P waves are also called Pressure waves for this reason. Longitudinal waves are waves in which the displacement of the medium is in the same direction as, or the opposite direction to, the direction of propagation of the wave. The other main type of wave is the transverse wave, in which the displacements of the me P-waves travel faster than other seismic waves and hence are the first signal from an earthquake to arrive at any affected location or at a seismograph. They leave behind a trail of compressions and rarefactions on the medium they move through. P waves, or Primary waves, are the first waves to arrive at a seismograph. A P-wave is one of the two main types of elastic body waves, called seismic waves in seismology. They are responsible, in particular, for the terrifying sounds accompanying large earthquakes. The P (primary) seismic waves are also longitudinal. Although solids also support transverse waves (known as Gerald E. Marsh (1996), Force-free Magnetic Fields, World Scientific, P waves are the fastest seismic waves and can move through solid, liquid or gas. The P waves travel with the fastest velocity and are the first to arrive. For the term used in electrocardiography, see The equations for sound in a fluid given above also apply to acoustic waves in an elastic solid. However, where a free surface is present (like the Earth–air interface) these two types of motion can combine to form complex surface waves. "Longitudinal waves" and "transverse waves" have been abbreviated by some authors as "L-waves" and "T-waves," respectively, for their own convenience.In the case of longitudinal harmonic sound waves, the The wavelength can be calculated as the relation between a wave's speed and ordinary frequency. The P waves (Primary waves) in an earthquake are examples of Longitudinal waves. To see a animations of spherical longitudinal waves check out: Sound Radiation from Simple Sources; Radiation from Cylindrical Sources. For sound waves, the amplitude of the wave is the difference between the pressure of the undisturbed air and the maximum pressure caused by the wave. In a longitudinal wave, each particle of matter vibrates about its normal rest position and along the axis of propagation , and all particles participating in the wave motion behave in the same manner, except that there is a progressive change in phase ( q.v. ) The motion and behavior of both Almost all the information available on the structure of the Earth's deep interior is derived from observations of the travel times, Advance earthquake warning is possible by detecting the nondestructive primary waves that travel more quickly through the Earth's crust than do the destructive The amount of advance warning depends on the delay between the arrival of the P-wave and other destructive waves, generally on the order of seconds up to about 60 to 90 seconds for deep, distant, large quakes such as the In typical situations the interior of the Earth, the density Typical values for P-wave velocity in earthquakes are in the range 5 to 8 km/s.
The precise speed varies according to the region of the Earth's interior, from less than 6 km/s in the Earth's crust to 13.5 km/s in the lower mantle, and 11 km/s through the inner core.This article is on the type of seismic wave. P-waves may be transmitted through gases, liquids, or solids. Mechanical longitudinal waves are also called compressional or compression waves, because they produce compression and rarefaction when traveling through a medium, and pressure waves, because they produce increases and decreases in pressure. Although often ignored in introduct… Primary and secondary waves are body waves that travel within the Earth. Through the body of the Earth these are called P-waves (for primary because they are fastest) and S-waves (for secondary since they are slower). Seismic waves are fundamentally of two types, compressional, longitudinal waves or shear, transverse waves. P Waves (Longitudinal Waves) For longitudinal waves, the direction of propagation coincides with the direction of vibration of the medium.