NHESS Natural Hazards and Earth System Sciences NHESS Nat. Hazards Earth Syst. Sci. 1684-9981 Copernicus Publications Göttingen, Germany 10.5194/nhess-8-135-2008 Detection of ionospheric perturbations associated with Japanese earthquakes on the basis of reception of LF transmitter signals on the satellite DEMETER Muto F. 1 Yoshida M. 1 Horie T. 1 Hayakawa M. 1 Parrot M. 2 Molchanov O. A. 3 Department of Electronic Engineering and Research Station on Seismo Electromagnetics, University of Electro-Communications, Chofu Tokyo, Japan LPCE/CNRS, Orleans, France Institute of Physics of the Earth, Moscow, Russia 26 02 2008 8 1 135 141 Copyright: © 2008 F. Muto et al. 2008 This work is licensed under the Creative Commons Attribution-NonCommercial-ShareAlike 2.5 Generic License. To view a copy of this licence, visit https://creativecommons.org/licenses/by-nc-sa/2.5/ This article is available from https://nhess.copernicus.org/articles/8/135/2008/nhess-8-135-2008.html The full text article is available as a PDF file from https://nhess.copernicus.org/articles/8/135/2008/nhess-8-135-2008.pdf

There have been recently reported a lot of electromagnetic phenomena associated with earthquakes (EQs). Among these, the ground-based reception of subionospheric waves from VLF/LF transmitters, is recognized as a promising tool to investigate the ionospheric perturbations associated with EQs. This paper deals with the corresponding whistler-mode signals in the upper ionosphere from those VLF/LF transmitters, which is the counterpart of subionospheric signals. The whistler-mode VLF/LF transmitter signals are detected on board the French satellite, DEMETER launched on 29 June 2004. We have chosen several large Japanese EQs including the Miyagi-oki EQ (16 August 2005; M=7.2, depth=36 km), and the target transmitter is a Japanese LF transmitter (JJY) whose transmitter frequency is 40 kHz. Due to large longitudinal separation of each satellite orbit (2500 km), we have to adopt a statistical analysis over a rather long period (such as 3 weeks or one month) to have reliable data set. By analyzing the spatial distribution of JJY signal intensity (in the form of signal to noise ratio SNR) during a period of 4 months including the Miyagi-oki EQ, we have found significant changes in the intensity; generally the SNR is significantly depleted before the EQ, which is considered to be a precursory ionospheric signature of the EQ. This abnormal effect is reasonably explained in terms of either (1) enhanced absorption of whistler-mode LF signals in the lower ionosphere due to the lowering of the lower ionosphere, or (2) nonlinear wave-wave scattering. Finally, this analysis suggests an important role of satellite observation in the study of lithosphere-atmosphere-ionosphere coupling.

 References Bell, T. F., James, H. G., Inan, U. S., and Katsufrakis, J. P.: The apparent spectral broadening of VLF transmitter signals during transionospheric propagation, J. Geophys. Res., 88, 4813–4816, 1983. Biagi, P. F., Castellana, L., Maggipinto, T., Maggipinto, G., Minafra, A., Ermini, A., Capozzi, V., Perna, G., Solovieva, M., Rozhnoi, A., Molchanov, O. A., and Hayakawa, M.: Decrease in the electric intensity of VLF/LF radio signals and possible connections, Nat. Hazards Earth Syst. Sci., 7, 423–430, 2007. Hayakawa, M.: Atmospheric and Ionospheric Electromagnetic Phenomena Associated with Earthquakes, Terra Sci. Pub. Co., Tokyo, 996 pp., 1999. Hayakawa, M.: Electromagnetic phenomena associated with earthquakes: A frontier in terrestrial electromagnetic noise environment, Recent Res. Devel. Geophysics, 6, 81–112, 2004. Hayakawa, M. and Molchanov, O. A.: NASDA/UEC team, Summary report of NASDA's earthquake remote sensing frontier project, Phys. Chem. Earth, 29, 617–625, 2004. Hayakawa, M., Molchanov, O. A., Ondoh, T., and Kawai, E.: The precursory signature effect of the Kobe earthquake on VLF subionospheric signals, J. Comm. Res. Lab., Tokyo, 43, 169–180, 1996. Hayakawa, M.: Whistlers, Chapt. 