The Earth's surface is on the move.


In Alaska in 1964, a magnitude 9.2 earthquake jarred the earth so strongly it caused fishing boats to sink in Louisiana. What causes the ground tremble like that? The answer is simple. The Earth's surface is on the move.

The surface of the earth, called the "crust," is not one solid piece. It's more like a 20 piece puzzle. Each puzzle piece is called a "plate." The plates constantly move. Fortunately for us, they don't move fast. Geologists estimate the fastest plate might shift 6 inches a year (15 centimeters). That's about as fast as your hair grows.

Earthquakes happen when a plate scrapes, bumps, or drags along another plate. When does this happen? Constantly. About a half-million quakes rock the Earth every day. That's millions a year. People don't feel most of them because the quake is too small, too far below the surface, or deep in the sea. Some, however, are so powerful they can be felt thousands of miles away.

A powerful earthquake can cause landslides, tsunamis, flooding, and other catastrophic events. Most damage and deaths happen in populated areas. That's because the shaking can cause windows to break, structures to collapse, fire, and other dangers.

Geologists cannot predict earthquakes. They hope they will in the future through continued research and improved technology.

Earthquakes can happen anytime or anywhere. But you can prepare for the unpredictable with a family safety plan, emergency kit, and supplies.