AVO reported that an increase in seismic and infrasound activity from Bogoslof was detected from stations on nearby islands starting at 2232 on 16 May, suggesting the beginning of an explosive eruption. The Aviation Color Code (ACC) was raised to Orange and the Volcano Alert Level (VAL) was raised to Watch. A pilot reported an ash plume rising as high as 10.4 km (34,000 ft) a.s.l., and the Worldwide Lightning Location Network detected lightning associated with the cloud. The ACC was raised to Red and the VAL was raised to Warning. The eruption lasted about 73 minutes.

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.

Source: US Geological Survey Alaska Volcano Observatory (AVO)