Eyjafjallajokull:
Southern Iceland's Eyjafjallajokull volcano continued to send clouds of ash several miles into the air on Sunday, as flight restrictions remained across much of Europe.
The volcano began erupting for the second time in a month on Wednesday.
Winds have pushed the ash south and east across Britain, Ireland, Scandinavia and into the heart of Europe, shutting down airports as far south and east as Bulgaria.
Footage of the volcano shot late on Saturday showed dark grey ash spurting out of the crater.
Iceland's emergency services have set up road blocks to prevent anyone except local residents from approaching the volcano.
A thick layer of ash covering roads close to the volcano made driving conditions hazardous.
A Civil Protection Agency spokesman in Iceland said on Sunday the eruption is continuing and there are no signs that the ash cloud is thinning or dissipating.
The British Meteorological Office said there was no way to be certain that areas clear of ash will remain that way.
The Met Office said the ash reached up to 20-thousand feet (6 kilometres), but that the grit also was dropping to low levels in some places and settling on the ground in parts of southern England.
Dr David Rothery, from the Earth Sciences department at the UK's Open University, said on Saturday that even if the eruption subsided, "we've still got to wait for that existing ash to drift by us and for all the transport situation to resolve itself."
He predicted "several more days of severe disruption at the least."
The aviation industry, already reeling from a punishing economic period, is facing at least 200 (m) million US dollars in losses every day, according to the International Air Transport Association.
Reykjavik's airport resumed flights to northern Norway on Saturday.
Flights from the airport to all other European destinations have been cancelled, but flights to North America have not been interrupted.
Several major airlines safely flew test flights without passengers over Europe on Sunday despite official warnings about the dangers of the plume to aircraft.
KLM Royal Dutch Airlines said that by midday on Sunday it had flown four planes through what it described as a gap in the layer of microscopic dust over Holland and Germany.
Air France, Lufthansa and Austrian Airlines have also sent up test flights, although most travelled below the altitudes where the ash has been heavily concentrated.
Eurocontrol, the European air navigation and safety organisation, said in a statement that by the end of Sunday more than 63-thousand flights will have been cancelled since April 15.