Very low frequency (VLF) electromagnetic radiation (in diapason 1 kHz – 1 MHz) in atmosphere, generated during earthquake preparation period, may be connected with linear size, characterizing incoming earthquake source. In order to argue this hypothesis very simple quasi-electrostatic model is used: local VLF radiation may be the manifestation of own electromagnetic oscillations of concrete seismoactive segments of lithosphere-atmosphere system. This model explains qualitatively well-known precursor effects of earthquakes. At the same time, it will be principally possible to forecast expected earthquake with certain precision if we use this model after diagnosing existed data. <br><br> As physical basis of working hypothesis is atmospheric effect of polarization charges occurred in surface layer of the Earth, it is possible to test the below constructed model in medium, where reasons of polarization charge generation may be different from piezoelectric mechanism, for example, due to electrolytic hydration