Katla (volcano)
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Katla () is one of the largest volcanoes in Iceland. It is situated to the north of Vík í Mýrdal and to the east of the smaller glacier Eyjafjallajökull. Its peak reaches 1,512 metres (4,961 ft) in height and is partially covered by the Mýrdalsjökull glacier with an area of 595 km² (230 sq mi). The Eldgjá canyon is part of the same volcanic system.[2][3]
The caldera of the volcano has a diameter of 10 km (6 mi) and is covered with 200–700 metres (660-2,300 ft) of ice. The volcano normally erupts every 40–80 years. The flood discharge at the peak of an eruption in 1755 has been estimated at 200,000–400,000 m³/s (7.1-14.1 million cu ft/sec), comparable to the combined average discharge of the Amazon, Mississippi, Nile, and Yangtze rivers (about 266,000 m³/s (9.4 million cu ft/sec)).
Catastrophic eruptions have occurred in Katla, generally with a Volcanic Explosivity Index (VEI) between 4 and 6 (scale goes between 0 to 8). In comparison Eyjafjallajökull 2010 eruption had a VEI4. The bigger VEI6 eruptions are comparable to Pinatubo 1991 eruption. It is thought that Katla is the source of the Vedde Ash (more than 6 to 7 cubic kilometers (1.4 to 1.7 cu mi) of tephra dated to 10,600 years BP)[1][4][5][6] found at a number of sites including Norway, Scotland and North Atlantic cores. Sixteen eruptions have been documented since 930. The last major eruption occurred in 1918 (VEI5), although there may have been small eruptions that did not break the ice cover in 1955[1] and 1999.[7] The 1918 eruption resulted in extending the southern coast by 5 km due to laharic flood deposits. The present volcanic repose since 1918 is among the longest known in historic times.[8]
Since 1500, major eruptions occurred in 1918 (VEI4 or VEI5; about 0.7 cubic Km ejected material), 1860 (VEI4), 1823 (VEI3), 1755 (VEI5; 1.5 cubic Km ejected material), 1721 (VEI5), 1660 (VEI4), 1625 (VEI5), 1612 (VEI4) and 1580 (VEI4). Most of these resulted in catastrophic and very large glacial floods. A severe fissure eruption occurred in 934 (VEI5 or VEI6), releasing 5 cubic Km of tephra and 18 cubic Km of lava, one of the largest lava eruptions in the past 10 000 years.[9]
Before the 1974 Hringvegur (Iceland's Ring Road) was constructed, people feared traversing the plains in front of the volcano because of the frequent jökulhlaup (or glacier burst) and the deep river crossings. Especially dangerous was the glacier outburst that followed the eruption of 1918. Katla has been showing signs of unrest since 1999, and geologists have concerns that it might erupt in the near future.[10] Particularly, monitoring has been intensified following the March 2010 eruptions of a smaller neighbouring volcano - Guðnasteinn - beneath the Eyjafjallajökull glacier.[11] The eruption of this nearby long-dormant volcano in March and April 2010 prompted fears among some geophysicists that it might trigger an eruption at the larger and more dangerous Katla.[12][13][14] In the past 1,000 years, all three known eruptions of Eyjafjallajökull have triggered subsequent Katla eruptions.[15] Following the 2010 Eyjafjallajökull eruptions, on 20 April 2010 Icelandic President Ólafur Grímsson said "the time for Katla to erupt is coming close ... we [Iceland] have prepared ... it is high time for European governments and airline authorities all over Europe and the world to start planning for the eventual Katla eruption".[16]
Increased earthquake activity has been noticed on Katla since after the eruption at Eyjafjallajökull, but no other signs of an imminent eruption have been observed. These are located mainly in the northwestern rim of the caldera. On the 9th October 2010, a sudden rise in Harmonic Tremor was observed in the stations around Katla, a sign of an impending eruption[17].
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The Mýrdalsjökull glacier
The name
The name Katla is derived from the word ketill m 'kettle' - referring to the form of the volcano. Katla is also used as a female first name.[18]
See also
- Glaciers of Iceland
- Glacial lake outburst flood
- Iceland plume
- Iceland hotspot
- List of volcanoes in Iceland
- Volcanism in Iceland
References
- ^ a b c "Katla Volcano". Institute of Earth Sciences. University of Iceland. Retrieved 2010-03-12.
- ^ "Katla". Global Volcanism Program. Smithsonian Institution. Retrieved 2010-03-26.
- ^ Gudmundsson, Magnús T. (January 2007). "Volcanic systems and calderas in the Vatnajökull region, central Iceland: Constraints on crustal structure from gravity data". Journal of Geodynamics. 43 (1): 153–169. doi:10.1016/j.jog.2006.09.015.
{{cite journal}}: Unknown parameter|coauthors=ignored (|author=suggested) (help) - ^ Mangerud , J., Lie, S.V., Furned, H., Kristiansen, I.L., Lømo, L. (1984) A Younger Dryas Ash Bed in Western Norway, and Its Possible Correlations with Tephra in Cores from the Norwegian Sea and the North Atlantic. Quaternary Research 21 85-104
- ^ Grönvold, K. (1995). "Ash layers from Iceland in the Greenland GRIP ice core correlated with oceanic and land sediments". Earth Planet Sci Lett. 135: 149–155.
{{cite journal}}: Unknown parameter|coauthors=ignored (|author=suggested) (help) - ^ "Postglacial Lava Production in Iceland" (PDF), PhD-thesis, Geological Museum, University of Copenhagen, 2003, pp. 95–108
{{citation}}: Unknown parameter|authors=ignored (help); Unknown parameter|editors=ignored (|editor=suggested) (help) (Dead link) - ^ 1999 Eruption, jökulhlaup
- ^ http://www.earthice.hi.is/page/ies_katla1918
- ^ http://www.volcano.si.edu/world/volcano.cfm?vnum=1702-03=&volpage=erupt
- ^ Soosalu, Heidi. "Katla seismicity". Institute of Earth Sciences. University of Iceland. Retrieved 2010-03-12.
- ^ "Hard to Predict How Long Iceland Eruption Will Last". Iceland Review. Iceland. March 21, 2010. Retrieved March 21, 2010.
- ^ Volcano erupts in south Iceland BBC online news. Retrieved March 21, 2010.
- ^ Boyes, Roger (2010-03-21). "Iceland prepares for second, more devastating volcanic eruption". Times Online. Retrieved 2010-03-22.
- ^ "Icelandic Volcano May Cause Bigger Eruption". Reuters. 2010-03-22. Retrieved 2010-04-20.
{{cite news}}: Italic or bold markup not allowed in:|publisher=(help) - ^ Boyes, Roger (2010-03-21). "Iceland prepares for second, more devastating volcanic eruption". Times Online. Retrieved 2010-03-22.
{{cite news}}: Italic or bold markup not allowed in:|publisher=(help) - ^ BBC Newsnight interview with President Grímsson of Iceland, 20 April 2010
- ^ http://www.jonfr.com/volcano
- ^ Katla - Nordic Names Wiki - Name Origin, Meaning and Statistics
External links
