Geography Glossary (Hazardous Environments) = Mass Movement

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Mass Movement

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Downhill movement of unconsolidated material (stores, rock, soil or regolith) in response to gravity

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Soil Creep

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the slowest of downhill movements, occurring on very gentle and well-vegetated slopes.
(material moves by less than 1 cm a year)

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Solifluction

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The slow movement or flow of water saturated soil and regolith downslope due to the pull of gravity often over a frozen lower layer of permafrost

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Landslides

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rapid downhill transfers of coherent slabs of dry, consolidated and unconsolidated material occurring from slope failure as a result of a weakening on the fault plane.

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Avalanches

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Rapid mass movements of snow, ice or rock on slopes usually greater than 22 degrees but less than 60 degrees; beyond which point it is unlikely that snow packs will build up

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Slab avalanche

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Most DESTRUCTIVE; weak layer of granulated snow loses cohesion with slab above causing top layer to slide down in a single slab

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Powder avalanche

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Very destructive;airborne dry snow due to a blast wave proceeding the snow creating a billowing cloud

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Loose-snow avalanche

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Not very destructive; occurs after fresh snowfall and starts from one point

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Wet avalanche

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Very destructive: rapid melting of snow (slushy flow)

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Rockfall

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most rapid type of mass movement, in which rocks ranging from large masses to small fragments are loosened from the face of a cliff.