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| Titel |
Variations of the critical foE-frequency of the ionosphere connected with earthquakes. Evaluation of observations of the vertical sounding station “Tokyo” |
| VerfasserIn |
Elena V. Liperovskaya, Claudia-Veronika Meister, Dieter H. H. Hoffmann, Alexandra S. Silina |
| Konferenz |
EGU General Assembly 2016
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 18 (2016) |
| Datensatznummer |
250123321
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| Publikation (Nr.) |
 EGU/EGU2016-2552.pdf |
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| Zusammenfassung |
| In the present work the critical frequencies foE and foF2 of the ionosphere are
considered as possible earthquake precursors. The statistical analysis of the critical
frequencies is carried out based on the data of the vertical sounding station (VSS)
“Kokubunji” (“Tokyo”) (ϕ = 35.7o N, λ = 139.5o E, 1957-1988) obtained every hour.
Disturbances are considered on the background of seasonal, geomagnetic as well as
11-years and 27-days Solar variations. Special normalized parameters E and F are
introduced, which represent the almost seasonal-independent parts of foE and foF2. Days
with high Solar (Wolf number > 100) and geomagnetic (ΣKp > 25) activities
are excluded from the analysis. For all data (observed every hour) analysed, no
correlations of the normalized parameters E and F are found. One day before the
seismic shock, a positive correlation is observed. The superimposed epochs method
is used to determine the temporal behaviour of E and F. It is found that E and F
decrease one day before the earthquakes provided that the seismic shocks occur at
distances 600 < R < 1000 km from the VSS, and that the focus of earthquakes with
magnitudes M > 5.5 is situated at depths smaller than 60 km. The reliability of the
effect is larger than 98 %. Possible physical mechanisms of the phenomenon are
discussed. |
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