Quicksand is a colloid hydrogel consisting of fine granular material (such as sand or silt), clay, and water formed in saturated loose sand when the sand is suddenly agitated. When water in the sand cannot escape it creates a liquefied soil that cannot support weight. Quicksand can form in standing or upwards flowing water. The saturated sediment may appear solid until a change in pressure or shock initiates liquefaction causing the sand to form a suspension and lose strength. Objects in liquefied sand sink to the level at which the weight of the object is equal to the weight of the displaced soil/water mix and the submerged object floats due to its buoyancy. Liquefaction is a special case of quicksand where an earthquake increases the pore pressure of shallow groundwater. The saturated liquefied soil loses strength, causing buildings or other objects on that surface to sink.
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