Displays of possible harbigers of earthquakes on recordings of VLF-signals depending on their characteristics

A complex of electromagnetic disturbances precedes an earthquake. One of the methods of searching for seismoionospheric effects in the D-region is a radiograph of the Earth-ionosphere waveguide by VLF waves. Such research of of the parameters of the environment allows to obtain additional information about the physical mechanisms of electromagnetic precursors of earthquakes, and the solution of the given problem is directly connected to forecasting possible time intervals between the beginning of preparation and the moment of the earthquake. Records of VLF-signal amplitude show abnormal variations of different intensity above the seismically active region before and after strong earthquakes. The validity of the dependence between the registered disturbances and earthquakes can be experimentally proven either by a statistical method based on general regularities, or by the presence of special characteristics in the signal, inherent to the specific process with regard to the geophysical conditions as a whole