Eyjafjallajökull glacier and volcano on the south coast of Iceland

Eyjafjallajökull rises above the farms and lowlands of Iceland’s south coast, west of Mýrdalsjökull and Katla. The volcano is largely covered by an ice cap and reaches about 1,666 metres above sea level, with an ice-filled summit caldera roughly 2.5 kilometres across.

It is one of the relatively few Icelandic central volcanoes that can properly be described as a stratovolcano, built over a long period from repeated eruptions of lava, tephra and other volcanic material.

For most visitors today, Eyjafjallajökull is inseparable from the eruption of 2010. That eruption became a global event when fine volcanic ash spread into European airspace and forced the cancellation of around 104,000 flights. But the consequences in Iceland were much more immediate: farms were covered in ash, rivers flooded, roads were cut, livestock had to be protected and meltwater poured from the glacier.

The photographs on this page were made during the eruption from Fljótshlíð and the countryside beneath Eyjafjallajökull. They record not only the eruption column itself, but ash moving across the farms, livestock beneath the plume, volcanic lightning and the ice and debris carried onto Markarfljótsaurar by the floods.

A glacier-covered stratovolcano

Eyjafjallajökull has developed through repeated volcanic activity under very different climatic conditions. Parts of its exposed flanks preserve volcanic sequences formed beneath glaciers, while others were produced during ice-free periods.

This long history has created a layered volcanic mountain rather than a single cone from one eruption.

Two important outlet glaciers descend north from Eyjafjallajökull. Gígjökull flows from the summit area towards Þórsmörk and the Markarfljót valley, while Steinsholtsjökull lies farther east.

Gígjökull became particularly important during the 2010 eruption because meltwater from beneath the summit travelled down through the glacier and into the lowlands.

Eyjafjallajökull lies about 25 kilometres west of Katla, the much larger volcanic system beneath Mýrdalsjökull. The two volcanoes are often mentioned together, but they are separate volcanic systems and Katla deserves to be understood on its own terms.

Earlier eruptions and warning signs

Eyjafjallajökull has erupted only a few times during Iceland’s written history. An eruption is considered likely to have occurred around 920, followed by eruptions in 1612–1613 and again from 1821 to 1823. The 2010 eruption was therefore the first at Eyjafjallajökull in almost two centuries.

The eruption did not begin entirely without warning. Seismic unrest was recorded beneath the volcano in 1994 and again in 1999. A decade later, in 2009, renewed earthquake activity was accompanied by measurable deformation of the mountain.

During the first months of 2010, both seismic activity and deformation increased considerably. By March it was clear that magma was moving beneath the volcano.

What happened next developed in two very different stages.

Fimmvörðuháls — the first eruption

Late on 20 March 2010, an eruptive fissure opened at Fimmvörðuháls, the high pass between Eyjafjallajökull and Mýrdalsjökull.

The fissure was around half a kilometre long and lay outside the main ice cap. Lava fountains rose from the vents and new lava spread across the mountain landscape.

Two new volcanic craters formed during the eruption and were later named Magni and Móði.

Because the eruption occurred on largely ice-free ground, it was relatively straightforward compared with what followed. Lava and tephra were produced without large quantities of meltwater interacting with the magma.

The Fimmvörðuháls eruption continued until 12 April. For two days the volcano appeared to have fallen quiet.

Then the eruption moved beneath the glacier.

14 April — eruption beneath the ice

During the early hours of 14 April, a new eruption began beneath the summit ice of Eyjafjallajökull. This second eruption was far more explosive.

Magma rising beneath the glacier came into contact with ice and meltwater, fragmenting into fine volcanic ash. The eruption column initially rose several kilometres above the volcano and at times exceeded 9 kilometres.

The interaction between magma and water produced enormous quantities of fine ash, much of which could remain suspended in the atmosphere long enough to travel considerable distances.

Approximately 0.27 cubic kilometres — around 270 million cubic metres — of airborne tephra was produced during the summit eruption.

It was this fine ash, rather than the size of the eruption itself, that caused the enormous disruption to aviation. European airspace closed repeatedly as the ash cloud spread across the continent. Around 104,000 flights were eventually cancelled.

For much of the world, this was the defining story of Eyjafjallajökull.

Below the volcano, however, the eruption was creating a very different crisis.

Floods, ash and the countryside below

As the eruption melted ice at the summit, large volumes of water travelled beneath and through Gígjökull. The resulting jökulhlaups surged down into the Markarfljót system, carrying ice, sediment and debris into the lowlands.

At one point authorities deliberately cut sections of the road across Markarfljótsaurar to allow floodwater to escape and reduce the danger to the main Route 1 bridge. Large blocks of glacier ice were carried out onto the floodplain, together with tree trunks and other debris.

At the same time, changing winds carried ash across the farms beneath Eyjafjallajökull. Fields, buildings and roads disappeared beneath a grey-black layer of volcanic material. Farmers had to move animals indoors or away from the worst affected areas, and ash entered buildings through the smallest openings.

The visual appearance of the eruption could change within minutes. At times the ash plume rose vertically above the volcano. At others it became a dark horizontal wall moving across the countryside.

Electrical activity inside the plume produced spectacular volcanic lightning during the night.

The photographs made here during April and May 2010 document these different sides of the eruption: horses standing beneath the plume, farms disappearing into ash, lightning inside the cloud and blocks of glacial ice left across Markarfljótsaurar after the floods.

Eruptive activity declined considerably during May and had effectively ceased by the end of that month, although monitoring continued for much longer.

Eyjafjallajökull today

Today Eyjafjallajökull once again appears quiet above the farms of the south coast.

One of the easiest places to understand the scale of the mountain is the area around Þorvaldseyri, directly beneath the volcano.

The former eruption visitor centre there is no longer operating, but the site has changed rather than disappeared. A walking path now leads through the area with information panels explaining the landscape and the 2010 eruption, ending at a viewpoint towards Eyjafjallajökull. The building that once housed the visitor centre is now used for other purposes, including a bakery.

Þorvaldseyri has its own destination page and is best treated as a separate stop rather than part of this article.

Gígjökull, where the 2010 meltwater floods descended from the volcano, also has its own page.

Fimmvörðuháls has an equally important connection to the eruption. The hiking route between Skógar and Þórsmörk crosses the area where the first 2010 fissure opened and passes the volcanic craters Magni and Móði. Because the route is a major destination in its own right, it is better covered separately.

Eyjafjallajökull can be seen from many places along the south coast, but views from Fljótshlíð and the farms below the volcano give the mountain its proper scale within the landscape.

• Eyjafjallajökull is a glacier-covered stratovolcano rising to about 1,666 metres.
• Its summit contains an ice-filled caldera roughly 2.5 kilometres across.
• Known or likely historical eruptions occurred around 920, in 1612–1613, 1821–1823 and 2010.
• The 2010 eruption began at Fimmvörðuháls on 20 March before moving beneath the summit glacier on 14 April.
• The craters Magni and Móði formed during the first stage of the eruption.
• Approximately 270 million cubic metres of airborne tephra was produced during the summit eruption.
• Around 104,000 flights were cancelled because of volcanic ash in European airspace.
• Gígjökull carried large quantities of meltwater from beneath the volcano during the 2010 eruption.