mass wasting

• Mass wasting is the downslope movement of rock, regolith, and soil

  under the direct influence of gravity.
• Landslide is a term used by many people to describe sudden event in which large quantities of rock and soil

  plunge down steep slopes.
• Slope angle is a component of gravity perpendicular to the slope which helps hold the object in place
• Water has the ability to change the angle of repose
• CONTROLLING FACTORS IN MASS WASTING

  Slope Angle

  Water

  Presence of troublesome earth materials

  Weak materials and structures
• Slope Failures. Sudden failure of the slope resulting in transport of

  debris downhill by rolling, sliding, and slumping.
• Slump. Type of slide wherein downward rotation of rock or regolith occurs along a curved surface.
• Rockfall & Debris fall. Free falling of dislodged bodies of rocks or a mixture of rock, regolith, and soil in the case of debris fall.
• Rockslide & Debris slide. Involves the rapid displacement of masses of rock or debris along an inclined surface.
• Sediment Flow. Materials flow downhill mixed with water or air;

  Slurry and granular flows are further subdivided based on velocity at which flow occurs.
• Solifluction. Common wherever water cannot escape from the saturated surface layer by infiltrating to deeper levels; creates distinctive features: lobes and sheets of debris
• Debris Flow. Results from heavy rains causing soil and regolith to be saturated with water; commonly have a tongue-like front.
• Mud Flow. Highly fluid, high velocity mixture of sediment and water; can start as a muddy stream that becomes a moving dam of mud and rubble; differs with debris flow in that fine- grained material is predominant.
• Creep. Slowest type of mass wasting requiring several years of gradual movement to have a pronounced effect on the slope.
• Grain Flow. Forms in dry or nearly dry granular sediment with air filling the pore spaces such as sand flowing down the dune face.
• Subaqueous mass wasting. occurs on slopes in the ocean basins
• Turbidity Current. sediment moves as a turbulent cloud
• Shocks and vibrations. Earthquakes and minor shocks such as those produced by heavy trucks on the road, man-made explosions.
• Slope modification. Creating artificially steep slope so it is no longer at the angle of repose.
• Undercutting. Due to streams eroding banks or surf action undercutting a slope.
• Changes in Hydrologic characteristics. Heavy rains lead to water-saturated regolith increasing its weight, reducing grain to grain contact and angle of repose.
• Changes in slope strength. Weathering weakens the rock and leads to slope failure.
• Volcanic eruptions. Produce shocks; may produce large volumes of water from melting of glaciers during eruption, resulting to mudflows and debris flows.
• Debris Avalanche. Very high velocity flows involving huge masses of falling rocks and debris that break up and pulverize on impact; often occurs in very steep mountain ranges.