ANCHORAGE, Alaska — The Alaska Volcano Observatory has lowered the alert level on an Aleutians Islands volcano that spewed ash for three hours Monday.

The observatory says no additional eruption has been detected at Bogoslof (BOH-gohs-lawf) Volcano and that the alert level has been lowered from “warning” to “watch.”

Bogoslof has erupted about 60 times since mid-December. The volcano is 850 miles (1,400 kilometers) southwest of Anchorage.

Ash clouds above 20,000 feet (6,100 meters) can harm jet airliners traveling between Asia and North America.

Bogoslof began erupting at 10 a.m. Monday. A pilot spotted the ash cloud Monday at 32,000 feet (9,750 meters). Pilots warned of ash clouds fly over or around them to avoid engine damage.

The observatory says additional eruptions sending ash into the air could occur at any time.