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Encyclopedia > Erta Ale
Erta Ale

Erta Ale volcano (EA) and Ethiopian Highlands (EH) as seen from space
Elevation 613 metres (2,011 feet)
Location Ethiopia
Range Erta Ale Range
Coordinates 13°36′N 40°40′E
Type Shield volcano
Age of rock < 10,000 yr
Last eruption 2006 (continuing)

Erta Ale is an active shield volcano in Ethiopia, known for its long-standing lava lake activity. Image File history File links STS41G-32-14. ... The Ethiopian Highlands are a rugged mass of mountains in Ethiopia and Eritrea in northeastern Africa. ... A topographical summit is a point on a surface which is higher in elevation than all points immediately adjacent to it. ... A mountain range (Sierra in the Spanish language) is a group of mountains bordered by lowlands or separated from other mountain ranges by passes or rivers. ... Map of Earth showing lines of latitude (horizontally) and longitude (vertically); large version (pdf) The geographic (earth-mapping) coordinate system expresses every horizontal position on Earth by two of the three coordinates of a spherical coordinate system which is aligned with the spin axis of the Earth. ... Mountains can be characterized in several ways. ... Mauna Kea, a shield volcano, on the Island of Hawai‘i with a light dusting of snow. ... // The geological time scale is used by geologists and other scientists to describe the timing and relationships between events that have occurred during the history of the Earth. ... A volcano is a geological landform usually generated by the eruption through a planets surface of magma, molten rock welling up from the planets interior. ... 2006 (MMVI) is a common year starting on Sunday of the Gregorian calendar. ... Mauna Kea, a shield volcano, on the Island of Hawai‘i with a light dusting of snow. ... A lava lake in Hawaii Lava lakes are large volumes of molten lava, usually basaltic, contained in a vent, volcanic crater, or broad depression. ...


This volcano is quite broad, about 50 km in diameter. It has an elliptical caldera some 0.7 x 1.6 km wide. The caldera contains two pit craters, both of which have had lava lake activity. The south pit crater has seen the most continuous lava lake activity, and the larger north pit crater has been less frequently so. A volcano is a geological landform usually generated by the eruption through a planets surface of magma, molten rock welling up from the planets interior. ... Crater Lake, Oregon A caldera is a volcanic feature formed by the collapse of a volcano into itself. ...


Erta Ale has erupted seven times in the past 125 years. Three of the early eruption dates, 1873, 1903, and 1904 are uncertain. However, 1906, 1940, 1960, and 1967 are well established events. Erta Ale has been erupting continuously since 1967. Observation of this volcano is limited due to the harshness of the Afar Triangle, as air temperatures can exceed 50°C (112°F), and the indigenous Afar people have a rather fierce reputation. Map of Ethiopia highlighting the Afar region. ... Afar (or Danakil) are a tribal people who reside principally in the Danakil Desert in the Afar Region of Ethiopia and in Eritrea and Djibouti. ...


Two new studies on Erta Ale have recently been published.

  • Oppenheimer and Francis (1998) looked at the implications of long-lived lava lakes. They believe that Erta Ale's lava lake has been active for at least the last 90 years (making it one of the longest known historic eruptions). Large amounts of heat are released by the volcano but the amount of lava that erupts is relatively small. They speculated that a higher magma density (caused by the lava lake cooling) inhibits eruptions. They proposed that most of the magma accumulates in the underlying crust as dikes and sills. Since the Afar region is under extension, conditions are favorable for injection of dikes and sills.
  • Barrat and others (1998) looked at the chemistry of the rocks at Erta Ale. Rocks range in composition from basalt to rhyolite. They found that two mantle sources were tapped for the basalts: one similar in composition to the source for mid-ocean ridge basalts (called MORB by geochemists) and one similar in composition to the source for ocean-island basalts (called OIB). Their data did not show a significant contribution of sialic material from the continental crust. The silica-rich volcanics are derived from fractional crystallization of basaltic magmas.

As of January 2004, visiting scientists have reported that the lava lake in the south pit crater has solidified at the surface, leaving only a small incandescent lava lake remaining. From 21 to 24 September 2005, Erta Ale erupted, probably in a Strombolian manner according to the locals, as inferred by scientists who visited afterwards. The south pit crater and its lava lake both have also enlarged considerably since. A dike in geology refers to a tabular intrusive igneous body. ... In geology, a sill is a tabular, often horizontal mass of igneous rock that has been intruded laterally between older layers of sedimentary rock, beds of volcanic lava or tuff, or even along the direction of foliation in metamorphic rock. ... Basalt Basalt is a common gray to black volcanic rock. ... Rhyolite Rhyolite is an igneous, volcanic (extrusive) rock, of felsic composition, with aphanitic to porphyritic texture. ... A mid-ocean ridge or mid-oceanic ridge is an underwater mountain range, formed by plate tectonics. ... A petrologic name for the upper layer of continental crust that is composed of rocks rich in silica and aluminium. ... The continental crust is the layer of granitic, sedimentary and metamorphic rocks which form the continents and the areas of shallow seabed close to their shores, known as continental shelves. ... This article is about the type of rock. ... It has been suggested that this article or section be merged with Strombolian activity. ...


References

  • Barrat, J.A., et al, 1998. J Volc Geotherm Res. 80, pp 85-100.
  • Oppenheimer C, Francis P, 1998. "Implications of longeval lava lakes for geomorphological and plutonic processes at Erta 'Ale volcano, Afar", J Volc Geotherm Res. 80: pp 101-111
  • Siebert, L. and T. Simkin (2002-). Volcanoes of the World: an Illustrated Catalog of Holocene Volcanoes and their Eruptions. Smithsonian Institution, Global Volcanism Program Digital Information Series, GVP-3. URL: http://www.volcano.si.edu/world/
  • Global Volcanism Program entry

External links

  • Erta Ale: Index of Volcanic Activity Reports

  Results from FactBites:
 
Erta Ale, Ethiopia (419 words)
Erta Ale is a shield volcano in the Afar region of East Africa.
Erta Ale is a remote and rarely visited volcano that is known currently to have an active lava lake in its summit crater.
Erta Ale has undergone seven eruption events in the past 125 years.
Erta Ale at AllExperts (566 words)
Erta Ale is an active shield volcano in Ethiopia, known for its long-standing lava lake activity.
They believe that Erta Ale's lava lake has been active for at least the last 90 years (making it one of the longest known historic eruptions).
From 21 to 24 September 2005, Erta Ale erupted, probably in a Strombolian manner according to the locals, as inferred by scientists who visited afterwards.
  More results at FactBites »

 
 

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