Coordinates: 64°25′12″N 17°19′48″W / 64.42000°N 17.33000°W / 64.42000; -17.33000
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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 / 64.42000°N 17.33000°W / 64.42000; -17.33000
Mountain typeVolcanic caldera
Last eruptionMay 2011
Geological features near the Grímsvötn central volcano (red outline). Shading also shows:   calderas, other   central volcanoes,   fissure swarms,   subglacial terrain above 1,100 m (3,600 ft),   seismically active areas between 1995 to 2007. Clicking on the image enables full window and mouse-over with more detail.

Grímsvötn (Icelandic pronunciation: [ˈkrimsˌvœhtn̥] ;[2] vötn = "waters", singular: vatn) is an active 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 / 64.417°N 17.333°W / 64.417; -17.333, at an elevation of 1,725 m (5,659 ft). Beneath the caldera is the magma chamber of the Grímsvötn volcano.

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 Grímsvötn-Laki volcanic system.[3] 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.[4] Within the Grímsvötn-Laki volcanic system is a second central volcano called Thordarhyrna (Þórðarhyrna).[5]


Eruptions in the caldera regularly cause glacial outbursts known as jökulhlaup.[6] Eruptions or geothermal activity, 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. Earthquakes and seismic tremor may occur.[7] Jökulhlaup can occur independent of eruptions or be followed by eruptions.[7] Jökulhlaup independent of eruptions occurred in November, December 2021 and October 2022.[7] Jökulhlaup which were followed by eruptions occurred in 1922, 1934 and 2004.[7] 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[8] 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[edit]

Gjálp 1996[edit]

(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 magnitude 5 , 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.[9][10]

1998 and 2004 eruptions[edit]

Satellite images of the November 2004 Grímsvötn Eruption. The lower image assigns a false color (red) to the surface ice.

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[edit]

Harmonic tremors were recorded twice around Grímsvötn on 2 and 3 October 2010, possibly indicating an impending eruption.[11] 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,[12][13][14][15] 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.[16]

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

Disruption to air travel in Iceland[17] commenced on 22 May, followed by Greenland, Scotland,[18] Norway, Svalbard[19] and a small part of Denmark on subsequent days. On 24 May the disruption spread to Northern Ireland and to airports in northern England.[17] The cancellation of 900 out of 90,000 European flights[20] 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.[21][22][23]

2020 onward threats of eruption[edit]

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.[24] No eruption occurred.

In September 2021, an increase in water outflow from under the Vatnajökull ice cap was reported. The water contains elevated levels of dissolved hydrogen sulfide, suggesting increased volcanic activity under the ice.[25] Jökulhlaup (glacial lake flooding) can occur before or after an eruption.

On 4 December 2021, a jökulhlaup occurred from Grímsvötn into the Gígjukvísl river, with an average flow of 2,600 m3/s (92,000 cu ft/s). Two days later, the Icelandic Meteorological Office increased the alert level for Grímsvötn from yellow to orange, after a series of earthquakes was detected. On 7 December, the alert level was lowered back to yellow, after seismic activity decreased and no signs of eruptive activity were detected.[26]

On 11 December 2023, a jökulhlaup followed in time,[7] a Mw4.5 earthquake.[27]

Bacteria in the subglacial lakes[edit]

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.[28][29]


There is the potential for mechanical interaction such as dyke propagation between Grímsvötn and Thordarhyrna.[30] Interactions can also occur with the nearby Bárðarbunga volcano, which is part of a separate volcanic system.[30] The volcano erupts predominantly tholeiitic basalt, [3] and a close chemical affinity exists with the other lavas of the Grímsvötn-Laki volcanic system.[31] It is part of the Eastern volcanic zone of Iceland, and is directly over the Iceland mantle plume.[32] The volcanic system has crater rows extending to the south east; the 25 km (16 mi) long Laki–Grímsvötn fissure system and the 30 km (19 mi) long Rauðhólar-Eldgígur fissure system.[31][3][5]

Future trends[edit]

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.[33]

See also[edit]


