Earthquakes are measured vibrations in the earth's crust caused by sudden ruptures. They are measured using seismometers and their magnitude indicates their size. The major types of damage from earthquakes include swinging hanging objects, falling plates and broken buildings. Earthquake waves called seismic waves include P and S body waves and surface waves. P waves travel through solids by pushing and pulling while S waves also travel through solids by side-to-side motion. The elastic rebound theory explains how strain energy builds up and is released in sudden ruptures at plate boundaries.

1. Earthquakes. Anthony Kroll Mrs. Smith 3rd Hour April 8, 2011