Page 108 - Navy Journal 219

Navy Journal 2019

c. Removal of vegetation cover and deforestation, etc.
d. Farming activities on slopes involve removal of vegetation cover usually
followed by terracing. Burring of vegetation to clear the land is a normal
practice in hilly areas adopted by farms this makes the land more prone to
landslides. Similarly there are several factors which may cause landslide
such as:
1) Intense rainfall or deposition of snow will raise the ground water
tables; decrease the soil strength and increase weight of associated
material.

2) Rapid melting of snow adds water to soil mass on slopes makes it
prone to land slide.
3) Erosion caused by continuous runoff over a slope can bring about
instability of the soil mass.

4) The removal of support of a soil mass by flow of water in rivers, ware
action etc.

5) Weathering and decomposition of rocks.
6) Ground vibrations created during earthquakes.

Types of landslides:
There are several of landslides depending on the topography of the area such as : 4

a. Creep: Creep is imperceptibly slow down slope movement of earth or
regolith. In the creep affected areas utility poles, fence posts and
gravestones etc appear tilted or deformed on the surfaces.
b. Debris fall: When rock as well as overlying sediments and vegetation is
free falling, it is known as debris fall.
c. Debris flow: Down slope movement of collapsed, unconsolidated
material typically along a stream channel.

d. Rock fall: Free falling of detached bodies of bedrock (boulders) from a
cliff or steep slope.
e. Rock slide: Rockslide is sudden down slope movement of detached
masses of bedrock.

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