Mudflow (Lahar)
A mudflow is a swiftly moving mixtures of mud and water. The mixture might move as slowly as a few centimeters per year or as rapidly as hundreds of kilometers per hour. Mudflows can be triggered by earthquakes or similar vibrations and are common in volcanic regions where the hear from a volcano melts snow on nearby slopes that have fine sediment and little vegetation. The meltwater fills the spaces between the small particles of sediment and allows them to slide readily over one another and move downslope.
Mudflows are also common in sloped, semiarid regions that experience intense, short-lived rainstorms. In such areas, periods of drought and forest fires leave the slopes with little protective vegetation. When heavy rains eventually fall in these areas, they can cause massive, destructive mudflows because there is little vegetation to anchor the soil.
A type of mudflow is a lahar which occurs after a volcanic eruption.Often a lahar results when a snow-topped volcanic mountain erupts and melts the snow on top of a mountain. The melted snow mixes with ash and flows downslope.
Mudflows are also common in sloped, semiarid regions that experience intense, short-lived rainstorms. In such areas, periods of drought and forest fires leave the slopes with little protective vegetation. When heavy rains eventually fall in these areas, they can cause massive, destructive mudflows because there is little vegetation to anchor the soil.
A type of mudflow is a lahar which occurs after a volcanic eruption.Often a lahar results when a snow-topped volcanic mountain erupts and melts the snow on top of a mountain. The melted snow mixes with ash and flows downslope.
In the 1980's, Mount St. Helens erupted with a mixture of mud and water flowing out of it.