Liquefied materials behave like a liquid, meaning the effects of the earthquake are reduced, as sheer stress does not travel through liquids.
Chapter 3: Earthquake Activity
When loose sediment becomes oversaturated with water, the individual grains lose their grain-to-grain contact as the water gets between them (Fig. 7.10). This occurs at three main times:
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after periods of heavy rainfall; when there is rapid melting of snow or ice;
strong vibrations from high magnitude earthquakes can force water upwards from several metres underground. If the solid surface of the ground cracks, saturated sand/soil will rise to the surface.
an earthquake Before particles Sand an earthquake During an earthquake After
Water EXAM LINK (HL)
Surface Processes (30 marks)
Describe and explain the factors governing the operation of any one mass movement process that you have studied.
2017, Q3B EXAM LINK (OL) Marking Scheme:
Mass movement identified = 2 marks
Examination = 14 SRPs × 2 marks
Landform Development (40 marks)
Describe and explain any two processes of mass movement.
2018, Q2B
Marking Scheme: 2 processes × 20 marks each. For each process: Process stated = 2 marks
Description/explanation = 6 SRPs × 3 marks
Water-saturated sediment: water fills pore space between grains. Friction between grains holds sediment together.
Fig. 7.10 Liquefaction. Liquefaction: water completely
surrounds all grains and eliminates all grain-to- grain contact. Sediment flows like a fluid.
Unequal settlement
due to soil liquefaction after an earthquake.
CHECK YOUR LEARNING
1. Explain two natural factors that can cause landslides. 2. Describe two human factors that can cause landslides. 3. List two factors that can trigger an avalanche. 4. Outline two ways humans attempt to manage avalanches. 5. Using your study of rocks, what type of rock is most commonly associated with rockfalls?
