9: Mass Wasting
- Page ID
- 28273
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This chapter discusses the fundamental processes driving mass-wasting, types of mass wasting, examples, and lessons learned from famous mass-wasting events, how mass wasting can be predicted, and how people can be protected from this potential hazard. Mass wasting is the downhill movement of rock and soil material due to gravity. The term landslide is often used as a synonym for mass wasting, but mass wasting is a much broader term referring to all movement downslope.
- 9.1: Slope Strength
- Mass wasting occurs when a slope fails. A slope fails when it is too steep and unstable for existing materials and conditions. Slope stability is ultimately determined by two principal factors: the slope angle and the strength of the underlying material.
- 9.2: Mass-Wasting Triggers and Mitigation
- Mass-wasting events often have a trigger: something changes that causes a landslide to occur at a specific time. It could be rapid snowmelt, intense rainfall, earthquake shaking, volcanic eruption, storm waves, rapid-stream erosion, or human activities, such as grading a new road. Increased water content within the slope due to rapidly melting snow or an intense rainfall event is the most common mass-wasting trigger.
- 9.3: Landslide Classification and Identification
- Mass-wasting events are classified by type of movement and type of material. In addition, mass-wasting types often share common morphological features observed on the surface, such as the head scarp at the top of the failure—commonly seen as crescent shapes on a cliff face; uneven surfaces; accumulations of talus—loose rocky material falling from above; and toe (bottom) of the slope, which covers existing surface material.
- 9.4: Examples of Landslides
- This page contains various examples of landslides, including details such as causes, effects, and severity.