http://www.rte.ie/news/2014/0824/639008-planes-on-alert-as-icelandic-volcano-erupts/   :

Aviation authorities are watching for developments in Iceland where planes are on high alert following a volcanic eruption.

Iceland closed airspace directly above Bardarbunga volcano yesterday after it began erupting.

The eruption is under the ice of Europe's largest glacier following thousands of earthquakes over the past week.

Magnus Tumi Gudmundsson, a professor of geophysics at the University of Iceland, has stressed that no eruption has breached the surface of the glacier.

Speaking to Icelandic television, Professor Gudmundsson said that although it was likely that no magma had reached the surface of the glacier yet it was better to be safe than sorry.

He said: "We dont know if this activity will show a similar pattern, but we have to be prepared. This run-up is positive in a way, because we have had time to prepare."

In 2010 an eruption of the Eyjafjallajokull volcano, in the south of the Iceland.

It produced an ash cloud that caused a week of aviation chaos with more than 100,000 flights cancelled across the UK and the rest of the world.

Just minutes before the eruption, officials in Iceland raised the country's aviation alert to the highest level of red, which warns that an eruption could cause "significant emission of ash into the atmosphere."

However, scientists who flew over the ice cap yesterday afternoon saw no visible signs of the eruption on the surface.

Experts in Iceland's Met Office said it was not clear when, or if, the eruption would melt through the ice.

The ice is between 330ft to 1,300ft thick.

The British Civil Aviation Authority said: "Volcanic ash can adversely affect aircraft in a number of ways. Jet aircraft engines in particular are susceptible to damage from volcanic ash.

Two working groups including airlines and scientists have also been established to act as advisers on ash forecasting and how best to use the output from the Met Office modelling system.