Travellers to and around northern Europe have something to worry about. Smoke billowing out of Iceland's Bardarbunga volcano has forced the meteorological office to raise their risk level to the aviation industry for an eruption to orange, which is the third level on a four-grade scale. The colour codes, which are in accordance with recommended International Civil Aviation Organisation procedures, are intended to inform the aviation sector about a volcano's status. Code Red, that follows orange, is the highest.

Although there has been no signs of eruption yet, Bardarbunga has witnessed intense seismic activity since August 16. Bardarbunga is Iceland's largest volcanic system, situated under the ice cap of the Vatnajokull glacier.

In 2010, ash from the eruption of Iceland's Eyjafjallajokull volcano had shut down much of Europe's airspace for six days, affecting more than 10 million travellers at a cost of nearly $1.7 billion. 

Iceland's met office officials fear a similar situation after Monday's earthquake in the region that was the strongest recorded since 1996. There is a strong indication of ongoing magma movement.

Eurocontrol, the Brussels-based agency that co-ordinates the European airspace, is in touch with the Icelandic Met Office and is following Bardarbunga's movements closely.