Skip to main content

All mass movements are landslides

Short answer

The correct relationship is that all landslides are mass movements, but not all mass movements are landslides. Mass movement includes falls, topples, flows, creep and spreads; landslides are only the subset that slide along a distinct slip surface.

Justify: "All mass movements are landslide but all landslides are not mass movement".

Note on the statement: the standard teaching is the other way round: all landslides are mass movements, but not all mass movements are landslides. Landslide is only one group within the larger family of mass movement, as shown below. The reasoning is as follows.

  • Mass movement is any downslope movement of soil, rock or debris under gravity. It includes falls, topples, slides, spreads, flows and creep (Varnes, 1978).
  • Landslide (in the strict sense) means sliding along a defined slip surface (rotational or translational slide). In popular and common usage "landslide" is used for nearly all slope movements.
  • Thus every landslide is a form of mass movement, because it is a gravity-driven downslope movement.
  • Some mass movements are not landslides: creep (very slow, no distinct slip surface), rock fall, topples, debris flow and mud flow (move like a fluid) and solifluction.
   MASS MOVEMENT
   +---------------------------------+
   | fall  topple  flow  creep spread|
   |        +------------+           |
   |        | LANDSLIDE  |           |
   |        | (slides)   |           |
   |        +------------+           |
   +---------------------------------+

So landslide is a subset of mass movement; the reverse is not true.

✓ Answer checked by Claude Opus 5.5 (high effort)

Related questions

All Engineering Geology I chapter 6 questions →