Mass movements occur based on several factors and causes differ depending on different regions. Mass movements are affected by the slope gradient, climate, rock type and structure, physical setting and geological and geomorphological outlines (Advances in Geosciences).
Mass-wasting events come in many shapes, sizes and speeds. Typically, the steeper the angle of a slope, the faster will be the down-slope movement of rock and sediment. Also, water can play a significant role in mass wasting, sometimes acting as the key component to a mass-wasting event, or serving as a lubricant within a mass of sediment and rock, enabling it to travel faster and further than it would otherwise.
One type of mass wasting can evolve into another type of mass wasting as the body of sediment/rock moves down a slope. This can make it difficult to classify a single event as being one type of mass wasting or another (Department of Geological Sciences, California State University).
A simple classification of the different types of mass wasting can be:
- Falls (rock fall and rock avalanche)
- Slides (rock slide, landslide and slump)
- Flows (rock avalanche, debris flow, earth flow and creep).