Grímsvötn

Grímsvötn (Icelandic pronunciation: ​[ˈkrimsvœʰtn̥];[2] vötn = "waters", singular: vatn) is a volcano with a (partially subglacial) fissure system located in Vatnajökull National Park, Iceland. The volcano itself is completely subglacial and located under the northwestern side of the Vatnajökull ice cap. The subglacial caldera is at 64°25′N 17°20′W, at an elevation of 1,725 m (5,659 ft). Beneath the caldera is the magma chamber of the Grímsvötn volcano.

Grímsvötn
Grímsvötn and the Vatnajökull glacier, Iceland, July 1972
Highest point
Elevation1,725 m (5,659 ft) [1]
ListingList of volcanoes in Iceland
Coordinates64°25′12″N 17°19′48″W 
Geography
Geology
Mountain typeVolcanic caldera
Last eruptionMay 2011

Grímsvötn is a basaltic volcano which has the highest eruption frequency of all the volcanoes in Iceland and has a southwest-northeast-trending fissure system. The massive climate-impacting Laki fissure eruption of 1783–1784 was a part of the same fissure system. Grímsvötn was erupting at the same time as Laki during 1783, but continued to erupt until 1785. Because most of the volcanic system lies underneath Vatnajökull, most of its eruptions have been subglacial and the interaction of magma and meltwater from the ice causes phreatomagmatic explosive activity.

Jökulhlaup

Eruptions in the caldera regularly cause glacial outbursts known as jökulhlaup.[3] Eruptions melt enough ice to fill the Grímsvötn caldera with water, and the pressure may be enough to suddenly lift the ice cap, allowing huge quantities of water to escape rapidly. Consequently, the Grímsvötn caldera is monitored very carefully.

When a large eruption occurred in 1996, geologists knew well in advance that a glacial burst was imminent. It did not occur until several weeks after the eruption finished, but monitoring[4] ensured that the Icelandic ring road (Hringvegur) was closed when the burst occurred. A section of road across the Skeiðará sandur was washed away in the ensuing flood, but no one was hurt.

Eruption history between 1990 and today

Gjálp 1996

(See also the main article: 1996 eruption of Gjálp

The Gjálp fissure vent eruption in 1996 revealed that an interaction may exist between Bárðarbunga and Grímsvötn. A strong earthquake in Bárðarbunga, about 5 on the Richter scale, is believed to have started the eruption in Gjálp. On the other hand, because of the magma erupted showed strong connections to the Grímsvötn Volcanic System acc. to petrology studies, the 1996 as well as a former eruption there in the 1930s are thought to have taken place within Grímsvötn Volcanic system.[5][6]

1998 and 2004 eruptions
Satellite images of the November 2004 Grímsvötn Eruption

A week-long eruption occurred at Grímsvötn starting on 28 December 1998, but no glacial burst occurred. In November 2004, a week-long eruption occurred. Volcanic ash from the eruption fell as far away as mainland Europe and caused short-term disruption of airline traffic into Iceland, but again no glacial burst followed the eruption.

2011 eruption
Main article: 2011 eruption of Grímsvötn

Harmonic tremors were recorded twice around Grímsvötn on 2 and 3 October 2010, possibly indicating an impending eruption.[7] At the same time, sudden inflation was measured by GPS in the volcano, indicating magma movement under the caldera. On 1 November 2010 meltwater from the Vatnajökull glacier was flowing into the lake, suggesting that an eruption of the underlying volcano could be imminent.

Satellite image from 22 May 2011 of the volcanic plume above Iceland
View of Icelandic landscape beneath the ash-cloud during the 2011 eruption
Grímsvötn in August 2011. Ash covering the surrounding snow and ice

On 21 May 2011 at 19:25 UTC, an eruption began, with 12 km (7 mi) high plumes accompanied by multiple earthquakes,[8][9][10][11] Until 25 May, the eruption scale had been larger than that of the 2010 eruption of Eyjafjallajökull.

The ash cloud from the eruption rose to 20 km (12 mi), and was so far 10 times larger than the 2004 eruption, and the strongest in Grímsvötn in the last 100 years.[12]

Satellite image from 23 May 2011 of the ash-cloud to the south of Iceland

Disruption to air travel in Iceland[13] commenced on 22 May, followed by Greenland, Scotland,[14] Norway, Svalbard[15] and a small part of Denmark on subsequent days. On 24 May the disruption spread to Northern Ireland and to airports in northern England.[13] The cancellation of 900 out of 90,000 European flights[16] in the period 23–25 May was much less widespread than the 2010 disruption after the Eyjafjallajökull eruption.

