You probably know that earthquakes can be huge natural disasters. The Earth's surface is formed of massive slabs of rock called plates . These plates, also called tectonic plates, are always moving. Sometimes they just slide past one another. At other times they actually collide with one another.
Plate movement causes the buildup of tremendous quantities of energy in the rock.
When the energy is released, it produces vibrations that travel through the rock, leading to earthquakes. During earthquakes, faults , or giant cracks, are produced by the pressure of the moving rock. Earthquakes and volcanoes occur along the edges of the plates. Scientists have developed a theory that explains how these giant plates move, thereby creating, destroying, and re-forming continents and oceans over long periods of time. This theory is called the theory of plate tectonics .