Abstract. Data from the low-orbiting satellite COSMOS-1809 were used to search for a correlation between seismic activity and increases in ELFNLF emissions and plasma density fluctuations for different regions. The data of ∼ 100 revolution of satellite were chosen for the analysis of ionospheric effects of this seismic activity. Analysis enables to draw the following conclusions. The electromagnetic emissions in the frequency range of 140–450 Hz arc regularly observed within the L-shells with the root in the seismoactive zone. Near a zone of seismic activity (Δλ = ±6) at the altitude ∼ 950 km bursts of ELF radiation are observed at the frequencies f = 140 and 450 Hz in the magnetic and electric components. The radiation excess above the background level can reach more than an order of magnitude. The radiation bursts are observed minutes to hours beforehand an earthquake and during several hours after it. The sizes of the disturbed region are usually ∼ 400–600 km, and greater in the period of aftershock activity than during the earthquake development. The small-scale plasma irregularities dN_e/N_e ∼ 3–8% with characteristic scales 4–10 km along the orbit has been revealed in geomagnetic field tubes connected with epicentral region in which seismogenic ELF emissions were observed simultaneously. The empirical models of distribution of ELF-emissions for different regions was constructed on the basis of statistical study of this measurements. For these regions amplitude-spatial distributions of siesmoelectromagnetic radiation were constructed both for electric and magnetic components and distributions of the signal (-to-) noise ratio were constructed as well. Analysis of seismogenic ELENLF radiation had shown that main signal characteristics (frequency, amplitude, etc.) were sufficiently different for different seismoactive regions of the Earth. This fact is evidence of seismoelectromagnetic parameters dependence on physical-chemical properties of Earth's crust and lithospheric processes. Characteristic features of ELFNLF radiation related lo submarine earthquakes were exposed (radiation of higher frequences, up to 15 kHz, were observed). It is obvious in the present case that amplification of natural ELFNLF radiation take place, because electromagnetic connection between lithosphere and ionosphere is absent.

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