Abstract: A system and method for controlling actuation of a vehicle safety device in response to an impact to a first portion of the vehicle includes a ferromagnetic element mechanically coupled with the first portion of the vehicle so as to receive elastic strain waves generated as a result of plastic deformation of the first portion of the vehicle. A permanent magnet is mounted on the vehicle adjacent to the ferromagnetic element so that the ferromagnetic element itself influences the magnetic field. An induction coil is also mounted on the vehicle so as to fall within the magnetic field generated by the magnet. Upon plastic deformation of the first portion of the vehicle, the ensuing elastic strain waves elastically deform the ferromagnetic element to vary its ferromagnetic properties and, in turn, alter the magnetic field so as to induce an electromotive force voltage in the induction coil. A signal processor receives the electromotive force voltage induced in the induction coil by the varying magnetic field.