Why do Earthquakes Happen?

Many people associate earthquakes with destruction caused by falling buildings or by the creation of a tsunami. While earthquakes may be associated with destruction in the time frame of human activity, in the evolution of the Earth they signal the geological forces that build our mountains and create our oceans. In many ways, earthquakes are one of nature's reminders that we are living on the thin outer crust of a planet whose interior is still cooling. Earth's rigid outer surface is broken into what geologists call plates. In general, earthquakes occur when plates move under, over, or slide past each other. The plates are moving in millimeters per year--about as fast as your fingernails grow.


Keypoints:

  • Earth’s rigid outer surface is broken into what geologists call plates
  • The locations of earthquakes provide evidence for the boundaries of these plates
  • In general, earthquakes occur when plates move under, over, or slide past each other

 

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