An earthquake is a sudden shaking of the ground. It happens when large blocks of rock deep in the Earth, called plates, suddenly move against each other and release energy. The point where the movement starts is called the focus, and the place on the surface above it is called the epicenter. Strong earthquakes can knock down buildings, break roads and cause giant sea waves known as tsunamis. Scientists cannot yet predict exactly when an earthquake will happen, but they know which areas are most at risk. In those areas, engineers design buildings that can bend a little without falling down. People are also taught what to do: stay away from windows, get under a strong table and wait until the shaking stops. These simple steps save many lives.

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