Mudflow
Topic: Geomorphic Processes: Weathering, Mass Movement, Erosion and Soil Formation · NCERT: Class 11, Ch 5 "Geomorphic Processes"
Meaning
A mudflow is a fast flow of soil and weathered debris that is thickly mixed with water. It happens after heavy rain on slopes with thin or no vegetation. The loose material becomes soaked, turns into a thick slurry and flows down, usually following stream channels. It can bury roads, fields and houses in its path. A mudflow on the slopes of a volcano is called a lahar. In a lahar, volcanic ash and debris mix with rainwater or melted snow and ice.
Example
In 1985 an eruption of the Nevado del Ruiz volcano in Colombia melted ice on its summit. The resulting lahar raced down river valleys and buried the town of Armero, killing most of its people.
Don't confuse with
- Debris avalanche: much faster. It carries coarser debris down steep, narrow tracks, more like a snow avalanche.
- Earth flow: soaked clay or silty material moving down low-angle slopes or hillsides. It is usually slower and is not confined to stream channels.
Related concepts
- Mass movement
- Activating causes of mass movement
- Soil creep
- Solifluction
- Debris avalanche
- Slump
- Rockslide
- Rock fall