landslide

A landslide is the downslope movement of rock, soil, and other earth materials under the influence of gravity. Landslides encompass a range of processes, including rockfalls, rockslides, rotational slides, translational slides, debris flows, and earth or debris avalanches. Movements can be slow and creeping or rapid and destructive, with varying volumes and travel distances.

Causes and triggers include natural factors such as slope steepness, geological structure, weathering, and hydrological conditions that raise pore-water pressure. Heavy or prolonged rainfall, rapid snowmelt, earthquakes, and volcanic activity can initiate failures. Human activities such as deforestation, mining, road construction, and improper drainage increase instability by altering loads, removing support, or concentrating seepage.

Common types include rockfalls, where blocks detach from cliff faces; translational and rotational slides, where a mass moves along a surface; debris flows and mudflows, which are fast, water-saturated movements of mixed material; and debris avalanches, which are rapid, turbulent failures.

Impacts from landslides include property damage, road and utility disruption, burial of infrastructure, injuries, and loss of life. They can also block rivers, create floods or tsunamis in reservoirs, or trigger secondary hazards. Risk is assessed by mapping past events, monitoring ground movement, and evaluating slope materials and rainfall response.

Mitigation and management strategies focus on reducing triggers and stabilizing slopes. Approaches include improving drainage, installing retaining structures and anchors, reinforcing slopes with vegetation, and restricting development on high-risk areas. Early warning systems may use rainfall thresholds, deformation monitoring, and surface infiltration measurements to alert communities.