LANDSLIDES

LANDSLIDES
Landslides cause severe loss of life, injury, damage to property, destruction of communication networks and loss of precious soil and land. Although the occurrence of land~lides is declining all over the world due to greater scientific understanding and public awareness, in many areas the mounting pressure of population at the base of slopes, canyons and unstable borders of plateau have led to an increase in dangers due to landslides. Landslides are universal phenomena, but more than being 'natural haz­ards', they are induced by human activity.

M.A Carson and M.J. Kirkby (1972) divided hill slopes into (i) weathering-limited slopes and (ii) transport-limited slopes. In the former case, rock disintegrates in situ, whereas, in the latter case, slopes are covered by thick soil or disintegrated rock materials, known as regolith. Due to the presence of regolith, transport-limited slopes experience frequent landslides.

The term, 'landslide' encompasses falling, toppling, sliding, flowing and subsidence of soil and rock materials und~r the strong influence of gravity and other f\lctors. Some geomorphologists thus prefer to use the term mass movement instead of landslides. The resultant landforms produced by mass movements are termed mass wasting. Mass movement occurs when the slope gradient exceeds its threshold angle of stability.