Tungnafellsjökull (, "''Tungna-fells glacier''" or "

tongue The tongue is a Muscle, muscular organ (anatomy), organ in the mouth of a typical tetrapod. It manipulates food for chewing and swallowing as part of the digestive system, digestive process, and is the primary organ of taste. The tongue's upper s ...

fell A fell (from Old Norse ''fell'', ''fjall'', "mountain"Falk and Torp (2006:161).) is a high and barren landscape feature, such as a mountain or Moorland, moor-covered hill. The term is most often employed in Fennoscandia, Iceland, the Isle of M ...

s glacier") is a icecap

glacier A glacier (; or ) is a persistent body of dense ice, a form of rock, that is constantly moving downhill under its own weight. A glacier forms where the accumulation of snow exceeds its ablation over many years, often centuries. It acquires ...

upon a

volcano A volcano is commonly defined as a vent or fissure in the crust of a planetary-mass object, such as Earth, that allows hot lava, volcanic ash, and gases to escape from a magma chamber below the surface. On Earth, volcanoes are most oft ...

of the same name in

Iceland Iceland is a Nordic countries, Nordic island country between the Atlantic Ocean, North Atlantic and Arctic Oceans, on the Mid-Atlantic Ridge between North America and Europe. It is culturally and politically linked with Europe and is the regi ...

. The volcano is also known as Vonarskarð.

Geography

It has an elevation of and is located north–west of the area of the

Vatnajökull Vatnajökull ( Icelandic pronunciation: , literally "Glacier of Lakes"; sometimes translated as Vatna Glacier in English) is the largest and most voluminous ice cap in Iceland, and the second largest in area in Europe after the Severny Island i ...

glacier under the

Bárðarbunga Bárðarbunga (, alternative name Veiðivötn), is an active and productive stratovolcano located under Vatnajökull in Vatnajökull National Park which is Iceland's most extensive glacier. The second highest mountain in Iceland, above sea le ...

central volcano A central volcano is a type of volcano formed by basalts and silica-rich volcanic rocks. They contain very few or no volcanic rocks of intermediate composition, such that they are chemically bimodal volcanism, bimodal. Large silicic eruptions at c ...

. To its west is the volcano of

Hofsjökull __NOTOC__ Hofsjökull (Icelandic language, Icelandic: "temple glacier", ) is the third largest ice cap in Iceland after Vatnajökull and Langjökull and covers the largest active central volcano in the country, which has the same name. It is si ...

. The Tungnafellsjökull volcanic system is located in a desert area that is fairly inaccessible, with little vegetation, and large areas of sand and sandy ridges. Three glacial rivers drain the Tungnafellsjökull glacier.

Geology

It is the eastern most part of the Mid-Iceland belt and thus at the north–eastern corner of the Hreppar microplate. There are two central volcanoes, with the most southern being called Hágöngur and the most northern called here Tungnafellsjökull. Tungnafellsjökull has two calderas, with the western most Tungnafellsjökull caldera being topped by a glacier and the eastern most Vonarskarð caldera facing towards Bárðarbunga having a geothermal field, and being the younger caldera. The system formed in the

Pleistocene The Pleistocene ( ; referred to colloquially as the ''ice age, Ice Age'') is the geological epoch (geology), epoch that lasted from to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was fin ...

and deposits from this time extend from the present edge of the Vatnajökull glacier. The fissure swarms of the Tungnafellsjökull–Vonarskarð volcanic system extend to the north and to the west–south–west. This later fissure swarm is associated with

hyaloclastite Hyaloclastite is a volcanoclastic accumulation or breccia consisting of glass (from the Greek ''hyalus'') fragments (clasts) formed by quench fragmentation of lava flow surfaces during submarine or subglacial extrusion. It occurs as thin marg ...

ridges ( tindars). The fissure swarms have erupted

olivine The mineral olivine () is a magnesium iron Silicate minerals, silicate with the chemical formula . It is a type of Nesosilicates, nesosilicate or orthosilicate. The primary component of the Earth's upper mantle (Earth), upper mantle, it is a com ...

tholeiite basalt which while dominant,

rhyolite Rhyolite ( ) is the most silica-rich of volcanic rocks. It is generally glassy or fine-grained (aphanitic) in texture (geology), texture, but may be porphyritic, containing larger mineral crystals (phenocrysts) in an otherwise fine-grained matri ...

is also found on the south-west margin of the Vonarskarð caldera and to the north–east of the Hágöngur central volcano.

Activity

The most recent eruptions of the central volcano have been at its north–east flank where young basaltic lava flows occur, that are no more than 4500 years old. These were from the Dvergar fissure row to the north–west of the Tungnafellsjökull central volcano, being in area and in volume and are partly separated lava patches. A larger

Holocene The Holocene () is the current geologic time scale, geological epoch, beginning approximately 11,700 years ago. It follows the Last Glacial Period, which concluded with the Holocene glacial retreat. The Holocene and the preceding Pleistocene to ...

eruption was from the northern fissure swarm due north of the Tungnafellsjökull central volcano, that created the long Tunguhraun lava flow and the Bokki lava shield, with its area of about and volume of about . Previously before the Holocene, while the area was under ice, lava fields erupted within the southern Vonarskarð caldera and north–west of the Hágöngur central volcano. After the

1996 eruption of Gjálp Gjálp () is a hyaloclastite ridge (tindar) in Iceland under the Vatnajökull glacier shield. Its present form resulted from an eruption series in 1996 and it is probably part of the Grímsvötn volcanic system.Snæbjörn Guðmundsson: ''Vega ...

well to the west, it was discovered that fault movements had taken place in the Tungnafellsjökull fissure swarm. Seismic swarms in 2008 and 2009 also caused faulting. Almost all recent seismic activity has been in the area adjacent to the Tungnafellsjökull central volcano, and is most consistent with magma movements at depth. The

2014–2015 eruption of Bárðarbunga The 2014–2015 eruption of Bárðarbunga was a Hawaiian eruption in the Bárðarbunga volcanic system in Iceland, that began on 29 August 2014, and ended on 27 February 2015. The eruption emitted large volumes of sulphur dioxide and impacted a ...

was associated with an earthquake swarm at the north–east edge of the Tungnafellsjökull central volcano, which was best modelled by stress changes due to the Bárðarbunga caldera subsidence.

Notes

References

External links