Earthquakes home//plate tectonics

I. Measuring Earthquakes

1.Seismic Waves

A. Seismic Waves are the vibrations that travel through the earth carrying the energy released during the earthquake.

B. Types of Seismic Waves

There are there three types of waves. P waves, s waves, and Surface waves. P waves, also known as Primary Waves, are earthquake waves that compress and expand ground like an accordion. They cause buildings to fall after compressing and expanding many times. S waves, a.k.a Secondary Waves, are earthquake waves that vibrate from side to side as well as up and down. They shake the ground back and forth. Surface Waves move more slowly then P waves and S waves, but they can produce severe ground movements. Some surface waves make the ground roll like ocean waves. Other surface waves shake buildings from side to side.