Velocity of travel (rate of movement)Extremely slow (less than 0.3 meter or 1 foot every 5 ears) to moderately fast (1.5 meters or 5 feet per month) to rapid.Triggering mechanismIntense and (or) sustained rainfall or rapid snowmelt can lead to the saturation of slopes and increased groundwater levels within the mass; rapid drops in river level following floods, ground-water levels rising as a result of filling reservoirs, or the rise in level of streams, lakes, and rivers, which cause erosion at the base of slopes. These types of slides can also be earthquake-induced.