Report on Erta Ale (Ethiopia) — 5 October-11 October 2005
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 5 October-11 October 2005
Managing Editor: Gari Mayberry
Please cite this report as:
Global Volcanism Program, 2005. Report on Erta Ale (Ethiopia). In: Mayberry, G (ed.), Weekly Volcanic Activity Report, 5 October-11 October 2005. Smithsonian Institution and US Geological Survey.
13.6°N, 40.67°E; summit elev. 613 m
All times are local (unless otherwise noted)
According to a news report, after a M 4.3 earthquake on 4 October an eruption occurred at Erta Ale. The earthquake occurred in the remote region of Afar and was the 11th earthquake in the region since September.
The following activity was incorrectly reported as occurring at Erta Ale when it actually occurred at Dabbahu. See the 12-18 October 2005 Weekly Volcanic Activity Report for the full report. A team of scientists visited the Da'Ure locality of Erta Ale on 4 and 5 October after there were reports of volcanic activity there on 26 September. They determined that a minor explosive eruption occurred from two semi-circular vents, producing ashfall that was ~5 cm thick near the vent and extended more than 500 m from the vent. Boulders ejected during the eruption were as large as 3 m and were deposited as far as 20 m away. The scientists noted intense degassing from the vents, the scent of sulfur dioxide, and the sound of boiling water in the vents.
Geologic Background. Erta Ale is an isolated basaltic shield that is the most active volcano in Ethiopia. The broad, 50-km-wide edifice rises more than 600 m from below sea level in the barren Danakil depression. Erta Ale is the namesake and most prominent feature of the Erta Ale Range. The volcano contains a 0.7 x 1.6 km, elliptical summit crater housing steep-sided pit craters. Another larger 1.8 x 3.1 km wide depression elongated parallel to the trend of the Erta Ale range is located SE of the summit and is bounded by curvilinear fault scarps on the SE side. Fresh-looking basaltic lava flows from these fissures have poured into the caldera and locally overflowed its rim. The summit caldera is renowned for one, or sometimes two long-term lava lakes that have been active since at least 1967, or possibly since 1906. Recent fissure eruptions have occurred on the N flank.
Sources: Gezahegn Yirgu, Department of Earth Sciences, Addis Ababa University, Agence France-Presse (AFP)