Askja

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  • Country
  • Volcanic Region
  • Primary Volcano Type
  • Last Known Eruption
  • 65.03°N
  • 16.75°W

  • 1516 m
    4972 ft

  • 373060
  • Latitude
  • Longitude

  • Summit
    Elevation

  • Volcano
    Number

Most Recent Weekly Report: 10 September-16 September 2014


IMO had maintained the Aviation Colour Code for Askja at Yellow since 28 August due to elevated seismicity and localized deformation. On 11 September the Colour Code was reduced to Green when seismicity had diminished significantly.

Source: Icelandic Met Office

Index of Weekly Reports


2014: September

Weekly Reports


10 September-16 September 2014

IMO had maintained the Aviation Colour Code for Askja at Yellow since 28 August due to elevated seismicity and localized deformation. On 11 September the Colour Code was reduced to Green when seismicity had diminished significantly.

Source: Icelandic Met Office


The Global Volcanism Program has no Bulletin Reports available for Askja.

Askja is a large basaltic central volcano that forms the Dyngjufjöll massif. It is truncated by three overlapping calderas, the largest of which is 8 km wide and may have been produced primarily from subglacial ring-fracture eruptions rather than by subsidence. A major rhyolitic explosive eruption from Dyngjufjöll about 10,000 years ago was in part associated with the formation of Askja caldera. Many postglacial eruptions also occurred along the ring-fracture. A major explosive eruption on the SE caldera margin in 1875 was one of Iceland's largest during historical time. It resulted in the formation of a smaller 4.5-km-wide caldera, now filled by Öskjuvatn lake, that truncates the rim of the larger central caldera. The 100-km-long Askja fissure swarm, which includes the Sveinagja graben, is also related to the Askja volcanic system, as are several small shield volcanoes such as Kollatadyngja. Twentieth-century eruptions have produced lava flows from vents located mostly near Öskjuvatn lake.

Summary of Holocene eruption dates and Volcanic Explosivity Indices (VEI).

Start Date Stop Date Eruption Certainty VEI Evidence Activity Area or Unit
1961 Oct 26 1961 Dec 5 ± 4 days Confirmed 2 Historical Observations North of Öskjuvatn lake (Vikraborgir)
1938 Dec 19 (?) Unknown Confirmed 2 Historical Observations South shore of Öskjuvatn lake
1926 Jul 15 ± 45 days Unknown Confirmed 2 Historical Observations South end of Öskjuvatn lake
1924 (?) Unknown Confirmed 0 Historical Observations South flank of Dyngjufjöll massif
1923 Jan 15 ± 45 days Unknown Confirmed 0 Historical Observations SE corner of Öskjuvatn Caldera
1922 Nov Unknown Confirmed 0 Historical Observations 1 km SW of Öskjuvatn Caldera
1921 Mar Unknown Confirmed 0 Historical Observations NE caldera wall, 0.6 km SE of Viti
1919 Unknown Confirmed 2 Historical Observations Dyngjufjöll
1875 Jan 1 1875 Oct 17 Confirmed 5 Historical Observations Öskjuvatn Caldera, Viti, Sveinagja
1797 (?) Unknown Confirmed 0 Historical Observations Holuhraun
1300 (?) Unknown Confirmed 1 Tephrochronology South of Dyngjufjöll Ytri
1250 BCE ± 300 years Unknown Confirmed 0 Tephrochronology Litladynga and Askja
2050 BCE ± 500 years Unknown Confirmed 0 Tephrochronology Flatadyngja, other areas NE of Dyngjufjöll
8910 BCE ± 200 years Unknown Confirmed 5 Radiocarbon (corrected) SE part of Askja caldera

This compilation of synonyms and subsidiary features may not be comprehensive. Features are organized into four major categories: Cones, Craters, Domes, and Thermal Features. Synonyms of features appear indented below the primary name. In some cases additional feature type, elevation, or location details are provided.


