The Anglo-Ethiopian Society

Lecture - The 2010 eruption of Erte Ale, Afar, Ethiopia

Lorraine Field

Thursday 15th March 2012

The Open University Geological Society (London Branch)

The Open University Geological Society (London Branch) meetings are held at 7:00pm in the Courtyard Rooms in the basement of the Natural History Museum, Cromwell Road, London, SW7 5BD.

A list of names has to be provided for the security point, so it is essential that you make contact and register online with them if you are at all interested in attending and to get confirmation of arrangements – you can always cancel. Note that the start time for talks is 7.00 pm and you can only enter between 6.30 and 7.00 pm when one of their members is positioned by the door with a swipe card.
Access to the Courtyard Room is usually via the big Bronze Doors just beyond the end of the garden railings. You will need to have your name ticked off at the security point, and will be directed to the Courtyard Rooms by the member on duty with the swipe card. Everyone normally leaves together. Usually some go on for an informal drink at the Hoop and Toy on Thurloe Place. All are welcome.

The Afar depression has been produced by the rifting between Africa and Arabia over the past ~30 Myr, and is characterised by ~60 km long magmatic segments where faulting and volcanic activity have become more localised . The Erta Ale magmatic segment is the most northern in Afar and is the sub-aerial southwards continuation of the Red Sea Rift. Erta Ale volcano is a basaltic shield (13°36’11.41”N, 40°39’50.08”E) situated towards the southern end of the Erta Ale magmatic segment which also contains five other main volcanic centres.

Erta Ale is well known for its lava lakes which have been observed in both the northern and southern pits within the main crater: one of just four volcanoes with long-lived lava lakes across the world.

The first systematic study of the lake began in 1967, but a lake (or lakes) are likely to have existed from much earlier than this: reports of a ‘smoking mountain’ and characteristic red summit glow have been recorded by early visitors to the area. Due to both the remoteness of the volcano and the political situation, the resulting observations have been sporadic. It was not until the CNR-CNRS campaigns of the late 1960s that the volcano began to be studied in detail. At this time a lava lake existed in both the northern and southern pits but the northern lake solidified between 1988 and 1992 following the emplacement of two lava flows. The southern lake solidified briefly between late 2004 until April 2005.

The southern lake again erupted in November 2010, overspilling into the main crater. This was the first such eruption from the southern pit within the main crater since 1973, and the first eruption at this remote volcano in the modern satellite age. Fortuitous timing allowed us to combine on-the-ground observations with multispectral imaging from the SEVIRI satellite to reconstruct the entire eruptive episode beginning on the 11th November, and ending prior to the 14th December 2010. Analysis of zero-age lava samples has provided pristine melt inclusions for the first time and analysis of these has enabled us to further our understanding of the plumbing system of this unique volcano.

More information can be found on the Open University Geological Society (London Branch) website.

Anglo-Ethiopian Society Web Listing Mar-12

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