Two fundamental quantities for characterizing nonlinear wave phenomena in plasmas are the spectral energy transfer associated with the energy redistribution between Fourier modes, and the linear growth rate. It is shown how these quantities can be estimated simultaneously from dual-spacecraft data using Volterra series models. We consider magnetic field data gathered upstream the Earth's quasiparallel bow shock, in which Short Large Amplitude Magnetic Structures (SLAMS) supposedly play a leading role. The analysis attests the dynamic evolution of the SLAMS and reveals an energy cascade toward high-frequency waves. These results put constraints on possible mechanisms for the shock front formation. ¿ 1999 American Geophysical Union