- travelpaLv 79 年前最佳解答
A mudslide is the most rapid (up to 80 km/h, or 50 mph) and fluid type of downhill mass wasting. It is a rapid movement of a large mass of mud formed from loose soil and water. Similar terms are mudflow, mud stream, debris flow in high mountains), jökulhlaup, and lahar.these terms show a broad variety in water content from loamy mud, to almost liquid, and even steam、in material such as wet soil, sandy sediments and/or silt, dirt, rock, debris, volcanic ash, small plants, and even trees and in length, total mass, and velocity.
Some broad mudflows are rather viscous and therefore slow at some meters/sec. Others begin very quick and continue like an avalanche. If "large enough" they can devastate villages and countrysides. They are composed of at least 50% silt and clay-sized materials and up to 30% water. The point where a muddy material begins to flow, depends on its grain and the water content. Fine grainy material or soil has a smaller friction angle than a coarse sediment or a debris flow, but falling rock pieces can trigger a material flow, too.