Mass Movement

2. 9.0 Mass Movement

3. 9.1 Mass Movement Mass movement is the movement of loose material down a slope under the influence of gravity The loose material is made up of soil, rocks and mud This loose material is known as regolith

4. 9.1 Mass Movement Factors That Influence Mass Movement Slope or Gradient Vegetation The steeper the gradient, the faster the loose material can move down the slope. Roots of plants and trees keep soil together and more stable. This can help to prevent mass movement. Water Human Activity Water makes the regolith heavier, causing it to move faster down the slope. Humans can speed up mass movement by making upland areas unstable. For example, by creating roads or quarries in hillsides.

5. 9.2 Types of Mass Movement Mass Movement Mass Movement Bog burst Gentle to steep slope; may be rapid movement Soil creep Gentle slope; very slow movement Mudflow Gentle to steep slope; rapid movement Landslide Very steep slope; rapid movement

6. 9.2 Types of Mass Movement Soil Creep The slowest type of mass movement and it occurs on gentle slopes.

7. 9.2 Types of Mass Movement Mudflow Mudflows occur when the soil and regolith become saturated with water, usually after heavy rainfall. They mix together to form mud, which then moves rapidly downslope. Mudflows are the fastest type of mass movement, with speeds of up to 100 km per hour. Mudslide damage to house in Wisconsin

8. 9.3 Types of Mass Movement Bog Burst Bog bursts can take place in these areas after long periods of heavy rainfall. If rain water cannot drain or soak away, peat can become saturated with water. Peat can then flow downslope and cause great damage over a large area. b A bog burst Attribution: Richard Webb

9. 9.3 Types of Mass Movement Landslide A landslide is the very rapid movement of regolith down a very steep slope. A landslide occurs when the slope becomes unstable. This can be caused by road-building, quarrying, earthquakes or sea erosion. A landslide A landslide

10. Video: Landslide Warning System