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Locations
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Because liquefaction only occurs in saturated soil,
its effects are most commonly observed in low-lying areas near bodies of water such
as rivers, lakes, bays, and oceans. The effects of liquefaction may include major
sliding of soil toward the body
slumping and of water, as in
the case of the 1957 Lake Merced slide shown above, or more modest movements that produce tension cracks such as those on the
banks of the Motagua River following the 1976 Guatemala Earthquake.
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Port and wharf facilities are often located in areas
susceptible to liquefaction, and many have been damaged by liquefaction
in past earthquakes. Most ports and wharves have major retaining
structures, or quay walls, to allow large ships to moor adjacent to
flat cargo handling areas. When the soil behind and/or beneath such a wall liquefies,
the pressure it exerts on the wall can increase greatly - enough to
cause the wall to slide and/or tilt toward the water. As illustrated
below, liquefaction caused major damage to port facilities in Kobe, Japan in the
1995 Hyogo-ken Nanbu earthquake.
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Liquefaction also frequently causes damage to bridges
that cross rivers and other bodies of water. Such damage can have
drastic consequences, impeding emergency response and rescue operations
in the short term and causing significant economic loss from business
disruption in the longer term.
Liquefaction-induced soil movements can push foundations out of place to the point
where bridge spans loose support
(above, SC) or are compressed to the
point of buckling (left, SC).
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