Updated

The Alaska Volcano Observatory has raised the aviation warning level after a volcano in the Aleutian Islands erupted again.

Bogoslof (BOH-gohs-lawf) Volcano erupted Friday morning, and the observatory says it generated an ash cloud that may be as high as 25,000 feet.

Volcanic ash above 20,000 feet is a threat to airliners flying between Asia and North America.

The volcano 850 miles southwest of Anchorage has erupted more than 25 times since mid-December and could continue periodic eruptions for months. It also erupted Thursday.

After Friday's event, the Aviation Color Code was raised from orange to red, the highest level. The observatory says the cloud could reach 30,000 feet.

The National Weather Service issues alerts to traffic controllers after significant eruptions.