Aludes

Aludes are rapid downslope movements of snow, rock, soil, or debris driven by gravity. The term is used in Spanish- and Portuguese-speaking contexts and can refer to avalanches (snow) or landslides (rock and soil) depending on material. They are a central topic in mass-wasting studies and are addressed in avalanche science and engineering geology.

Snow avalanches occur when a cohesive layer of snow detaches from a slope and slides down, often entraining more snow and debris. Rock and debris avalanches involve blocks of rock or soil that detach from cliffs or steep hillslopes, and may evolve into debris flows when water is present. Triggers include rapid warming, heavy snowfall, rain-on-snow events, earthquakes, and slope instability.

Risk factors include steep terrain, weak layers within snowpack, high moisture, seismic shaking, deforestation, and anthropogenic modifications of slopes. Aludes can threaten infrastructure, roads, railways, ski areas, and communities, and can occur with little warning.

Monitoring and mitigation rely on hazard assessment, weather and snowpack analysis, slope-stability modeling, and early-warning systems. Preventive measures include controlled avalanche release in high-consequence areas, snow fences and nets, drainage improvements, retaining structures, and targeted land-use planning.

Notable events include the 1970 Huascarán disaster in Peru, the 1999 Vargas tragedy in Venezuela, the 2014 Oso mudslide in Washington, United States, and the 2018 Montecito mudslides in California.