Iceland’s Vatnajökull glacier is Europe’s largest icecap
Vatnajökull (2110 m) is the largest glacier in Iceland and it’s also the largest glacier mass in Europe. It covers an area of roughly 8300 km2 and it’s about 1000 m thick at its thickest point. Its average thickness is between 400 and 500 m, and the total ice volume of Vatnajokull is probably in the vicinity of 3300 cubic km.
In 2008, Vatnajökull glacier and its magnificent surroundings were declared a national park. Two existing national parks, Skaftafell in the south and Jökulsárgljúfur in the north, as well as several nature reserves, were integrated into the newly established Vatnajökull National Park, thereby creating the largest national park in Europe. Vatnajökull National Park covers 13% of Iceland. The Park showcases a stunning variety of landscape features, shaped by nature’s mightiest forces.
Vatnajokull glacier is named after subglacial lakes in a very volcanically active region in its centre. The ice cap covers an undulating highland plateau, generally reaching 600-800 m altitude. The subglacial landscape is dissected by numerous broad and narrow subglacial valleys and spectacular canyons. The Equilibrium-Line Altitude (ELA), level at which accumulation and ablation are in balance, lies at approximately 1100 m a.s.l. along its southern margins, at 1200 m along its western part, and at 1300 m in its northern part. About 60% of the glacier surface is above the ELA. A great number of glacier snouts of different sizes flow down onto the lower lying areas.
No glacier in Iceland has been researched more thoroughly than Vatnajökull. The research started in 1934 when the lake region erupted and, ever since the Iceland Glaciological Society was founded in 1950, it has continued every year. The Iceland Glaciological Society owns huts in several places on the icecap. The latest eruptions of the lake region took place in 1996, 1998, 2004 and 2011. The first confirmed trip across the icecap from the south and back was accomplished in 1875 by an Englishman and a few Icelanders. They were the first to see the Askja eruption the same year and report it to the people living on Lake Mývatn (Myvatn).
Vatnajokull’s concealed volcanoes
Seven volcanoes are located underneath the Vatnajokull icecap and most of them are active volcanoes. The western part of the great Vatnajokull icecap partly conceals the volcanic fissure systems of the Mid-Atlantic Ridge plate boundary. Two major volcanic centres lie beneath the ice: the Bárðarbunga (Bardarbunga) volcanic centre and the Grímsvötn (Grimsvotn) volcanic centre, both with large subglacial caldera depressions.
The Bardarbunga (2000 m) centre is part of a fissure system extending over 100 km to the south and some 50 km to the north of the glacier. The last eruption within the Bardarbunga centre occurred in 1910, but eruptions on the fissure system have occurred in 871 AD, 1477 AD and 1862 AD, all producing substantial amounts of lava. Grímsvötn volcano (1725 m), together with Hekla, has been Iceland's most active volcano since the Middle Ages. Grimsvotn last erupted in 1996, 1998, 2004 and yet again in 2011.
Kverkfjöll (Kverkfjoll), around 1920 m high, is a large glaciated central volcano on the northern edge of Vatnajokull. Due to a fault scarp, there is a powerful high temperature area consisting of hot springs, mud-holes, steam blowholes and a luke-warm lake. The hot springs area is around 3 km long and almost 1 km wide. Underneath the glacier, there is an ice cavern system several km long.
Öræfajökull (Oraefajokull), 2110 m high, is a broad glacier-clad stratovolcano at the SE end of the Vatnajökull icecap. A major silicic eruption which occurred in 1362 was Iceland's largest historical explosive eruption. Another eruption occurred during 1727-28. Both eruptions were accompanied by major jökulhlaup (glacier outburst floods) that caused property damage and fatalities.
1996 subglacial eruption & jökulhlaup
Late in the evening of September 30, 1996, seismometers detected the beginning of an eruption under the Vatnajökull icecap. One of the volcanoes had previously collapsed and formed a caldera named Grímsvötn, in which a subglacial lake had accumulated. Late on October 1, the surface of the ice over the caldera had risen 10-15 metres. The next day, the eruption broke through the surface of the ice, emitting an ash cloud ten kilometres high. The volcano quieted on the thirteenth, but the ice continued to melt and overflow the Grímsvötn lake. More than three cubic kilometres of ice melted, but little was emitted through normal runoff points. Since an ice dam and the caldera itself held the melt back, the jökulhlaup would not occur until November, or at least one month later.
At 7:20am on the fifth of November, the meltwater burst vertically from two kilometres above the tongue of the glacier. By four that afternoon, the jokulhlaup was fully realized. A mixture of sediment, meltwater, and ice moved at ten kilometres per hour from the full twenty-kilometre width of the glacier's terminus across Skeiðarársandur (Skeidararsandur), forming standing waves three and four metres high. The total flow peaked at over fifty thousand cubic metres per second in the five outwash channels, making it briefly the second largest river of the world. The flood obliterated a 376-metre-long bridge, the majority of a second bridge, nine hundred metres in length, twelve kilometres of roadway and twenty-three power-line towers, causing fourteen million US dollars in damage, while adding seven square kilometres to the area of Iceland. Thankfully, there were no fatalities or injuries, and the flood did not reach any nearby settlements.
There is little doubt that these events occurring in the eastern part of Iceland in late 1996 had an impact felt around the world. The phenomenon of a subglacial volcanic eruption is not often encountered; therefore, numerous journalists and scientists from around the world met in Iceland during the eruption to study the events and ramifications of these occurrences. The study of volcanoes, especially active volcanoes located under glaciers, has since broadened its scope of research into the distinct volcanism of volcano-glacial ice interactions, or glaciovolcanism, in order to unlock more of the secrets of our planet. Undoubtedly, anything learned from the Vatnajokull incident and others like it can be applied to other fields, including plate tectonics and the behaviour of land on other planets.
Iceland´s highest peak, Hvannadalshnúkur /Hvannadalshnjúkur (Hvannadalshnjukur) is in Vatnajökull glacier and rises 2110 metres above Iceland´s south shore. One of the most amazing sights of Vatnajökull glacier is the Jökulsárlón (Jokulsarlon) glacial lagoon.