[1] Because of the dependency on water content for the velocity of the flow, it can take minutes or years for the materials to move down the slope.
As earthflows are usually water-dependent, the risk of one occurring is much higher in humid areas especially after a period of heavy rainfall or snowmelt.
[4] The high level of precipitation, which saturates the ground and adds water to the slope content, increases the pore-water pressure and reduces the shearing strength of the material.
As the slope becomes wet, the earthflow may start as a creep downslope due to the clay or silt having less friction.
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.