Landslide

Sweeping trees, homes and people in a flow of earth and debris, landslides can thunder down mountains and hillsides, often with little or no warning to those in danger. They can occur in many places around the world, costing billions of dollars and causing numerous fatalities and injuries each year. They can occur on a spectrum from very suddenly to slowly, and may be triggered by both natural and human-induced changes in the environment, most commonly slope loading or excavation, land-use change, such as deforestation, and hydrological changes, such as increased seepage. These factors when combined with the forces of gravity can cause instability.