Rayleigh wave
= Rayleigh wave
{c}
{title2=$(1+\beta^2)^2=4\alpha\beta$}
A <Rayleigh wave> propagates along a stress-free boundary of an isotropic elastic half-space and decays into its interior. It combines an evanescent longitudinal wave with an evanescent vertically polarized shear wave. If its speed is $0<c<c_S<c_P$, the decay factors are $\alpha=\sqrt{1-c^2/c_P^2}$ and $\beta=\sqrt{1-c^2/c_S^2}$. Vanishing shear and normal traction gives the displayed determinant condition.