Iceland experiences frequent volcanic activity, due to its location both on the Mid-Atlantic Ridge, a divergent tectonic plate boundary, and being over a hotspot. Nearly thirty volcanoes are known to have erupted in the Holocene epoch; these include Eldgjá, source of the largest lava eruption in human history. Some of the various eruptions of lava, gas and ash have been both destructive of property and deadly to life over the years, as well as disruptive to local and European air travel.
Eyjafjallajökull, sometimes referred to by the numeronym E15, is one of the smaller ice caps of Iceland, north of Skógar and west of Mýrdalsjökull. The ice cap covers the caldera of a volcano with a summit elevation of 1,651 metres (5,417 ft). The volcano has erupted relatively frequently since the Last Glacial Period, most recently in 2010, when, although relatively small for a volcanic eruption, it caused enormous disruption to air travel across northern and western Europe for a week.
Katla is an active volcano in southern Iceland. This volcano has been very active historically with at least twenty documented major eruptions since 2920 BC. In its recent history though, Katla has been less active as the last major eruption occurred in 1918. These eruptions have had a Volcanic Explosivity Index (VEI) of between 4 and 5 on a scale of 0 to 8. In comparison, the Eyjafjallajökull 2010 eruption had a VEI of 4. Larger VEI-5 eruptions are comparable to Mount St. Helens 1980 eruption. These eruptions have produced very large glacial outburst floods. Several smaller (minor) events measuring VEI-1 and below have occurred since.
Öræfajökull is an ice-covered volcano in south-east Iceland. The largest active volcano and the highest peak in Iceland at 2,110 metres (6,920 ft), it lies within the Vatnajökull National Park and is covered by part of the glacier.
Hengill is a volcanic table mountain situated in the south-west of Iceland, to the south of Þingvellir.
The subglacial Esjufjöll volcano is located in the south-east part of the Vatnajökull icecap. Esjufjöll is a strict nature reserve.
Ljósufjöll is a fissure vent system and central volcano on the Snæfellsnes Peninsula in Iceland. The name derives from the central volcano and translates into English as "Mountains of the Light".
The peak Prestahnúkur with a height of 1,223 m (4,012 ft), is in the Western Volcanic Zone to the west of the Highlands of Iceland to the west of Langjökull glacier, or to be more specific, to the west of Geitlandsjökull glacier, a part of the Langjökull. The volcano Prestahnúkur includes the terrain under the Geitlandsjökull glacier continuous to the peak and also includes fissure fields to its north and south.
Theistareykjarbunga is a shield volcano in north-eastern Iceland with two fissure vents called Þeistareykjahraun and Borgahraun, and two cones: the 370 m (1,210 ft) Stórahversmór and the 540 m (1,770 ft), 30 km3 (7.2 cu mi) Stóravíti. They both are currently extinct, although there is evidence suggesting the potential for activity such as recent localised uplift and seismicity. The multiple vents make up the Theistareykir (Þeistareykir) volcanic system, with more recent evidence that the former classification as a shield volcano is better considered an embryonic central volcano with associated fissure swarm, as rhyolite has erupted in a limited area. The recent lava has picrite, olivine tholeiite basalt characteristics but before the ice age there were basaltic andesite and rhyolite eruptions. There is a central high temperature geothermal area with numerous steam vents and fumaroles. This has been utilised by a 90 MWe power station.
Hrómundartindur is a mountain in Iceland north of Hveragerði with an elevation of 540 metres (1,770 ft). It to the east of Hengill and is the central volcano of an adjacent 25 km (16 mi) long Hrómundartindur volcanic system, which contains the Ölkeduháls geothermal field. Like Hengill this area is close to the south-eastern triple junction of the Hreppar microplate, is seismically active, and associated with the Western volcanic zone and the South Iceland seismic zone. To the north-east are multiple tindars, and there is a Holocene lava flow called Tjarnahnúkshraun which covers 4 km2 (1.5 sq mi) with a volume of 0.03 km3 (0.0072 cu mi). The lava ranges from picrite basalt, being predominantly tholeiite basalt with some basaltic andesite.
