The Power of the Earth

The Power of the Earth

Power Hour 85

The Power of the Earth

Rumble, rumble! Sometimes the earth shakes beneath people's feet. That shaking is called an earthquake. An earthquake can happen on land or in the ocean. Earthquakes can rattle walls, cause giant waves, and even bring down buildings.

Here is why earthquakes happen.

The earth is not one solid rock. If you could drill deep into our planet, you would find four layers. The top layer is thecrust. Below the crust is the mantle. Under that is the outer core. The deepest layer of the earth is the inner core.

The crust and the top part of the mantle are broken into giant pieces of rock called tectonic plates.

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!

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