Dispersion of surface waves

Summary

Seismic surface waves, the Rayleigh waves and Love waves, travel at speeds that depend on their frequency. Long waves reach deeper into the Earth, where the rock is usually faster, so they travel faster than short waves. The phase velocity and group velocity as functions of period are dispersion curves. They can be inverted for the speed of shear waves at each depth. Dispersion is why the surface waves of a distant earthquake arrive as a long wave train instead of a single pulse.