A lot of earthquakes happen in the world every year. Why do earthquakes happen? Scientists tell us the outside of the earth is made of a number of different plates. The plates move very slowly. Sometimes they stop and don't move for a long time. When some of the earth's plates move suddenly, an earthquake happens. Many earthquakes happen under the sea. Sometimes they happen near mountains. In fact, earthquakes may happen anywhere on the earth. During an earthquake, the shakings make rocks rise suddenly and even break open. Houses fall. People are killed or hurt. Sometimes whole villages or cities are destroyed.