There are two types of seismic waves: 1) fast primary (P) or longitudinal waves, which vibrate parallel to the direction in which the wave propagates, and 2) slower secondary (S) waves or shear waves, which vibrate perpendicular to the propagation direction. Seismic waves (elastic waves) are sound waves, which travel with speeds VP and VS respectively. Shear waves don’t propagate in fluids like air or water, but are transmitted by solid material.
The picture shows the particle motion in waves. The direction of wave propagation is to the right (large arrow) and the particle motion is indicated by the smaller double arrows. (a) Undisturbed particles. (b) In a compressional
wave the particle motion is along the propagation direction. (c) In a shear or transverse wave the particle motion is perpendicular to the propagation direction.
Originally uploaded in Cutting Edge:Courses:Mineralogy:Mineral Physics.
Image 32335 is a 137 by 300 pixel JPEG
Uploaded: Feb6 12