Atmospheric Pressure Modulates Granular Avalanche Dynamics

Landslides, debris flows, avalanches and related granular flow processes pose severe geological hazards in high-altitude regions and extraterrestrial terrains, where ambient atmospheric pressures are markedly reduced. Such low-pressure environments fundamentally alter gas–solid interactions, yet their influence on landslide dynamics remains poorly understood. This study investigated the effect of ambient pressure on geotechnical granular avalanche behavior using a custom-designed horizontal rotating drum apparatus that simulated pressure conditions ranging from 1 atm to 0.05 atm. Experiments employing uniform spherical particles and high-speed imaging captured key flow parameters, including repose angles, avalanche timing, velocity fields, and internal flow structures. The results demonstrated that lower pressure significantly reduced the critical initiation and deposition angles of granular slopes, indicating enhanced flow mobility and slope instability.