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| Titel |
Anomalous ELF phenomena in the Schumann resonance band as observed at Moshiri (Japan) in possible association with an earthquake in Taiwan |
| VerfasserIn |
M. Hayakawa, A. P. Nickolaenko, M. Sekiguchi, K. Yamashita, Y. Ida, M. Yano |
| 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 ; 8, no. 6 ; Nr. 8, no. 6 (2008-12-02), S.1309-1316 |
| Datensatznummer |
250005902
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| Publikation (Nr.) |
 copernicus.org/nhess-8-1309-2008.pdf |
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| Zusammenfassung |
| The ELF observation at Moshiri (geographic coordinates: 44.29° N,
142.21° E) in Hokkaido, Japan, was used to find anomalous phenomena in
the Schumann resonance band, possibly associated with a large earthquake
(magnitude of 7.8) in Taiwan on 26 December 2006. The Schumann resonance
signal (fundamental (n=1), 8 Hz; 2nd harmonic, 14 Hz, 3rd harmonic, 20 Hz,
4th, 26 Hz etc.) is known to be supported by electromagnetic radiation
from the global thunderstorms, and the anomaly in this paper is
characterized by an increase in intensity at frequencies from the third to
fourth Schumann resonance modes mainly in the BEW component with a
minor corresponding increase in the BNS component also. Spectral
modification takes place only in the interval of 21:00 UT±1 h, which
corresponds to the global lightning activity concentrated in America. While
distortions were absent in other lightning-active UT intervals, in
particular, around 08:00 UT±1 h (Asian thunderstorms) and around 15±1 h
(African lightning activity). The anomaly occurred on 23 December three days
prior to the main shock. The results observed were explained in
terms of ELF radio wave perturbation caused by the lower ionospheric
depression around the earthquake epicenter. The difference in the path
lengths between the direct radio wave from an active global thunderstorm
center and the wave scattered from the non-uniformity above Taiwan causes
interference at higher resonance modes, which is successful in explaining
the observational data. |
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