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The EarthWord: Liquefaction

Definition:

• Although it sounds like one side of a battle between the states of matter, liquefaction is actually something a bit more worrisome. It’s what can happen when an earthquake strikes land that is made up of loose sand and silt that is saturated with water. The intense shaking of the earthquake can actually cause the solid land to behave like a liquid.

• When that happens, the soil can lose its ability to support structures; flow down even very gentle slopes; and erupt to the ground surface to form sand boils.

Etymology:

• Liquefaction comes from the Latin liquefacere, which means “to make liquid” or “to melt.”

Use/Significance in the Earth Science Community:

• Liquefaction is an important area of study in seismology, because many significant earthquake zones also have the kinds of landforms that are prone to liquefaction.

• Scientists have determined that liquefaction requires three things to occur:

  • The land has to be made up of loose, granular sediments, such as swamps and marshlands, riverbanks and beaches, or floodplains made up of river deposits.

  • The land has to be saturated with water, such as areas with high water tables and large amounts of groundwater.

  • The earthquake has to produce strong shaking.

USGS Use:

• USGS studies liquefaction hazards as part of its Earthquake Hazards Program in order to help decision-makers prepare for possible impacts from a large earthquake.

• In particular, USGS studies liquefaction risks in California, such as the San Francisco Bay area.

• USGS also has several liquefaction hazard maps for parts of California.

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