Ale Bagu Volcano - John Seach


Erta Ale Range, Ethiopia

13.52 N, 40.63 E
summit elevation 1031 m

Ale Bagu is the southernmost volcano in the Erta Ale Range.
The main cater is 750 m x 450 m depression.

In the south, some of the lava flows of Ale Bagu reach the northern lava fields of the Alaita unit. At the East, the flows are covered by those of Erta Ale and Hayli Gub

Ale Bagu Volcano

The volcano is unique for volcanoes in the Erta Ale Range. It has a large summit crater, and it is the only volcano where large explosive activity has occurred.

Ale Bagu is the only volcano in Erta Ale range which is not aligned on the median fissure of the chain. It is located on a parallel Eritrean fissure displaced 10 km at the West.

The basaltic lava fields building the base of the volcano are well seen only in the west. In the other areas they are mostly covered by recent flows emitted through the median fissures of the chain.

The lava fields are affected in the southern part by an unusual structure. It consists of a thin graben, 2 km long and 100 m wide, which affects the main axis of a panhoehoe flow over a thickness of tens of metres. This structure probably corresponds to a collapse of the lava pile along an open fissure.

The summit of the Ale Bagu is covered by mostly basic pyroclastics consisting of an alternation of cinerite, lapilli and scoria layers.

The composition of the lapilli is quite heterogeneous; white pumice, fragments of obsidian, plagioclase and olivine. Several blocks, up to 1 metre in size, are found in these deposits, and are dispersed on the surface of the volcano.

The main craters of Ale Bagu are located in the summit part of the volcano, and aligned along the NNW-SSE fissure. The main crater forms an imperfect ellipse 750 X 450 m in diameter, and 100 m deep. A small cone, formed by accumulation of lava, occupies the bottom of the main crater and has produced a recent lava flow. Fumaroles are present on the summit of the small cone and at the bottom of the recent flow. Fumarolic activity, with local steam emission, is seen in several places in the walls of the crater.

A series of small craters aligned along the main fissure are locaated on the northern flank of the volcano. Their diameter regularly decreases from the central zone to the North. The largest is 80 m deep and has a subcircular form, with a diameter of 250 m.

Ale Bagu Volcano Eruptions

No recent eruptions.