Anchorage - The Alaska Volcano Observatory has raised the aviation warning level after a volcano in the Aleutian Islands erupted again.
Bogoslof Volcano erupted the second time since Thursday and the observatory says it generated an ash cloud that may be as high as 7 700m.
Volcanic ash above 6 000m is a threat to airliners flying between Asia and North America.
The volcano, about 1 400km southwest of Anchorage has erupted more than 25 times since mid-December and could continue periodic eruptions for months.
