Variations in the parameters of thunderstorm electromagnetic signals on paths over earthquake regions |
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| Authors: | V A Mullayarov L M Abzaletdinova V V Argunov A A Korsakov |
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| Institution: | 1.Shafer Institute of Cosmophysical Research and Aeronomy, Siberian Branch,Russian Academy of Sciences,Yakutsk,Russia |
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| Abstract: | The specific features of a method for radiosounding the lower ionosphere over earthquake epicenters using LF electromagnetic
signals of thunderstorm sources (atmospherics) have been considered. The effects of shallow-focus earthquakes with magnitudes
larger than 4.0 and their precursors manifest themselves in amplitude characteristics of atmospherics. It has been assumed
that variations in the signal characteristics are related to disturbances in the lower ionosphere. According to the results
of azimuthal scanning, cross-sectional dimensions of disturbed regions, as a rule, correspond to the dimensions of the first
two Fresnel zones for signals at a frequency of 10 kHz. Azimuthal scanning also indicated that the positions of disturbed
regions during and before earthquakes could have a certain dynamics and differ from the projection onto the earthquake epicenter.
The ratio of the amplitudes of electric and magnetic signal components, in the variations of which seismic effects before
earthquakes can also be observed, has been considered. An analysis of the ratio makes it possible to increase the probability
of predicting earthquakes when using the characteristics of the electromagnetic signals of lightning discharges as an additional
method of complex monitoring of disturbances in the lower ionosphere caused by seismic processes. |
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