Synonyms

Trolladyngja | Dynjufjöll | Dyngjufjall

Cones

Feature Name Feature Type Elevation Latitude Longitude
Fjarholadydyngja Shield volcano 787 m 65° 9' 0" N 16° 36' 0" W
Flatadyngja Shield volcano 780 m 65° 11' 0" N 16° 32' 0" W
Flotudyngjuhraun Shield volcano 676 m 65° 11' 0" N 16° 30' 0" W
Hrossaborg Tuff ring 400 m 65° 37' 0" N 16° 16' 0" W
Kollóttadyngja Shield volcano 1168 m 65° 13' 0" N 16° 33' 0" W
Litladyngja Shield volcano 65° 6' 0" N 16° 37' 0" W
Svartadyngja Shield volcano 758 m 65° 6' 0" N 16° 32' 0" W
Veggjabunga Shield volcano 585 m 65° 24' 0" N 16° 27' 0" W

Craters

Feature Name Feature Type Elevation Latitude Longitude
Batshraun Fissure vent 65° 3' 0" N 16° 48' 0" W
Botnahraun Fissure vent 65° 3' 0" N 16° 48' 0" W
Dyngjufjallahraun Crater Row 65° 0' 0" N 16° 50' 0" W
Dyngjufjöll Crater Row 64° 58' 0" N 16° 48' 0" W
Gigoldugjoska Crater Row 64° 54' 0" N 17° 0' 0" W
Herdubreidartaglagjoska Crater 65° 9' 0" N 16° 21' 0" W
Holuhraun Crater Row 64° 48' 0" N 16° 52' 0" W
Hrutshalsar Fissure vent 1040 m 65° 18' 0" N 16° 35' 0" W
Kistufellsgjoska Fissure vent 64° 56' 0" N 17° 13' 0" W
Kistufellshraun Crater Row 64° 48' 0" N 17° 11' 0" W
Lindahraun Fissure vent 65° 8' 0" N 16° 35' 0" W
Myvetningahraun Fissure vent 65° 3' 0" N 16° 48' 0" W
North caldera Caldera
OSKJUVATN Caldera 65° 2' 0" N 16° 45' 0" W
Skalaralda Crater 64° 52' 0" N 17° 13' 0" W
Sveinagja Fissure vent 575 m 65° 32' 0" N 16° 27' 0" W
Vikahraun Fissure vent 65° 3' 0" N 16° 48' 0" W
Vikraborgir Crater
Viti Crater 65° 3' 0" N 16° 44' 0" W
The dark lava flow in the foreground was erupted from the NE side of Askja caldera in 1961. The flat-topped mountain in the distance to the NE is Herdubreid, the most famous of Iceland's "table mountains." These steep-sided mountains were formed by repeated eruptions during the Pleistocene through the glacial icecap. The subglacial lava flows and fragmental hyaloclastite rocks ponded against the melted walls of the glacier. Only at the last stage were minor subaerial lavas erupted above the icecap, forming the small summit peak.

Photo by Richie Williams, 1973 (U.S. Geological Survey).
Steam rises in 1967 from a scoria cone along the Vikraborgir crater row, which was formed during an eruption of Askja volcano in 1961. The eruption began on October 26 from a fissure cutting the NE caldera floor. A chain of small scoria cones formed over the eruptive fissure, which fed lava flows that traveled 9.5 km to the east.

Photo by Richie Williams, 1967 (U.S. Geological Survey).
An eruption from a radial fissure on the NE floor of the Askja caldera took place in 1961, during which lava fountains reached a height of 300 m. The Vikraborgir scoria-cone row, seen here, was built over the eruptive fissure. The fissure fed a 0.1 cu km basaltic lava flow that traveled 9.5 km to the east. The eruption began between 1056 and 1430 hrs on October 26, and ended in early December.

Photo by Richie Williams, 1981 (U.S. Geological Survey).
Askja's largest historical eruption began on New Years day, 1875. Minor explosive eruptions, lava flow emission, and slow caldera collapse preceded a powerful March 28-29 eruption. Subsidence of the caldera continued for several years and resulted in the formation of Askja's inner caldera, now filled by Öskjuvatn lake, seen here from the west. The Askja eruption and collapse were intimately related to the 1875 Sveinagjá fissure eruption, which began on February 18, 1875, about 50-km north along the Askja fissure system.

Photo by Michael Ryan, 1984 (U.S. Geological Survey).
The 1921 Batshraun lava flow descends from a vent (left center) into Öskjuvatn lake across several fault blocks related to subsidence of the Öskjuvatn caldera in 1875. This aerial view from the west shows the small 100-m-wide Viti maar (lower center), which formed during the 1875 eruption. Following slow subsidence of the caldera during the 1875 eruption and several subsequent years, the depression was filled by the waters of Öskjuvatn lake. During the 1920's, several lava flows erupted from vents surrounding the caldera and flowed into the lake.

