Translations:Dictionary:Anisotropy (seismic)/3/en

• In isotropic media (the simplest case) there are only two independent constants among 12 nonzero elements of this matrix. These may be taken as the longitudinal modulus M and the shear modulus $\mu$. A non-zero linear combination, $\lambda =M-(2*\mu )$ also appears in the matrix. Other elastic parameters, such as the bulk modulus $K=M-(4/3)\mu$ may also be computed from these, see E-5. In the isotropic case, the longitudinal wave is exactly longitudinal (polarization vector exactly parallel to wave vector), and the two shear waves degenerate to one (with a velocity independent of polarization direction, which may lie anywhere within the plane exactly perpendicular to the wave vector, hence no shear-wave splitting).