The landslides are simply defined as the mass movement of rock, debris or earth down and have to include a broad range of motions whereby falling, sliding and flowing under the influence of gravity dislodges earth material. They often take place in conjunction with earthquakes, floods and volcanoes. The Himalayan Mountain, the north-east hill ranges and the Western Ghats and the Nilgiris experience considerable landslide activities of varying intensities. Also called landslip; Downward mass movement of earth or rock on unstable slope including many forms resulting from differences in rock structure, coherence of material involved, degree of slope, amount of included water, extent of natural or artificial undercutting at the base of slope, relative rate of movement and relative quantity of material involved. Many terms cover these variations: creep, earth flow, mudflow, solifluction and debris avalanche are related forms in which mass movement is by flowage. If shearing movement occurs on a surface on consolidated rock, the dislocated mass is a debris slide. Cliffs may become so steep through undercutting by rivers, glaciers or waves that masses of rocks will fall freely and constitute a rock-all type of landslide.
Causes of Landslides:
There are several factors which lead to the occurrence of landslides. Seismic activity, intensity of rainfall, steep slopes, rigidity of slopes, highly weathered rock layers, soil layers formed under gravity, poor drainage these all are natural factors that cause the landslides. Not only this there are many man-made factors also which contribute to the occurrence of landslides. These are land use pattern, non-engineered construction, mining and quarrying, non-engineered excavation and deforestation leading to soil erosion. Protection Measures:
Generally landslides happen where they have already occurred in the past, or in identifiable hazard locations. Following are the areas that are distinctly considered safe...
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