  The only restriction on the values of the elasticity parameters is the
stability condition. Within this condition, we examine Christoffel equation for
nondetached $qP$ slowness surfaces in transversely isotropic media. If the $qP$
slowness surface is detached, each root of the solubility condition corresponds
to a distinct smooth wavefront. If the $qP$ slowness surface is nondetached,
the roots are elliptical but do not correspond to distinct wavefronts; also,
the $qP$ and $qSV$ slowness surfaces are not smooth.

Geophysics