Home > Encyclopedia of Science > Earthquake

• Causes of earthquakes
• The motion of earthquakes: Seismic waves
• Words to Know
• Measuring earthquakes
• Tsunami
• Earthquake occurrence and prediction

An earthquake is an unpredictable event in which masses of rock shift below Earth's surface, releasing enormous amounts of energy and sending out shock waves that sometimes cause the ground to shake dramatically. Not all earthquakes are enormous, but they can become one of Earth's most destructive forces.

Causes of earthquakes

Earth's crust is composed of many huge, rocky plates known as tectonic plates. These plates constantly move slowly across the surface of Earth, bumping...