Chapter 8 Summary
Mass movements occur when the shearing stress acting on rocks or soil exceeds the shear strength of the material to resist it. Gravity provides the main component of shearing stress. The basic susceptibility of a slope to failure is determined by a combination of factors, including geology (nature and strength of materials), geometry (slope steepness), and moisture content. Sudden failure usually also involves a triggering mechanism, such as vibration from an earthquake, addition of moisture, steepening of slopes (naturally or through human activities), or removal of stabilizing vegetation. Landslide hazards may be reduced by such procedures as modifying slope geometry, reducing the weight acting on the slope, planting vegetation, or dewatering the rocks or soil. Damage and loss of life can also be limited by restricting or imposing controls on development in areas at risk, and where adequate data are available, through landslide warning systems.
