The word "landslide" is actually a general term for several kinds of slope
movements and they can be classified in several kinds of ways. They can be
classified by rate of movement (from several centimeters a year
a.k.a. creep...to many miles per hour), type of material (bedrock,
unconsolidated sediment, or organic debris) and nature of movement
(slide, slump, flow or fall). (Landslides in British Columbia) The
following diagrams are courtesy of the Landslides in British Columbia
page.
Click here to see a slump landslide in action!
Debris Flows
Debris flows are fast moving flows of mud and rock and they are the most
numerous and dangerous of all the landslides. Debris flows generally
occur during periods of intense rainfall or snow melt. They usually begin
on the top of steep hills with saturated soil as They are so dangerous
because they move quickly, destroy without warning, and obliterate
everything in their path. They can destroy homes, knock down trees,
and obstruct streets and roadways. Their average speed is 10 miles an
hour, but some have been known to exceed 35 miles per hour! Their
viscosity ranges from thick, rocky mud to water mud. The following are
several types of debris flows. (Talking About Disasters)
