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Eyjafjallajökull

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Map showing the location of
Map showing the location of
Location in Iceland
LocationIceland
Area100 square kilometres (40 sq mi)

Eyjafjallajökull ([pronunciation?]) (listenⓘ) is one of the smaller glaciers of Iceland. It is situated to the north of Skógar and to the west of the larger glacier Mýrdalsjökull.

The icecap of the glacier covers a volcano (1,666 m in height) which has erupted relatively frequently since the Ice Age. The latest eruption began in March 2010, and the most recent eruption before then was from 1821 to 1823, causing a fatal glacier run. A previous eruption was in 1612. The crater of the volcano has a diameter of 3–4 km and the glacier covers an area of about 100 km².

The south end of the mountain was once part of the island's Atlantic coastline. As the sea has since retreated some 5 km, the former coastline has left behind sheer cliffs with a multitude of beautiful waterfalls, the best known of them being Skógafoss. In strong winds, the water of the smaller falls can even be blown up the mountain.

The eruption of Eyjafjallajökull in the years 1821-23

In this case it was a rather small volcanic eruption. [1]

But inspite of that it caused some damage. This was especially due to the fact that the ash contained a lot of fluoride, a toxic gas which has a very negative influence on the bone structure of cattle, horses, sheep and men. The eruption caused also some small and medium glacier runs and flooding at the nearby rivers Markarfljót and Holtsá.

The eruptive phase started on 19th and 20th of December by an series of explosive eruptions continuing during the next days. The sources talk about heavy ash fall in the areas around the volcano especially to the south and west.

After that the eruption continued on a more subdued level until June 1822.

From end of june til beginning of August 1822 some other series of explosive eruptions followed. The eruption columns were shot in considerable hights with ash fall as well far in the north of the country in Eyjafjörður as in the southwest on the peninsula of Seltjarnarnes near Reykjavík.

The period from August to December 1822 was seemingly quieter. But farmers attributed the death of cattle and sheep in the Eyjafjörður to fluor poisoning from this eruption. Some small glacier runs occurred in the river Holtsá. A bigger one flooded the plains near the river Markarfljót. The sources don’t indicated the exact date of that.

In 1823 some men went hiking up on Eyjafjallajökull to inspect the craters. They discovered an fissure vent near the summet caldera a bit to the west of Guðnasteinn.

In the spring of 1823, the nearby volcano Katla under the glacier Mýrdalsjökull erupted and at the same time steam colomns were seen on the summet of Eyjafjallajökull.

The ash of Eyjafjallajökull’s 1821 eruptions is to be found all over the south of Iceland. It is darkgrey in colour, small-grained and intermediate rock containing about 68-70% SiO2.

2010 eruption

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Around Christmas 2009, seismic activity began around the Eyjafjallajökull volcano area, with thousands of small earthquakes (mostly magnitude 1–2 on the Richter magnitude scale) 7–10 kilometres beneath the volcano.[2] On 26 February 2010, the GPS navigation tools used by the Meteorological Institute of Iceland at Þorvaldseyri farm in the Eyjafjöll area (around 15 kilometres southeast of the location of the recent eruption[3]) had shown 3 centimetres displacement of the local earth crust in a southward direction, of which a 1 centimetre displacement took place within four days. This unusual seismic activity along with that rapid expansion of the earth's crust gave geophysicists evidence that magma were pouring from underneath the crust into the magma chamber of the Eyjafjallajökull volcano and that pressure stemming from the process caused the huge crustal displacement at Þorvaldseyri farm[4]. The seismic activity continued to increase and from March 3 to 5, close to 3,000 earthquakes were measured at the epicentre in the volcano. Most were too small (magnitude 2 on Richter scale) to be read as presaging an eruption, but some could be detected in nearby towns.[5] The eruption is thought to have begun on 20 March 2010, sometime between 10:30 pm and 11:30 pm local time (UTC), a few kilometres east of the glacier in the northern slopes of Fimmvörðuháls mountain pass.[6][7]

