Seismic surface waves pass along the surface of the earth. They can be classified in a form of mechanical surface waves hence they are called surface waves, as they shrink as they get far from the surface. They travel slower than seismic body waves (P and S). In heavy earthquakes, surface waves can have an amplitude of some centimeters
Rayleigh waves, also known as ground roll, are surface waves that pass as waves with motions that are parallel to those of waves on the surface of water (even though the related particle motion at shallow depths is retrograde, and the reinstating force in Rayleigh and in other seismic waves is flexible, not gravitational as for water waves).
Love waves are waves which are horizontally polarized and shear (SH waves), standing only in the presence of a semi-infinite medium covered by an upper layer of limited thickness.
A Stoneley wave is an interface wave or boundary wave that transmits along a solid-fluid boundary or, under specific conditions, also along a solid-solid border. Scales of Stoneley waves have their maximum values at the boundary between the two contacting points and decay exponentially at the depth of each of them. These waves can be produced along the walls of a fluid-filled well, being a vital source of coherent noise in VSPs and building up the low-frequency component of the source in sonic logging.
When an earthquake takes place, seismographs which are near the epicenter are able to record both P and S waves, but those which are far from the distance make detection harder for the high frequencies of the first S wave. Since shear waves cannot pass from liquids, this process was original evidence for the now well-established thought that the Earth has a liquid external core, as proven by Richard Dixon Oldham.
A P-wave is one of the two main forms of elastic body waves, called are seismic waves in seismology. P-waves travel sooner than other seismic waves and therefore are the first signal from an earthquake to reach at any affected place or at a seismograph. P-waves can be transmitted through, liquids, gases or solids. The name P-wave can be either for pressure wave (as it is made from alternating densities and rarefactions) or primary wave (as it has high speed and is, therefore, a seismograph measures the first wave).
|Primary wave is the first wave that hit seismographs during Earthquake and records it|
They are compression waves
|They Can move through solids and liquids|
|They Shake the medium in the direction in which they are propagating|
The velocity of P-waves in a standardized isotropic medium is given by