1. Mass Wasting

2. What is Mass Wasting? The downslope movement of slope material. Gravity is the key to mass wasting. Landslides are mass wasting.

3. Colluvium The term “colluvium” describes the angular pieces of rock that are moved by mass wasting [contrasting with “alluvium” or water moved rock.]

4. Weathering, then Detachment Solid rock must first weather. Then, the weathered rock must detach.

5. Lots of ways to organize processes that influence people 1.Creep 2.Rock Fall 3. Topple 4. Rotational Slump 5. Translational Slide (Block Glide) 6. Rock slide 7. Flows

6. Key is gravity

7. Order Present 1. Creep 2. Rock Fall 3. Topple 4. Rotational Slump 5. Translational Slide ( & Block Glide) 6. Rock slide 7. Flows

8. Soil Creep

9. In the wetting or freezing soil zone

10. Very Slow, mm/yr to cm/yr

12. rock fall

15. rock fall produces talus, often Talus Cones at Angle of Repose

17. Detachment and Gravity Fall not limited to rocks

18. How do you discuss this?

19. topple

20. Top falls, but bottom stays

21. Rotational Slump

23. Laguna Beach

27. Translational Slide

28. Translational Slide at Torrey Pines

29. Snow Avalanches Often Start As Translational Slides, that then flow

30. Often Occur in Same Places: Avalanche Chutes

31. 3 Strategies: Avoid, Engineer, Ignore

32. Engineer

33. Mostly Ignore

34. Rock Slide

35. Gros Ventre Rock Slide

38. Madison Canyon Slide

40. crushed dolomite stayed on top

41. Army Corp Prevent Disaster

42. Attabad Pakistan (Hunza River)

43. Steep Jointing - Set Stage

44. Spillway Creation & Widening: Race to Avoid Bursting the Dam

45. More added, keep widening

46. Marcus Rockslide in Scottsdale

48. Virtual Field Trip to Marcus Slide

49. Can occur elsewhere there is steep jointing, and weathered granite on slick, fresh joint faces

50. Flows, mudflow (few rocks)

52. Flows, debris flow (more rocks mixed with mud)

53. KOA Campground

55. Slide Mountain, Nevada

57. La Canada, California

58. Debris flows can occur in Phoenix

59. Earth flow, slower & thicker

60. Why? What Causes Mass Wasting? GRAVITY!! Steeper slopes = more likely

61. Steep Slopes One Reason why California experiences problem Az Can Too

62. Undercutting steepens the slope, wave action in this case

64. Undercutting steepens the slope, stream action in this case

66. Undercutting can be from earlier mass wasting

67. Human activities dangerous around steep slopes: Telegraph Hill 2007

68. Or from construction

69. Oversteepening from from new fault scarp

70. Hard caprock creates situation where weaker material erodes away until slope is so steep that caprock erodes

71. Whole idea of a Mesa relies on undercutting by erosion of weaker rock

72. Another Reason: Weak Material

73. Palos Verdes: Weak & Undercut

74. Best solution: land use that can be disturbed, like a golf course

75. Another Reason: Weak Material

76. Weakness can be a joint (fracture) in a strong rock

77. Weakness can be a joint (fracture): but orientation is important

78. Lots of water

79. Lots of water (rain, snowmelt)

80. Exert pore pressure

81. Reaches thixotropic behavior (solid, then liquify into plastic)

82. Get some corn starch …

83. Result: Liquifaction

84. Liquifaction leads to flows (debris flows, mudflows, earthflows)

86. Entire valley filled with mud

87. Russian Roulette

88. Alaska Landslide from 1980 Quake

89. Earth Shaking (earthquakes, or even bouncing large trucks)

90. 1970 Earthquake

91. disaster

92. Earthquake & Moisture: Las Colinas, El Salvador Disaster (2001)

93. Earthquake in Wet Winter: Future California Disaster

94. Blackhawk Landslide Example

95. Shaking can be from volcanic eruption, case of Mt Shasta

96. Big Az Concern: Fire & Hydrophobic soils

98. Cave Creek Complex Fire

99. Forest Wildfires: Idaho

100. Los Alamos Fire

101. Online Video/Animations Mass Wasting and Landslide Animations http://serc.carleton.edu/NAGTWorkshops/visualization/http://serc.carleton.edu/NAGTWorkshops/visualization/colle ctions/mass_wasting.html

102. Net Effect: Slow, Steady Inevitable