Spherical Seismic Waves
This Demonstration shows the propagation of spherical elastic waves, commonly known as seismic waves, from a point source. Shown here are two types of seismic waves: pressure wave (P-wave) and shear wave (S-wave). The P-wave is longitudinal, and thus oscillates along the direction of the wave propagation, while the S-wave shakes perpendicular to the travel direction.[more]
By combining these two types, you can simulate other types, such as Rayleigh waves.[less]
In the event of a real earthquake, the P-wave always precedes the S-wave. The reason is that the speed of P-waves is
while the speed of an S-wave is
where is the bulk modulus, μ is the shear modulus, and ρ is the density.