Definition of Ground Liquefaction

Earthquakes dramatically decrease the stability of saturated cohesionless soil. The soil becomes a viscous fluid creating problems with any structure from bridges to buildings and to buried pipes and tanks. This phenomenon of liquefaction develops from repeated disturbances of saturated cohesionless soil and can cause excessive displacements of the ground. Building foundations can slide or unevenly settle, bridges can collapse and empty fuel tanks buried under ground can rise to the surface. The video clip demonstrates this phenomenon and a few pictures show examples of its effects. The pictures and the information about them were obtained from the National Information Service for Earthquake Engineering at the University of California at Berkeley.

Film Strip

Video Clip of the Liquefaction Experiment - MPEG, 2.1 MB

This video clip simulates two occurances of ground settlement of saturated cohesionless soil from liquefaction during an earthquake. The yellow block represents a building. Because its density is greater than the density of the saturated soil, the building will sink when the soil liquefies. At the end of the clip, a fuel tank will emerge from the ground because the density of the empty tank is less than that of the soil.

Picture Gallery

Below are a number of examples of the effects of ground liquefaction during various seismic events. Click on a picture to enlarge it.

Niigata Earthquake, Japan, 1964: Tilting of apartment buildings at Kawagishi-Cho, Niigata, produced by liquefaction of the soil.

Alaska Earthquake, 1964: Displacement and tilting of houses due to soil liquefaction in the Turnagain Height area of Anchorage.

Niigata Earthquake, Japan, 1964: Collapse of the super-structure of the Showa Bridge by falling off its piers.

Hyogoken-Nanbu Earthquake, Japan, 1995: Collapse of a span of the Nishihomiya bridge on the new Harbor Expressway.

Hyogoken-Nanbu Earthquake, Japan, 1995: Graben caused by lateral displacement of the quay wall on Port Island. Note the cranes straddling the graben and the lateral deformation of the crane rails.

Hyogoken-Nanbu Earthquake, Japan, 1995: Collapse of crane due to lateral movement (~2 m) of quay wall on Rokko Island. Note settlement of 1-2 m also occurred behind wall.

Hyogoken-Nanbu Earthquake, Japan, 1995: Vans and trucks ready for shipment before earthquake. Lateral spreading caused 1.5 m-2 m drop of paved surface and local flooding.

Hyogoken-Nanbu Earthquake, Japan, 1995: Damage to the end of Hyogo Pier No. 2.

Nihonkai-Chubu Earthquake, Japan, 1983: Tilting of a school flag pole due to ground failure caused by liquefaction.

Hyogoken-Nanbu Earthquake, Japan, 1995: Damaged column-beam connection on north side of Harborland ferry terminal.

References

National Information Service for Earthquake Engineering at the University of California at Berkeley.

Earthquake Engineering Research Center at the University of California at Berkeley.

Housner, George W., Liquefaction of Soils During Earthquakes. National Academy Press: Washington, D.C., 1985.