Iceland´s Glaciovolcanoes
Eyjafjallajökull (Eyjafjallajokull) is an icecap covered stratovolcano, rising to 1666 m a.s.l. in height. It is a mountain range formed as a result of subglacial eruptions over thousands of years. Volcanoes of this kind are also called glaciovolcanoes and, in Iceland, several subglacial volcanoes belong to this category, including the volcanoes Katla, Hekla and Askja. In Icelandic, Eyjafjallajökull (translated literally) means “Island Mountains’ Glacier”, perhaps obscuring the fact that it's also an active volcano.

Fimmvorduhals Eruption
Preceding the eruption of the Eyjafjallajokull volcano, there was seismic and volcanic activity at Fimmvörðuháls (Fimmvorduhals). The area is located on about a 2 km wide pass of ice-free land between Eyjafjallajokull and the nearby Katla volcano with its overlying cap of the Mýrdalsjökull (Myrdalsjokull) glacier. The initial visual report of the eruption happened around midnight on 20 March 2010 when a red cloud was noticed lighting up the sky above the site. The eruption broke out with fire fountains when about a 500 m long fissure vent opened. Lava flows occurred and a minor plume of less than 1 km. Two new craters erupted about a week later, with spectacular fireworks of magma and lava flows.

2010 Eyjafjallajokull Eruption
Eyjafjallajokull volcano erupted on 14 April 2010 for the first time after two centuries, bringing Europe’s air travel to a halt, grounding an estimated 10 million travellers worldwide, and focussing a lot of attention on Iceland. The volcano’s 10 week long series of eruptions has been well documented: topics covered ranged from the descriptions of “the power and wrath” of Eyjafjallajokull and the turmoil it brought to stranded passengers, to the predictions on whether or not Iceland's far more powerful neighbouring volcano Katla might erupt in the aftermath – as it had done in the past.

Located south of the intersection between the South Iceland Seismic Zone and the Eastern Volcanic Zone, Eyjafjallajokull is close to a propagating rift zone – and, close to an inhabited region. On the 14th of April 2010, a phone-call in the dead of night was the first hint the people living at the foot of Eyjafjallajokull had that the volcano was about to erupt (the call had come from a Civil Protection official). Shortly after, the volcano started erupting from the top crater in the centre of the glacier, where the melt had made its way into the central crater. It unleashed a jokulhlaup (glacial outburst flood) necessitating some 800 people to be evacuated, ejecting an estimated 250 million cubic metres of tephra, sending a 9 km (30, 000 ft) high ash plume into the air. After 24 hours, with the volcanic activity still intensifying, the plume had risen to some 11 km, increasing in size several times, as it stretched to eventually cover an area nearly the size of Western Europe. Electrical storms were also observed. Information about Eyjafjallajokull's past eruptions can be found on the site’s ‘Glaciers’ - Eyjafjallajokull page.

Experts have since suggested that the Eyjafjallajokull eruptions were precipitated by several “microearthquakes”, which, in turn, triggered a chain reaction of expanding magma chambers descending into the Earth at various depths below the surface. At the time, Icelandic scientists had been quick to add more seismometers to the network close to the volcano, enabling collection of excellent satellite imaging data for analysis. The data, and samples of matter spewed from the volcano in the course of the eruptions, have revealed that each separate chamber had contained magma of distinct age and specific geological composition.

As well as providing insights into the Earth’s geological past, studies of glaciovolcanoes’ deposits are helping scientists get a better understanding of Earth’s long term climate cycles, since the volcanic shards also provide clues about the climates of the past. As to just how complex and hazardous glaciovolcanoes can be, Iceland´s Eyjafjallajokull has already shown.

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