Pavlof is probably the most consistently active volcano in the Aleutian arc, with nearly 40 eruptions since 1790.
Eruptions are typically Strombolian.
A 1928 expedition to Pavlof was directed by Dr. Thomas Jaggar, founder of the Hawaiian Volcano Observatory. Pavlof Sister is less active, with a single eruption from 1762-1786. Slightly dissected cone of Pavlof Sister. Photograph by U.S. Army Air Force, 1942.