1. What is Mass Wasting? Rapid types Slow types

2. Selected Landslides DATE LOCATIONTYPE DEATHS 1556 China Landslides-earthquake triggered 1,000,000 1806 Switzerland Rock slide 457 1920 China (Kansu) Landslides-earthquake triggered 200,000 1963 Italy (Vaiont Dam) Landslide-subsequent flood 2,000 1966 U. K. (Wales) Debris flow-collapse of mining-waste 144 1970 Peru (Mt. Huascaran) Rockfall & debris avalanche 25,000  earthquake triggered 1972 USA (WV) Landslide & mudflow-collapse of 400 mining-waste 1979 Indonesia (Sumatra) Landslide 80 1980 USA (Washington) Avalanche and mudflow 63 1989 Tadzhikistan Mudflow-earthquake triggered 274 1996 Brazil (Recife) Mudflow 49 1999 Venezuela Mudflow 10,000

3. Why Should You Study Mass Wasting?

4. Shear strength of slope mat.  Angle of repose  Gravity  3 Factors Influencing Mass Wasting:

5. Gravitational forces exceed resisting forces  Dynamic equilibrium

6. 5 Causes of Mass Wasting:

7. Slope Angle  {Steep slope = _________ stability} Oversteepening slopes:

8. Highway excavations remove support often resulting in slope failure. Pan-American Highway, Mexico

9. Weathering & Climate Weathering decomposes & disintegrates rock, ____________shear strength & ____ mass wasting. Mass movement ______________ in deeply weathered material. (prevalent in tropics) Deserts  Lack of vegetation (_______________) & cloudbursts frequently produce rapid mass wasting (i.e., mudflows).

10. Water Content Slope stability  How does water affect slope stability?

11. Vegetation Golden State Freeway,1987

12. Overloading … Under natural conditions, a slope’s load is supported by friction of grain-to-grain contacts w/in slope material. Overloading __________________________________ w/in slope material. Dec. shear strength 

15. Triggering Mechanisms Most common: Most common: In highly unstable slopes: La Conchita, Ca.1995

16. Types of Mass Movements Falls Rockfalls Slides Slump Rockslides Flows Mudflow Debris flow Earthflow Creep Complex movements

17. Rockfalls: (_________________________) Slopes are sometimes covered w/ wire mesh to reduce the hazard. Hawaii

18. Slides  Slumps  Rock slides  AB

19. Flows  Earthflows Baraga, Michigan

20. Mudflows Debris flows Estes Park, Colorado

21. Creep Effects: Marathon, TX

22. Complex movements {combo of several types} Debris avalanches  1970  killed 25,000 in Yungay & Ranrahirca Peru, 1970

23. Geologic investigation identifies Analysis of a material’s properties (composition, susceptibility to weathering, cohesiveness, & ability to transmit fluids) ( Info is used to assess risks before construction begins.) Recognize & Minimize Effects of Mass Movement

24. Dewatering Ways to dewater: Perforated drainpipes inserted horizontally into slopes are used to reduce the amt of water w/in slope material. Pt. Fermin, CA

25. Cut-and-Fill method How Can We Minimize Mass Movement?

26. Benching How Can We Minimize Mass Movement?

27. Retaining walls  Most successful when: How Can We Minimize Mass Movement?

28. Rock bolts How Can We Minimize Mass Movement? Brisbane, Aust..