Eyjafjallajökull

Eyjafjallajökull is a glacier-covered stratovolcano on Iceland’s south coast. The volcanic massif rises to about 1,651 metres and supports an ice cap covering roughly 100 square kilometres, although its area and thickness vary with climate. The summit crater, called Goðabunga or the Eyjafjallajökull caldera in different descriptions, is partly concealed by ice. ¹

The volcano lies within Iceland’s rift-related volcanic zone, where the North American and Eurasian plates separate. Its magma is generally basaltic, but the 2010 activity also involved more evolved magma capable of producing ash-rich explosive eruptions. Meltwater from subglacial activity can travel rapidly beneath the ice and create hazardous floods known as jökulhlaups.

Eyjafjallajökull has erupted repeatedly during the Holocene, with historically documented activity in 1612, 1821–1823, and 2010. The nineteenth-century eruption was prolonged and intermittent, producing ash and lava while causing local disruption. Earlier eruptions are reconstructed from tephra layers preserved in Icelandic soils and sediments. ¹²

Its eruptions are closely related to the nearby Katla volcanic system, but the two volcanoes are distinct. Historical observations encouraged the belief that activity at Eyjafjallajökull could precede an eruption at Katla; however, a simple inevitable sequence is not established. Monitoring therefore treats each volcano as a separate hazard while also examining their geological connections.

The 2010 eruption began on 20 March with a relatively effusive fissure eruption at Fimmvörðuháls, a pass east of the ice cap, and shifted on 14 April to an explosive subglacial eruption beneath the summit ice. Contact between hot magma and meltwater fragmented the magma into fine ash, generating an ash plume that reached the atmosphere and spread across northern and western Europe. ³

Airspace closures followed because volcanic ash can melt inside jet engines, damage turbine components, and impair flight instruments. The disruption affected millions of passengers and prompted new risk-management procedures based on measured ash concentrations rather than blanket closures alone. The eruption also produced flooding, evacuations, agricultural damage, and valuable observations of magma–ice interaction.

Eyjafjallajökull’s best-known eruption was not the largest Icelandic ash event, but its location and wind patterns gave it unusual global visibility. The 2010 ash was particularly disruptive to aviation because it entered busy European flight corridors, while much of the eruption itself remained remote and visually dominated by glacier, steam, and ash. ³

The volcano is also a natural laboratory for studying subglacial hazards. Seismic tremor, GPS measurements, satellite radar, gas observations, river discharge, and ash sampling were combined to track the eruption. The Fimmvörðuháls phase formed new lava features and attracted scientific attention because it displayed a comparatively open, low-explosivity style before the summit eruption became water-driven and ash-producing. ²

ice cap

A broad mass of glacier ice covering a mountainous area but smaller than an ice sheet.

jökulhlaup

A sudden glacial outburst flood, often caused by volcanic or geothermal melting beneath an Icelandic glacier.

tephra

Fragmented material, including ash, lapilli, and larger blocks, ejected during a volcanic eruption.

subglacial eruption

An eruption occurring beneath glacier ice, where magma can melt ice and interact explosively with water.