Mechanical wave

[1] (Vacuum is, from classical perspective, a non-material medium, where electromagnetic waves propagate.)

While waves can move over long distances, the movement of the medium of transmission—the material—is limited.

Mechanical waves can be produced only in media which possess elasticity and inertia.

The speed of the longitudinal wave is increased in higher index of refraction, due to the closer proximity of the atoms in the medium that is being compressed.

Rayleigh waves have energy losses only in two dimensions and are hence more destructive in earthquakes than conventional bulk waves, such as P-waves and S-waves, which lose energy in all three directions.