AVO reported that during 12-18 July no significant activity at Bogoslof was observed in cloudy or mostly cloudy satellite images; weakly elevated surface temperatures were noted on 12 and 16 July. In addition no activity was detected in seismic, infrasound, or lightning data. 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 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)