How Landslides Work

On 26 August 2026 a mass of rock and glacier ice fell from Langtang Lirung in the Himalaya and swept down valleys in Nepal and Tibet; scientists from World Weather Attribution called it a compound crisis of warming, thawing ice and unstable rock. This film explains the established science of landslides behind that news: the balance of gravity against friction and cohesion on a slope, the factor of safety, why water in the ground is the commonest trigger, the main kinds of mass movement from rockfalls to debris flows and creep, the triggers from rain and earthquakes to volcanoes and people, landslide dams and the floods they release, the Vajont disaster of 1963, and how places like Hong Kong learned to watch their slopes.

When the mountain lets go

How landslides work, what sets them off, and how we watch for them.

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