Natural Hazards and Earth System Science www.nat-hazards-earth-syst-sci.net 1561-8633 1684-9981 8 1 2008 10.5194/nhess-8-135-2008 http://www.nat-hazards-earth-syst-sci.net/8/135/2008/ http://www.nat-hazards-earth-syst-sci.net/8/135/2008/nhess-8-135-2008.html http://www.nat-hazards-earth-syst-sci.net/8/135/2008/nhess-8-135-2008.pdf 135 141 2008-02-26 Detection of ionospheric perturbations associated with Japanese earthquakes on the basis of reception of LF transmitter signals on the satellite DEMETER F. Muto M. Yoshida T. Horie M. Hayakawa hayakawa@whistler.ee.uec.ac.jp M. Parrot O. A. Molchanov 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 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. 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