These buildings in Japan toppled when the soil underwent liquefaction. Buildings can even sink into the ground if soil liquefaction occurs. When the water and soil are mixed, the ground becomes very soft and acts similar to quicksand. If liquefaction occurs under a building, it may start to lean, tip over, or sink several feet. The ground firms up again after the earthquake has past and the water has settled back down to its usual place deeper in the ground.
Liquefaction is a hazard in areas that have groundwater near the surface and sandy soil.
Buildings can also be damaged by strong surface waves making the ground heave and lurch. Any buildings in the path of these surface waves can lean or tip over from all the movement. The ground shaking may also cause landslides, mudslides, and avalanches on steeper hills or mountains, all of which can damage buildings and hurt people. This road, which crosses the San Andreas fault, was cut in half by the 1906 earthquake. The third main hazard is flooding .