Map of Eyjafjallajökull glacier showing its named glacial catchments (light grey shading with white outline). Clicking on the map to enlarge it enables mouse over that allows identification of individual named glacial catchments in Iceland.
Eyjafjallajökull
Guðnasteinn Hámundur
Gígjökull, Eyjafjallajökull's largestoutlet glacier, covered in volcanic ash
North view of (from left to right) Mýrdalsjökull, Fimmvörðuháls and Eyjafjallajökull on 4 April 2010, taken from an altitude of 10,000 metres (32,800 ft)
Eyjafjallajökull consists of a volcano completely covered by an ice cap. The retreating ice cap covered an area of 66 km2 (25 sq mi) in 2019,[1] but was previously more than 80 square kilometres (30 square miles),[9] with manyoutlet glaciers. The main outlet glaciers are to the north: Gígjökull, flowing into Lónið, and Steinsholtsjökull, flowing into Steinsholtslón.[10] In 1967, there was a massive landslide on the Steinsholtsjökull glacial tongue. On 16 January 1967 at 13:47:55 there was an explosion on the glacier. It can be timed because the seismometers atKirkjubæjarklaustur monitored the movement. When about 15,000,000 cubic metres (530,000,000 cubic feet) of material hit the glacier a massive amount of air, ice, and water began to move out from under the glacier into the lagoon at the foot of the glacier.[10]
The mountain itself, astratovolcano,[11] stands 1,651 metres (5,417 ft) at its highest point, and has acrater three to four kilometres (2 to2+1⁄2 miles) in diameter, open to the north.[12] The crater rim has three main peaks (clockwise from the north-east): Guðnasteinn ([ˈkvʏðnaˌsteitn̥]), 1,500 m (4,900 ft); Hámundur ([ˈhauːˌmʏntʏr̥]), 1,651 m (5,417 ft); and Goðasteinn ([ˈkɔːðaˌsteitn̥]), 1,497 m (4,911 ft). The south face of the mountain was once part of Iceland'scoastline, from which, over thousands of years, the sea has retreated some 5 km (3 mi). The former coastline now consists of sheer cliffs with manywaterfalls, of which the best known isSkógafoss. In strong winds, the water of the smaller falls can even be blown up the mountain. The area between the mountain and the present coast is a relatively flat strand, 2–5 km (1–3 mi) wide.[13]
The name means "glacier of Eyjafjöll" (or more properly here "ice cap").Eyjafjöll is the name of the southern side of the volcanicmassif together with the small mountains which form the foot of the volcano. The wordjökull[ˈjœːkʏtl̥], meaning glacier or ice cap, is acognate with theMiddle English wordikil surviving in the-icle of Englishicicle.
The nameEyjafjöll is made up of the wordseyja[ˈeiːja] (genitive plural ofey, meaningeyot orisland), and the plural wordfjöll[ˈfjœtl̥], meaningfells ormountains, and together literally means: "the mountains of the islands". The name probably refers to the close by archipelago ofVestmannaeyjar.
The wordfjalla[ˈfjatla] is the genitive plural offjöll, and soEyjafjalla[ˈeiːjaˌfjatla] is the genitive form ofEyjafjöll and means: "of the Eyjafjöll".A literal part-by-part translation ofEyjafjallajökull would thus be "Islands' Mountains' glacier".
