What Are Earthquakes?

Earthquakes can cause major changes to the Earth's surface.  The changes happen very quickly.  You probably already know that earthquakes cause a lot of shaking.  But do you know how they were formed?

An earthquake happens when 2 tectonic plates get stuck together.  When they release it causes a sudden shift.  The quick movement makes the earth vibrate.  

To help you understand this,  snap your fingers in slow motion.  At first your fingers press together, building up pressure.  Then when you snap, both fingers suddenly move.  An earthquake is similar to this.  The plates of the earth press against each other, perhaps for thousands or millions of years.  Lots of pressure builds up.  Then all of the sudden the plates release and this makes the earth move.  The sudden movement is called an earthquake.  

To find out more about earthquakes, visit this wonderful site provided by the United States Geological Survey’s (USGS) Earthquake Hazards Program.