The Elf Band As A Possible Spectral Window For Seismo-Ionospheric Diagnostics

Parameters of the electromagnetic instruments employed at the Ukrainian Antarctic station (UAS) Akademik Vernadsky for data collection in the ULF-ELF band are described briefly along with the methodology of polarization processing. Spectral and polarization parameters of resonant Alfven oscillations in the ionosphere (10 10 Hz) have been analyzed using the data of ELF electromagnetic monitoring at the UAS over the year 2006. As has been found, the discrete resonance structure of the ionospheric Alfven spectra is suppressed some time before a seismic event, to recover only hours later. Spectral parameters of Schumann resonances (10 Hz) may also show an observable reaction to a distant earthquake, which manifests itself as a re-distribution of power of odd and even harmonics. The broadband ELF magnetic noise component that was present in one of the records changed its polarization a few hours before a distant quake and showed a behavior markedly different from the regular one. All this confirms the existence of seismo-ionospheric coupling, allowing us to observe earthquake precursory phenomena in the ionosphere over the epicenter. © 2007 BBSCS RN SWS. All rights reserved.