It takes place when a quake has increased water pressure in saturated soil and made particles in the soil lose contact with each other, making the soil - particularly sandy soil - act like liquid.
The effect has been likened to slapping a wet, hard beach and the sand beneath your palm becomes jelly. In the Palu neighborhood of Balaroa, about 1, houses were swallowed up when the earthquake caused soil to liquefy, the national rescue agency said. We estimate units of houses are there. Amateur video footage appeared to show trees, buildings and even a large communications tower being tossed around in fast-moving landslides.
The length of the arrows represent the size of the contact forces between individual soil grains. The contact forces are large when the porewater pressure is low. Liquefaction occurs when the structure of a loose, saturated sand breaks down due to some rapidly applied loading.
As the structure breaks down, the loosely-packed individual soil particles attempt to move into a denser configuration. Liquefaction and related phenomena have been responsible for tremendous amounts of damage in historical earthquakes around the world.
The building codes in many countries require engineers to consider the effects of soil liquefaction in the design of new buildings and infrastructure such as bridges, embankment dams and retaining structures.
Describe the effect of earthquakes on mud and sand. Per Demo or Group: metal cake pan sand water smooth brick rubber mallet ping pong ball or cork optional. What happens to the sand and brick? Was this the same as your predictions? These tilted buildings and liquefaction in this area are probably the most well known examples of liquefaction and loss of bearing strength.
Image and caption by USGS. Liquefaction occurs when vibrations or water pressure within a mass of soil cause the soil particles to lose contact with one another. As a result, the soil behaves like a liquid, has an inability to support weight and can flow down very gentle slopes. This condition is usually temporary and is most often caused by an earthquake vibrating water-saturated fill or unconsolidated soil. California liquefaction map: A portion of a liquefaction susceptibility map of an area near Oakland, California produced by the United States Geological Survey.
The map is color-coded to show areas of very high red , high orange , moderate yellow , low green and very low white susceptibility to liquefaction. This type of map is valuable in making land-use and development decisions.
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