\nLet’s evaluate each statement regarding landslides:
\n1. Landslides can be sudden and catastrophic events, occurring without much warning, especially when triggered by intense rainfall or seismic activity. The term “sporadic” also fits, as they are not constant but happen at irregular intervals or locations. While some landslides (like creep) are slow, major destructive landslides are often sudden. This statement is generally correct in describing a common characteristic of significant landslides.
\n2. Landslides occur when the force pulling material downslope (primarily gravity) exceeds the shear strength of the slope material. This failure is more likely to occur on steeper slopes where the gravitational force parallel to the slope is greater. Gentle slopes are less susceptible to mass movements like landslides, although they can experience very slow forms of movement like creep. Thus, stating that they result when the slope is gentle is incorrect; they are more likely on steeper slopes.
\n3. Mining activities, such as excavation, blasting, removal of vegetation, changes in drainage patterns, and placement of waste piles, can destabilize slopes and significantly increase the risk of landslides. This is a recognised anthropogenic cause of landslides. This statement is correct.
\nBased on the analysis, statements 1 and 3 are correct, while statement 2 is incorrect.
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