Today's demo: P and S-wave propagation using a slinky. When talking about earthquakes, it's often hard for students to "see" the relative motion of energy through rocks. We often use a slinky or a large spring to demonstrate the behavior of waves moving through a solid material. Trouble is, the movement of the wave is so fast, it's sometimes hard to see. What better way to slow things down than with the high-speed camera?
I haven't done any motion tracking, but I don't think the pressure wave is traveling any faster than the transverse (shear) wave in the spring - I think the spring is too "springy" so there's no discernible difference in velocity between the two.