Iceland has raised its aviation alert for the restless Bardarbunga volcano to red, indicating that some type of eruption is imminent or in progress.
Thousands of small earthquakes have rattled the volcano deep beneath Iceland's Vatnajokull glacier in the last week, with activity picking up today after a lull the day before.
The eruption of Iceland's Eyjafjallajokul volcano in 2010 produced an ash cloud that caused international aviation chaos, with more than 100,000 flights cancelled.
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