fails. Though water is often the key factor in slope failure, triggering an earthflow, there can also be dry granular flows made up of granular material. The speed also depends on the angle of slope as earthflows can happen on moderate or steep slopes. Because earthflows are usually water-dependent, they can take many years or just minutes to move a significant amount. An earthflow may affect as few as several square meters or up to several hectares in either time frame. Effects Earthflows can have sudden impacts on the amount of sediment that is deposited into a river system, which can have effects on the life in and around the river itself. They can also cause damage to roads and constructions built near the slope. One of the best mitigation techniques to avoid serious earthflow and landslide damage is properly draining the slope of water, especially in places of high levels of precipitation. Areas of risk The areas most at risk for earthflows are: Slopes that have been undercut or loaded with more sediment for human construction Slopes that have been undercut by rivers or stream beds Areas that receive heavy rainfall or snowmelt Hill slopes made up of clay, silt, or other fine-grained materials Areas with limited vegetation on hill slopes Areas with evidence of past earthflows See also Landslide mitigation References External links Slumgullion earthflow, USGS Bulletin 2130, a National Natural Landmark in Colorado, USA. New landslide video: a fascinating and huge Russian earthflow - American Geophysical Union, 17 April 2015 Geological hazards Soil mechanics