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
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
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
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.
Viaont, Italy, October 9, 1963 1800 people died.