Volcano Profile: Erta Ale

The latest in my Volcano Profiles series, this one on Erta Ale in Ethiopia.

The summit crater at Erta Ale in 1994

Location: The Afar region of Ethiopia.

Height: 613 m / 2,011 feet
Tectonic setting: Erta Ale (meaning "smoking mountain") is part of the East African Rift, where the African Continent is tearing apart along a seam that runs from the Red Sea/Gulf of Aden (two other arms of the rift themselves) south through eastern Africa. Many of the large lakes of eastern Africa such as Lakes Albert, Tanganyika, Nyasa and Kariba fill rift valleys created by the cracking of the continental plate from rising asthenopheric mantle. This upwelling produces the magma underneath the rift.
Type: Shield volcano
Hazards: Lava flows - the volcano has a long-lived active lava lake, possibly as long as the last 100 years (Oppenheimer and Francis, 1998). There is also evidence of more explosive eruptions (VEI 2) in the last 150 years from Erta Ale, but its remote location makes accurate records sparse.
Monitoring: There is not much in the way of nearby monitoring of Erta Ale, as the eruption of Dallafilla in 2008 shows - there was no one on the scene to find out which volcano in the range (conveniently also called Erta Ale) had erupted. Most eruptions in the area are first noticed by their sulfur dioxide plumes or the lava lakes by satellite, then by reports from the few locals who live near the volcano.

Erta Ale.

Summary: Erta Ale is one of the most remote volcanoes in the Afar region of Ethiopia part of the East African Rift. It is rarely visited and most of our knowledge of the volcano's activity comes from remote sensing data. The volcano itself is a large shield volcano with the typical summit caldera with craters that we see at many shield volcanoes. This summit caldera is more unique, though, thanks to the long-lived lava lake that sits in the summit crater pit. Over the last 100 years, this lava lake is sometimes joined by a second lava lake. Studies of the lake surface temperatures suggest that the flux of lava through the lake (at least in the late 1990s) is ~510-580 kg/s of basaltic lava (Burgi, 2002). Fresh-looking lava flows on the flanks of Erta Ale indicate that the lava lake will periodically overflow (as it may have in 2005), sending lava flows down the slopes of the volcano - this is a significant hazard, as superheated lava from a lava lake at Nyiragongo breached in 1977, sending lava downslope at ~100 km/h (60 mph) and killing 70 people. Most eruptions are sourced from the summit caldera area, however there have been rift vent eruptions along the northern flank of the volcano as well.
Current status: Just this week, new reports arrived that the lava lake at Erta Ale has risen to just 20 meter below the rim of th summit crater pit. Last year, an expedition visited the volcano and noted several changes since the last visit in 2002, including changes in the crater shapes and alignments at the summit.
Notable Recent Eruptions and History: An eruption of Erta Ale in 2005 forced evacuations of the region near the volcano and killed 250 heads of livestock. This eruption followed an M5.5 earthquake in the region. The volcano erupted again in 2007, prompting evacuations again, and possibly killing 5 people.
Mitigation: Evacuations are common near Erta Ale when eruptions begin, and geologists from the University of Adis Adaba usually respond quickly when evidence arises that the volcano may be erupting.

The lava lake in the crater of Erta Ale.

Selected resources of Erta'Ale:
Bizhourd, H., Barberi, F. and Varet, J., 1980, Mineralogy and Petrology of Erta Ale and Boina Volcanic Series, Afar Rift, Ethiopia. Journal of Petrology, Volume 21, Number 2. Pages 401-436.

Burgi, P.Y., Caillet, M., Haefeli, S., 2002, Field temperature measurements at Erta'Ale Lava Lake, Ethiopia. Bulletin of Volcanology, Vol. 64, No. 7. pp. 472-485.

Oppenheimer C., Francis P., 1997, Remote sensing of heat, lava and fumarole emissions from Erta 'Ale volcano, Ethiopia. International Journal of Remote Sensing, Volume 18, Number 8. pp. 1661-1692.

Oppenheimer, C., Francis, P., 1998, Journal of Volcanology and Geothermal Research, Volume 80, Issues 1-2. Pages 101-111

Oppenheimer, C., McGonigle, A.J.S., Allard, P., Wooster, M.J. and Tsanev, V., 2004, Sulfur, heat, and magma budget of Erta 'Ale lava lake, Ethiopia, Geology, v. 32 no. 6. p. 509-512

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Ah, Erte Arle. I'd love to visit - the lava lake is like a mini plate tectonic laboratory, with cooled and solidified lava "plates" floating on top of the magma and interacting with each other.

There's lots of nice photos and videos to be found here

It looks from the aerial shot that the cone is sitting right on a crack, the actual spreading area. Are those steep pale yellowish cliffs actually the faces of the rift? Remarkable pictures!

The semi-permanent lava lake seems like a prime candidate for geothermal power generation. The remote location rules out any traditional, complex powerplant, but maybe a sturdy thermoelectric system could cope with the adverse conditions without much maintenance -ask NASA for ideas.
I suspect Djibouti and much of Eritrea could get electricity this way.
And anthropologists digging up hominids on the adjacent plain could set up electrified, permanent exploration bases with internet access, for real-time identification of fossils by experts overseas....
If only it was feasible to condense water from the volcanic gases, Erta Ale might support a research base compareable to the Antarctic ones.

By Birger Johansson (not verified) on 16 Mar 2010 #permalink

Addendum: If a lava lake should overflow, would it be possible to redirect the lava to a safe direction with a quickly built wall/dyke made from a mixture of cement and volcanic ash?
The material would have to be strong enough to stop a rapid flow of a dense, very hot liquid, so I am not sure traditional engineering experience will be useful...but unlike redirecting a pyroclastic flow, it would at least be feasible (especially if there is enough water nearby to cool it by spraying the lava with fire hoses to make it run slowly, the way it was done at the Heimaey eruption).

By Birger Johansson (not verified) on 16 Mar 2010 #permalink

Just a small point in your description of the rift lakes. Lake Kariba is a reservoir on the Zambesi not a rift lake. The other major rift lake is Lake Malawi.

By Paul Callander (not verified) on 16 Mar 2010 #permalink

More! I want more! My lust for info re Erta Ale is not slaked. I want first-hand accounts of treks up to the crater, illustrated with copious photos. I want stories of intrepid Victorian explorers.

I want more about the Afar Triangle. I want to see more sensationalist coverage like this story (http://www.spiegel.de/fotostrecke/fotostrecke-12946.html) in Der Spiegel, illustrated with copious photos.

Volcano porn, that's what I want.

Good luck acquiring folks behind this 1. However you make some Very fascinating factors, youre going to need to do much more than carry up a few things that might be various than what weve previously heard. What are attempting to say here? What do you would like us to think? It seems like you cant seriously get behind a unique thought. Anyway, thats just my opinion.

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