1. UVM Geohazards 1 LANDSLIDES VS. MUDFLOWS MUDFLOW LANDSLIDE

2. UVM Geohazards 2 What is a Landslide?

3. UVM Geohazards 3 Slide Venuzuala, Coast Road

4. UVM Geohazards 4 Three major controls... Where do Landslides Occur?

5. UVM Geohazards 5 WHAT CAUSES LANDSLIDES? STEEP SLOPES AND WATER. WHY?

6. UVM Geohazards 6 Why do landslides occur? Strength of rock/soil exceeded DRIVING force RESISTING force DRIVING force RESISTING force >>

7. UVM Geohazards 7 FORCE BALANCE GRAVITY FRICTION AND COHESION DRIVING VERSUS RESISTING

8. UVM Geohazards 8 Simple Physics……vectors  DRIVING force is gravity,  RESISTING force is soil/rock strength/friction  Steep slopes give greater Driving Force

9. UVM Geohazards 9 WHY STEEP SLOPES ? STEEP SLOPES INCREASE DRIVING FORCE, DECREASE STRENGTH Yungay, Peru

10. UVM Geohazards 10 GRAVITY FRICTION AND COHESION NORMAL FORCE GREATER THE NORMAL FORCE THE GREATER THE RESISTING FORCE What is normal anyhow?

11. UVM Geohazards 11 What does slope have to do with normal forces????? LENGTH OF VECTOR = MAGNITUDE Can demo dry TAKE HOME MESSAGE: Steep slopes reduce normal force and thus resistance to sliding

12. UVM Geohazards 12 WHY WATER ? WATER DECREASES STRENGTH BY LOWERING NORMAL FORCE -- “FLOATING”

13. UVM Geohazards 13 SUBTRACTING VECTORS FORCE BALANCE TIPS WET NORMAL FORCE BOUYANCY FORCE IF DRY

14. UVM Geohazards 14 WHAT CAUSES MUDFLOWS? WATER, LOOSE SEDIMENT, STEEP SLOPES San Rafael,CA

15. UVM Geohazards 15 HOW DO MUDFLOWS WORK?  Intimate mixture of sediment and water  OFTEN start from landslides  One phase flow  Move under gravity force  Have a yield strength -- plastic behavior  Stop when they get too thin or slope lessens -- DRIVING vs. RESISTING FORCES

16. UVM Geohazards 16 Three phases of a mud/debris flow.. Bouldery snout Mud and rock middle Watery tail

17. UVM Geohazards 17 MUD AND DEBRIS FLOWS LEAVE DIAGNOSTIC CLUES  Bouldery snouts -- frozen on low slope  Marginal levees -- too thin to keep flowing, bouldery  Unsorted sediments -- not enough water to sort material snout levee v

18. UVM Geohazards 18 Bouldery Snouts Sierra Nevada, Lone Pine, Owens Valley

19. UVM Geohazards 19 Marginal levees Sierra Nevada, Lone Pine, Owens Valley RV for scale

20. UVM Geohazards 20 Unsorted sediments

21. UVM Geohazards 21 WHERE ARE MUDFLOWS MOST LIKELY TO STRIKE? ANY WHERE WITH STEEP SLOPES, VERY HEAVY RAIN, AND LOOSE SEDIMENT... THIS INCLUDES DESERTS, THE ARCTIC, AND THE TROPICS.

22. UVM Geohazards 22 DESERT EXAMPLE, SIERRA NEVADA, CALIFORNIA

23. UVM Geohazards 23 ARCTIC EXAMPLE. CANADA MELVILLE ISALND

24. UVM Geohazards 24 WHAT SETTINGS EXACERBATE MUDFLOW HAZARDS?

25. UVM Geohazards 25 Valleys NEAR VOLCANOES are risky places to be

26. UVM Geohazards 26 WHAT ARE MUDFLOW DANGERS? Erosion then deposition

27. UVM Geohazards 27 INFRASTRUCTURE DISRUPTION VERDUGO HILLS CEMETARY, Glendale California Apartments, Venezuela

28. UVM Geohazards 28 BURIAL LOS ANGELES

29. UVM Geohazards 29 Debris Delivery

30. UVM Geohazards 30 USGS Debris Flow Video