Liquefaction is a geological phenomenon that occurs when saturated soil loses its strength and stiffness due to applied stress, such as during an earthquake. This process transforms solid ground into a fluid-like state, causing buildings and structures to sink or tilt. This effect is most common in areas with loose, water-saturated sand or silt. Liquefaction can lead to significant damage during seismic events, making it a critical consideration in civil engineering and urban planning in earthquake-prone regions.