Seismic waves

When the dislocation reaction, the accumulation in the elastic deformation of the rock's energy consumption has a part in the fault plane dislocation friction generated heat, has a part of consumption in the fragmentation of rock, one part of the rock has generated a rebound seismic waves to carry, to spread in all directions. Generated by the seismic source has two types of seismic waves, called P waves (Primary wave), the spread of faster; another known as the S waves (Secondary wave), slow. These two waves can be found in the rock mass internal transfer, it also as the body wave (also known as entity-wave) (Body wave). 

P-wave in the dissemination, the particle direction and the sport spread shock waves direction, that is, the particle Chuanbo spread along the direction of the turn produce compression and expansion changes, like sound waves in general. P-wave in solids and liquids can be spread. 


S wave in the dissemination, the particle movement in the direction and vertical direction of shock wave transmission, that is, particle Chuanbo vertical transmission in the direction of vibration, of media distortions. As a result of such properties, so S-wave are unable to spread a liquid or gas, as liquid or gas can not be distorted. 

In addition, S-wave particle because exercise direction and wave propagation direction perpendicular to the vertical direction can be divided into upper and lower vertical and around the vertical, up and down vertical direction for vertical movement known as the SV-wave (V express vertical), vertical to the horizontal direction about sports known as the SH-wave (H express horizontal). 



Body wave in the dissemination of material at the Earth's interior because of the layered structure and the role of the surface interface (such as refraction, reflection of the role), but also by the development of only part of the surface spread of SAW (Surface wave), its amplitude with the distance from the surface reduce the depth. 


SAW can be divided into two, one for(Love wave), the particle movement along the horizontal plane like the way the S-wave (SH wave), in the vertical direction on the ground there is no vibration. Another called SAW (Rayleigh wave), the particle vibration Rayleigh wave is in the vertical plane of elliptical exercise. 

SAW speed slower than the body wave, which Rayleigh wave slower than Love wave. So after the earthquake, seismic instruments are first received P wave, followed by S SAW affected. If not too far away when the wave speed due to a variety of small differences, it is not easy, respectively.