What types of waves are earthquakes

I need to know what the most common type of wave is during earthquakes. I am talking about mechanical waves, as in longitudinal waves.

Are longitudinal waves a type of wave that is sent through the earth because of an earthquake?

If they aren't part of an earhquake, what are some practical applications of the study of longitudinal waves? What can we use that information for?

Every tremor produces different types of seismic waves, which travel through rock with different velocities:
Longitudinal P-waves (shock- or pressure waves)
Transverse S-waves (both body waves)
Surface waves—(Rayleigh and Love waves)

seismic waves