Landslides/Mass Movements – Types and Classifications


Landslides occur in many manifestations and are usually classified according to the type of material involved and the mode of downslope movement.  The material can range from loose earth to blocks of solid rock to tree trunks.  Modes of transport include freefall, bouncing, sliding down a slip surface, flowing in a slurry, or moving particle-by-particle. Landslides are usually triggered by heavy rainfall, rapid snow melt, stream incision, or earthquakes, while certain man-made changes to the land, such as slope modification or drainage alteration, can greatly increase the likelihood of landslides. The following are some of the more important types of landslides or mass movements:[1]


Rockfalls entail large blocks of bedrock breaking off a cliff face and tumbling downslope.

Generally an individual rockfall includes one to only a few rocks, and sizes from gravel to boulders (~2 inches to 5 feet dia.). 

Rockfall is the fastest type of landslide and is common in mountainous areas near cliffs of broken, faulted, or jointed bedrock, on steep slopes of rocky soils, or where cliffy bedrock ledges are undercut by erosion or human activity.[2]



Rockslides occur when a detached section of bedrock moves down an inclined surface, frequently along a bedding plane.





Earthslide or Landslide[5]

Earthslides involve masses of soil moving down a slip face, usually the top of the bedrock.



Creep is the slow, continuous, imperceptible downslope movement of soil and rock particles.



Slump or Rotational Landslide[7]

Slumps, or rotational landslides, result from the rotation of a cohesive unit of soil or rock down a slip surface, leaving a curved scarp.


Debris Flow[8]

Debris flows, also known as mudslides, develop on steep slopes as a result of heavy rainfall or rapid snow melt that saturates the soil, which under the extra weight and lubrication breaks loose and becomes a slurry that takes everything with it, including large trees and houses. Channeled debris flows can reach speeds approaching a hundred miles an hour and strike without warning.

Mudslides develop when water rapidly accumulates in the ground and results in a surge of water-saturated rock, earth, and debris. Mudslides usually start on steep slopes and can be activated by natural disasters. Areas where wildfires or human modification of the land have destroyed vegetation on slopes are particularly vulnerable to landslides during and after heavy rains.

Avalanche is a term reserved mainly for landslides composed of snow and ice. However, avalanches can also be composed of ice and rocks.

On 7 April 2012, an ice-rock avalanche hit a Pakistani military base near the Siachen Glacier region, killing 138 soldiers and civilian contractors under 25m of debris and ice. It is the worst avalanche that the Pakistani military has experienced in the area.



  1. Virginia Department of Mines, Minerals and Energy – Landslides:
  2. Colorado Department of Natural Resources – Colorado Geological Survey – Rockfall in Colorado:
  3. Image Source: [Accessed: January 14, 2014]
  4. Image Source: [Accessed: January 14, 2014]
  5. Image Source: [Accessed: January 14, 2014]
  6. Image Source: [Accessed: January 14, 2014]
  7. Image Source: [Accessed: January 14, 2014]
  8. Image Source: [Accessed: January 14, 2014]