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Earthquake
An earthquake also known as a quake, tremor or temblor
It is the result of a sudden release of energy in the Earth’s crust that
creates seismic waves.
What Are Seismic Waves?
Seismic waves are the waves of energy caused by the sudden
breaking of rock within the earth or an explosion. They are the energy
that travels through the earth and is recorded on seismographs.
The seismic activity of an area refers to the frequency, type and size
of earthquakes experienced over a period of time.
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Why do earthquakes happen?
Earthquakes are usually caused when rock underground suddenly
breaks along a fault. This sudden release of energy causes the
seismic waves that make the ground shake.
When two blocks of rock or two plates are rubbing against each
other, they stick a little. They don't just slide smoothly; the rocks
catch on each other. The rocks are still pushing against each other,
but not moving. After a while, the rocks break because of all the
pressure that's built up. When the rocks break, the earthquake
occurs.
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Causes of earthquake
Earthquakes are caused by disturbances in the interior of the earth and
other causes.
Tectonic movements: The disturbances inside the earth are called
tectonic movements.
These forces bring about changes on the earth surface and physical
features like mountains, plateaus and rift valleys are formed
Most disastrous
Earthquakes are
caused by
Tectonic forces
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Volcanic eruptions
Volcanic Eruptions: The volcanic eruptions are often very violent and
cause vibrations in the earth crust
Sometimes the vent of a volcano is blocked temporarily and explosive
eruption takes place suddenly causing tremors in the earth crust
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Other reasons for earthquake
Other Reasons: The roofs of underground caves sometimes give way
and release great force to cause minor tremors in the earth crust.
Nuclear explosions also release massive energy to cause tremors in the
earth crust.
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Effects of Earthquake
Earthquakes are less advantageous and more harmful to man
Loss of Property: Severe earthquakes reduces human structures to
rubble ranging from huts to palaces and single storey to multi storey
buildings. Even pipelines laid under the ground and railway lines are
damaged or displaced
Loss of Life: Earthquake tremors of a few seconds takes the lives of
thousands of people. Many people have been rendered homeless or
suffered injuries in various ways.
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Effects of Earthquake
Tsunamis: The earthquakes in the sea generate massive waves. It
causes great damage to life and property of people living in coastal
areas as well as to tourists
Tsunami caused by an earthquake in the sea near Sumatra on 26th
Dec,2004 hit south east Asian countries including India and Sri
Lanka.There was heavy damage in these countries and more than 3
lakh people died
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Earthquake
Safety Measures
Drop down; take cover under a desk or table and hold on.
Stay indoors until the shaking stops and you're sure it's safe to exit.
Stay away from bookcases or furniture that can fall on you.
Stay away from windows. In a high-rise building, expect the fire alarms
and sprinklers to go off during a quake.
If you are in bed, hold on and stay there, protecting your head with a
pillow.
If you are outdoors, find a clear spot away from buildings, trees, and
power lines. Drop to the ground.
If you are in a car, slow down and drive to a clear place. Stay in the car
until the shaking stops.
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