  To characterize a destruction of Anderson localization by nonlinearity, we
study the spreading behavior of initially localized states in disordered,
strongly nonlinear lattices. Due to chaotic nonlinear interaction of localized
linear or nonlinear modes, energy spreads nearly subdiffusively. Based on a
phenomenological description by virtue of a nonlinear diffusion equation we
establish a one-parameter scaling relation between the velocity of spreading
and the density, which is confirmed numerically. From this scaling it follows
that for very low densities the spreading slows down compared to the pure power
law.
