Bardarbunga: A Deep Dive into Iceland's Hidden Giant
Hidden beneath Vatnajokull, Iceland's largest ice cap, lies Bardarbunga, one of the country's biggest and most powerful volcanic systems. Largely concealed by ice, it rarely makes headlines until it stirs, and when it does the results can be immense. In 2014 and 2015, a Bardarbunga eruption produced the largest lava flow in Iceland in more than two centuries, a spectacular outpouring of basalt across the highland desert of Holuhraun.
A volcano beneath the ice
Bardarbunga is a large central volcano largely buried beneath the Vatnajokull ice cap, with a summit caldera hidden under hundreds of metres of ice. Reaching around 2,000 metres, it is one of the highest and most voluminous volcanic systems in Iceland. Its concealment beneath the glacier makes it difficult to observe directly and adds the hazard of ice-magma interaction to its eruptions.
A long fissure system
Bardarbunga is not a single peak but the centre of an extensive volcanic system, including a long fissure swarm that extends across the highlands. Eruptions can occur far from the central volcano, along these fissures, as fluid basaltic magma travels underground before reaching the surface. This rift-related plumbing is characteristic of Iceland's position on the Mid-Atlantic Ridge.
The 2014-2015 Holuhraun eruption
In August 2014, after a period of intense earthquakes, magma from Bardarbunga travelled underground for tens of kilometres before erupting at Holuhraun, north of the glacier. The eruption that followed lasted about six months and produced an enormous lava field, the largest in Iceland since the Laki eruption of the eighteenth century. Fountains of lava fed rivers of basalt across the highland plain.
Gas and its reach
The Holuhraun eruption released vast quantities of volcanic gas, particularly sulphur dioxide, which affected air quality across Iceland and drifted toward Europe. This gas emission, rather than explosive ash, was the eruption's main hazard to people, echoing on a smaller scale the deadly gas-rich eruptions that Iceland has experienced in its history, such as Laki.
Caldera subsidence
As magma drained from beneath Bardarbunga to feed the Holuhraun eruption, the volcano's caldera floor subsided dramatically beneath the ice. Scientists tracked this subsidence in detail, gaining valuable insight into how calderas form and how magma moves through large volcanic systems. The event was a natural experiment in caldera collapse, observed with modern instruments.
A subglacial hazard
Because Bardarbunga lies beneath a glacier, its eruptions carry the risk of jokulhlaups, glacial floods caused by the rapid melting of ice by volcanic heat. These sudden, powerful floods are a serious hazard in Iceland, and the possibility of an eruption beneath the ice cap, rather than at an ice-free fissure like Holuhraun, remains a key concern for the volcano.
Monitoring a hidden volcano
Iceland's Meteorological Office monitors Bardarbunga closely, using seismic networks, GPS, and other tools to track activity beneath the ice. The 2014-2015 eruption demonstrated the value of this monitoring, allowing scientists to follow the underground movement of magma and to anticipate where it might erupt, even at a volcano largely hidden from view.
Explore on the map
Bardarbunga stands among Iceland's great volcanic systems, alongside Grimsvotn, Hekla, and the fissures of Laki. Explore it on the interactive map — filter by country to see Bardarbunga among Iceland's volcanoes and to appreciate the power of the volcanic systems hidden beneath the island's glaciers.