The subglacial Esjufjöll () volcano is located in the south-east part 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 ...

icecap. Esjufjöll is a strict nature reserve (IUCN category Ia).

Geography

The recognisable mountains associated with the volcano are

nunatak A nunatak (from Inuit language, Inuit ) is the summit or ridge of a mountain that protrudes from an ice field or glacier that otherwise covers most of the mountain or ridge. They often form natural pyramidal peaks. Isolated nunataks are also cal ...

s within Vatnajökull. These are located about 20 km to the north of

Öræfajökull Öræfajökull (; 'Öræfi glacier' or 'wasteland glacier') is an ice-covered volcano in south-east Iceland. The largest active volcano and the highest peak in Iceland at , it lies within the Vatnajökull National Park and is covered by part of ...

volcano and about 20 km north-west of the

Jökulsárlón Jökulsárlón (; translates to "glacial river lagoon") is a large glacial lake in southern part of Vatnajökull National Park, Iceland. Situated at the head of the Breiðamerkurjökull glacier, it developed into a lake after the glacier started r ...

glacial lake. The highest part of volcano is an ice-covered ridge called Snæhetta, whose assigned height is lower than previous figures, at . The mountain range to this ridge's south consists of four nunatak mountain massifs called Vesturbjörg, Skálabjörg, Esjubjörg and Austurbjörg, in a north-west to south-east alignment, with three valleys in between them.Ari Trausti Guðmundsson, Pétur Þorsteinsson: Íslensk fjöll. Gönguleiðir á 151 tind. Reykjavík 2004, p. 200. In the second half of the 20th century, a number of small nunataks appeared as the more southern ice cover decreased; and two of the largest are named Bræðrasker and Kárasker. The glaciers flowing around them are feeding the

Breiðamerkurjökull Breiðamerkurjökull (, ) is an outlet glacier of the larger glacier of Vatnajökull and a piedmont glacier in the southern part of Vatnajökull National Park, Iceland. Emerging as a tongue of the Vatnajökull, it ends in two lagoons, famous J ...

, the most south-easterly part of the Vatnajökull icecap, immediately adjacent to Jökulsárlón, which it flows into. Breiðamerkurjökull, which had in 2010 an area of , covers the volcano. There are three main glacial catchments, with the western arm draining the north western slopes of the

volcano, being separated from the central arm by the Mávabyggðir (Fingurbjörg), , and Kárasker nunataks. To its west the central arm is associated with the Vesturbjörg and Skálabjörg nunataks and the eastern arm is associated with the Esjubjörg and Austurbjörg nunataks.

Volcanism

Esjufjöll is a volcanic system and is part of Iceland's Öræfi volcanic belt. Also part of this zone are Öræfajökull and Snæfell (north-east of Vatnajökull). The volcanic system consists of the Snæhetta

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 ...

with an assumed large

caldera A caldera ( ) is a large cauldron-like hollow that forms shortly after the emptying of a magma chamber in a volcanic eruption. An eruption that ejects large volumes of magma over a short period of time can cause significant detriment to the str ...

, but this has not yet been mapped well. Most of the volcano, including the caldera, is covered by the icecap. The latest data is suggestive of a volcano that may be in diameter and its northern part is underlain by a dense intrusive body. Satellite imaging suggests a caldera that may be . Vesturbjörg, Skálabjörg, Esjubjörg and Austurbjörg constitute the south-eastern flank of this caldera. Most of the exposed rocks are mildly alkaline

basalt Basalt (; ) is an aphanite, aphanitic (fine-grained) extrusive igneous rock formed from the rapid cooling of low-viscosity lava rich in magnesium and iron (mafic lava) exposed at or very near the planetary surface, surface of a terrestrial ...

s, but to the east there are

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

rocks. In the beginning of September 1927, a glacial flood (

jökulhlaup A jökulhlaup ( ) (literally "glacial run") is a type of glacial outburst flood. It is an Icelandic term that has been adopted in glaciological terminology in many languages. It originally referred to the well-known subglacial outburst floo ...

) came down the Jökulsá á Breiðamerkursandi (a short river from Breiðamerkurjökull to the sea). The glacier run was accompanied by a

sulfur Sulfur ( American spelling and the preferred IUPAC name) or sulphur ( Commonwealth spelling) is a chemical element; it has symbol S and atomic number 16. It is abundant, multivalent and nonmetallic. Under normal conditions, sulfur atoms ...

stench. On one occasion, ash fall on the Breiðamerkurjökull was thought to have possibly originated from Esjufjöll. Although

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 ...

eruptions from Esjufjöll have not been confirmed, earthquake swarms that could indicate magma movements were detected in October 2002, and again in October 2010.

Mountaineering

Ari Trausti Guðmundsson proposed a mountaineering tour crossing Breiðamerkurjökull and up on Lyngbrekkutindur.

Notes

References

External links