Mass Movements + Resultant Hazards

Question 1

What is mass movement?

Answer 1

• large scale movement of materials on a hill slope, caused when the stress exerted exceeds the internal strength of the hill slope, causing instability
• will always be downhill due to force of gravity
• can occur over a range of timescales + also depend on the moisture in the hill slope material

Question 2

Causes of mass movement

Answer 2

• caused by slope instability which is either due to an increase in external stress on the slope, or decrease in the internal strength of the slope
• slope may become too saturated, causing material to give way e.g. mudslides
• weathering + erosion can weaken the internal strength until it can no longer bear the load on the slope e.g. freeze thaw processes can cause large rocks to fall (rock fall)
• seismic waves may trigger rockslides, landslides, mudflows etc.
• human activity can add stress to the slope or remove its strength e.g. deforestation removes tree roots which causes soil to be less cohesive + therefore risk of mass movement

Question 3

Primary + secondary environmental hazards

Answer 3

• primary = ecosystems damaged through destroyed slop, wildlife killed
• secondary = debris + mud can block waterways + cause other environmental issues

Question 4

Primary + secondary economic hazards

Answer 4

• primary = businesses + industries destroyed or disrupted
• secondary = jobs lost, money needed to rebuild + clean up, investment into slope stability

Question 5

Primary + secondary social hazards

Answer 5

• primary = people killed/injured, homes destroyed, roads blocked, infrastructure destroyed
• secondary = power outages, gas leaks caused by broken infrastructure, homelessness

Question 6

Primary + secondary political hazards

Answer 6

• primary = govt buildings + other important areas destroyed or disrupted
• secondary = conflicts or disagreements concerning govt response