Photo by Michael Ryan, 1984 (U.S. Geological Survey).
An eruption from a radial fissure on the NE floor of Askja caldera took place in 1961. It produced this 0.1 cu km basaltic lava flow, seen here from the SE, which traveled 9.5 km to the east. Vigorous lava fountains feeding the eruption reached a height of 300 m. The eruption began on the afternoon of October 26, when athe ash column reachd 6 km. Lava effusion began almost immediately, and the lava flow had traveled 7.5 km from the vent at Vigraborgir by October 26. The eruption continued until early December.

Photo by Michael Ryan, 1984 (U.S. Geological Survey).
The lava flow at the lower right was erupted during 1961 from a vent on the NE side of Askja caldera and flowed 9.5 km to the east. Snowfields cover part of the far wall of the caldera in the distance, beyond its flat lava-covered floor. The lake at the upper left is Öskjuvatn, which fills Askja's youngest caldera, formed in 1875. The irregular slopes of the Dyngjufjöll massif in the foreground are formed almost entirely by the products of subglacial eruptions.

Photo by Michael Ryan, 1984 (U.S. Geological Survey).
Askja is a large central volcano that forms the Dyngjufjöll massif. It is truncated by three calderas, the largest of which is 8 km wide. This view from the SE looks across Öskjuvatn lake, which fills the youngest caldera. It formed in 1875 during Askja's largest historical eruption and truncates a larger caldera, whose wall is seen in the distance above the lava-covered caldera floor. The 100-km-long Askja fissure swarm, which includes the Sveinagjá graben, is also related to the Askja volcanic system.

Photo by Michael Ryan, 1984 (U.S. Geological Survey).
The massive Askja shield volcano, seen here from the north, forms the Dyngjufjöll massif. Almost all of the massif is composed of subglacial pillow lavas and hyaloclastites. The broad summit of the volcano is truncated by three overlapping calderas, the youngest of which formed during an eruption in 1875. An extensive 100-km-long fissure system extends north of Askja, well beyond the point of this photo. The Askja fissure system includes the Sveinagjá fissure, which was active during 1875.

Photo by Michael Ryan, 1984 (U.S. Geological Survey).
The small 100-m-wide, steep-walled Viti maar crater, filled by a turquoise lake, was formed by phreatic explosions following a major plinian eruption at Askja on March 28-29, 1875. Note the fault cutting the left-hand crater wall. The dark lava flow in the background was erupted from a vent on the NE caldera wall of Askja. The lava flow traveled west into Öskjuvatn lake, out of view to the right.

Photo by Michael Ryan, 1984 (U.S. Geological Survey).
The dark Batshraun lava flow descending from the left into Öskjuvatn lake was erupted during 1921. The lava flow originated from a vent below the rim of Askja's central caldera, and flowed over the low rim of the younger 1875 caldera into the lake. The lava flow was the first of several during the 1920's that flowed into the NE, SE, and west sides of Öskjuvatn lake.

Photo by Michael Ryan, 1984 (U.S. Geological Survey).
Askja, seen here in an aerial view from the south, is a large central volcano that is truncated by three overlapping calderas. The youngest caldera, formed during Askja's largest historical eurption in 1875, is filled by Öskjuvatn lake (center). This caldera partially truncates the largest Askja caldera, whose floor forms the flat-surfaced area left of the lake. The 100-km-long Askja fissure swarm has also erupted during historical time. Twentieth-century eruptions at Askja have produced lava flows from vents located mostly near Öskjuvatn lake.

Photo by Oddur Sigurdsson, 1977 (Icelandic National Energy Authority).

The following references have all been used during the compilation of data for this volcano, it is not a comprehensive bibliography. Discussion of another volcano or eruption (sometimes far from the one that is the subject of the manuscript) may produce a citation that is not at all apparent from the title.

Carey R J, Houghton B F, Thordarson T, 2008. Contrasting styles of welding observed in the proximal Askja 1875 eruption deposits I: Regional welding. J Volc Geotherm Res, 171: 1-19.

