- By Esme Stallard
- Climate and science reporter, BBC News
Iceland is preparing for a volcanic eruption in the coming days. Why does this happen and what could be the consequences?
Since the end of October, the region around the Icelandic capital, Reykavik, in the southwest has experienced an increase in earthquake activity.
This is because an underground river of magma – hot liquid or semi-liquid rock – about 15 km (10 miles) in length is moving upwards below the earth’s surface.
This runs under Iceland and part of the Atlantic Ocean, and the impact of an eruption on land – and further afield in terms of aviation – will depend on where exactly the magma breaks the surface.
One town, Grindavik, which lies directly above the magma, has already been evacuated due to the risk of ‘fire fountains’ and noxious gases.
Dr. Bill McGuire, Professor Emeritus of Geophysical & Climate Hazards, UCL, said: “Grindavik is very close to the position of the new fracture and its survival is far from assured. Everything depends on where the magma eventually reaches the surface, but the situation does not look good for the residents of the city.”
If a volcano erupts offshore, or erupts on land and then flows into the sea, there is a risk of an explosive ash cloud as the super-hot rock comes into contact with the water.
In April 2010, the Eyjafjallajokull volcanic eruption caused the largest closure of European airspace since World War II, as a result of an extensive ash cloud, with losses estimated at between 1.5 billion and 2.5 billion euros (£1.3-2.2 billion).
The circumstances of this volcanic activity are very different and therefore such an extensive impact is not expected.
“The 2010 Eyjafjallajokull eruption was completely different as it was associated with a shield volcano topped by a glacier. It was the interaction of magma with ice and meltwater that made that eruption so explosive and dangerous for aviation. This is not the case for Fagradalsfjall” , said Dr. Michele Paulatto, volcanologist at Imperial College London.
The Icelandic Meteorological Office estimates that the magma is currently 800m from breaking ground, and as a result the probability of an eruption of the Fagradalsfjall volcano is “high” and could happen in the coming days.
Last night’s quakes were weaker, but ground deformation continued, with fissures and cracks up to a meter deep reported in roads suggesting the magma could be even closer to the surface – a sign things could be heading towards each other .
“For the past few years, we’ve had a lull and pause in earthquakes before volcanic eruptions happen,” said Dr. Evgenia Ilyinskaya, Icelandic geophysicist and co-director of the International Volcanic Health Hazard Network, to the BBC.
Iceland is very used to volcanic activity – successfully building a tourism industry on it – because it sits above the Mid-Atlantic Ridge. The Earth’s crust is divided into different plates, and at the ridge, the Eurasian and North American plates move apart by a few centimeters a year. This allows magma to rise to the surface, which erupts as lava and/or ash.
The nature of volcanic eruptions varies depending on the rock type and how the plates move.
One of the most extensive eruptions in Iceland was back in 1783 when there was a lava flow that lasted for eight months and produced extensive sulfur clouds that hung over northern Europe for more than five months and is estimated to have caused a cooling of about 1, 3 C for the following two years.
Dr. Ilyinskaya, who is in regular contact with geologists on the ground, told the BBC that: “It looked worrying on Friday and Saturday that we could have something on that scale, in the rare but large events which of course would have huge implications for air quality in the Northern Hemisphere.
“That is not the situation that is likely at the moment.”
The latest evidence that emerged Sunday and Monday, she said, suggests the eruption will be much smaller than previously thought.