What are the hazards associated with mass movement and slope failure? 

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  • Created by: Jake199
  • Created on: 24-05-14 17:19
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  • What are the hazards associated with mass movement and slope failure?
    • Causes
      • Rainfall
      • Rock type
      • Snow melt
      • Lack of vegetation
      • Gradient
      • Dip of strata
      • Water table
      • Weathering and erosion
      • Temperature
      • Human activity
      • Load
      • Quakes
      • Earthmovement
      • Volcanic activity
    • Types
      • Flow
        • Top layers of rock slide quicker than bottom layers
        • Fast, wet
        • Mud flow
      • Slide
        • All layers move at same speed
        • Fast, dry
        • Rockfall
      • Heave
        • Freezing and expanding and then melting dislodges particles
        • Solifluction
        • Slow, wet
    • Vajont Dam, 9th October 1963
      • The Dam
        • 262m tall
        • 27m thick at base
        • Constructed for HEP purposes
        • Upstream geology wasn't taken into account during construction
      • Pre-disaster
        • A geologist was tasked to do a survey of the area, he found an ancient landslide 100m away from the dam
        • Feb 1960- Reservoir filled to 170m deep
        • Farmers discovered a 171m crack on slopes above the reservoir, widening by 3cm per day
      • Causes
        • Chief engineers planned to slowly lower landslide into reservoir by changing level in the reservoir
        • Scale models showed a max wave height of 20m
        • Landslide accelerated as it got near to falling, even after the water level was dropped
        • Slide moving at 30cm per day close to the end
        • Usually high rainfall
      • Impacts
        • Landslip from Monte Toc caused wave 200m high
        • 2000 people killed
        • 260,000,000 cubic meters of earth fell into reservoir in 45 seconds
        • Longarone, Pirago, Rivalta, Villanova and Faè were all destroyed
        • The Piave valley was turned into a mudflat
      • Human causes
        • Model used did not account for 1cm thick bands of clay in Monte Toc
        • One of 3 boreholes dug gave readings to suggest a clay layer.  These results were assumed to be faulty and ignored
        • Slide was though to take minimum of 1min
    • Izu-Oshima -Japan
      • Landslide influenced by typhoon Wipha
      • 16th October 2013
      • Heavy rainfall from typhoon (824mm total)
      • Slope fall of unstable volcanic ash
      • 27 deaths, 22 missing
      • Searching
      • 283 homes destroyed
      • Evacuation

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