A volcano on a remote island in Alaska's Aleutian chain has erupted again, prompting an aviation alert.
The Alaska Volcano Observatory says the Bogoslof (BOH-goh-slawf) volcano sent an ash plume about 20,000 feet in the air by early Friday morning.
The eruption caused the observatory to issue its highest alert level for aircraft.
During an eruption of the volcano last week, the Federal Aviation Administration said flights were rerouted around the plume.
The center says the volcano began erupting shortly before midnight Thursday and its activity was recorded by seismic data and in satellite images.
The volcano is located on an island of the same name in the Bering Sea about 850 miles southwest of Anchorage.
An ash-producing eruption started at 23:45 Dec 29 AKST (08:45 Dec 30 UTC) and is continuing as recorded by seismic data on nearby islands and as seen in recent satellite images. Cloud-top temperatures from satellite suggest a cloud height of around 20,000 ft asl. Regional winds are from the southwest. We are raising the Aviation Color Code to RED and the Alert Level to WARNING.
AVO has no ground-based volcano monitoring equipment on Bogoslof volcano. We continue to monitor satellite images, information from the Worldwide Lightning Location Network pertaining to volcanic-cloud lightning, and data from seismic and infrasound instruments on other islands for indications of volcanic activity. At present, these observations should allow timely detection of additional explosive events.
Bogoslof's last major eruption occurred in 1992 when a large new lava dome grew on the north side of Bogoslof Island, according to the Smithsonian Institution's Global Volcanism Program at the National Museum of Natural History. That event lasted 18 days, with pilots and fishermen reporting columns of steam, a rapidly rising mushroom shaped cloud, and a rocky new island.