7, in: Handbook of Atmospheric Electrodynamics, edited by: Volland, H., vol.II, CRC Press, 155–193, 1995. Hayakawa, M. and Molchanov, O. A.: Seismo Electromagnetics: Lithosphere-Atmosphere – Ionosphere Coupling, TERRAPUB, Tokyo, 477 pp., 2002. Hobara, Y. and Parrot, M. : Ionospheric perturbations linked to a very powerful seismic event, J. Atmos. Solar-Terr. Phy., 67, 677–685, 2005. Hobara, Y., Lefeuvre, F., Parrot, M., and Molchanov, O. A.: Low latitude ionospheric turbulence observed by Aureol-3 satellite, Ann. Geophys., 23, 1259–1270, 2005. Horie, T., Maekawa, S., Yamauchi, T., and Hayakawa, M.: A possible effect of ionospheric perturbations associated with the Sumatra earthquake, as revealed from subionospheric very-low-frequency (VLF) propagation (NWC-Japan), Int. J. Remote Sensing, 28, 13, 3133–3139, 2007a. Horie, T., Yamauchi, T., Yoshida, M., and Hayakawa, M.: The wave-like structures of ionospheric perturbation associated with Sumatra earthquake of 26 December 2004, as revealed from VLF observation in Japan of NWC signals, J. Atmos. Solar-Terr. Phy., 69, 1021–1028, 2007b. Liu, J. Y., Chen, Y. I., Pulinets, S. A., Tsai, Y. B., and Chuo, Y. J.: Seismo-ionospheric signatures prior to M$>$6.0 Taiwan earthquakes, Geophys. Res. Lett., 27, 3113–3116, 2000. Liu, J. Y., Chen, Y. I., Chuo, Y. J., and Chen, C. S.: A statistical investigation of preearthquake ionospheric anomaly, J. Geophys. Res., 111, A05304, https://doi.org/10.1029/2005JA011333, 2006. Maekawa, S., Horie, T., Yamauchi, T., Sawaya, T., Ishikawa, M., Hayakawa, M., and Sasaki, H.: A statistical study on the effect of earthquakes on the ionosphere, based on the subionospheric LF propagation data in Japan, Ann. Geophys., 24, 2219–2225, 2006. Miyaki, K., Hayakawa, M., and Molchanov, O. A.: The role of gravity waves in the lithosphere-ionosphere coupling, as revealed from the subionospheric LF propagation data, in: Seismo Electromagnetics: Lithosphere-Atmosphere-Ionosphere Coupling, edited by: Hayakawa, M. and Molchanov, O. A., TERRAPUB, Tokyo, 229–232, 2002. Molchanov, O. A., Akentieva, O. S., Afonin, V. V., Mareev, E. A., and Fedorov, E. N.: Plasma density-electric field turbulence in the low-latitude ionosphere from the observation on satellites; possible connection with seismicity, Phys. Chem. Earth, 29, 569–577, 2004. Molchanov, O. A., Rozhnoi, A., Solovieva, M., Akentieva, O., Berthelier, J. J., Parrot, M., Lefeuvre, F., Biagi, P. F., Castellana, L., and Hayakawa, M.:Global diagnostics of the ionospheric perturbations related to the seismic activity using the VLF radio signals collected on the DEMETER satellite, Nat. Hazards Earth Syst. Sci., 6, 745–753, 2006. Molchanov, O. A., Hayakawa, M., and Miyaki, K.: VLF/LF sounding of the lower ionosphere to study the role of atmospheric oscillations in the lithosphere-ionosphere coupling, Adv. Polar Upper Atmos. Res., 15, 146–158, 2001. Molchanov, O. A. and Hayakawa, M.: Subionospheric VLF signal perturbations possibly related to earthquakes, J. Geophys. Res., 103, 17, 489-17, 504, 1998. Molchanov, O. A. and Hayakawa, M.: Seismo-electromagnetics and Related Phenomena: History and Latest Results, TERRAPUB, in press, 2008. Parrot, M.: First results of the DEMETER micro-satellite, Planet. Space Sci., 54, 5, 2006. Rozhnoi, A., Solovieva, M. S., Molchanov, O. A., and Hayakawa, M.: Middle latitude LF (40 kHz) phase variations associated with earthquakes for quiet and disturbed geomagnetic conditions, Phys. Chem. Earth, 29, 589–598, 2004. Sorokin, V. M., Yaschenko, A. K., Chmyrev, V. M., and Hayakawa, M.: DC electric field amplification in the mid-latitude ionosphere over seismically active faults, Nat. Hazards Earth Syst. Sci., 5, 661–666, 2005.