New Geography in Action Junior Cycle Geography Avalanches
An avalanche is the rapid movement of snow and ice downslope when the weight of the snow is too much for the slope to hold.
An avalanche in a ski resort in the Italian Alps killed three skiers in March 2017. The skiers were skiing off-piste through fresh and unstable snow. Heavy snowfalls and strong winds probably caused the avalanche.
Controlling mass : Figure 6.22 The destructive power of an avalanche
movement Humans can try to control natural disasters caused by mass movement. These hazards can be reduced or prevented in the following ways.
• Vegetation such as trees and vines can be planted on slopes to stabilise them.
• Steps can be built into a mountainside to trap moving material. • Restricting overgrazing keeps vegetation cover and stops soil creep. • Controlled explosions in mountainous areas can be used to trigger small avalanches, making large, life-threatening avalanches less likely.
( Figure 6.24 Old tyres being used to prevent a landslide in Brazil
PORTFOLIO ACT VITY 6.2
Choose one type of mass movement listed above and research an example. Go to page 26 of your Portfolio and create your own Case Study.
(i) List five factors that influence mass movement. (ii) Name two types of mass movement. (iii) What evidence might prove that soil creep is occurring? (iv) Give an example of a mudflow that you have studied and explain why it happened. (v) Explain three things humans can do to try to stop mass movement from occurring.
(vi) Explain two ways that humans cause mass movement with reference to examples you have studied.
/ I can list and explain the factors that affect mass movement. / I can name and explain examples of slow and fast mass movement. / I understand the impact of mass movement on people. / I understand the methods used to control mass movement.
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: Figure 6.23 Throwing explosives to control avalanches in Squaw Valley, California
