Landslides Fact file

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  • Created by: jameelach
  • Created on: 30-09-16 12:45
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LANDSLIDES
A landslide is a mass movement of material, e.g. rock, earth or debris, down the slope of a hill or
cliff. They can happen suddenly or move slowly over long periods of time.
Causes:
Landslides occur when the stability of the slope changes from a stable to an unstable condition. A
change in the stability of a slope can be caused by a number of factors, acting together or alone.
Natural causes:
Erosion of the toe of a slope by rivers or ocean waves
Weakening of a slope through saturation by snow melting, glaciers melting, or heavy rain
Earthquakes adding loads to an unstable slope
Volcanic eruptions
Human Causes:
Deforestation, cultivation and construction, which destabilize the already fragile slopes.
Vibrations from machinery or traffic
Removal of deeprooted vegetation in shallow soils, that binds colluvium to bedrock
Construction, agricultural or forestry activities (logging), which change the amount of
water which infiltrates the soil.
Are landslides becoming an increasing threat?
Yes, landslides are becoming an increasing threat due to human activity.
Tree felling, construction, mining and quarrying, combined with heavy rainfall, have increased
the fragility of slopes.
Regions under threat
Of all the world's landslides, 30% occur in the Himalaya. Most South Asian countries are
witnessing an increasing trend in landslides in recent years and scientists say extreme rainfall
patterns, seismicity, and uncontrolled human activities are to blame.
There has been a rise particularly in northern parts of India, Nepal, Pakistan, Afghanistan and
some areas of Bangladesh.
Of the total landslides that happened across the globe in 2009, nearly 60% was in South Asia
where around 280 people died because of the disaster that year.
Also, in December 2012 there were 75 UK landslides, compared with a typical annual average of
60.

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