Monitoring Alaska’s Remote and Restless Bogoslof Volcano

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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.

map of Alaska and Aleutian Island chain showing location of Bogoslof volcano and nearby towns.
Index map showing the location of Bogoslof Volcano(Public domain.)
Aerial photo of snow-covered mountaIns with umbrella-shaped volcanic ash plume rising in the background
February 19 Bogoslof eruption plume as seen from Unalaska Island, 53 miles ESE of Bogoslof volcano. Photo taken from helicopter during fieldwork by AVO geologists at 5:22PM, approximately 14 minutes after the start of the eruption.(Credit: Janet Schaefer, Alaska Volcano Observatory, Alaska Division of Geological & Geophysical Surveys. Public domain.)















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.

Map of Aleutian Island chain with locations of volcanoes and commercial air traffic routes indicated
North Pacific and Russian Far East air routes (gray lines) pass over or near more than a hundred potentially active volcanoes (red triangles). Aircraft flying along these routes, some of the busiest in the world, carry more than 50,000 passengers and millions of dollars of cargo each day to and from Asia, North America, and Europe. In the North Pacific region, several explosive eruptions occur every year. Ash from these eruptions, which has caused jet engines to fail, is usually blown to the east and northeast, directly across the air routes.(Public domain.)

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.

View across open ocean water with volcanic ash plume on the horizon, Seagulls flying in mid-ground.
Plume from Bogoslof Volcano, January 5, 2017. Photo courtesy of Trever Shaishnikoff. (Credit: Trever Shaishnikoff. Public domain.)

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.

Satellite image of small crescent-shaped ocean island.
Analysis of shoreline changes at Bogoslof volcano due to eruptive activity between January 11 and 24, 2017. The base image is a Worldview-2 satellite image collected on January 24, 2017. The approximate location of the shoreline on January 11, 2017 is shown by the dashed orange line.(Credit: David Schneider, U.S. Geological Survey. Public domain.)


Annotated aerial photo of crescent shaped island surrounded by open ocean.
Annotated photograph of Bogoslof Island showing the cumulative effects of 2016-17 eruptive activity. A layer of fine muddy appearing ash drapes most of the landscape and covers pre-existing vegetation. The dashed line indicates the area excavated by explosive eruptive activity so far. A prominent zone of upwelling is probably the surface expression of a shallow submarine vent. Photograph taken by Dan Leary, Maritime Helicopters, January 10, 2017.(Credit: Christopher Waythomas, U.S. Geological Survey. Public domain.)
Five sequential drawings of crescent-shaped island, showing changes in size and shape over two years/
Morphologic changes in the size and shape of Bogoslof Island resulting from the eruptive activity of 2016-17 as of January 24, 2017. Island outlines derived from satellite images. Location of the active vent is approximate.(Credit: Christopher Waythomas, U.S. Geological Survey Alaska Volcano Observatory. Public domain.)