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| Titel |
Results of subionospheric radio LF monitoring prior to the Tokachi (M=8, Hokkaido, 25 September 2003) earthquake |
| VerfasserIn |
A. V. Shvets, M. Hayakawa, S. Maekawa |
| 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 ; 4, no. 5/6 ; Nr. 4, no. 5/6 (2004-10-19), S.647-653 |
| Datensatznummer |
250001380
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| Publikation (Nr.) |
 copernicus.org/nhess-4-647-2004.pdf |
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| Zusammenfassung |
| Results of simultaneous LF subionospheric monitoring over two different
propagation paths prior to the very strong Tokachi earthquake (near the east
coast of Hokkaido Island, 25 September 2003) of magnitude 8.3 are presented
firstly. Nighttime amplitude fluctuations of the Japanese Time Standard
Transmitter (JG2AS, 40kHz) signal received at Moshiri (Japan, 142°E,
44°N) and at Petropavlovsk-Kamchatski (Russia, 158°E, 53°N)
were analyzed. As a possible precursory signature we observed synchronous
intensification of quasi periodical 16-day variations of the dispersion in
the signals received at both observation stations before the earthquake. The
strongest deviations observed as a rule were depletions of signal amplitude
probably connected with increase of loss in the ionosphere by the
enhancement of turbulence. This is due to dissipation of internal gravity
waves (IGW) at the lower ionosphere heights. A scheme for
seismo-IGW-planetary waves (PW) interconnection has been justified to
explain the observed connection with strong earthquakes. It considers the
seasonal variability in the signal. |
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