Landslide is the downslope movement of soil, rock and organic materials under the effects of gravity, which occurs when the gravitational driving forces exceed the frictional resistance of the material resisting on the slope. Landslides could be terrestrial or submarine (Varnes, 1978).
Landslides can be triggered by geological and physical causes such as glacier or snow melts, heavy rains and water pressure, earthquakes, volcanic eruptions and overly steep slopes. Landslides can also be triggered by human action, the most common being building on unstable slopes. Submarine landslides, or massive slides and rock falls hitting the sea can also cause tsunamis.
Landslides can reach speeds of over 50 km/h and can bury, crush or carry away people, objects and buildings. Landslides cannot be predicted but warning systems measuring rainfall levels can provide warning to people living in landslide-prone areas.