Nonlinear corrections to the frequencies of surface and subsurface waves in a laminated heterogeneous liquid

Nonlinear corrections to the frequencies of surface and subsurface waves are obtained in calculations of the third order of smallness in dimensionless amplitude. It is found that the corrections are of a resonance character; that is, they indefinitely grow at certain values of physical quantities, going out of an asymptotic limit. Under resonance conditions, the nonlinear correction to the frequency of waves on the free surface may change sign and so both increase and decrease the frequency. At the interface, the nonlinear correction to the frequency is everywhere negative except in the neighborhood of the resonance point. Therefore, it decreases the frequencies of the waves as a rule.