New eruptions in Iceland's Bardarbunga volcano system prompted authorities to raise the warning level for the risk of ash to aviation to the highest level of red.
The area has been hit by thousands of earthquakes over the last two weeks and scientists have been on high alert.
In 2010, an ash cloud from the Eyjafjallajokull volcano, in a different region of Iceland, closed much of Europe's air space for six days.
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The band announced at a free concert on Friday that they would take over the event's Pyramid stage on Saturday June 25.
The victims were collecting permits and escorts a day after their home town was liberated from the extremists.
Scotland Yard said the male youths will appear in custody at Westminster Magistrates' Court on Saturday.