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   Why do they happen?
Although the ground we walk on seems solid,
the earth is actually made up of huge pieces
of flat rock called tectonic plates.

These move very slowly, and where they meet is called a fault.

When the plates rub together, the movement forces
waves of energy to come to the earth's surface.

This causes tremors and shakes -
and this is what causes earthquakes.

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Are they dangerous?
Earthquakes can be very dangerous,
if you are in the wrong place.
They can make buildings fall down and set off landslides,
as well as having many other deadly effects.

Earthquakes are measured on the Richter Scale.

The higher the number on the scale,
the more powerful the quake.
The more powerful a quake is,
the more damage it can cause.

Earthquakes have killed hundreds of thousands of
people even though scientists are able to
make buildings much safer than in the past.

Unfortunately many quakes happen in parts of
the world where people can't afford
to spend lots of money on safety measures.

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How often do they happen?
They happen all the time in various parts of the world.

Thankfully most of them are so small that we don't notice them,
or they happen at sea or places where there are no people.

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Have there been serious ones recently?
In the last 10 years there have been lots of big earthquakes.

December 2003:
Over 50,000 people are killed in a quake in Iran,
which measured 6.3 on the Richter scale.

May 2003:
Over 1,000 people are killed and nearly 7,000
hurt in a quake in Algeria,
which measured 6.7 on the Richter scale.

March 2002:
Thousands die in a remote area of Afghanistan after
an earthquake measuring 6 on the Richter scale.

January 2001:
30,000 people die and more than 50,000 are injured by an
earthquake measuring 7.9 on the Richter scale in Gujarat, India.

January 2001:

1,000 people die in a 7.2 earthquake in El Salvador.

September 1999:
2,500 people are killed by an earthquake measuring
7.6 on the Richter scale in Taiwan.

May 1998:
4,000 people are killed by a quake in Northern Afghanistan.

January 1995:
6,430 people are killed after the Hyogo quake in Kobe, Japan.

June 1994:
1,000 people are killed by an earthquake and landslide in Colombia.

September 1993:
22,000 villagers are killed in western and southern India.

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Why is it dangerous after a quake?
Earthquakes are often followed by aftershocks.

These are smaller quakes which bring more
damage to already weakened buildings and roads.

Land, especially hills, can also be damaged by earthquakes
and can result devastating landslides and mudslides.

After the El Salvador earthquake in 2001,
a landslide hit the small town of Las Colinas.

It buried 500 houses and killed 315 people.
Many more were never found.

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