NATURAL EVENTS SUCH AS VOLCANIC ERUPTIONS AND METEOR IMPACTS CAN CAUSE EARTHQUAKES, BUT THE MAJORITY OF NATURALLY-OCCURRING EARTHQUAKES ARE TRIGGERED BY MOVEMENT OF THE EARTH'S PLATES.
AN UNDERSEA EARTHQUAKE IN THE INDIAN OCEAN TRIGGERED A SERIES OF DEVASTATING TSUNAMIS ON DEC. 26, 2004. THE TSUNAMIS STRUCK THE COASTS OF MOST LANDMASSES BORDERING THE INDIAN OCEAN, BRINGING 100-FOOT WAVES AND KILLING OVER 225,000 PEOPLE IN 11 COUNTRIES.