Definition:

Mass movement, Landslides and Avalanches

Mass movement denotes the collective term for all gravitational or downslope movement of weathered rock debris. Gravity plays the sole important role in transporting materials mostly down the slop and other transporting medium such as water, wind, waves; glaciers are not involved in the process but they may aggravate or trigger the condition of mass wasting by adding additional weight or by generating seepage pressure or lubrication.  Weakening internal cohesionis the most common cause of mass movements. Landslides denote the perceptible downslope movement of rock, debris or earth. Landslides are caused by a large volume and combination od rock, debris, soil and water, moving downslope under the influence of gravity and water. Avalanches refer to the fall or very rapid down slope movement of snow as a result of structural weakness (Such as reduction of stability by the existence of solid bad rock that acts as a slide planebelow the weak material) or gravity. Avalanches tend to recur in the same places. Methods of stabilizing hill slopes may help to reduce the impact and vulnerability of the avalanche related hazards. Ski resorts are particularly prone to avalanches.

Movement category	Types of materials			Speed of onset
	Bed rock	Coarse	Fine	High (slope angle or gradient plays the major role) Low (water plays an important role)
Fall	Rock fall	Debris fall	Earth fall
Topple	Rock topple	Debris topple	Earth topple
Slide	Rock slide	Debris slide	Earth slide
Spread	Rock spread	Debris spread	Earth spread
Flow	Rock flow	Debris flow	Earth flow
Creep	Rock creep	Talus creep	Soil creep/Terracettes