A scale, composed of 12 increasing levels of intensity that range from imperceptible shaking to catastrophic destruction, that is designated by Roman numerals. Named for Andrija Mohorovicic, the Croatian seismologist who first suggested its existence. P wave Primary, longitudinal, irrotational, push, pressure, dilatational, compressional, or push-pull wave. P waves are the fastest body waves and arrive at stations before the S waves, or secondary waves. The waves carry energy through the Earth as longitudinal waves, moving particles in the same line as the direction of the wave.
P waves can travel through all layers of the Earth.
P waves are generally felt by humans as a bang or thump. The natural magnetic traces that reveal the intensity and direction of Earth's magnetic field in the geologic past. Also, the study of these magnetic traces. The time between two successive wave crests. The onset of a displacement or oscillation on a seismogram indicating the arrival of a different type of seismic wave.