Global Volcanism Program | Image GVP-05348
The primary 1931 eruption site is nestled against the NW wall of Aniakchak caldera. This 600-m-wide crater was the site of intermittent explosions of pumice-lithic tephra over the course of several weeks in May and June 1931. During the final phases of the eruption, a small lava flow formed in the bottom of the crater. The fissure eruption cut through Vent Mountain and across the caldera floor to the western caldera wall.
Photo by Game McGimsey, 1992 (Alaska Volcano Observatory, U.S. Geological Survey).