Concept:

• An earthquake is a sudden movement of the earth's surface, caused by the release of energy that has been stored beneath the surface over a long time.
• Nobody has been able to predict earthquakes reliably enough and ober short enough time scales to allow the evacuation of threatened cities. In 1975, the Chinese government made a successful prediction based on precursors like foreshocks, and as a result casualties from a magnitude-7.3 quake in the Haicheng-Yingkow region were relatively light. In the United States, scientists have hoped to predict quakes by noticing changes in the speed of seismic waves passing through at-risk faults.(Quake Prediction by Daniel Pendick: http://www.pbs.org/wnet/savageearth/earthquakes/html/sidebar2.html)
• Earthquakes happen everyday in the world. The majority of them is small ones. But a large earthquake may cause many deaths, injuries, and property damages. Earthquakes that occur beneath the oceans or seas may cause or give a rise to tsunamis.