About 500 farmers and their families from the areas of Fljótshlíð, Eyjafjöll, and Landeyjar were evacuated overnight, and flights to and from Reykjavík and Keflavík International Airport were postponed, but in the evening of 21 March, domestic and international air traffic was allowed again.[8][9][10] Inhabitants of the risk zone of Fljótshlíð, Eyjafjöll, and Landeyjar area were allowed to return to their farms and homes after an evening meeting with the Civil Protection Department on 22 March and the evacuation plan was temporarily dismissed. Instead, the police closed the road to Þórsmörk, and the jeep trail from Skógar village to Fimmvörðuháls mountain pass, but these roads and trails were reopened on 29 March, only though for suitable jeeps, however when the second fissure appeared the road was closed again because of the danger of flash floods, which could have been the case if the fissure had opened near big ice caps or other snow reservoirs, but the road was again opened at around noon of the 1 April [11][12][13]

The eruption on the 25th of March, 2010

The fissure is 500 metres long pointing northeast–southwest, with 10–12 erupting lava craters which spew around 1,000 °C (1,832 °F) hot lava up to 150 metres into the air. The lava is alkaline and viscous so the motion of the lava stream to the west and east of the fissure is slow, so this makes it a typical effusive eruption.[14] The molten lava has flowed more than 4000 metres to the northeast of the fissures, and into Hrunagil canyon, forming a more than 200 meter (620 ft) long "lava"-fall and is slowly approaching Þórsmörk on a slow rate, but has not yet reached the flood plains of Krossá[15][16][17]. On 25 March 2010, scientists witnessed on location, for the first time in history, the formation of a pseudocrater during a steam explosion, while studying the eruption[18]. Crustal expansion continued at Þorvaldseyri for two days after the eruption began, but has been slowly decreasing, along with increasing volcanic activity, indicating that the input of magma into the magma chamber of the volcano is roughly equal to the magma output out of the eruption, giving evidence that this volcanic activity has reached equilibrium[19]. A new fissure opened around 19:00 UTC local time (7 pm) on 31 March, around 200 meters northwest of the original fissure. Many witnesses were present while the new fissure opened. It is a bit smaller, around 300 meter long according to witnesses, and lava coming from it has now started to flow into Hvannárgil canyon. These two erupting fissures share the same magma chamber according to geophysicists. No unusual seismic activity was detected at the time the new fissure appeared, nor any crustal expansion according to many seismometers and GPS recorders situated in nearby areas [20][21].

Geophysicist Magnús Tumi Einarsson said (at a press meeting in Hvolsvöllur on 21 March 2010) that this eruption is small compared to, for example, the eruption of Hekla in 2000. The eruption, rather than taking place under the ice cap of the glacier, occurred in the mountain pass between the Eyjafjallajökull and Mýrdalsjökull glaciers. As long as the fissure is not near the glacier, the risk of flooding is minimal; however, the fissure could extend into the ice cap thereby greatly increasing the risk of flooding.[22] The radar stations of the Meteorological Institute of Iceland did not detect any appreciable amount of volcanic ashfall during the first 24 hours of the eruption.[23] However, during the night of 22 March 2010, they reported some volcanic ash fall reaching the Fljótshlíð area (20–25 kilometres northwest of the eruption's location)[3] and Hvolsvöllur town (40 kilometres northwest of the eruption location)[3] leaving vehicles with a fine grey layer of volcanic ash. At around 7 am on 22 March, an explosion launched eruption columns as far as 4 kilometres straight up into the air. This was the highest plume since the eruption started.[24] At 08:30 UTC local time on 23 March 2010, a small vapour explosion took place, when hot magma came into contact with nearby snowdrifts, omitting a huge vapour plume which reached an altitude of 7 kilometres, and were detected on radars from the Meteorological Institute of Iceland. Since than many vapour explosions have taken place[25]

