EAS205 Chapter 8: Causes of Mass Movements
16 Mar 2016
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Mass movement/wasting: caused by gravity tugging downward on every mass of material. Landslide: rapid mass movement (causes great damage, a lot of property and lives lost) Shearing stress: causes parts of an object to slide past each other across a plane, also downslope pull leading to mass movement. Shear strength: ability to resist being torn apart along a plane by shearing stress. [when shearing stress is bigger than frictional resistance and shear strength, sliding occurs] [*anything that increases mass, for example saturating soil with water, increases slide risks] [*the steeper the slope, the greater the shearing stress] It is the max slope angle at which material is stable. Smooth/rounded material support only very low angle slopes. Rough/sticky irregular particles can be piled more steeply. [coarse fragments can maintain steeper slope angle than fine ones] [slopes may be steepened to unstable angles by natural erosion by water or ice]
