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# Seismic Body Waves | Wave Type (and names) | Particle Motion | Other Characteristics | |---|---|---| | P, Compressional, Primary, Longitudinal | - Alternating compressions ("pushes") and dilations ("pulls") - directed in the same direction as the wave is propagating (along the raypath); | - P mo...

# Seismic Body Waves | Wave Type (and names) | Particle Motion | Other Characteristics | |---|---|---| | P, Compressional, Primary, Longitudinal | - Alternating compressions ("pushes") and dilations ("pulls") - directed in the same direction as the wave is propagating (along the raypath); | - P motion travels fastest in materials, so the P-wave is the first-arriving energy on a seismogram. - Generally smaller and higher frequency than the S and Surface-waves. | | S, Shear, Secondary, Transverse | - Alternating transverse motions (perpendicular to the direction of propagation, and the raypath) | - S-waves do not travel through fluids, so do not exist in Earth's outer core (inferred to be primarily liquid iron) - S waves travel slower than P waves in a solid and, therefore, arrive after the P wave. | # Seismic Surface Waves | Wave Type (and names) | Particle Motion | Other Characteristics | |---|---|---| | L, Love, Surface waves, Long waves | - Transverse horizontal motion, perpendicular to the direction of propagation and generally parallel to the Earth's surface. | - They are largest at the surface and decrease in amplitude with depth. - Love waves are dispersive, that is, the wave velocity is dependent on frequency, generally with low frequencies propagating at higher velocity. - Depth of penetration of the Love waves is also dependent on frequency, with lower frequencies penetrating to greater depth. | | R, Rayleigh, Surface waves