Mudflow, in the simplest terms, can be defined as the rapid flow of mud that has mixed with a sufficient quantity of water so as to liquefy the entire mass and cause the flow. The water for mudflow is typically provided by rain or snow melt. Mudflows are also (generally) called mudslides; however, the mudslide does not include as much water as a mudflow, although mudflows typically originate as a result of mudslides.
Mudflows typically occur in mountainous regions where long dry seasons are followed by heavy rains. The water is provided by the rains and the flow is assisted by the slope. Sometimes volcanic eruptions also cause the flow of material (debris, pyroclastic matter, etc.). Such mudflow is known as Lahar and may receive water due to the melting of snow as a result of a volcanic eruption.
Mudflows cause extensive damage to property and land. Areas with steep slopes or where slopes have been altered for road construction or where vegetation has been destroyed (either by forest fires or human intervention) are more prone to mudflows.