lu 38 mass movement

• what is mass movement?

  geomorphic process by which materials, including sand, soil, weathered and rock move downslope, under the influence of gravity
• how are materials held?

  materials held on the slope by friction in a state of dynamic equilibrium
• when is a slope stable?

  if the shear strength of the material is equal to or exceeds the shear stress acting on the slope
• what is shear stress?


  force exerted by the weight of the material under the influence of gravity acting in the downslope direction
• what is shear strength?

  • measure of the resistance of earth materials to be removed downhill
  • refers to internal cohesiveness of material on slope and how susceptible the material is to shearing
• when does a slope become unstable?

  shear stress> shear strength causing due to fall in shear strength or increase in shear stress -> mass movement
• how does mass movement vary?

  a result of slope instability, varies in scale, rate and type of movement
• what are the types of mass movement?

  • heave (creep)
  • flow
  • slide
  • fall