This paper is concerned with the problem of the generation of low-frequency Alfven and fast magnetosonic (FMS) waves due to excitation of the conductive gyrotropic E layer of the ionosphere. The wave source is a system of currents excited in the ionosphere (e.g., by an acoustic wave due to an earthquake or any other reason). A theoretical model is considered using equations with the constant Hall and Pedersen conductivities for the E region; the upper regions are described by equations for a cold collisionless plasma. The case of the vertical magnetic field is investigated. The main purpose of this work is to research the influence of the dispersion properties of the ionosphere on the front structure of the Alfven and FMS waves radiated into the Earth's magnetosphere. It has been shown that the main features of the signal are brought about by processes such as the oscillatory current diffusion across the E layer. The function describing the wave front is an oscillatory one; the oscillation period increasing in time. The universal character of this dependence allows us to deduce that in this frequency range there is a strong dispersion of signals passing the ionosphere. This unique effect can be explained by the affect of the Hall conductivity on the E layer. ¿ American Geophysical Union 1996