What is a landslide?

A landslide is defined by Cruden (1991) for the Working Party on World Landslide Inventory as a movement of a mass of rock, earth or debris down a slope. Landslides are divided into the following types of movement:

Fall

Rock fall

Falls are landslides that involve the collapse of material from a cliff or steep slope. Falls usually involve a mixture of free fall through the air, bouncing or rolling. A fall type landslide results in the collection of rock or debris near the base of a slope.

Topple

Topple

Topple failures involve the forward rotation and movement of a mass of rock, earth or debris out of a slope. This failure is noted to occur around an axis or point at or near the base of the block. A topple often results in the formation of debris or a debris cone at the base of the slope.

Slide — rotational, translational

Rotational

A slide type landslide is a down-slope movement of material that occurs along a distinctive surface. If the surface is straight then it is termed translational or planar. If this surface is curved the slide is called a rotational.

Flow

Flow

Flows are landslides that involve the movement of material down a slope in the form of a fluid. Flows often leave behind a distinctive upside-down funnel shaped deposit where the landslide material has stopped moving.

Landslides in more detail