An earthquake is a sudden, rapid shaking of the earth caused by the movement of tectonic plates or the release of energy in the earth's crust. Earthquakes can range in intensity from those that are so weak that they cannot be felt to those that can cause severe damage and loss of life.

The magnitude of an earthquake is measured on the Richter scale, which ranges from 1 to 10. Earthquakes with a magnitude of less than 2.0 are generally not felt by humans, while those with a magnitude of 7.0 or greater can cause significant damage.