Which of the following statements in respect of landslides are correct? 1. These occur only on gentle slopes during rain. 2. They generally occur in clay-rich soil. 3. Earthquakes trigger landslides. Select the correct answer using the code given below.

Landslides are complex mass movements influenced by geological and environmental factors. Statement 1 is incorrect because landslides primarily occur on steep slopes, such as cliffs or mountainous regions, rather than only on gentle slopes [3]. While rainfall is a major trigger, the gravitational force required for sudden collapse typically necessitates a significant gradient [3]. Statement 2 is correct as soil composition, particularly clay-rich horizons containing minerals like smectite, significantly increases susceptibility by promoting water stagnation and reducing shear strength. Statement 3 is correct because earthquakes are a primary natural trigger for landslides, especially in young folded mountains like the Himalayas, where seismic vibrations loosen rock and soil masses [3]. Therefore, while rainfall and earthquakes are common triggers, the requirement for steep terrain makes the first statement false, leaving statements 2 and 3 as the correct descriptors.

Sources

1. [3] Environment and Ecology, Majid Hussain (Access publishing 3rd ed.) > Chapter 8: Natural Hazards and Disaster Management > Causes of Landslides > p. 39
2. [1] Geography of India ,Majid Husain, (McGrawHill 9th ed.) > Chapter 17: Contemporary Issues > Landslides (Landslips) > p. 4