How Earthquakes Happen

Our Earth has a hard outside. It is like a big puzzle with many pieces. We call these pieces plates. These plates are always moving, but very slowly. They float on hot, gooey rock deep inside the Earth. Sometimes, two plates push against each other. Other times, they might slide past each other. When they get stuck, a lot of energy builds up. It is like stretching a rubber band tighter and tighter. When the plates finally slip, that energy is set free all at once. The ground begins to shake very fast. This sudden shaking is called an earthquake. It happens deep under our feet.