Earth's surface is formed by gigantic, slowly moving plates of solid rock. When these plates lurch past one another with sudden large bursts of energy, one of the most awesome forces of nature is unleashed-a major earthquake. About 3,000 earthquakes are recorded every day on our planet. Most are too small to notice, but when a powerful one hits, it can be very destructive. Learn all about the forces that shake and shape Earth with acclaimed science writer Seymour Simon.