  1. ^ "Grímsvötn". Global Volcanism Program. Smithsonian Institution. Retrieved 15 August 2006.
  2. ^ "How to pronounce /grímsvötn/". Retrieved 23 May 2011.
  3. ^ a b c Guðmundsson, Magnús T.; Larsen, Guðrún (2019). "Grímsvötn Alternative name: Grímsvötn-Laki". Retrieved 31 March 2024.
  4. ^ Jude-Eton, T. C.; Thordarson, T.; Gudmundsson, M. T.; Oddsson, B. (2012-03-08). "Dynamics, stratigraphy and proximal dispersal of supraglacial tephra during the ice-confined 2004 eruption at Grímsvötn Volcano, Iceland". Bulletin of Volcanology. 74 (5): 1057–1082. Bibcode:2012BVol...74.1057J. doi:10.1007/s00445-012-0583-3. ISSN 0258-8900. S2CID 128678427.
  5. ^ a b Guðmundsson, Magnús T.; Larsen, Guðrún (2019). "Þórðarhyrna central volcano (Grímsvötn-Laki volcanic system) e: Thordarhyrna". Retrieved 31 March 2024.
  6. ^ Andrew, R. E. B. (2008). PhD Dissertation: Volcanotectonic Evolution and Characteristic Volcanism of the Neovolcanic Zone of Iceland (PDF) (Thesis). Georg-August-Universität, Göttingen. pp. 1–122. Archived from the original (PDF) on 2012-03-09. Retrieved 2011-05-24. : pages 38,39, Jökulhlaup figure 8.1 
  7. ^ a b c d e "Flood tremor gradually increasing". 12 January 2023. Retrieved 13 January 2023.
  8. ^ 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.
  9. ^ 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.
  10. ^ See also: Anne Schöpa: Subglacial volcanism with examples from Iceland. TU Freiberg. (2008)
  11. ^ "Possible Harmonic tremor pulse at Grímsfjall volcano | Iceland Volcano and Earthquake blog". 2010-10-02. Archived from the original on 2010-10-10. Retrieved 22 May 2011.
  12. ^ Eldgos í Grímsvötnum Archived 2011-08-03 at the National and University Library of Iceland, 24 May 2011 (in Icelandic)
  13. ^ Njörður Helgason (14 April 2011). "Vegurinn um Skeiðarársand lokaður". Retrieved 22 May 2011.
  14. ^ "Iceland's most active volcano erupts – Europe". Al Jazeera English. 21 May 2011. Retrieved 22 May 2011.
  15. ^ "Iceland volcanic eruption 'not linked to the end of the world' | IceNews – Daily News". Archived from the original on 24 May 2011. Retrieved 22 May 2011.
  16. ^ "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.
  17. ^ a b Eurocontrol news
  18. ^ Scottish flights grounded by Iceland volcanic ash cloud, BBC, 23 May 2011
  19. ^ Iceland eruption hits Norwegian flights, The Foreigner, 23 May 2011
  20. ^ 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.
  21. ^ "Volcanic Ash Advisory at 1241 on 25 May 2011". Met Office UK. Retrieved 25 May 2011.
  22. ^ "Iceland volcano ash: German air traffic resuming". BBC News. 25 May 2011. Retrieved 25 May 2011.
  23. ^ "Update on volcanic activity in Grímsvötn". Iceland Met Office. Retrieved 27 May 2011.
  24. ^ "Evidences that Grímsvötn volcano is getting ready for the next eruption | News". Icelandic Meteorological office. Retrieved 2020-08-05.
  25. ^ "Grimsvötn volcano (Iceland): subglacial meltwater flood in progress". Volcano Discovery. 3 September 2021. Retrieved 9 September 2021.
  26. ^ "IWO:Flood in Grímsvötn". 8 December 2021. Retrieved 13 January 2023.
  27. ^ "UGS:M 4.5 - 109 km W of Höfn, Iceland". Retrieved 13 January 2023.
  28. ^ 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.
  29. ^ Peplow, Mark (2004). "Glacial lake hides bacteria". Nature. doi:10.1038/news040712-6.
  30. ^ a b Gudmundsson, A.; Andrew, R.E. (2007). "Mechanical interaction between active volcanoes in Iceland". Geophysical Research Letters. 34 (10): L10310. Bibcode:2007GeoRL..3410310G. doi:10.1029/2007GL029873.
  31. ^ a b Manning, C.J.; Thirlwall, M.F. (2014). "Isotopic evidence for interaction between Öræfajökull mantle and the Eastern Rift Zone, Iceland". Contributions to Mineralogy and Petrology. 167: 1–22. Bibcode:2014CoMP..167..959M. doi:10.1007/s00410-013-0959-1.: 958 
  32. ^ Andrew, Ruth E. B.; Gudmundsson, Agust (20 November 2008). "Volcanoes as elastic inclusions: their effects on the propagation of dykes, volcanic fissures, and volcanic zones in Iceland". Journal of Volcanology and Geothermal Research. Volcanic Flows and Falls. 177 (4). Elsevier: 1045–1054. doi:10.1016/j.jvolgeores.2008.07.025.: 4. Mechanical interaction 
  33. ^ "Icelandic Met Office on 1 September 2011". Icelandic Met Office. Retrieved 2 September 2011.

External links[edit]