Landslides and Rock Movements: Types, Causes, and Regional Differences

Landslides

Relatively rapid movements of dry materials influenced by slope steepness and rock discontinuities.

Slump

Slipping of rock debris units with backward rotation over the slope.

Debris slide

Rapid rolling or sliding of earth debris without backward rotation.

Debris fall

Free fall of earth debris from a vertical or overhanging face.

Rockslide

Sliding of individual rock masses down bedding, joint, or fault surfaces.

Rock sliding behavior on steep slopes

It is very fast and destructive.

Reasons for frequent debris avalanches and landslides in the Himalayas

• Tectonically active

• made up of sedimentary rocks

• unconsolidated and semi-consolidated deposits

• very steep slopes.

Differences between Nilgiris and Western Ghats vs Himalayas

• Tectonically stable

• made up of very hard rocks

• less frequent landslides and debris avalanches.

Factors contributing to landslides in the Nilgiris and Western Ghats

• Steep slopes with vertical cliffs

• mechanical weathering from temperature changes

• heavy rainfall over short periods.

Rock composition in the Himalayas

Sedimentary rocks, unconsolidated deposits, semi-consolidated deposits.

Common geological feature in the Western Ghats

Almost vertical cliffs, escarpments.