Liquefaction

Liquefaction

Prepared by :

December 2012

Nariman Dehghani

Earthquake

An earthquake is the motion or trembling of the ground produced by sudden displacement of rock in the Earth's crust. Earthquakes result from crustal strain, volcanoes, landslides, and collapse of caverns.

The effects of earthquakes include, but are not limited to, the following:

Shaking and ground ruptureLandslidesFiresSoil liquefactionTsunamiFloodsHuman impacts

Earthquake Effects - Ground Shaking

Northridge, CA 1994

Earthquake Effects -

Ground Shaking

Northridge, CA 1994

Earthquake Effects - Ground Shaking

Loma Prieta, CA 1989

Earthquake Effects - Ground Shaking

Kobe, Japan 1995

Earthquake Effects - Ground Shaking

Kobe, Japan 1995

Earthquake Effects - Surface Faulting

Landers, CA 1992

Earthquake Effects - Liquefaction

Niigata, Japan 1964

Earthquake Effects - Landslides

Turn again Heights, Alaska,1964 (upper left inset);Santa Cruz Mtns, California , 1989

Earthquake Effects - Fires

Loma Prieta, CA 1989

Earthquake Effects - Tsunamis

1957 Aleutian Tsunami

Soil liquefaction describes a phenomenon whereby a saturated soil substantially loses strength and stiffness in response to an applied stress, usually earthquake shaking or other sudden change in stress condition, causing it to behave like a liquid.

Liquefaction

Liquefaction occurrence:

Liquefaction is more likely to occur in loose to moderately saturated granular soils with poor drainage, such as silty sands or sands and gravels capped or containing seams of impermeable sediments.

Earthquake liquefaction:

The pressures generated during large earthquakes with many cycles of shaking can cause the liquefied sand and excess water to force its way to the ground surface from several meters below the ground.

Effects:

The effects of soil liquefaction on the built environment can be extremely damaging. Buildings whose foundations bear directly on sand which liquefies will experience a sudden loss of support, which will result in drastic and irregular

settlement of the building causing structural damage, including cracking of foundations and damage to the building structure itself, or may leave the structure unserviceable afterwards, even without structural damage.

Niigata Japan 1964

Loma Prieta 1989

Kobe Japan 1995

Niigata 1964