Original title: Possible Seismic Influence on VLF Wave Intensity: Observations by a Low-Altitude Satellite
Translated title: Možný vliv zemětřesení na nízkofrekvenční elektromagnetické vlny: pozorování na družici s nízkou orbitou
Authors: Němec, František ; Santolík, Ondřej ; Parrot, M.
Document type: Papers
Conference/Event: Week of Doctoral Students 2008 /17./, Prague (CZ), 2008-06-03 / 2008-06-06
Year: 2008
Language: eng
Abstract: [eng] [cze]
We present results of a statistical study of VLF (up to 10 kHz) wave intensity measured by a low-altitude spacecraft in the vicinity of earthquakes. The data from the French DEMETER spacecraft (altitude about 700 km, nearly Sun-synchronous orbit) that was specially developed for such kind of studies are used. The recently developed two-step data processing method is briefly introduced and the main obtained results are reviewed. Finally, a simple independent test of the obtained results is done in order to give an additional evidence for the existence of possible seismic-related effect. Our results indicate that there is a decrease of power spectral density of electric field fluctuations shortly (0-4 hours) before the time of the main shock. This decrease was observed close to surface earthquakes (depth less than 40 km) with magnitude larger than or equal to 4.8 and only during the night. No similar effect was observed for deep earthquakes nor during the day. Výsledky statistické studie nízkofrekvenčních (f < 10 kHz) elektromagnetických vln pozorovaných na družici s nízkou orbitou v blízkosti zemětřesení. Naše výsledky indikují, že krátce (0-4 hodiny) před hlavním otřesem dochází k poklesu výkonové spektrální hustoty elektrických fluktuací. Tento efekt byl pozorován v blízkosti povrchových (hloubka menší než 40 km) zemětřesení s magnitudou větší nebo rovnou 4.8 během noci. Žádný podobný efekt nebyl pozorován během dne.
Keywords: DEMETER; seismo-electromagnetic effects; VLF electromagnetic waves
Project no.: CEZ:AV0Z30420517 (CEP), GA205/06/1267 (CEP), PICS-3725 (CEP)
Funding provider: GA ČR, CNRS/DREI
Host item entry: WDS'08 Proceedings of Contributed Papers: Part II - Physics of Plasmas and Ionized Media , ISBN 978-80-7378-066-1

Institution: Institute of Atmospheric Physics AS ČR (web)
Document availability information: Fulltext is available at the institute of the Academy of Sciences.
Original record: http://hdl.handle.net/11104/0173651

Permalink: http://www.nusl.cz/ntk/nusl-40348


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