Abstract
Abstract. Very low frequency (VLF) electromagnetic radiation (in diapason 1 kHz–1 MHz) in the atmosphere, generated during an earthquake preparation period, may be connected with the linear size characterising the expected earthquake focus. In order to argue this hypothesis, a very simple quasi-electrostatic model is used: the local VLF radiation may represent the self-generated (own) electromagnetic oscillations of interactive seismoactive segments of the lithosphere-atmosphere system. This model qualitatively explains the well-known precursor effects of earthquakes. In addition, using this model after diagnosing existing data makes it principally possible to forecast an expected earthquake with certain precision. As a physical basis of the working hypothesis is the atmospheric effect of polarization charges occurring in the surface layer of the Earth, it is possible to test the following constructed model in the Earth's crust, where the reason for polarization charge generation may be different from piezo-electric mechanism, e.g., some other mechanism.
Highlights
In a solid medium, some considerable accumulation of polarization charge may take place in such an environment where heterogeneity having definite scale lines, is already formed or is being formed
It is possible that the total length of the canal with high electric conductivity, is related to the Very low frequency (VLF) electromagnetic emission according to Eq (2)
It may mean that during earthquakes preparing period, before origination of the main fault there are plenty of cracks to which electromagnetic emission with characteristic MHz frequencies correspond, and as the cracks begin to join in the main fault, a range of KHz frequencies appear in the electromagnetic spectrum
Summary
Some considerable accumulation of polarization charge may take place in such an environment where heterogeneity having definite scale lines, is already formed or is being formed. As to ULF diapason, it seems that it is caused by magnetic field perturbations, the reason of which may be inside the Earth, as well as current processes in the conductive atmosphere (Bleier et al, 2009) Though there exists another version according to which the electric oscillations frequency variation in the ionosphere is not necessarily connected with seismic phenomena only. A sharp change of electric conduction of the lithospheric medium prior to an earthquake and its subsequent atmospheric effect caused by the emanation of charged particles or ionization of the medium may be considered as a special case (Freund, 2006). It seems that such phenomenon is very rare. There would have been some considerable materials quantitatively strengthening, e.g., a qualitative model of VLF radiation constructed on the principle of the sharp break of electric conduction of medium (Yoshino, 1991)
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