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Monitoring Alaska’s Remote and Restless Bogoslof Volcano
Alaska's Bogoslof Volcano
Bogoslof volcano, located in the Aleutian Islands about 98 km (61 mi) northwest of Dutch Harbor/Unalaska, is in an active eruption sequence that began in mid-December 2016 and continues today.
Eruptive activity has been dominated by a series of explosive events originating from below sea level and lasting from about 30 to 60 minutes each. The explosions can put volcanic ash to altitudes exceeding 30,000 feet, resulting in drifting clouds of ash that threaten not only local air traffic, but also wide-body jets flying between North America and Asia.
The most significant – and common – hazards from Alaska volcanoes are those created by ash clouds and ashfall. Alaska’s volcanoes are distributed under Pacific great circle aircraft routes (traversed by tens of thousands of people per day), and can erupt ash clouds into commercial and recreational airspace. Ash and aircraft do not mix, as volcanic ash is abrasive, melts at jet engine temperatures, and can cause engine failure.
It is uncertain how long eruptions of Bogoslof will continue. Some past eruptions have lasted for many months, so it is quite possible that the volcano will remain active for some time. Continued submarine eruptive activity is expected to be similar to the events observed so far, and volcanic clouds reaching flight levels, local fallout of ash, and further explosions causing changes to Bogoslof Island can be expected while the volcano remains active.
Bogoslof is not monitored by a local geophysical network, which limits scientists’ ability to forecast and closely track activity at this volcano. The USGS Alaska Volcano Observatory (AVO) is using seismic and infrasound (airwave) sensors on neighboring Umnak and Unalaska Islands to monitor activity. In addition, AVO is using satellite imagery and information from the Worldwide Lightning Location Network to detect activity and track any drifting clouds of ash. AVO will continue to provide timely warnings of activity and will issue Volcanic Activity Notices (VANs) and Volcanic Observatory Notices for Aviation (VONAs) as needed.
At least 8 historical eruptions have been documented at Bogoslof. The most recent prior to 2016 occurred from July 6-24, 1992, and produced episodic steam and ash emissions including an ash cloud up to 26,000 feet (8 km) above sea level on July 20, followed the next day by extrusion of a new 150 m (500 ft) by 275 m (900 ft) lava dome on the north end of the island. Previous eruptions of the volcano have lasted weeks to months, and have on occasion produced ashfall on Dutch Harbor/Unalaska. Eruptions of the volcano are often characterized by multiple explosive, ash-producing events such as we have seen since December 2016, as well as the growth of lava domes.
Bogoslof is the largest of a cluster of small, low-lying islands making up the summit of a large submarine stratovolcano. The highest point above sea level prior to this eruption was about 100 m (300 ft). Bogoslof volcano is within the U.S. Fish and Wildlife Service Alaska Maritime National Wildlife Refuge and is habitat for marine mammals and seabirds. Volcanic activity, combined with erosion from wave action, likely will continue to modify the island further.
For more details about the current eruption, monitoring efforts, and information about the volcano's previous eruptions and possible hazards, please refer to AVO’s Bogoslof Activity Page.