An Alaska volcano that has been active for nearly six months has erupted again.

The Alaska Volcano Observatory says Bogoslof Volcano in the Aleutian Islands erupted at 2:16 p.m. Sunday and sent a cloud of ash at least 35,000 feet high. The eruption lasted 55 minutes.

Ash can harm and stop jet engines. Ash from southwest Alaska volcanos is a threat for airliners operating between North America and Asia when a cloud rises above 20,000 feet.

This spectacular photo of Bogoslof's eruption plume was captured on Tuesday Dec. 20 at around 3:30 PM AKST at 36,000 feet. The aircraft was about 20 miles north of Bogoslof island flying westbound. Image courtesy of Paul Tuvman. Paul Tuvman via Alaska Volcano Observatory

Bogoslof is an island west of mainland Alaska framed by the Bering Sea and Pacific Ocean.

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After the eruption, the Aviation Color Code was raised to red, the highest level.

The agency says a person on nearby Unalaska Island reports seeing a large white-gray mushroom cloud form over Bogoslof, with ash falling out to the west.

There's been no new volcanic activity since Sunday's eruption, according to the Alaska Volcano Observatory.