On 22 March 2010, around 10:00 local time (UTC), a flow meter device situated in the Krossá glacial river (which provides drainage for Eyjafjallajökull and Mýrdalsjökull glaciers) in the Þórsmörk area (a few kilometres northwest of the erupting location) started to record a sudden rise in water level and in water temperature, the total water temperature rise reaching 6 °C (43 °F) over a two hour period, which has never previously occurred this quickly in the Krossá river since measurements began. Shortly afterwards the water level returned to normal and water temperature decreased as well.[26] It is thought that this rise in water temperature is related to the eruption nearby and is affecting part of Krossá drainage basin. Hruná river which flows through the narrow Hrunárgil canyon, where the part of the lava stream has been flowing into, was recently recorded by geologists to be between 50 °C (122 °F)- 60 °C (140 °F) hot, indicating that the river has been cooling down the lava in that canyon[27].

On Wednesday 31 March a new fissure opened up on the volcano.[28]

Samples of volcanic ash collected near the eruption showed the concentration of water-soluble fluoride is 1/3 of the concentration typical in Hekla eruptions, with a mean value of 104 milligrams of fluoride per kilogram of ash. Farmers in nearby locations have been warned not to let their livestock drink from local ponds and streams[29] as high concentrations of fluoride can have deadly renal and hepatic effects in livestock (particularly sheep).[30], but agriculture remains important in this region of Iceland.[31]

'Volcano tourism' quickly sprang up in the wake of the eruption, with tour companies offering trips to see the volcano.[32]

Eyjafjallajökull and Katla

Over the past 1,100 years, Eyjafjallajökull has erupted three times: in 920, 1612, and between 1821–1823. Each of these incidents directly preceded a major eruption in the nearby subglacial volcano, Katla.[33] There is so far no evidence that Katla will erupt because of its vicinity to the current eruption in Fimmvörðuháls mountain pass. Katla, which is a much more active volcano, known for its powerful subglacial eruptions and its large magma chamber, much larger than that of the Eyjafjallajökull volcano system, has still not shown any unusual activity, like expansion of the crust or seismic activity. However, one can not rule out that possibility, since history has shown that Eyjafjallajökull can be a precursor to additional Katla activity.[34] Some geophysicists in Iceland support the notion that the recent volcanic eruption at Eyjafjallajökull may trigger a second eruption at Katla, which would cause a major flooding event due to melting of glacial ice.[35]

Eyjafjöll

The name usually describes the small mountains which form the foot of the volcano. The village and museum of Skógar are also part of the region "undir Eyjafjöllum" (under the mountains Eyjafjöll).

