a weakness point in a slope causes material above it to crash down at high speeds. land can be destabilised by heavy rainfall or earthquakes and can trigger tsunamis or block waterways to create lakes
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2
what are mudflows
clay rich soil that is not bound by plant matter becomes saturated and flows. they behave like a liquid so often follow river valleys. lahars are a type of mudflow
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3
what is soil creep
shear stress is not strong enough to cause a landslide or rockfall so land slowly inches forward over years or centuries
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4
what are the three types of soil creep (3)
continuous, seasonal according to soil moisture, progressive in the build up to another mass movement
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5
what is a slump
when a layer of a slope slips downwards. they form in sediment rich soils that behave as a coherent body
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6
what is the role of gravity in mass movements
it is the initial force that pulls earth down or props it up
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7
what is the role of pore pressure in mass movements
it destabilises slopes when it increases such as in saturated soil
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8
what is the role of slope angle in mass movements
steeper slopes are more likely to trigger landslides
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9
what is shear strength
how much the earth resists being moved
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10
what is shear stress
the combination of forces encouraging earth to move
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11
what are the two ways mass movements can be classified (2)
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