Bogoslof erupts ash possibly as high as 13.7 km (45 000 feet), Alaska

Bogoslof erupts ash possibly as high as 13.7 km (45 000 feet), Alaska

A powerful eruption took place at Alaska's Bogoslof volcano on May 28, 2017. It was the second powerful eruption after more than months of relative calm. Aviation Color Code was raised to Red.

The Alaska Volcano Observatory (AVO) reported a powerful explosive eruption started at Bogoslof volcano at 22:16 UTC on May 28 and lasted about 50 minutes. "Satellite images and pilot reports indicate that the cloud reached at least 10.7 km (35 000 feet), and possibly as high as 13.7 km (45 000 feet) above sea level."

"An observer on Unalaska Island reported seeing a large white-gray mushroom cloud form over Bogoslof, with ash fall out to the west. Winds in the area are currently to the northwest," AVO added.

At 05:09 UTC, AVO said that no further eruptions have occurred at the volcano and that seismicity remains low. It, therefore, lowered the Aviation Color Code to Orange and Alert Level to Watch.

The volcano remains at a heightened state of unrest and in an unpredictable condition. Additional explosions producing high-altitude volcanic clouds could occur at any time.

"Low-level explosive activity that is below our ability to detect in our data sources may be occurring. These low-level explosions could pose a hazard in the immediate vicinity of the volcano," the Observatory warns.

The last major eruption of this volcano took place on May 17, 2017, sending a plume of ash up to 10.4 km (34 000 feet) above sea level. It was Bogoslof's first major eruption since March 8, 2017.

Trace ashfall in the community of Nikolski after eruption of Bogoslof volcano

Trace ashfall in the community of Nikolski from the eruption of Bogoslof volcano on May 17, 2017. Photo courtesy of Lilly Stamm.

Geological summary

Bogoslof is the emergent summit of a submarine volcano that lies 40 km north of the main Aleutian arc. It rises 1500 m above the Bering Sea floor. Repeated construction and destruction of lava domes at different locations during historical time has greatly modified the appearance of this "Jack-in-the-Box" volcano and has introduced a confusing nomenclature applied during frequent visits of exploring expeditions.

The present triangular-shaped, 0.75 x 2 km island consists of remnants of lava domes emplaced from 1796 to 1992. Castle Rock (Old Bogoslof) is a steep-sided pinnacle that is a remnant of a spine from the 1796 eruption. Fire Island (New Bogoslof), a small island located about 600 m NW of Bogoslof Island, is a remnant of a lava dome that was formed in 1883. (GVP)

Featured image: Bogoslof from the NW. Fire Island in foreground. Bogoslof Island aerial recon opportunity courtesy of U.S. Coast Guard Air Station Kodiak and U.S.C.G Cutter Mellon. Photographer: Max Kaufman.


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