100*40/2 cm 2 = 2000 cm 2 (4 years) = 500 cm 2 /year Removed from 1 km slope per year = 500 cm 2 /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 cm 2 /year, so movement = 500 cm 2 /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.
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 ?