The movement of tectonic plates causes earthquakes when two plates that are in contact with each other move in opposite directions and release built-up stress. For example, one plate may move north, while the other may move south. Stress can build up to a significant amount while the plates are held stationary, but trying to move, which can then be released as an earthquake.
Earthquakes are one type of natural disaster. They cause large tremors that can bring down man-made buildings. While earthquakes cannot be predicted, their size can be measured on the Richter scale. A higher number indicates a more severe earthquake.