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Earthquake damage and hazards - Coggle Diagram
Earthquake damage and hazards
Fault slippage
The
rock on
either
side of
a
fault
may
shift only slightly during an earthquake
,
or
may
move several feet.
In some cases
,
only the rock deep in the ground shifts
, and no movement occurs at Earth’s surface.
In an
extremely large
earthquake, the
ground
may
suddenly heave 20 feet or more
. Any
structure
that spans a
fault
may
be ripped apart
.
Ground shaking
Ground shaking
causes structures to sway from side to side
,
bounce up and down
, and
move in other violent ways.
Buildings
may
slide off their foundations, collapse, or be shaken apart
when they are too weak or rigid to resist strong, rocking forces.
In addition,
tall buildings may vibrate wildly
during an earthquake
and knock into each other
.
Fires
A
major cause of death and property damage
in earthquakes is
fire.
Fires may start if an earthquake ruptures gas or power lines.
Liquefaction
In areas with soft, wet soils, a process called liquefaction may intensify earthquake damage.
Liquefaction
occurs when strong ground shaking causes wet soils to behave temporarily like liquids
rather than solids.
Anything on top of liquefied soil may sink into the soft ground
. The
liquefied soil
may also
flow toward lower ground, burying anything in its path
.
Landslides and Flooding
The
shifting blocks
of earth may also
loosen the soil and rocks along a slope and trigger a landslide
.
In addition,
fault slippage may break down the banks of rivers, lakes, and other bodies of water, causing flooding
.
Tsunami
An
earthquake on the ocean floor
can
give a tremendous push to surrounding seawater and create a series of large, destructive waves called a tsunami
.
The waves of a tsunami may build to
heights of more than 100 feet when they reach shallow water near shore.
In
the
open ocean, tsunami waves
typically
move at speeds of 500 to 600 miles per hour
.
They
can travel great distances while diminishing little in power and can flood coastal areas
thousands of miles from their source.
Other hazards
Other hazards during an earthquake include
spills of toxic chemicals and falling objects
, such as tree limbs, bricks, and glass.
Sewage lines may break, and sewage may seep into water supplies.
Drinking of such impure water may cause serious diseases or even death.
Recovery delays
Loss of power, communication, and transportation after an earthquake may hamper rescue teams and ambulances, increasing deaths and injuries.
In addition, businesses and government offices may lose records and supplies, slowing recovery from the disaster.
Reducing earthquake damage
Earthquake resistant structure
: Engineers have developed a number of ways to build earthquake–resistant structures. Their techniques range from extremely simple to fairly complex.
Small to medium buildings
: the simpler reinforcement techniques include bolting buildings to their foundations and providing support walls called
shear walls
. Builders also
protect medium–sized buildings
with devices that act like
shock absorbers
between the building and its foundation. These devices, called
base isolators
Skyscrapers
: Skyscrapers need special construction to make them earthquake–resistant.
They must be anchored deeply and securely into the ground.
They need a reinforced framework with stronger joints than an ordinary skyscraper has.
Personal safety precautions
Standing under a door frame or crouching under a table or chair until the shaking stops.
They should not go outdoors until the shaking has stopped completely.
Even then, people should use extreme caution. A large earthquake may be followed by many smaller quakes, called aftershocks.
People should stay clear of walls, windows, and damaged structures, which could crash in an aftershock.
Predicting earthquakes
Scientists
cannot yet predict
the day or even the year when an earthquake will occur.
Scientists are
working to make accurate forecasts
on when earthquakes will strike.