The Power of the Earth

These plates float on top of the rest of the mantle like icebergs floating on the ocean. The plates move so slowly, however, that people cannot feel them moving.

The plates sometimes move apart or slide past each other. One plate can even sink beneath another. But occasionally the edges of the plates get stuck. When that happens, pressure builds. Eventually, the pressure releases enough energy for the plates to break loose.

A relatively small amount of energy is usually required for the plates to break loose, and the nearby ground shakes just a little. Sometimes, however, a lot of energy is needed. And the result is a big and dangerous earthquake!