An alternative to using potentials to find seismic wave solutions to the equation of motion in terms of displacements is to formulate wave equations for the dilatation and curl of the dissplacement field. To see this: (a) Take the divergence of the following equation to obtain a wave equation for the dilataion O. At what velocity does 0 propegate. PU(x, t) (A + 2) v (vdotU(x, t)) V cross(VcrossU (x, t)) =