Hence the southern slopes of the mountain Eyjafjöll result in the sea side strip of land beyond being calledUndir Eyjafjöllum.[13]
Thestratovolcano, whose vents follow an east–west trend, is composed ofbasalt toandesitelavas. Most of its historical eruptions have beenexplosive.[14] However,fissure vents occur on both (mainly the west) sides of the volcano.[14] The volcano is 800,000 years old.[15]: 15
The volcano is fed by amagma chamber under the mountain, which in turn derives from thetectonicdivergence of theMid-Atlantic Ridge. It is part of a chain of volcanoes stretching across Iceland. Its nearest active neighbours areKatla, to the northeast, andEldfell, onHeimaey, to the southwest.[12]The volcano is thought to be related to Katla geologically, in that eruptions of Eyjafjallajökull have generally been followed by eruptions of Katla.[16]
Eyjafjallajökull in March 2006, viewed from a recreation area on the Sólheimajökull, a glacier on theKatla volcano
Eyjafjallajökull erupted in the years 920, 1612, 1821, and 2010.[17] The Skerin Ridge eruption in 920 was aVEI 3 radial fissure eruption while the subsequent 1612 and 1821 eruptions were VEI 2 small summit eruptions.[15]: 16 In the case of the 1821 eruption, a short explosive phase in December 1821 was followed by a year of intermittent explosive to effusive activity.[17]
Some damage was caused by a minor eruption in 1821.[18] Notably, the ash released from the eruption contained a large fraction offluoride, which in high doses may damage the bone structure of cattle, horses, sheep and humans. The eruption also caused some small and mediumglacier runs (jökulhlaups) and flooding in nearby riversMarkarfljót andHólsá [pl][ˈhɔl̥(t)sˌauː].[15]: 16 The eruptive phase started on 19 and 20 December 1821 by a series of explosive eruptions and continued over the next several days. The sources describe heavyash fall in the area around the volcano, especially to the south and west.[18]: 2
After that event the sequence of eruptions continued on a more subdued level until June 1822.[18]: 3
From the end of June until the beginning of August 1822, another sequence of explosive eruptions followed. The eruption columns were shot to considerable heights, with ashfall in both the far north of the country, inEyjafjörður, and in the southwest, on the peninsula ofSeltjarnarnes nearReykjavík.[18]: 3
The period from August to December 1822 seemed quieter, but farmers attributed the death of cattle and sheep in the Eyjafjörður area to poisoning from this eruption, which modern analysis identifies asfluoride poisoning. Some small glacier runs occurred in the river Hólsá. A bigger one flooded the plains near the river Markarfljót. (The sources do not indicate the exact date.).[19]
In 1823, some men went hiking up on Eyjafjallajökull to inspect thecraters. They discovered afissure vent near the summitcaldera a bit to the west ofGuðnasteinn.[18]: 4
In early 1823, the nearby volcanoKatla under theMýrdalsjökull ice cap erupted and at the same time steam columns were seen on the summit of Eyjafjallajökull.[18]: 5
The ash of Eyjafjallajökull's 1821 eruptions is to be found all over the south of Iceland. It is dark grey in colour, small-grained anddaciticintermediate rock containing about 28–40%silicon dioxide.[15]: 16 [20]
A photo of Eyjafjallajökull taken fromRoute 1 in August 2009
On 26 February 2010, unusual seismic activity along with rapid expansion of the Earth's crust was registered by theIcelandic Meteorological Office.[21] This gavegeophysicists evidence that magma was pouring from underneath the crust into themagma chamber of the Eyjafjallajökull volcano and that pressure stemming from the process caused the huge crustal displacement at Þorvaldseyri[ˈθɔrval(t)sˌeiːrɪ] farm.[22] In March 2010, almost three thousand smallearthquakes were detected near the volcano, all having a depth of7–10 kilometres (4+1⁄2–6 miles).[23] The seismic activity continued to increase and from 3–5 March, over a thousand earthquakes were measured at the epicenter of the volcano.[2]
The eruption begun on 20 March 2010, about 8 km (5 mi) east of the top crater of the volcano, onFimmvörðuháls, the high neck between Eyjafjallajökull and the neighbouring icecap, Mýrdalsjökull.[2] This first eruption, in the form of a 300-meter-long radialfissure vent,[17] did not occur under the glacier and was smaller in scale than had been expected by some geologists. The eruption consisted of 15 lava fountains reaching heights of up to 185 m (607 ft).[17] The fissure opened on the north side of Fimmvörðuháls, directly across the popular hiking trail between Skógar, south of the pass, andÞórsmörk, immediately to the north.[24]
The eruption on 27 March 2010The crater three years post eruption in March 2013Eyjafjallajökull seen from the sea in summer 2014.