Reykjanes is a small headland on the south-western end of the Reykjanes Peninsula in Iceland, giving the main peninsula its name. Volcanic action is responsible for forming the entire peninsula. The nearest town is Keflavik.
The geological deformation of Iceland is the way that the rocks of the island of Iceland are changing due to tectonic forces. The geological deformation help to explain the location of earthquakes, volcanoes, fissures, and the shape of the island. Iceland is the largest landmass situated on an oceanic ridge. It is an elevated plateau of the sea floor, situated at the crossing of the Mid-Atlantic Ridge and the Greenland-Iceland-Scotland ridge. It lies along the oceanic divergent plate boundary of North American Plate and Eurasian Plate. The western part of Iceland sits on the North American Plate and the eastern part sits on the Eurasian Plate. The Reykjanes Ridge of the Mid-Atlantic ridge system in this region crosses the island from southwest and connects to the Kolbeinsey Ridge in the northeast.
Guðrún Þorgerður Larsen is a professor emerita at the School of Engineering and Natural Sciences at the University of Iceland.
The Reykjanes Peninsula in southwest Iceland is the continuation of the mostly submarine Reykjanes Ridge, a part of the Mid-Atlantic Ridge, on land and reaching from Esja in the north and Hengill in the east to Reykjanestá in the west. Suðurnes is an administrative unit covering part of Reykjanes Peninsula.
Hveravellir is a geothermal field of the Oddnýjarhnjúkur-Langjökull volcanic system -Icelandic pronunciation:[ˈlauŋkˌjœːkʏtl̥] in the north of the Langjökull glacier.
Sundhnúksgígar or Sundhnúkagígar are volcanic craters east of Eldvörp–Svartsengi in Iceland. They are named after Sundhnúkur, which is a hill just south of Sundhnúksgígar. The craters are aligned in a row called Sundhnúksgígaröðin. The first eruption of the crater row took place about 2000 years ago. There was volcanic activity nearby during the period known as the Reykjanes fires with the last previous eruption being about 1240 CE. In December 2023, as part of the Sundhnúkur eruptions, some craters began to erupt. On 14 January 2024, a second eruption began following seismic activity associated with the area of the Sundhnúksgígar craters. As of November 2024 there had been seven eruptions.
Helgrindur is a volcanic mountain range or massif in the middle of the Snæfellsnes peninsula that provides a backdrop to the port of Grundarfjörður. The volcano can be regarded as potentially active, with a risk of lava flows and much more rarely explosive tephra eruptions. The range with its prominent peaks, of Tröllkerling at 891 m (2,923 ft) in its south-east, Böðvarskúla at 988 m (3,241 ft) and Kaldnasaborgir (Kaldnasi) in its north-west at 986 m (3,235 ft) is popular with hikers or mountaineers.
The Reykjanes Fires were a series of volcanic eruptions that took place on the Reykjanes Peninsula in south-west Iceland between approximately 1210 and 1240. They caused widespread physical and economic damage, covering large areas of the peninsula in lava and tephra and causing the mass starvation of livestock, as well as a number of deaths of people due to earthquakes. The peninsula's volcanic systems were subsequently dormant for 800 years until a fresh series of eruptions began in 2021, which have been called the New Reykjanes Fires.
Snæfell at 1,833 m (6,014 ft) high, is an ice-capped stratovolcano located in the north-east part of Vatnajökull National Park, Iceland. While it has been dormant in the Holocene, it is now known to have had repose times of over 100,000 years between eruptions, so it cannot be assumed to be extinct.
The Oddnýjarhnjúkur-Langjökull (Langjökull) volcanic system of Iceland last erupted about 3600 years ago and is associated with current geothermal activity. The area of its central volcano is at present under the second largest ice cap in Iceland.
