liquefaction
1. The sudden, large decrease of shearing resistance of a cohesionless soil caused by a collapse of the soil structure, produced by shock or small shear strains, associated with a sudden but temporary increase of pore water pressures.
2. The process of transforming a soil from a solid state to a liquid state, usually as a result of increased pore pressure and reduced shearing resistance. For example, an action in which a soil deposit (e.g., loose sand) loses its shear resistance temporarily and takes on the character of a liquid; such action, for example, may occur during an earthquake.
McGraw-Hill Dictionary of Architecture and Construction. Copyright © 2003 by McGraw-Hill Companies, Inc.