On 14 April 2010 Eyjafjallajökull resumed erupting after a brief pause, this time from the top crater in the centre of the glacier, causingjökulhlaup (meltwater floods) to rush down the nearby rivers, and requiring 800 people to be evacuated.[8] This eruption was explosive, due to meltwater getting into the volcanic vent. It was estimated to be ten to twenty times larger than the previous one inFimmvörðuháls. Pulsating explosive activity on 17 April 2010 was later understood to be due to periodic clogging/plugging of the conduit associated with the rise and degassing of more magma.[15]: 80 This second eruption threw volcanic ash several kilometres up in the atmosphere, which led toair travel disruption in northwest Europe for six days from 15 to 21 April 2010.[25] This disruption affected over 20 countries and as many as 10 million air travelers.[26] The volcano erupted again in May 2010, causing the closure ofairspace over many parts of Europe.[27] The eruptions also createdelectrical storms.[28] The LondonVolcanic Ash Advisory Centre declared the eruption to have stopped on the 23rd of May 2010, but stated that they were continuing to monitor the volcano.[29] As a direct result of this disruption being viewed by some as excessive, new standards for the closure of airspace as a result of air contamination by dust/ash were agreed internationally.[27] The volcano continued to have several earthquakes daily, withvolcanologists watching the volcano closely.[30] As of August 2010, Eyjafjallajökull was considered dormant.[31]Infrasound sensors have been installed around Eyjafjallajökull to monitor for future eruptions.[32]
In total, the 2010 eruptions generated about 0.27 cubic km (270,000,000 cubic metres) of tephra, causing ash fallout over central southern Iceland and parts of continental Europe. Nearby areas saw an ash layer of up to several centimeters, and surrounding glaciers saw a significant albedo reduction due to the ash.[9]
Eyjafjallajökull lies25 km (15+1⁄2 mi) west of another subglacial volcano,Katla, under theMýrdalsjökull ice cap, which is much more active and known for its powerfulsubglacial eruptions and its large magma chamber.[33] Each of the eruptions of Eyjafjallajökull in 920, 1612, and 1821–1823 has preceded an eruption of Katla.[34] Katla did not display any unusual activity (such as expansion of the crust or seismic activity) during the 2010 eruptions of Eyjafjallajökull, though geologists have been concerned about the general instability of Katla since 1999. Some geophysicists in Iceland believe that the Eyjafjallajökull eruption may trigger an eruption of Katla, which would cause major flooding due to melting of glacial ice and send up massive plumes of ash.[34][35] On 20 April 2010, Icelandic PresidentÓlafur 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 the world to start planning for the eventual Katla eruption".[36]
Volcanologists continue to monitor Katla, aware that any eruption from Katla following an eruption from Eyjafjallajökull has historically occurred within months of an Eyjafjallajökull eruption. The Icelandic Meteorological Office updates its website with reports of quakes at both Eyjafjallajökull and Katla.[30] On 8 July 2011 there was ajökulhlaup that destroyed a bridge on theRing Road and caused cracks to appear on Katla's glacier.[37]
Icelandic Post issued three specialstamps in 2010 for the eruption of the Eyjafjallajökull volcano. All stamps contain realvolcanic ash which fell on 17 April 2010.[38]
^Schleicher, N.; Kramar, U.; Dietze, V.; Kaminski, U.; Norra, S. (2012). "Geochemical characterization of single atmospheric particles from the Eyjafjallajökull volcano eruption event collected at ground-based sampling sites in Germany".Atmospheric Environment.48: 113.Bibcode:2012AtmEn..48..113S.doi:10.1016/j.atmosenv.2011.05.034.
^abcdefLarsen, G. (1999).Gosið í Eyjafjallajökli 1821–1823 [The eruption of the Eyjafjallajökull volcano in 1821–1823](PDF) (in Icelandic). Reykjavík: Science Institute. p. 13. Research Report RH-28-99. Archived fromthe original(PDF) on 2010-11-22.
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