Scenario-based volcano slope stability hazard analysis: Case study of Augustine volcano, Alaska

Several active volcanoes worldwide have slope failures where large parts of their structure collapse, generating destructive mass flows called volcanic debris avalanches. These flows travel long distances and sometimes have cascading hazards like eruptions and tsunamis. Subsequently, the volcano's structure rebuilds with new material ejected during eruptions. Augustine Volcano in Alaska has a history of these cycles of slope failures and reconstruction. This study aims to understand the volcano's current slope stability hazard considering factors such as inherent topographic structure and several conditions that can occur in active volcanic environments (e.g., changes in the volcano's structure and strength of rocks, earthquakes, and pore pressure conditions). In all scenarios assessed in this study, the volcano's slopes remain stable, with the relatively least stable slope occurring in the southwestern parts of the volcano. Overall, the steep landscape and structure underneath the volcano are vital in determining where relatively less stable areas exist. Factors such as weakening of the rocks, pressure from water in cracks and voids in the rock, and ground shaking due to earthquakes can make such slopes susceptible to sliding.