The eruption stopped at 02:40 UTC on 25 May 2011, although there was some explosive activity from the eruptive vents affecting only the area around the crater.[17][18][19]

2020 threat of eruption

In June 2020, the Icelandic Meteorological Office (IMO) issued a warning that an eruption might take place in the coming weeks or months, following scientists reporting high levels of sulfur dioxide, which is indicative of the presence of shallow magma. IMO warned that a glacial flood as a result of melting ice could trigger an eruption.[20] According to scientists, the effects of a future eruption of Grímsvötn would not be as severe as the 2010 eruptions of Eyjafjallajökull.,[21] a.o. because Grímsvötn erupts a different igneous rock, basalt, as compared to the trachyandesite of the Eyjafjallajökull 2010 eruption.[22]

Bacteria in the subglacial lakes

In 2004, a community of bacteria was detected in water of the Grímsvötn lake under the glacier, the first time that bacteria have been found in a subglacial lake. The lakes never freeze because of the volcanic heat. The bacteria can also survive at low concentrations of oxygen. The site is a possible analogue for life on the planet Mars, because there are also traces of volcanism and glaciers on Mars and thus the findings could help identify how to look for life on Mars.[23][24]

Studies indicate that volcanic activity in Iceland rises and falls so that the frequency and size of eruptions in and around the Vatnajökull ice cap varies with time. It is believed that the four eruptions between 1996 and 2011 could mark the beginning of an active period, during which an eruption in Grímsvötn in Vatnajökull may be expected every 2–7 years. Parallel volcanic activity in nearby Bárðarbunga is known to be associated with increased activity in Grímsvötn. Seismic activity has been increasing in the area in recent years, indicating the entry of magma.[25]

See also

References
  1. "Grímsvötn". Global Volcanism Program. Smithsonian Institution. Retrieved 15 August 2006.
  2. "How to pronounce /grímsvötn/". youtube.com. Retrieved 23 May 2011.
  3. "Archived copy" (PDF). Archived from the original (PDF) on 2012-03-09. Retrieved 2011-05-24.CS1 maint: archived copy as title (link) Jökulhlaup figure 8.1
  4. Russell, Andrew J.; Gregory, Andrew R.; Large, Andrew R. G.; Fleisher, P. Jay; Harris, Timothy D. (2007). "Tunnel channel formation during the November 1996 jökulhlaup, Skeiðarárjökull, Iceland". Annals of Glaciology. 45 (1): 95–103. Bibcode:2007AnGla..45...95R. doi:10.3189/172756407782282552.
  5. See eg.: Elín Margrét Magnúsdóttir: Gjóska úr Grímsvötnum 2011 og Bárðarbungu 2014-2015 : Ásýndar- ogkornastærðargreining. BS ritgerð. Jarðvísindadeild Háskóli Íslands (2017) (in Icelandic, abstract also in English) Retrieved 24 August 2020.
  6. See also: Anne Schöpa: Subglacial volcanism with examples from Iceland. TU Freiberg. (2008)
  7. "Possible Harmonic tremor pulse at Grímsfjall volcano | Iceland Volcano and Earthquake blog". Jonfr.com. 2010-10-02. Retrieved 22 May 2011.
  8. Eldgos í Grímsvötnum Archived 2011-08-03 at the National and University Library of Iceland, 24 May 2011 (in Icelandic)
  9. Njörður Helgason (14 April 2011). "Vegurinn um Skeiðarársand lokaður". mbl.is. Retrieved 22 May 2011.
  10. "Iceland's most active volcano erupts – Europe". Al Jazeera English. 21 May 2011. Retrieved 22 May 2011.
  11. "Iceland volcanic eruption 'not linked to the end of the world' | IceNews – Daily News". Icenews.is. Retrieved 22 May 2011.
  12. "Largest Volcanic Eruption in Grímsvötn in 100 Years". Daily News. Iceland Review Online. 22 May 2011. Archived from the original on 24 May 2011. Retrieved 22 May 2011.
  13. Eurocontrol news
  14. Scottish flights grounded by Iceland volcanic ash cloud, BBC, 23 May 2011
  15. Iceland eruption hits Norwegian flights, The Foreigner, 23 May 2011
  16. David Learmount (26 May 2011). "European proceedures (sic) cope with new ash cloud". Flightglobal. Archived from the original on July 3, 2015. Retrieved September 28, 2015.
  17. "Volcanic Ash Advisory at 1241 on 25 May 2011". Met Office UK. Retrieved 25 May 2011.
  18. "Iceland volcano ash: German air traffic resuming". BBC News. 25 May 2011. Retrieved 25 May 2011.
  19. "Update on volcanic activity in Grímsvötn". Iceland Met Office. Retrieved 27 May 2011.
  20. "Evidences that Grímsvötn volcano is getting ready for the next eruption | News". Icelandic Meteorological office. Retrieved 2020-08-05.
  21. "Iceland hit by thousands of quakes and threat of volcanic eruption". Deutsche Welle. 22 June 2020. Retrieved 23 June 2020.
  22. AMY R DONOVAN*, CLIVE OPPENHEIMER: The 2010 Eyjafjallajökull eruption and the reconstruction of geography. The Geographical Journal, Vol. 177, No. 1, March 2011, pp. 4–11, doi: 10.1111/j.1475-4959.2010.00379.x
  23. Gaidos, E; Lanoil, B; Thorsteinsson, T; Graham, A; Skidmore, M; Han, SK; Rust, T; Popp, B (2004). "A viable microbial community in a subglacial volcanic crater lake, Iceland". Astrobiology. 4 (3): 327–44. doi:10.1089/1531107041939529. PMID 15383238.
  24. Peplow, Mark (2004). "Glacial lake hides bacteria". Nature. doi:10.1038/news040712-6.
  25. "Icelandic Met Office on 1 September 2011". Icelandic Met Office. Retrieved 2 September 2011.
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