Askja

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File:Viti geothermal lake at Askja.jpg
Víti geothermal lake at Askja
File:Island Askja.jpg
Askja and Víti (in the foreground)

Askja (Script error: No such module "IPA".) is an active volcano situated in a remote part of the central highlands of Iceland. The name Askja refers to a complex of nested calderas within the surrounding Dyngjufjöll Script error: No such module "IPA". mountains, which rise to Script error: No such module "convert"., askja meaning box or caldera in Icelandic.[1]

Geography

The Askja central volcano is Template:Cvt in diameter and is associated with the Askja volcanic system which has a Template:Cvt long fissure swarm that extends north from beneath the Vatnajökull glacier towards the north coast of Iceland.[2] The Hrúthálsar area which is Template:Cvt to the north-east is now usually regarded as part of the system.[2]

The outer caldera of Askja, representing a prehistoric eruption, is about Template:Cvt in area, and there is evidence of other later caldera-forming events within it. These include the main summit caldera, that is about Template:Cvt in diameter, to its north-east the Template:Cvt diameter Kollur caldera, and the 1875 Öskjuvatn caldera with a diameter of about Template:Cvt. The main crater floor lies at about Template:Cvt.[2]

The central volcano region is only accessible for a few months of the year. Being situated in the rain shadow to the northeast of the Vatnajökull glacier, the area receives only about Template:Cvt of rainfall annually.

NASA

The area was used by NASA during training for the Apollo program to prepare astronauts for the lunar missions. Their main objective in Askja was to study geology. The Astronaut Monument in Húsavík lists the 32 astronauts who participated.[3][4]

Eruptions

Most eruptions are small, basaltic and effusive.[2] There have been at least 175 eruptions from the Askja system in the last 7200 years.[5]

1961

The last eruption of Askja was between 26 October and 5 December 1961 near the northern rim of the caldera.[6] It produced the Template:Cvt basaltic Vikrahraun lava flow and also near the caldera another local permafrost layer under the Template:Cvt of tephra.[7][2]

1875

Askja was virtually unknown until a large 17 hour subplinian eruption which started on March 28, 1875.[8] The volcanic system had been active since 1 January 1875.[6] This was followed by the devastating rhyolitic phreatoplinian explosion on March 29, 1875,[2][9] which erupted Template:Cvt dense-rock equivalent.[7] The eruption finished on 17 October 1875.[6] Locally around the caldera this ash fall on snow cover has resulted in the formation of a layer of permafrost ice.[7] Especially in the Eastfjords of Iceland, the ashfall was heavy enough to poison the land and kill livestock. Ash more than 1 cm in thickness covered Template:Cvt and the total population in Iceland of sheep declined by 2% and cattle by 6.2% between 1874 and 1876.[8] At least 16 farms were abandoned in 1876.[8] Ash, or tephra from this eruption was wind-blown to Norway, Sweden, Germany and Poland.[7] The eruption triggered a spike in emigration from Iceland but not as much as the Grímsvötn eruptions in the 1880s.[8] Between February and October 1875 about Template:Cvt north of the Askja central volcano there were episodic basaltic fissure eruptions, which erupted a comparable volume of magma to the explosive phase.[8] The eruption had no direct effect on regional or Northern Hemisphere vegetation and climate.[8]

Early Holocene

Another less well-known large rhyolitic eruption, called Askja-S (Skolli), occurred in the early Holocene, 10,824 ± 97 years BP.[2][10] Tephra from this eruption has been found in south-east Sweden, Northern Ireland and north Norway and recently as far south as Romania, which makes it one of the most far-travelled Icelandic tephras.[10]

Summary

List of Recent Eruptions
Start Date[6] End Date[6] VEI[6] Scale[2] Tephra volume
(km3)[2] 		Comments
Template:Dts Template:Dts 2 Small 0.004
Template:Dts Un­known 2 Small Un­known
Template:Dts 2 Moderate Un­known Lasted about 45 days, Thorvaldshraun lava[5]
Template:Dts Un­known 0 Small Un­known
Template:Dts 0 Small Un­known Lasted about 45 days
Template:Dts Un­known 0 Small Un­known
Template:Dts Un­known 0 Small Un­known
Template:Dts Un­known 2 Small Un­known
Template:Dts Template:Dts 5 Major 1.8 Lava flows mainly south and north-east of Öskjuvatn caldera[5]
Template:Dts Un­known 0 Small Un­known Lava flow on west caldera margin dated as to before 1873 by tephra studies[5]
Template:Dts Un­known - Small Un­known Older than 1717 from tephra studies with lava flows on north-east caldera margin[5]
Template:Dts Un­known - Small Un­known Older than 1619 from tephra studies with lava flows on north caldera margin[5]
Template:Dts Un­known - Small Un­known Older than 1510 from tephra studies with lava flows to west caldera margin[5]
Template:Dts Un­known - Small Un­known Older than 1477 from tephra studies with lava flows around caldera margin[5]
Template:Dts Un­known 1 Small Un­known Older than 1341 from tephra studies with lava flows to north-east[5]
Template:Dts Un­known - - Un­known Older than 1158 from tephra studies with lava flows to north-east

[5]

Template:Dts Un­known - - Un­known Older than 1104 from tephra studies with lava flows to immediate north-east of caldera[5]
Template:Dts Un­known - - Un­known Older than 871 from tephra studies with lava flow to south-east of caldera[5]
1250 ± 300 BCE Un­known 0 Major Un­known Older than 1045 BC from tephra studies with large lava fields north and south of caldera[5]
2050 ± 500 BCE Un­known 0 Small Un­known Older than 2285 BC from tephra studies[5]
3750 BCE Un­known - - Un­known Basalt tephra A5700 from Torfdalsvatn[11]
8874 ± 97 BCE Un­known 5 Major Un­known 1.5 ± 0.5 km3 DRE[10]