Carey R J, Houghton B F, Thordarson T, 2010. Tephra dispersal and eruption dynamics of wet and dry phases of the 1875 eruption of Askja volcano, Iceland. Bull Volc, 72: 259-278.

de Zeeuw-van Dalfsen E, Rymer H, Sigmundsson F, Sturkell E, 2005. Net gravity decrease at Askja volcano, Iceland: constrainsts on processes responsible for continuous caldera deflation, 1988-2003. J Volc Geotherm Res, 139: 227-239.

Gudmundsson A T, 1986b. Iceland-Fires. Reykjavik: Vaka-Helgafell, 168 p.

Hjartardottir A R, Páll Einarsson P, Sigurdsson H, 2009. The fissure swarm of the Askja volcanic system along the divergent plate boundary of N Iceland. Bull Volc, 71: 961-975.

IAVCEI, 1973-80. Post-Miocene Volcanoes of the World. IAVCEI Data Sheets, Rome: Internatl Assoc Volc Chemistry Earth's Interior..

Sigbjarnarson G, 1988. Krepputunga and Bruardalir--Explanatory Text to Geologic Map. Reykjavik: Orkustofnun OS-88038/VOD-06, 44 p (in Icelandic with English summary).

Sigurdsson H, Sparks R S J, 1978. Rifting episode in North Iceland in 1874-1875 and the eruptions of Askja and Sveinagja. Bull Volc, 41: 149-167.

Sigvaldason G E, 1979. Rifting, magmatic activity, and interaction between acid and basic liquids. Nordic Volc Inst Univ Iceland, no 7903, 43p.

Sigvaldason G E, 2002. Volcanic and tectonic processes coinciding with glaciation and crustral rebound: an early Holocene rhyolitic eruption in the Dyngjufjoll volcanic centre and the formation of the Askja caldera, Iceland. Bull Volc, 64: 192-205.

Sigvaldason G E, 1992. Recent hydrothermal explosion craters in an old hyaloclastite flow, central Iceland. J Volc Geotherm Res, 54: 53-63.

Sigvaldason G E, Annertz K, Nilsson M, 1992. Effect of glacier loading/deloading on volcanism: postglacial volcanic production rate of the Dyngjufjoll area, central Iceland. Bull Volc, 54: 385-392.

Steinthorsson S, et al., 2002. Catalog of Active Volcanoes of the World - Iceland. Unpublished manuscript.

Sturkell E, Sigmundsson F, 2000. Continuous deflation of the Askja caldera, Iceland, during the 1983-1998 noneruptive period. J Geophys Res, 105: 25,671-25,684.

Thorarinsson S, Sigvaldason G E, 1962. The eruption in Askja, 1961, a preliminary report. Amer J Sci, 260: 641-651.

Volcano Types

Stratovolcano
Caldera(s)
Fissure vent(s)

Tectonic Setting

Rift zone
Oceanic crust (< 15 km)

Rock Types

Major
Basalt / Picro-Basalt
Minor
Rhyolite

Population

Within 5 km
Within 10 km
Within 30 km
Within 100 km
0
0
0
13,028

Affiliated Databases

Large Eruptions of Askja Information about large Quaternary eruptions (VEI >= 4) is cataloged in the Large Magnitude Explosive Volcanic Eruptions (LaMEVE) database of the Volcano Global Risk Identification and Analysis Project (VOGRIPA).
WOVOdat WOVOdat is a database of volcanic unrest; instrumentally and visually recorded changes in seismicity, ground deformation, gas emission, and other parameters from their normal baselines. It is sponsored by the World Organization of Volcano Observatories (WOVO) and presently hosted at the Earth Observatory of Singapore.
EarthChem EarthChem develops and maintains databases, software, and services that support the preservation, discovery, access and analysis of geochemical data, and facilitate their integration with the broad array of other available earth science parameters. EarthChem is operated by a joint team of disciplinary scientists, data scientists, data managers and information technology developers who are part of the NSF-funded data facility Integrated Earth Data Applications (IEDA). IEDA is a collaborative effort of EarthChem and the Marine Geoscience Data System (MGDS).
Smithsonian Collections Search the Smithsonian's NMNH Department of Mineral Sciences collections database. Go to the "Search Rocks and Ores" tab and use the Volcano Name drop-down to find samples.