As a seismologist with extensive experience in the study of earthquakes and the seismic waves they produce, I can explain the function of P waves. P waves, or primary waves, are the first type of body wave to arrive at seismic stations after an earthquake. They are characterized by their high frequency and compressional nature, meaning they cause particles of the medium through which they travel to oscillate back and forth in the direction of the wave's propagation. P waves are faster than other types of seismic waves because they can travel through both solid and liquid layers of the Earth, including the mantle and the outer core. This ability to travel through different mediums allows P waves to reach seismic stations before other waves, such as S waves (secondary waves), which can only travel through solids. The arrival time of P waves is critical for seismologists as it helps them determine the distance to the earthquake's epicenter and provides valuable information about the Earth's interior structure. read more >>

Earthquakes radiate seismic energy as both body and surface waves. Traveling through the interior of the earth, body waves arrive before the surface waves emitted by an earthquake. These waves are of a higher frequency than surface waves. The first kind of body wave is the P wave or primary wave.read more >>