Activity

In June 2010, Volcano expert Hazel Rymer said seismic activity was increasing at Askja.[12] The increased earthquake activity was located to the northeast of the central volcano, in the direction of Herðubreið. It was ruled out that any activity from Eyjafjallajökull was responsible for the increase in activity at Askja. The news came as scientists continue to watch Katla. In early April 2012 it was noted that the lake in the caldera was totally clear of ice, which usually does not happen until in June or July in a normal year. It was believed that increased geothermal activity in the volcano is heating the lake. Travel in the area was restricted until further research could be carried out.[13]

In early September 2021, GPS and Satellite data showed that an inflation at the rate of five cm per month, most likely attributed to magma intrusion, of the caldera had started in August.[14] An Article published on September 9 from the Icelandic Meteorological Office(IMO) stated the Aviation Color Code was upgraded from "Green" to "Yellow" due to the changes.[15] The Article also says, "Next week IMO and the Institute of Earth Sciences (UÍ) will potentiate the monitoring network around Askja to allow a better coverage and surveillance of the volcano." On 9 November 2022 deformation data showed continuing magma accumulation at depth, with accumulated uplift of Template:Cvt since August 2021.[6]

Öskjuvatn lake

Öskjuvatn is a large lake that fills much of the smaller caldera resulting from the 1875 eruption. Its surface lies about Template:Cvt below the level of the main caldera floor and covers about Template:Cvt. When the lake originally formed it was warm, but today it is frozen over for most of the year. Öskjuvatn is the second deepest lake in Iceland at Template:Cvt deep.[16]

Missing scientists

In 1907, the German scientists Walter von Knebel and Max Rudloff visited Askja to study the caldera. While exploring Öskjuvatn in a small boat, they disappeared without a trace. Von Knebel's fiancée Ina von Grumbkow led an expedition to search for them, but no indication of what happened to them was ever found. Recent observations on the effects of a landslide, on 21 July 2014, has led to renewed speculation that the scientists were killed by a similar sudden event, a massive wave similar to the one estimated to be Script error: No such module "convert". high seen in 2014.[17]

Social context of 1875 Askja eruption

The eruption took place at a time that Iceland was newly self governing under Danish rule, with a strong nationalist element, had a large rural agricultural population, and needed the fodder ruined by the eruption to overwinter livestock, in an up to then, relatively prosperous farming area. Following local publicity of the plight of farming communities in May 1775, and a letter to The Times in July 1775, fund-raising efforts in the UK, Denmark, and Norway took place and relief supplies were organised. The combined donations helped many of the most affected and paid for fodder to help keep livestock alive over the winter of 1875/6. The emigration options were limited, as the possibility of organised self funded emigration from Iceland to Canada or Brazil only became possible in January 1873, and by the time of the eruption the experiences reported home of the emigrants were far from all being positive. Canada in particular successfully promoted itself and addressed partially the initial issues, with partially subsidised emigration that excluded deliberately the Icelandic poor, for multiple reasons both commercial and social. However the Iceland nationalist political movement tried to block emigration, even misrepresenting that its new Emigration Law made the Canadian plan impossible, when the law had yet to be ratified in Denmark. A deposit paid to the Danish Governor of Iceland and advertising emphasising the impact of the eruption eased the Canadian plan. While most emigration in 1876 was by Icelanders resident outside the areas most affected by the ash it did result in up to 10% of the population in those districts most affected, leaving Iceland.[8]

Sights and tourism in the area

File:Drekagil-pjt2.jpg
Drekagil canyon

The Dyngjufjöll mountains which surround the Askja caldera, also contain the Drekagil Script error: No such module "IPA"., the canyon of dragons. Within Template:Cvt and Template:Cvt of Askja, are two other volcanic systems: Herðubreið and Kverkfjöll.

Askja is a popular tourist destination. There are two mountain huts and a campsite at Dreki Script error: No such module "IPA"., by Drekagil, which is about Template:Cvt by a 4x4 F-road, from the Icelandic ring-road. The road continues Template:Cvt up from Dreki into the Askja caldera. It is a walk of about Template:Cvt from the car park to Öskjuvatn and Víti Script error: No such module "IPA".. The roads are usually only open for about three to four months, from late June until early October.

See also

References

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  1. ↑ See e.g.: Stóra Tölvuorðabókin. Úfgáfa 6.0
  2. ↑ a b c d e f g h i Script error: No such module "citation/CS1".
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  6. ↑ a b c d e f g Cite error: Script error: No such module "Namespace detect".Script error: No such module "Namespace detect".
  7. ↑ a b c d Script error: No such module "Citation/CS1".
  8. ↑ a b c d e f g Script error: No such module "Citation/CS1".
  9. ↑ Script error: No such module "Citation/CS1".
  10. ↑ a b c Script error: No such module "Citation/CS1".
  11. ↑ Script error: No such module "Citation/CS1".
  12. ↑ Script error: No such module "citation/CS1".
  13. ↑ Script error: No such module "citation/CS1".
  14. ↑ Script error: No such module "citation/CS1".
  15. ↑ Script error: No such module "citation/CS1".
  16. ↑ Script error: No such module "citation/CS1".
  17. ↑ Script error: No such module "citation/CS1".

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External links

Photos and videos

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Scientific papers

Template:Volcanoes of Iceland

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