UPSC Mains 2016 GS1 Q14: Himalayan Landslides — Causes & Mitigation

A landslide is the downslope movement of rock, debris, or soil under gravity. It ranges from slow creep to sudden, fast-moving slides.

The Himalaya is a geologically young fold mountain range. Its rocks are weak, fractured, and still rising, which makes slopes inherently unstable.

The range sits on active thrust faults like the Main Boundary Thrust and Main Central Thrust. Frequent earthquakes shake already-weak slopes loose.

The Himalaya has very steep slopes and high relative relief. Greater slope angle means greater gravitational stress on loose material.

Heavy monsoon rain saturates soil and raises pore-water pressure inside slopes. This is the single most common landslide trigger in the region.

Snowmelt in higher reaches adds extra water to already-saturated slopes. A glacial lake outburst flood can also trigger large slides downstream.

Tree roots bind soil and slow water infiltration. Clearing forest cover for farming or fuelwood removes this natural anchor.

Roads and buildings cut into hillsides for tourism and infrastructure undercut natural slope support. This is a major human-driven cause in hill towns.

Rivers erode the base of valley-side slopes during high flow. Removing this toe support can destabilize the slope above it.

The Geological Survey of India prepares Landslide Susceptibility Zonation maps. These identify high-risk stretches before construction is permitted there.

Retaining walls, terracing, and proper slope drainage reduce landslide risk on already-built slopes. Afforestation on bare slopes adds long-term stability.

Enforcing building codes and relocating high-risk settlements reduce exposure. Early-warning systems using rainfall thresholds give residents time to evacuate.