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

A. Rozhnoi (1) , M. Solovieva (1) , O. Molchanov (1) , P.-F. Biagi (2) , M. Hayakawa (3)

1 IPE - Schmidt United Institute of Physics of the Earth [Moscow]
2 UNIBA - Università degli studi di Bari Aldo Moro = University of Bari Aldo Moro
3 UEC - University of Electro-Communications [Tokyo]

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.

Domaines: Interfaces continentales, environnement; Océan, Atmosphère; Sciences de la Terre

A. Rozhnoi, M. Solovieva, O. Molchanov, P.-F. Biagi, M. Hayakawa. Observation evidences of atmospheric Gravity Waves induced by seismic activity from analysis of subionospheric LF signal spectra. Natural Hazards and Earth System Sciences, 2007, 7 (5), pp.625-628. ⟨hal-00299458⟩