera

Eruption history

Detailed timeline

External links