An earthquake is the quick shaking of the ground. Rock under the ground breaks and moves.
The top layer of the Earth is in big pieces called plates. They push and slide very slowly. Sometimes they get stuck.
A fault is a crack in the rocks of the Earth. One side can move past the other.
Most earthquakes start where plate edges meet. Volcanoes do too. Moving plates also build mountains.
The shaking spreads out in every direction. It is like ripples from a rock in a pond.
A machine called a seismograph records the shaking of the ground.
A big earthquake under the sea can cause a tsunami. That is a series of ocean waves.
An earthquake can come at any time of year. It comes with no warning. No one can say when.
So people practice. When the ground shakes, drop, cover, and hold on. Hold on until it stops. Families and classes do drills.
If you are inside, stay inside. Do not run out. Stay away from windows. Stay away from heavy things that could fall, like bookcases.
If you are outside, stay outside. Go to an open place. Keep away from buildings, trees, and wires.
Families can get ready. They can make an emergency kit. They can plan where to meet if they get separated.
Words to know
- plates: big earth pieces
- fault: crack in rock
- seismograph: shaking recorder
- tsunami: giant ocean waves
