P-waves (compressional) and S-waves (shear) in an elastic solid — click to send pulse
In elastic media: P-waves (pressure/longitudinal) travel at vₚ = √((λ+2μ)/ρ);
S-waves (shear/transverse) at vₛ = √(μ/ρ).
Ratio vₚ/vₛ = √(2(1−ν)/(1−2ν)) always > √2 since ν>0.
Earth seismology: P-waves arrive first (faster), then S-waves.
S-waves cannot travel through liquid cores (μ=0 for fluids).