How does soil liquefaction occur?
Soil liquefaction is the temporary loss of strength in loose water-saturated sand and silt during strong shaking.
Formation process and geographic mechanism
Shaking drives grains toward tighter packing, but if pore water cannot escape quickly its pressure rises. Grain-to-grain contact falls and the soil may deform like a liquid. Sand boils, lateral spreading, settlement and uplift of buried structures can occur. Not every wet soil liquefies; grain size, density, groundwater and shaking duration all matter.
Spatial outcomes, measurement and management
Hazard maps combine deposit history, boreholes, groundwater and expected shaking. Mitigation may use densification, drainage, deep foundations or load redistribution. Liquefaction can occur far from the fault on alluvium and fill. Site-specific engineering study is required beyond regional maps.