Influences on Mass Movement

Mass Movement

Mass movement is the downhill movement of soil, rock, regolith, or debris under the influence of gravity. It is one of the most important processes of denudation and can occur slowly (soil creep) or very rapidly (landslides and mudflows). Mass movement plays a key role in shaping landscapes, particularly in upland and coastal regions, and its speed and scale depend on a range of physical and human factors

Causes of Mass Movement

1. Slope Gradient

The steepness of the slope is one of the most important factors influencing mass movement. On steep slopes, gravity acts more forcefully, which makes it easier for material to move downslope. Gentle slopes are more stable, while steep or over-steepened slopes are far more prone to landslides and avalanches.

2. Water Content

The presence of water within soil and regolith increases the risk of movement. Water adds weight to the material and reduces friction between particles, making them more likely to slide. When soil becomes fully saturated, it can lead to mudflows or landslides, especially during heavy rainfall or snowmelt.

3. Human Activity

Human actions can greatly increase the risk of slope failure. Construction, mining, quarrying, and deforestation can destabilise slopes by removing vegetation and altering the structure of the land. Roads, buildings, and artificial drainage systems can also change natural water flow, often increasing the risk of landslides and soil erosion.

4. Vegetation Cover

Vegetation plays a key role in stabilising slopes. Plant roots help to bind soil and regolith together, reducing the likelihood of downslope movement. When vegetation is removed through farming, burning, or deforestation, slopes become less stable and more vulnerable to mass movement events.

5. Regolith Depth and Type

Regolith is the loose, unconsolidated material that lies on top of solid rock. The deeper and more unstable the regolith, the more likely it is to move downslope. Loose material such as broken rock, soil, and ash is particularly prone to slipping or flowing, especially when it is saturated with water.