mudslide

Mudslide is a rapid mass-wasting event in which saturated soil, rock, and organic material move downslope as a slurry. The term is often used interchangeably with mudflow or debris flow, though scientists distinguish mudflows (water-rich with fine material) from debris flows (which contain larger rocks and debris). Mudslides occur on destabilized slopes and are typically triggered by heavy rainfall, rapid snowmelt, earthquakes, or volcanic activity that introduces water and weakens cohesion.

During a mudslide, the material flows en masse, sometimes beginning as a relatively slow creep that accelerates to dangerous speeds. Flow may be confined to existing channels or spread out over flat ground, potentially burying anything in its path. The composition, water content, slope angle, soil and rock types, and the presence of vegetation or human structures influence flow behavior and runout distance.

Impacts include loss of life, property damage, road and utility disruption, and environmental disturbance. Mudslides are more common in mountainous terrain, areas with steep slopes, loose sediment, and high rainfall. They can be triggered by wildfires that remove root cohesion and increase runoff.

Prevention and mitigation focus on land-use planning, slope stabilization, drainage management, revegetation, and early warning systems. Post-event response involves assessment of slope stability, debris removal, and restoration of roads and utilities.