liquefaction

The process by which saturated, loose soil loses its strength during seismic shaking and behaves as a liquid — buildings sink, buried pipes and tanks float to the surface, and the ground erupts in sand boils. Liquefaction occurs when earthquake vibrations increase the water pressure between soil grains until the grains lose contact with each other and the soil collapses into a suspension. It transforms solid ground into quicksand in seconds. The devastation in Christchurch (2011) and parts of San Francisco (1906 and 1989) was caused less by the shaking itself than by the ground beneath the buildings ceasing to be ground.