Lateral wave

In electromagnetics, acoustics and seismology, lateral waves or head waves are interfacial waves that are launched at or near grazing incidence with respect to the interface of two different media with different physical properties, such as permittivity, acoustic impedance or slowness. While lateral waves are often classified as surface waves, they are distinct from conventional surface waves such as surface plasmon polaritons in optics or surface acoustic waves in acoustics.

Lateral waves play a role in various different physical phenomena, such as radio propagation at large distances, extraordinary optical transmission and total internal reflection. In exploration seismology and geophysics, lateral waves constitute the basis of the seismic refraction method.