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Titel |
Possible seismo-ionosphere perturbations revealed by VLF signals collected on ground and on a satellite |
VerfasserIn |
A. Rozhnoi, O. Molchanov, M. Solovieva, V. Gladyshev, O. Akentieva, J. J. Berthelier, M. Parrot, F. Lefeuvre, M. Hayakawa, L. Castellana, P. F. Biagi |
Medientyp |
Artikel
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Sprache |
Englisch
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ISSN |
1561-8633
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Digitales Dokument |
URL |
Erschienen |
In: Natural Hazards and Earth System Science ; 7, no. 5 ; Nr. 7, no. 5 (2007-10-25), S.617-624 |
Datensatznummer |
250004737
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Publikation (Nr.) |
copernicus.org/nhess-7-617-2007.pdf |
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Zusammenfassung |
The results of the monitoring of three VLF/LF signals collected in
Petropavlovsk station (Kamchatka, Russia) and one VLF signal collected on
board of the DEMETER French satellite are presented. Two periods of the
seismic activity occurred in the Japan-Kamchatka area during
November–December 2004 and July–September 2005 were investigated and the
earthquakes with M≥6.0 in the Japan-Kamchatka area, located inside
one or more of the third Fresnel zones of the three radio paths were
considered. The ground data were analysed using residual signal of phase dP
or of amplitude dA, defined as the difference between the signal and the
average of few quiet days (±5 days) immediately preceding or following
the current day. Also the satellite data were processed by a method based on
the difference between the real signal and the reference one, but in order
to obtain this last signal it was necessary to construct previously a model
of the signal distribution over the selected area. The method consists: (a)
in averaging all the data available in the considered region over a period
characterized by low level seismicity, regardless of the global
disturbances, in particular, of the magnetic activity; (b) in computing a
polynomial expression for the surface as a function of the longitude and the
latitude. The model well describes the real data in condition of their
completeness and in absence of magnetic storms or seismic forcing. In the
quoted periods of seismic activity clear anomalies both in the ground and in
satellite data were revealed. The influence of the geomagnetic activity
cannot to be excluded, but the seismic forcing seems more probable. |
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