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Mass-Wasting
Movement of Large Amounts of Material Downhill under Gravity
Types of Mass Wasting
• Slow vs. Fast• Wet vs. Dry• Cohesive vs. Fragmented
Types of Mass Wasting
• Creep• Slow Landslide• Earthflow, Mudflow, Debris Flow• Avalanche• Rockfall• Slump• Complex Landslide
Factors in Mass Wasting
• Climate• Moisture• Steep Slopes• Weak Rocks• Existing Failure Surfaces
Soil Creep
Soil Creep
Soil Creep
Soil Creep, California
Creep, North Carolina
Colluvium, San Bernardino Mountains, California
Mystery or Soil Creep?
Four Years’ Mass-Wasting, Bosnia
Four Years’ Mass-Wasting, Bosnia
• 100*40/2 cm2 = 2000 cm2 (4 years)
• = 500 cm2 /year• Removed from 1 km
slope per year = 500 cm2 /100,000 cm= 1 cm/200 yr= 5000 cm (50 m)/m.y. = 50m /m.y.
• A 1-m (100 cm) soil mantle yields 500 cm2 /year, so movement = 500 cm2 /year/100 cm= 5 cm/year
Debris Flow, Utah
Landslide, Wyoming
Geological Disneyland, Utah
Landslide, Utah
Landslide, Wyoming
Landslide and Slope Control, Wyoming
Landslide, Wyoming
Bridge of the Gods, Washington
Bridge of the Gods, Washington
Gros Ventre Slide, Wyoming, 1925
Slide Lake, Wyoming
Gros Ventre Slide, Wyoming
Landslide, Pakistan, January 4,
2010
Landslide, Pakistan, January 4,
2010
Urban Planning, San Diego
Martian Landslide
Active Landslide on Mars
Active Landslide on Mars
Rockfalls, Yosemite, California
Rockfalls, Yosemite, California
Block Slide, Yosemite
Rockslide, Yosemite
Slumps? Baird Creek
Avalanche Chute, Colorado
Landslide, Mount Saint Helens
Aberfan, Wales
• October 21, 1966, a large waste pile from coal mining collapsed
• Village school was in the path of the slide• 144 people killed, 116 of them children• Weathering of coal mine waste liberates
sulfuric acid and weakens waste piles• Seepage beneath pile contributed
Coal Tip, England
Inquiry Board, 1967
• the Aberfan Disaster is a terrifying tale of bungling ineptitude by many men charged with tasks for which they were totally unfitted, of failure to heed clear warnings, and of total lack of direction from above. Not villains but decent men, led astray by foolishness or by ignorance or by both in combination, are responsible for what happened at Aberfan.
Sherman Glacier, Alaska, March 27, 1964
Sherman Glacier, Alaska,
March 27, 1964
Blackhawk Landslide, California
Saidmareh Landslide,
Iran
Landslide on Iapetus
Viaont, Italy, October 9, 1963
1800 people died.
Yungay, Peru, May 31, 1970
Yungay, Peru, May 31, 1970
Lituya Bay, Alaska, July 9, 1958
Lituya Bay, Before and
After
The Scour Line
The Highest Wave Ever Recorded
Dealing With Mass-Wasting• Proper Land Use – Stay out of Danger• Take warnings seriously• Structural Control– Retaining Structures– Drainage– Terraces
• Warning System• Accept the Risk and Responsibility• Abolish Insurance ?
