Landslides:
- A landslide is the movement of rock, debris or earth down a slope. Landslides are known also as landslips, slumps or slope failure.
- Reasons: They result from the failure of the materials which make up the hill slope and are driven by the force of gravity. Landslides can be triggered by natural causes or by human activity.
Types of Landslide Movement:
- Fall: This is generally characterised by a rapid to extremely rapid rate of movement with the descent of material characterised by a freefall period.
- Topple: This is characterised by the tilting of rock without collapse, or by the forward rotation of rocks about a pivot point. Topples have a rapid rate of movement and failure is generally influenced by the fracture pattern in rock. Material descends by abrupt falling, sliding, bouncing and rolling.
- Flow: This is the most destructive and turbulent form of landslide. Flows have a high-water content which causes the slope material to lose cohesion, turning it into a slurry. They are channelled by the landscape and move rapidly.
- Spread: This phenomenon is characterised by the gradual lateral displacement of large volumes of distributed material over very gentle or flat terrain.
