Grimsvotn:
Iceland's most active volcano has started erupting just over a year after another eruption on the North Atlantic island shut down European air traffic for days.
Iceland's Meteorological Office confirmed that an eruption had begun at the Grimsvotn volcano, accompanied by a series of small earthquakes.
Smoke could be seen rising from the volcano, which lies under the uninhabited Vatnajokull glacier in southeast Iceland.
Local television and amateur video filmed by a passenger on a commercial airlines flight showed what appeared to be a large ash cloud rising into the sky.
A no fly zone has been designated for 120 nautical miles (220 kilometres) in all directions from the eruption.
Isavia, the company that operates and develops all airport facilities and air navigation services in Iceland, described this as standard procedure around eruptions.
Grimsvotn last erupted in 2004.
Scientists have been expecting a new eruption and have said previously that this volcano's eruption will likely be small and should not lead to the air travel chaos caused in April 2010 by ash from the Eyjafjallajokul volcano.
History shows that previous eruptions in Grimsvotn have not had much influence on flight traffic - unlike the massive disruption caused last year.
A plane from the Icelandic Coast Guard carrying experts from the University of Iceland will fly over the volcano and evaluate the situation.
Last year's Eyjafjallajokul eruption left some 10 million air travellers stranded worldwide after winds pushed the ash cloud toward some of the world's busiest airspace and led most northern European countries to ground all planes for five days.
Whether widespread disruption occurs again will depend on how long the eruption lasts, how high the ash plume rises and which way the wind blows.