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?
Earthquake 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.