August 20, 2014

expert reaction to seismic activity in Bárðarbunga volcano

Further expert reaction to the detection of seismic activity in Bárðarbunga, a large sub-glacial volcano in Iceland.

Dr Nicolas Bellouin, an expert on atmospheric dust clouds at the University of Reading, said:

“Volcanic ash is made of tiny pieces of sand and minerals, blasted out from an erupting volcano, which are then suspended in the atmosphere and transported by winds. Where the ash goes is dependent on the direction of the wind. If winds continue to blow from Iceland to the UK, as they are at the moment, ash from an eruption will be transported to the UK and northern Europe.

“Volcanic ash is a hazard to aircraft, because of sandblasting of the outside of the plane and because particles are sucked into the turbines where they can melt and disable the engines. For that reason, aviation authorities impose a limit on the maximum concentration of ash aircraft can fly through. In the UK, the current limit is 4 mg per cubic metre.

“Detection of volcanic ash plumes is primarily based on satellite and ground-based instruments. Satellites give a picture of the extent of the plume, but are less useful to work out how high or low the plume is in the atmosphere. Ground-based instruments, such as lidars — lasers shot vertically into the sky — are able to give the altitude of the plume, and an estimate of its concentration, over the locations where they are installed.

“Numerical models, which simulate the dispersion of the ash plume with winds and its removal from the atmosphere, are used to forecast the location and extent of the plume.

“Following the eruption in Iceland in April 2010, the Met Office, which is one of nine Volcanic Ash Advisory Centres around the world, deployed a permanent network of lidars to cover the British Isles, and also has a dedicated research aircraft which can fly through plumes to take measurements. The Met Office dispersion model, called NAME (Numerical Atmospheric-dispersion Modelling Environment), has also been improved. This should provide a better picture and forecast of where any future volcanic ash plume exists, and where it is headed.

“People with health conditions affected by pollution should not be overly worried, and a plume of dust is unlikely to have much effect on our weather or climate. Compared to local sources of pollution, such as dust particles from car exhausts, the impact of the volcanic ash is limited, because it tends to exist mainly high in the atmosphere and is not around long enough to cause problems.”

Professor Giles Harrison, an atmospheric physicist at the University of Reading, said:

“During the eruptions of the Eyjafjallajökull and Grímsvötn  volcanoes in Iceland in 2010 and 2011, the UK government asked the University of Reading’s Department of Meteorology to work with the Met Office on measuring and modelling the dust cloud, which closed UK airspace for several days.

“Since then, Reading scientists have been working with the Icelandic Met Office to test new sensors for weather balloons, aimed at measuring volcanic plumes emitted near to their source in Iceland. These instruments could provide a new source of information for calculations predicting the spread of a plume, and have been developed from our previous balloon measurements during the Icelandic eruptions of 2010 and 2011. This work contributes to a more sophisticated system for detecting and predicting how any future volcanic eruption could affect aviation, particularly for the UK.”

Declared interests

None declared