Eyjafjallajökull Eruption (2010): The Ash Cloud Over Europe

The Eyjafjallajökull eruption of 2010 was a volcanic eruption in southern Iceland that caused the largest shutdown of European air travel since the Second World War. After an explosive phase began beneath the volcano’s ice cap on 14 April 2010, winds carried a cloud of fine ash over northern and central Europe, and around 100,000 flights were cancelled over about a week. Although modest in size, the eruption exposed how vulnerable modern aviation was to volcanic ash and led to new international rules.

Background: a volcano under ice

Eyjafjallajökull is an ice-capped volcano about 1,650 metres high near the south coast of Iceland. Iceland sits on the Mid-Atlantic Ridge, where the North American and Eurasian plates are pulling apart, and also above a hotspot of rising hot rock, which together make it one of the most volcanically active places on Earth. Volcanic eruptions have shaped the island’s history since the settlement of Iceland in the 9th century, most destructively in the Laki eruption of 1783.

Eyjafjallajökull itself erupted infrequently. Its last eruption before 2010 lasted from 1821 to 1823. From late 2009, scientists recorded increasing earthquakes and swelling of the ground beneath the mountain, signs that magma was moving into its roots.

The eruption

The first phase began on the night of 20 March 2010 at Fimmvörðuháls, a pass on the volcano’s flank between the Eyjafjallajökull and Mýrdalsjökull glaciers. This was a so-called “tourist eruption”: lava fountains and flows on ice-free ground that posed little danger, and thousands of people came to watch.

That phase ended in mid-April, and on 14 April 2010 a new eruption began from the summit crater, beneath about 200 metres of ice. When magma meets water and ice, it cools suddenly and shatters into very fine, glassy ash, making the eruption strongly explosive. Meltwater floods, known in Icelandic as jökulhlaups, poured down the valleys, and about 800 people living nearby were evacuated. Farms south of the volcano were covered in ash, and livestock had to be kept indoors.

The ash plume rose to heights of about 9 kilometres. Activity varied through April and May, with a second period of strong ash emission in early May, before the eruption declined in late May. Scientists considered it over by the autumn of 2010. Overall, it was rated 3 to 4 on the Volcanic Explosivity Index, a small to moderate eruption.

The ash cloud closes Europe’s skies

The timing and weather made the eruption unusually disruptive. A stable weather pattern brought persistent north-westerly winds that carried the ash straight towards Britain, Scandinavia and continental Europe. From 15 April, countries began closing their airspace: first Norway, the United Kingdom and Ireland, then much of northern and central Europe, including the major hubs of London Heathrow, Paris and Frankfurt.

At the time, international guidance from the International Civil Aviation Organization was simple: aircraft should avoid volcanic ash completely. The danger was real. In 1982 a British Airways Boeing 747 lost power in all four engines after flying through ash from Galunggung in Indonesia, and in 1989 a KLM Boeing 747 suffered the same over Alaska; both crews managed to restart engines and land safely. Because forecasters at the London Volcanic Ash Advisory Centre could not say where ash was safe, large areas were closed.

Between 15 and 21 April, according to Eurocontrol, about 100,000 flights were cancelled, and on the worst days about 80 percent of normal European flights did not operate. Around 10 million passengers were affected. Travellers were stranded around the world, some for more than a week, and many crossed Europe by train, coach, ferry or hire car. The British government sent Royal Navy ships to bring citizens home from the Continent.

Disputes and new rules

As the shutdown went on, airlines protested that the closures were too cautious and based on computer models rather than measurements. Several carried out test flights without passengers, which reported no damage. The International Air Transport Association estimated airlines’ lost revenue at about 1.7 billion US dollars, and wider economic losses, including tourism and exports of fresh goods, were estimated at several billion dollars.

On 20 April, after consultations between regulators, engine manufacturers and airlines, the British Civil Aviation Authority introduced a new approach: flights would be allowed where ash concentrations were below a set limit, initially 2 milligrams per cubic metre of air, later supplemented by a higher-risk zone up to 4 milligrams. Other European regulators followed, and air traffic recovered over the following days.

Ash caused further, shorter disruptions in early and mid-May 2010, affecting Ireland, the United Kingdom, Spain, Portugal and transatlantic routes. Afterwards the European Union and the International Civil Aviation Organization developed a risk-based system in which airlines, with their regulators’ approval, can decide whether to fly through areas of low ash concentration. When Iceland’s Grímsvötn volcano erupted in May 2011, far fewer flights were cancelled.

Timeline

• 2009, late: Increasing earthquakes and ground swelling are detected beneath Eyjafjallajökull.
• 2010, 20 March: A flank eruption begins at Fimmvörðuháls.
• 2010, 14 April: An explosive eruption begins beneath the summit ice cap; about 800 people are evacuated.
• 2010, 15 April: The United Kingdom, Ireland, Norway and other countries begin closing their airspace.
• 2010, 20 April: New ash-concentration limits are introduced and flights gradually resume.
• 2010, early May: Renewed ash emission causes further airspace closures in parts of Europe.
• 2010, late May: The eruption declines; it is later declared over.
• 2011, May: An eruption at Grímsvötn causes far smaller disruption under the new rules.

By the numbers

The figures for passengers and economic losses are estimates, and different organisations calculated them in different ways. What is not disputed is that the shutdown was the largest in Europe since 1945 and lasted longer than the closure of US airspace after the attacks of 11 September 2001. Businesses that depended on air freight, such as Kenyan flower growers and fresh-fish exporters, also suffered, showing how far the effects of a small Icelandic eruption could travel.

Legacy

The eruption made an unpronounceable Icelandic name famous around the world and became a byword for the fragility of modern, interconnected transport. It showed how a moderate natural event, in the wrong place and with the wrong winds, could disrupt the economy of a continent.

Scientifically, it led to major investment in measuring ash in the atmosphere, with research aircraft, lidar instruments and satellites, and to better models of how ash clouds spread. It also prompted planning for a larger eruption at neighbouring Katla, whose eruptions have historically often followed those of Eyjafjallajökull, though Katla has not erupted on a large scale since 1918.

Tourism to Iceland rose sharply in the years after 2010, helped in part by the publicity, and a visitor centre now stands at the foot of the volcano.

Why it matters

Eyjafjallajökull caused the greatest disruption to air travel in Europe since 1945, stranding millions of people. It forced governments, airlines and scientists to replace an all-or-nothing ban with a risk-based approach to volcanic ash that still governs aviation today.