The rate of noise-induced escape from a metastable state of a periodically
modulated overdamped system is found for an arbitrary modulation amplitude A.
The instantaneous escape rate displays peaks that vary with the modulation from
Gaussian to strongly asymmetric. The prefactor ν in the period-averaged
escape rate depends on A nonmonotonically. Near the bifurcation amplitude
Ac it scales as ν∝(Ac−A)ζ. We identify three scaling
regimes, with ζ=1/4,−1, and 1/2