Seismology can be used to measure a physical property of a material, the velocity of elastic waves. A. Elastic waves are oscillations of particle displayment in a solid about an equilibrium postion. True elastic waves involve do not permanently deform the solid or move particles away from their permanent positions. The proportionality constant in this relattionship is called an elastic constant.
Elastic constants are fundamental physical properties of a solid.
Elastic waves in air and water are called sound waves or acoustic waves. B.Unlike the oscillations of particles due to heat, elastic waves propagate in a very organized way. 1.Body waves propagate outward from a source along three-dimensional surfaces called wavefronts, similar to the rings of waves seen propagating outward in a pond centered where a pebble has splashed. The perpendiculars to wavefronts are called rays. Body wave propagation, including reflection and refraction is often summarized by drawing ray paths.