What do we call the phenomenon of the collapse of unstable hillsides?

The phenomenon of the collapse of unstable hillsides is referred to as landslides. A landslide occurs when soil, rock, or debris moves down a slope under the influence of gravity. This movement can happen suddenly, often triggered by factors such as heavy rainfall, earthquake activity, or human activities that destabilize the slope.

Landslides can vary in size and speed, ranging from small rockfalls to massive movements that can devastate landscapes and infrastructure. Understanding this process is crucial in urban planning and development, especially in areas prone to such geological activities, as it helps mitigate risks to communities and preserve safety.

Other terms relate to different processes; for instance, slips may refer to smaller movements on a slope but do not encompass the broader and often more destructive implications of landslides. Floods describe water overflow typically caused by excessive rain, while erosion refers to the gradual wearing away of land surfaces without the dramatic collapse associated with landslides. Each of these terms captures different natural phenomena that can affect urban environments but does not specifically describe the sudden movement associated with unstable hillsides.