A debris flow is a fast-moving mass of loose mud, sand, soil, rock, and water that flows down a slope, typically triggered by heavy rainfall, volcanic activity, or rapid snowmelt. Debris flows are highly destructive and pose significant hazards in mountainous regions. They are important in the study of mass wasting, geomorphology, and natural hazards.
Reference: Iverson, R. M. (1997). “The Physics of Debris Flows.” Reviews of Geophysics, 35(3), 245-296.