Dictionary:P-wave

Series	Geophysical Reference Series
Author	Robert E. Sheriff
DOI	http://dx.doi.org/10.1190/1.9781560802969
ISBN	978-1-56080-118-4
Store	SEG Online Store

An elastic body wave in which particle motion is in the direction of propagation. The type of seismic wave assumed in conventional seismic exploration. Also called primary wave (undae primae), compressional wave, longitudinal wave, push-pull wave, pressure wave, dilatational wave, rarefaction wave, and irrotational wave. In an isotropic homogeneous solid, the P-wave velocity V_P can be expressed in terms of the elastic constants and the density (ρ):

$V_{\mathrm {P} }={\sqrt {\frac {\lambda +2\mu }{\rho }}}={\sqrt {\frac {E(1-\sigma )}{\rho (1-2\sigma )(1+\sigma )}}}={\sqrt {\frac {K+{\frac {4}{3}}\mu }{\rho }}}$

where λ and μ are the Lamé constants, E is Young’s modulus, K is the bulk modulus, and σ is Poisson’s ratio. See also wave notation and Sheriff and Geldart (1995, 44–45).