Body waves can be divided into two typesprimary waves and secondary waves. What is the difference ...

 Primary waves, as their name suggests, are the first to register on a seismograph. P-waves are fast, longitudinal waves that move out in all directions from their source. Because both solids and liquids respond to compressional/expansional movement, P-waves can travel through any type of material. Secondary waves are slower than P-waves; as such they are the second to register on a seismograph. S-waves are transverse; they vibrate in an up-down, side-to-side fashion. Because liquids cannot support this type of movement, S-waves cannot travel through liquids.

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