How Earthquakes Happen
Earthquake is one of the most destroying natural disasters.
Unluckily it often happens in several regions. Recently a horrible earthquake
has shaken West Sumatra. It has brought great damages. Why did it occur? Do you
know how an earthquake happens?
Earthquakes are usually caused
when rock underground suddenly breaks along a fault. This sudden release of
energy causes the seismic waves. It 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 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. During the earthquake and
afterward, the plates or blocks of rock start moving, and they continue to move
until they get stuck again. The spot underground where the rock breaks is
called the focus of the earthquake. The place right above the focus is called
the epicenter of the earthquake.
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