Liquefaction occurs under which soil conditions during shaking?

• A. Liquefaction occurs in dense, dry soils
• B. Occurs only in dry soils
• C. Only occurs in bedrock
• D. Liquefaction is loss of soil shear strength due to increased pore water pressure during shaking

Answer: (D)

Liquefaction happens when saturated, loose soils are shaken during an earthquake. The shaking increases pore water pressure in the voids between soil grains, and when this pressure rises enough, the effective stress that keeps the grains interlocked drops. With less shear strength, the soil can no longer support loads and behaves like a liquid, leading to ground failure and deformation. The statement describing liquefaction as the loss of soil shear strength due to increased pore water pressure during shaking captures this mechanism, which is why it’s the best description. Dense or dry soils don’t experience this pore pressure buildup, and bedrock isn’t typically susceptible because it isn’t a loose, saturated soil.