1. n. [Geophysics]
The process of changing volume as stress is applied to a body.
3. n. [Geophysics]
A rarefaction, or decrease in pressure and density of a medium as molecules are displaced by a P-wave. As P-waves pass through the Earth, the Earth undergoes compression and expansion. These changes in volume contribute to the positive and negative amplitudes of a seismic trace.
Alternate Form: rarefaction
See related terms: amplitude, P-wave, seismic trace
