A landslide is the failure and movement of a mass of rock, sediment, soil, or artificial fill under the influence of gravity. Landslides range in volume from tens of cubic meters to tens of cubic kilometers, and they move at rates ranging from millimeters per year to more than 100 meters per second. Landslides are primarily associated with mountainous terrain but also occur in areas of low relief, for example, in roadway and building excavations, mine-waste piles, and river bluffs.