Essay On Landslides

A “landslide” is the mass movement of slope forming materials downslope and/or outward along the surface of separation by falling and/or flowing at a fast or slow rate, but under the influence of gravity. Slope forming materials include rocks, soils, artificial fills (disposal), or a combination of all these materials. Landslides can be sub-aerial and subaqueous, and different phenomena cause landslides, including intense or prolonged rainfall, earthquakes, rapid snow melting, volcanic activity, and multiple human actions. Landslides can involve flowing, sliding, toppling, or falling, and many landslides exhibit a combination of two or more types of movements, at the same time or during the lifetime of a landslide (Cruden and Varnes, 1996).

Likewise, susceptibility maps provide a better understanding of how landslide hazard and risk can be assessed. These maps also can lead to intelligent planning that will help in reducing losses of life and property (Evany and Rajashi, 2010).

2.2 Types of landslides

Landslides can involve flowing, sliding, toppling, or falling, and many landslides exhibit a combination of two or more types of movements, at the same time or during the lifetime of a landslide (Cruden and Varnes, 1996). However, there is no simple way to classify such movements. Classification of landslides depends on the composition and the texture of the material, the amount of water or air presence, and the steepness of the slope, and the velocity of the movement.

Table 2.1 shows a schematic landslide classification adopting the classification of Varnes (1978) and taking into account the modifications made by Cruden and Varnes (1996). Some integration has been made by using the definitions of Hutchinson (1988).

Table 2.1 Schematic landslide classification

(Source: Cruden and Varnes, 1996; modified after Varnes, 1978; Hutchinson