How do seismic waves travel through the earth?
Earthquakes radiate energy (in what we see as S and P waves) as both body and surface waves. Traveling through the interior of the earth, body waves arrive before the surface waves emitted by an earthquake. The body waves are of a higher frequency than surface waves. The first kind of body wave is the P wave or primary wave. This can be seen on a seismograph , which is recorded by a seismometer.