Mass wasting refers to the downhill movement of material under gravity's influence, affected by factors such as slope stability, angle of repose, and water saturation. It can occur in various forms like rock slides and slumps, often triggered by events such as earthquakes or heavy rain. Control measures include improving drainage, reducing slope steepness, and using retaining walls for support.

1. Processes of Mass WastingJanet KochEDU 290PowerPoint Presentation

2. DefinitionMass wasting is the down-slope movement of material under direct influence of gravity

3. Water influences the effects of mass wasting but gravity is the most important factorDetermining Factors of Mass WastingSlope StabilityGravityFriction

4. Angle of Repose

5. Type of Material (Rock, soil, sediment)

6. Water saturation (increases slope failure) How Does it Happen?RockSlide componentStick componentShear stress vs. shear strength

7. When Gravity WinsWhen the force of gravity exceeds the friction of the slope, material begins to move

8. Shear strength resists movement, if gravity is too strong the object loses frictionAngle of ReposeThe steepness of a slope is an important factorSteeper the slope  increase in the amount of gravity pulling on the objectThe angle of repose is the steepest angle a slope can maintain without collapseAround 25-40 degrees

9. Weathering and ClimateWeathering: wind and water erosion weakens surfaces

10. Weathering decomposes material and reduces the strength of the slope

11. Loose materials are most susceptible as they are not stableTriggering Events Events that encourage mass wasting:EarthquakesSnowmeltHeavy rainstormsWhy?

12. VegetationIncreases slope stability! Absorb water from rainfall and roots stabilize within soil

13. Criteria for Mass WastingType of material…Type of movement…Rate of movement…Rock, debris, soil, mudFall, slide, slump, flow, creepFast, slow, not visible

14. FallsVery rapid movement, talus formation, often triggered by earthquakes.

15. SlumpMovement along a curved surface, caused by steepening of the slope

16. FlowSlow to rapid movement but often appears to have a plastic movement (Debris-flow vs. Mudflow)

17. SolifluctionCommon in areas of permafrost, very slow movement when frozen surface melts in summer