definition and causes of mass movement

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Global issues (environmental issues) earth hazards
Earth hazards: mass movement
Mass movement: downhill movement of rock/soil under the influence of
gravity
Causes of mass movement
Geological
Rock strength: more resistant or less resistant e.g. granite or sandstone
Rock porosity: percentage of pore space in rocks. The more porous the
more water that is held. This makes it heavier so it is more likely to move.
Rock structure: folding or faulting rocks have weak areas making them more
likely to move
Slope angle/angle of rest: the higher the angle the higher the influence of
gravity so the higher chance the rock has of moving.
Climate
Precipitation regime: amount/ intensity of rainfall over time. Saturated
ground leads to heavier ground leading to collapse.
Water table/Groundwater level: high water table lubricates soil increasing
chances of flow.
Rate/type of weathering/ erosion: chemical/biological/physical weathering
Temperature: higher temperature range leads to weathering types such as
freeze thaw which weakens rock.
Vegetation coverage: binds soil together and intercepts rainfall, low
vegetation leads to mass movement due to a lack of strength in the soil and
more wetness.
Human activity
Mining/tourism/farming: can all weaken the land and lead to mass
movement. Mining can cause mass movement due to controlled explosions
and tunnelling, tourism can cause mass movement due to erosion of footpaths
and farming can cause mass movement due to run off from field increasing
erosion and weathering.

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