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Titel |
Magnetic storm free ULF analysis in relation with earthquakes in Taiwan |
VerfasserIn |
S. Wen, C.-H. Chen, H.-Y. Yen, T.-K. Yeh, J.-Y. Liu, K. Hattori, H. Peng, C.-H. Wang, T.-C. Shin |
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 ; 12, no. 5 ; Nr. 12, no. 5 (2012-05-25), S.1747-1754 |
Datensatznummer |
250010836
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Publikation (Nr.) |
copernicus.org/nhess-12-1747-2012.pdf |
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Zusammenfassung |
Despite early optimism, pre-earthquake anomalous phenomena can be determined
by using enhanced amplitude at the ultra-low-frequency range from
geomagnetic data via the Fourier transform. In reality, accuracy of the
enhanced amplitude in relation to earthquakes (deduced from time-varied
geomagnetic data) would be damaged by magnetic storms and/or other unwanted
influences resulting from solar activity and/or variations in the ionosphere,
respectively. We substitute values of the cross correlation between
amplitudes, summarized from the earthquake-related (0.1–0.01 Hz) and the
comparable (0.01–0.001 Hz) frequency bands, for isolated amplitude
enhancements as indexes of determination associated with seismo-magnetic
anomalies to mitigate disturbance caused by magnetic storms. A station
located about 300 km away from the others is also taken into account to
further examine whether changes of the cross correlation values are caused
by seismo-magnetic anomalies limited within local regions or not. Analytical
results show that the values suddenly decrease near epicenters a few days
before and after 67% (= 6/9) of earthquakes (M > = 5) in Taiwan between September 2010
and March 2011. Seismo-magnetic signals determined by using the values
of cross correlation methods partially improve results yielded from the
Fourier transform alone and provide advantageous information of earthquake
locations. |
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