This view from the NW shows the steaming summit of Augustine in 1986 reflected in a shallow lagoon separating the main island of Augustine from West Island. Twentieth-century eruptions have included explosive activity with pyroclastic flows and lava dome extrusion. Photo by Lee Siebert, 1986 (Smithsonian Institution).
Augustine volcano, rising above Kamishak Bay in the southern Cook Inlet about 290 km SW of Anchorage, is the most active volcano of the eastern Aleutian arc. It consists of a complex of overlapping summit lava domes surrounded by an apron of volcaniclastic debris that descends to the sea on all sides. Few lava flows are exposed; the flanks consist mainly of debris-avalanche and pyroclastic-flow deposits formed by repeated collapse and regrowth of the volcano's summit.