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Erta Ale – The World’s Most Inconvenient Volcano. Geographic Setting. Latitude: 13°36′N. Longitude: 40°40′E. The Afar Desert region has one of the hottest and driest climates on earth. Tectonic Setting. Erta Ale lies on the Afar Triple Junction , where three plates are diverging:
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Geographic Setting Latitude: 13°36′N Longitude: 40°40′E The Afar Desert region has one of the hottest and driest climates on earth
Tectonic Setting Erta Ale lies on the Afar Triple Junction, where three plates are diverging: Arabian Plate African Plate (Nubian) African Plate (Somalian) Part of a chain of volcanoes along the East African Rift Zone
Dimensions Erta Ale’s base is about 100 meters below sea level 613 meters high 50 kilometers wide
Form Basaltic shield volcano Summit caldera with one—and sometimes two—active lava lakes
Calderas and Craters The summit caldera is 1.6 km x 0.7 km with two pit craters Active lava lake in one crater since at least 1967 One of only a few active lava lakes in the world!
Eruptive History 1873, 1903, 1904, 1906, 1940, 1960, 1967-present Historical records on eruptions up through 1906 are undependable 2005: 250 livestock killed and thousands evacuated due to lava flows
Eruptive characteristics Consistent degassing and heat production from lava lake Central vent eruptions Pahoehoe lava flows Lava lake overflows Hornitos http://www.youtube.com/watch?v=PFMgTfgKcpg
Similarities with Kilauea in many regards - extensive red eruption-borne lava flows -Lapilli and Pahoehoe; not much evidence of A’a
Moderate levels of degassing, nothing particularly unique in this regard - Erupts large amounts of heat, but relatively little lava
Petrology • - Basaltic to rhyolitic magma • Silica-rich magma from continental crust • Traces of glass in magma
Why does the lava lake continue to convect and stay active? • Volcano’s heat ejection and surface eruption levels do not match • Only 1:10 difference in surface lava ejection and heat; yet, lava lake does not cool into a solid plug • Magma most likely erupts into extensive network of sills and dykes along volcano’s wide flanks as well as surface to allow a continuously active lake
Conclusion: An Inconvenient Volcano • Geophysical monitoring difficult due to isolated location, less-than-comfortable weather conditions, and regional tensions (notably ARDUF) • Most monitoring done remotely from Addis Ababa University • Hazardous eruptions, difficult and dangerous tourist destination, difficult monitoring site makes for a sad volcano
Sources http://www.volcano.si.edu/world/volcano.cfm?vnum=0201-08= Global Volcanism Project http://www.photovolcanica.com/VolcanoInfo/Erta%20Ale/Erta%20Ale.html = Photo Volcanica “Erta Ale Volcano” http://volcano.oregonstate.edu/vwdocs/volc_images/img_erta_ale.html = “Erta Ale Volcano: Volcano World” Oregon State University 16 Feb 2003 http://news.bbc.co.uk/2/hi/science/nature/7950845.stm = “Inside the hottest place on earth,” BBC Online 19 March 2009 http://www.volcanodiscovery.com/erta_ale.html = “Erta Ale Volcano,” Volcano Discovery http://www.volcanodiscovery.com/ertaale/photos.html = “Erta Ale Photos,” Volcano Discovery http://pubs.usgs.gov/gip/dynamic/East_Africa.html = “Map of East Africa” USGS 5 May 1999 http://www.atlasobscura.com/places/erta-ale = “Erta Ale” Atlas Obscura http://www.sveurop.org/gb/articles/articles/ErtaAle.htm = “Erta Ale Volcano – Ethiopia,” Fieldworks SVE November 2004 – January 2005 http://www.stormchaser.ca/Volcanoes/Erta_Ale/Erta_Ale.html = “Expedition to Erta Ale Volcano” Stormchaser.ca January 2005