Flexi Says: Almost all earthquakes occur at plate boundaries. All types of plate boundaries have earthquakes. Convection within the Earth causes the plates to move. As the plates move, stresses build. When the stresses build too much, the rocks break. The break releases the energy that is stored in the rocks. The sudden release of energy is an earthquake. During an earthquake, the rocks usually move several centimeters. Rarely, they may move as much as a few meters. Elastic rebound theory describes how earthquakes occur.