Iceland lies on a constructive plate margin, the Eurasian is moving eastwards while the North American plate is moving westwards. This is creating the North Atlantic Ridge, the sea floor is currently spreading at 1-5cm/year. Iceland also lies on top of a hotspot. As the plates move apart, magma is forced upwards and is ejected onto the crust, where it cools and solidifies, this creates the layers for the volcanic formation. This whole process is causing Iceland to expand.
Eyjafjallajokull is a stratovolcano. This is due to the multiple eruptions creating layers od strata. However, unlike most composite cone volcanoes, Eyjafjallajokull is actually quite flat, this could be because volcanoes produced at constructive margins tend to be shield volcanoes rather than composite ones. Still, the magma from Eyjafjallajokull is mainly rhyolitic and andesitic. Basaltic magma is also possible due to the multiple chambers in the volcano.
Causes of the 2010 Eruption + Resulting Hazards
CausesThere was a mixing of lava types within the magma chamber. Basaltic lava mixed with a higher viscosity silica rich lava (andesitic/rhyolitic). this mixing created an increase in pressure and triggered the eruption. The reason that Eyjafjallajokull released so much ash is because over the vent there was a 200m thick glacial ice sheet which underwent sublimation underneath when Eyjafjallajokull erupted and this produced a fine, ash, glassy particle called silica.
Resulting HazardsLava flows + hot lava projected into the air with more than 100million cubic metres if lava erupted in total. The ash plume rose 11000 metres in the air, this was then carried by the jet stream. The ash then spread across European air space and stopped air travel and the silica particles had the potential to shred jet engines. On Iceland glacial flooding also followed due to the melted glaciers.
Primary10 million air passengers were affected. 48% of air traffic was cancelled (107000 flights). Surrounding areas were covered with ash. 500 farmers living near the volcano had to be evacuated. Some water contamination occurred due to chemicals from erupted material diffusing into the water (e.g. fluorine), this is dangerous to livestock for example. there was a huge loss in trade. Airlines lost $200million each day. Other transport links flourished e.g. the Eurostar received an extra 50000 passengers a day.
Secondary and Environmental0.15 million tonnes of CO2 was released into the atmosphere but due to restricted air travel, 2.8 million tonnes of CO2 was thought to have been prevented from being emitted. Phytoplankton bloomed in the Atlantic due to iron from the ash. Silted up rivers resulted in floods. Shares in travel and tourism declined by 4% and Europe lost $2.6billion.
PrimaryEnforce a no-fly zone over Europe. Alternative transport routes were promoted, 800 people in total had to be evacuated due to the eruption and resulting floods. Even though the economic loss was huge, Iceland and Europe had a high enough GDP to cope with the loss, also no major response was needed as Iceland was well equipped to deal with the hazard and there were no casualties.
SecondaryFurther research into the effects on ash on aircraft. Reconstruction of roads, local flood defences needed reconstructing. Also the Icelandic Meteorological Office monitor Earth movement, water conditions and weather to be able to predict the next eruption. They also give out warnings on local tv if there is significant activity. The IMO also work closely with the UK Met office and Iceland University.
Predicting the Eruption
For 11 weeks before the volcano began erupting in March, one flank was swollen by more than 15cm (6in). Magma had been flowing from deep underground into shallower compartments under the mountain. The deformation of the Earth's crust around Eyjafjallajökull, and the resulting small earthquakes, began to increase in January. A few weeks later, sensors and GPS stations began detecting rapid expansion of the mountain.The first eruption, caused by magma flowing into the mountain from underneath, began on 20 March. It continued for three weeks before pausing for two days and then resuming on 22 April.The second time around, the erupting lava punched through the ice at the top of the mountain. The water exploded into steam and rapidly cooled the magma, which is a mixture of molten rock and various solid impurities, and normally circulates under the Earth's crust. The magma turned into a fine-grained dust cloud that rose high into the atmosphere and was blown around the whole of northern Europe. Sustained, highly variable activity continued until 22 May, with an average of 30,000-60,000 litres (6,600-13,200 gallons) of magma coming out every second.Normally, when volcanoes erupt, they deflate as the magma drains out. But for some reason, Eyjafjallajökull kept its shape after the first eruption.The researchers suggested that this could be because of a limited supply of magma in the first place, and the position of the volcano. The volcanoes of Iceland are the surface peaks of the Mid-Atlantic Ridge, but Eyjafjallajökull lies at some distance from the main rift zone. This means less heat from magma reaches it than reaches volcanoes nearer the rift zone.The eruption was probably started by an intrusion of magma deep inside the volcano, though this is something that needs to be confirmed at other volcanoes.The researchers stress that study of the events leading up to the eruption will not necessarily help to predict future events. "We're still trying to figure out what wakes up a volcano," said Feigl."The explosiveness of the eruption depends on the type of magma, and the type of magma depends on the depth of its source. We're a long way from being able to predict eruptions. But if we can visualise the magma as it moves upward inside the volcano, then we will improve our understanding of the processes driving volcanic activity."