Mass Movements

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Mass Movements

• downward movement of loose sediments weathered
  rock resulting from the force of GRAVITY

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Triggers of Mass Movements

• 1. Water
• Heavy rain
• Rapid snow melt
• Causes ground to become saturated therefore,
  loose and vulnerable

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• 2. Oversteepened Slopes
• Loose material is stable until a certain angle is
  reached then its too steep
• Usually around 200 400

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• 3. Removal of vegetation
• roots bind the soil together and make it stable
• Example Menton, France
• Farmers replaced olive trees (have deep roots)
  with carnations (more profitable, shallow roots)
• Slopes were less stable
• Landslide occurred and killed 11 people

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• 4. Earthquakes
• Also, aftershocks can dislodge material
• Can cause more damage than the quake itself

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How to classify

• What kind of material moved
• How it moved
• How fast it moved

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Slide - Flow - Fall

• slide moves a block of earth
• flow mixes particles WITHIN moving mass
• fall free fall of earth material

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Creep - SLOW, steady, downhill flow
Description maybe a few millimeters or
centimeters a year SURFACE ONLY!
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Mudflow

• Fast moving flows of mud and water thick fluid
• Can be triggered by earthquakes
• Volcanic areas may provide enough heat to melt
  snow on the mountain and cause sliding
• Usually in dry climates that experience quick and
  intense rainstorms - surface becomes saturated
  and slides

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Mudflow
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Landslides

• Some landslides get up to 125 mph
• This form of m.m. causes almost 2 billion in
  damage several deaths per year in the US alone.
• Usually in areas with steeper slopes

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Landslides
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Not looking good
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Slump

• If the material rotates and slides along a curved
  surface
• Usually doesnt travel fast or far

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scarp
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Rock Falls

• Rock fragments fall freely through the air
• Common at high elevations, in steep road cuts,
  and on rocky shorelines
• Talus the pile at the bottom

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Avalanches

• Landslides in the mountains with thick snows
• There are over 10,000 avalanches in the mountains
  in the western US every year

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Danger! Danger!

• Living on steep terrain
• Deforestation
• Location location location - pick wisely where to
  build - consider the possible paths of debris

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