See also

References

  1. ^ The following description is an abstract on: Larsen, G., 1999. Gosið í Eyjafjallajökli 1821-1823 (The eruption of the Eyjafjallajökull volcano in 1821-1823). Science Institute Research Report RH-28-99. 13 p. Reykjavík. [1] (PDF)
  2. ^ Veðurstofa Íslands (5 Mars 2010) "Jarðskjálftahrina undir Eyjafjallajökli". Veðurstofa Ísland (The Meteorological Institute of Iceland).
  3. ^ a b c Measurements made by using maps and measurement tools from Fasteignaskrá Íslandskort "Fasteignaskrá measurement tools".
  4. ^ Morgublaðið (26.02.2010) "Innskot undir Eyjafjallajökli". Morgunblaðið.
  5. ^ "Fyrsta háskastigi lýst yfir". Morgunblaðið.
  6. ^ "Eldgosið á Fimmvörðuhálsi".
  7. ^ Volcano Erupts Under Eyjafjallajökull Reykjavík Grapevine, March 21, 2010
  8. ^ Gos hafið í Eyjafjallajökli, Visir, March 21, 2010
  9. ^ Volcanic eruption in Eyjafjallaglacier - flights to Iceland are on hold. Icelandair, retrieved March 21, 2010.
  10. ^ "Fyrsta vél frá Boston í loftið klukkan hálf fimm". Vísir.
  11. ^ Morgunblaðið 1. Apríl "Gosslóðirnar opnaðar aftur". Morgunblaðið.
  12. ^ Eyjan 1.Apríl "Litlar líkur taldar á öðru gosi við Eyjafjallajökul". Eyjan.
  13. ^ Morgunblaðið 22. Mars 2010 "Rýmingu aflétt". Morgunblaðið.
  14. ^ "Gossprungan um 1 km að lengd". Morgunblaðið.
  15. ^ "Gosið enn í gangi - Farið að bera á öskufalli". Vísir fréttvefur.
  16. ^ Morgunblaðið 22. March 2010 (13:11 GMT) "Hraunflæði niður í Hrunagil". Morgunblaðið.
  17. ^ Ríkisútvarpið fréttavefur "Eldgosið í jafnvægi". Rúv.
  18. ^ Kvöldfréttir Stöðvar Tvö "Viðtal við Ármann Höskuldsson eldfjallafræðing" |work= Fréttastofa Stöðvar Tvö
  19. ^ Veðurstofa Íslands (24 Mars 2010) "GPS mælingar". Veðurstofa Íslands.
  20. ^ Veðurstofa Íslands "Ný gossprunga - skráð 01.04.2010 kl. 10:00". Veðurstofa Íslands (Icelandic Meteological Office).
  21. ^ Morgunblaðið 1. Apríl "Vel gekk að rýma gossvæðið". Morgunblaðið.
  22. ^ "Eldgosið er lítið". Morgunblaðið.
  23. ^ "Eldgos í Eyjafjallajökli".
  24. ^ "Tímabundinn kraftur í gosinu". Morgunblaðið.
  25. ^ Ríkisútvarpið fréttavefur "Krafturinn ekki aukist". RÚV.
  26. ^ Meteorological Institute of Iceland: Eruption in Fimmvörðuháls mountain pass "Elsdgosið í Fimmvörðuhálsi". Veðurstofa Ísland.
  27. ^ Morgunblaðið 29. Mars "Mikill hiti í Hruná". Morgunblaðið.
  28. ^ http://www.guardian.co.uk/travel/2010/apr/03/iceland-erupting-volcano-hyjafjallajoekull
  29. ^ Morgunblaðið 23.Mars 2010 "Ekki mikið af flúor í öskunni". Morgunblaðið.
  30. ^ "Experimental Acute Sodium Fluoride Poisoning in Sheep: Renal, Hepatic, and Metabolic Effects". M. KESSABI, A. HAMLIRI,J. P. BRAUN and A. G. RICO: Département de Toxicologie, Pharmacie et Biochimie, Institut Agronomique et Vétérinaire Hassan II B.P. 6202, Rabat-Agdal, Maroc {dagger}Département de Biochimie et Biophysique, Ecole Nationale Vétérinaire 23, chemin des Capelles, 31076 Toulouse, France. 1985.
  31. ^ A report in Icelandic: Landbúnaður skiptir máli (transl. "Agriculture matters") says that 28% of the total workforce in agriculture are scattered throughout Southern Iceland."Landbúnaður skiptir máli". Bændasamtök Íslands.
  32. ^ http://www.guardian.co.uk/travel/2010/apr/03/iceland-erupting-volcano-hyjafjallajoekull
  33. ^ Roger Boyes. ""Iceland prepares for second, more devastating volcanic eruption"". TimesOnline. {{cite web}}: Unknown parameter |access date= ignored (|access-date= suggested) (help)
  34. ^ Kastljósið 22.3.2010, Sjónvarpið, "Viðtal við Dr. Pál Einarsson, jarðeðlisfræðing"
  35. ^ Boyes, Roger (March 21, 2010). "Iceland prepares for second, more devastating volcanic eruption". Times Online. Retrieved 22 March 2010.
Wikimedia Commons has media related to Eyjafjallajökull.

Photos

Eruption of March 2010

Geological articles

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