DEFINITION of ‘Liquefaction’
A loss of stability and strength in water-saturated soil due to violent ground movements caused by earthquakes or by explosions such as construction blasts. Liquefaction is a major problem when the soil is supporting a structure such as a building, because the soil becomes unable to support the weight of the building and the building will be severely damaged or destroyed. A building may be structurally sound enough to withstand the shaking of an earthquake, but then be destroyed by liquefaction.
BREAKING DOWN ‘Liquefaction’
In addition to buildings, liquefaction can ruin roads, railways, airport runways, dams and anything else that sits on the ground. It can also damage below-ground utilities. Liquefaction can cause landslides, settlement and eruptions of mud or water from the ground. To understand liquefaction, think of how quicksand, a type of liquefied soil, works.
Soil type, the depth of ground water and the probability of earthquakes determine the risk of liquefaction in a particular area. For example, certain areas of Utah are at high risk of liquefaction because they have sandy soil that is easily saturated by shallow groundwater and there is a high risk of moderate to severe earthquakes. Locations near rivers, streams and lakes are also more prone to liquefaction.
Improving the soil through drainage or compaction and carefully designing building foundations can reduce susceptibility to property damaged caused by liquefaction. Specialized maps created by geologists show the probability of liquefaction in a particular area, and examining these maps prior to building and avoiding areas shown to have higher liquefaction risks is another way to limit damage from liquefaction. Liquefaction hazard and liquefaction susceptibility maps are available to the public for free from the United States Geological Survey. These maps provide a general overview of liquefaction risk in an area; a geologist or geotechnical engineer can evaluate the liquefaction risk of a specific parcel of property. Liquefaction hazards must be disclosed when real property is sold to make the buyer aware of one of the risks of ownership.