Initial value problem for the third-order nonlinear evolution equation
governing wave propagation in relaxing media is considered for the ca
se of two space dimensions and small initial data. Existence and uniqu
eness of the classical solution is established and the solution itself
is constructed in the form of a series in the small parameter present
in the initial conditions. Long time asymptotic representation is fou
nd, which shows that the nonlinearity does not contribute to its major
term, The latter consists of mio parts corresponding to isotropic and
nonisotropic transfer of small perturbations in space.