AVO reported that during 6-12 September nothing significant was observed in mostly cloudy satellite images of Bogoslof, and no activity was detected in seismic or infrasound data. The 8 September report noted that the crater lake had been bisected by a narrow isthmus of land. Elevated surface temperatures were identified in one satellite image during 10-11 September. The Aviation Color Code remained at Orange and the Volcano Alert Level remained at Watch.

Geological Summary. Bogoslof is the emergent summit of a submarine volcano that lies 40 km N of the main Aleutian arc. It rises 1,500 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 by 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. The small Fire Island (New Bogoslof), about 600 m NW of Bogoslof Island, is a remnant of a lava dome formed in 1883.

Source: US Geological Survey Alaska Volcano Observatory (AVO)