Augustine Volcano (Sugpiaq: Utakineq;[3] Dena'ina: Chu Nula) is a stratovolcano in Alaska consisting of a central complex of summit lava domes and flows surrounded by an apron of pyroclastic, lahar, avalanche, and ash deposits.

[4] It forms Augustine Island in southwestern Cook Inlet in the Kenai Peninsula Borough of southcentral coastal Alaska, 174 miles (280 km) southwest of Anchorage.

The irregular coastline of Augustine Island is due to the repeated catastrophic collapse of the summit dome, forming debris avalanches down the flanks and into Cook Inlet.

The surface of such deposits is hummocky, a field of steep conical mounds and intervening depressions with many meters of local relief.

The hummocky deposits on Augustine's lower flanks resemble both topographically and lithologically those of the great landslide or debris avalanche that initiated the spectacular May 18, 1980, eruption of Mount St. Helens.

The precursory phase began as a slow, steady increase in microearthquake[notes 1] activity beneath the volcano on April 30, 2005.

Several ash columns were generated, each 9 km (6 mi) above sea level; these plumes were steadily influenced to the north and northeast of the volcano.

On January 16, a new lava dome was observed on the summit; and the next day another explosive eruption sent ash 13 km (8 mi) into the atmosphere.