  We present numerical simulations of coupled Ginzburg-Landau equations
describing parametrically excited waves which reveal persistent dynamics due to
the occurrence of phase slips in sequential pairs, with the second phase slip
quickly following and negating the first. Of particular interest are solutions
where these double phase slips occur irregularly in space and time within a
spatially localized region. An effective phase diffusion equation utilizing the
long term phase conservation of the solution explains the localization of this
new form of amplitude chaos.
