The movement sends out shockwaves that can have enough power to actually shake the Earth's surface at the fault line. That's why most earthquakes occur at or near fault lines. Cities that are located near fault lines, like Los Angeles, must make their structures strong enough to withstand earthquakes. The point on the surface of the Earth located directly above the earthquake's origin is called the epicenter. That's where the strongest shaking occurs, but major earthquakes can shake things up hundreds of miles away from the epicenter.
Earthquakes can range from tiny, undetectable tremors to huge, devastating disasters.
Scientists who study earthquakes, called seismologists, measure their severity on a Richter Scale. The scale measures the earthquake from 1-10, with 10 being the most severe. Major earthquakes kill about 10,000 people every year and can cause massive destruction to buildings and other structures. Their vibrations can also trigger landslides, fires, and floods. Cover your head with your arms.