Gedemsa
Caldera in Ethiopia
Key Facts
Elevation
1,909 m (6,263 ft)
Type
Caldera
Location
8.363°, 39.172°
Region
Main Ethiopian Rift Volcanic Province
Rock Type
Rhyolite
Tectonic Setting
Rift zone
Location
Loading map...
Overview
The Gedemsa caldera covers 7 x 9 km along the Main Ethiopian Rift E of Lake Koka and SW of Wonji Sugar Estate Farm. The steep-sided edifice has walls 100-200 m high whose upper part consists primarily of rhyolitic lava flows, formed by the eruption of a series of trachytic ignimbrites, It is also cut by many NNE-SSW-trending regional faults, particularly on the E side. Late-Pleistocene to Holocene volcanics form a chain of rhyolitic lava flows and pumice deposits, known as Ittisa, that rises 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. Small basaltic spatter cones have formed inside the caldera rim.
Weak fumarolic activity was reported at two locations.
Volcanic Hazards & Risk Assessment
Primary Hazards
- Pyroclastic flows and surges
- Large explosive eruptions (VEI 4+)
- Ash fall and tephra deposits
- Lahars and debris flows
Risk Level
Geological Composition & Structure
Rock Types
Tectonic Setting
Age & Formation
Eruption Statistics & Analysis
| Metric | Value | Global Ranking | Significance |
|---|---|---|---|
| Total Recorded Eruptions | Unknown | Low | Moderately active volcano |
| Maximum VEI | VEI Unknown | Minor | Local impact potential |
| Recent Activity | Unknown | Historical | Historically active |
Monitoring & Alert Status
Monitoring Networks
Current Status
Nearby Volcanoes in Eastern Africa Volcanic Regions
Quick Info
- •Smithsonian ID: 221230
- •Evidence: Evidence Credible
- •Epoch: Holocene
About the Photo
The 7 x 9 km Gedemsa caldera is located along the Main Ethiopian Rift, east of Koka Lake (left), seen in this 5 December 2019 Sentinel-2 satellite image (N is at the top). The caldera has produced ignimbrites, pyroclastic surge, ashfall, and has constructed scoria cones, with a 1-km-wide crater in the eastern portion. A younger lava dome and flow are on the SW flank.
Satellite image courtesy of Copernicus Sentinel Data, 2019.
Authority Sources
Related Volcanoes
Basic Information
This page shows basic data from the Smithsonian Global Volcanism Program. For more detailed information, visit the official Smithsonian page.