Articles | Volume 7, issue 5
Nat. Hazards Earth Syst. Sci., 7, 625–628, 2007

Special issue: Seismo-tectonic electromagnetic effects and precursory...

Nat. Hazards Earth Syst. Sci., 7, 625–628, 2007

  26 Oct 2007

26 Oct 2007

Observation evidences of atmospheric Gravity Waves induced by seismic activity from analysis of subionospheric LF signal spectra

A. Rozhnoi1, M. Solovieva1, O. Molchanov1, P.-F. Biagi2, and M. Hayakawa3 A. Rozhnoi et al.
  • 1Institute of the Earth Physics, RAS, Bolshaya Gruzinskaya 10, Moscow, Russia
  • 2University of Bari, Bari, Italy
  • 3University of Electro-Communications, Chofu, Tokyo, Japan

Abstract. We analyze variations of the LF subionospheric signal amplitude and phase from JJY transmitter in Japan (F=40 kHz) received in Petropavlovsk-Kamchatsky station during seismically quiet and active periods including also periods of magnetic storms. After 20 s averaging, the frequency range of the analysis is 0.28–15 mHz that corresponds to the period range from 1 to 60 min. Changes in spectra of the LF signal perturbations are found several days before and after three large earthquakes, which happened in November 2004 (M=7.1), August 2005 (M=7.2) and November 2006 (M=8.2) inside the Fresnel zone of the Japan-Kamchatka wavepath. Comparing the perturbed and background spectra we have found the evident increase in spectral range 10–25 min that is in the compliance with theoretical estimations on lithosphere-ionosphere coupling by the Atmospheric Gravity Waves (T>6 min). Similar changes are not found for the periods of magnetic storms.