Landslides can result from a variety of both natural and human causes. Factors that influence landslides include slope angle, climate, weathering, water content of the land, vegetation, geology and slope stability.
Natural causes of landslides include earthquakes, volcanic eruptions, the undercutting of cliffs and banks by water erosion due to tidal waves, and the elevation of pore water pressure by prolonged rainfall and seepage. All of these natural causes are influencing factors of landslides. Together, they can create a small or large landslide that affects the geology and geography of an area.
The human causes of landslides include removal of vegetation, interference with the natural drainage of the land, leaking water or sewage pipes, overloading slopes, mining and quarrying activities, vibrations from heavy traffic, construction or mine blasting, and the excavation or displacement of rocks. Together, human and natural factors can create a landslide. Landslides can be very small and only affect the general ecology of an area, or they can be catastrophic, affecting entire communities by destroying homes and community infrastructures, impacting water and land resources, and even causing fatalities. In the United States, landslides account for approximately 15 deaths every year. Worldwide, the death toll reaches the thousands.