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| Titel |
Fractal analysis for the ULF data during the 1993 Guam earthquake to study prefracture criticality |
| VerfasserIn |
Y. Ida, M. Hayakawa |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1023-5809
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| Digitales Dokument |
URL |
| Erschienen |
In: Nonlinear Processes in Geophysics ; 13, no. 4 ; Nr. 13, no. 4 (2006-08-11), S.409-412 |
| Datensatznummer |
250011810
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| Publikation (Nr.) |
 copernicus.org/npg-13-409-2006.pdf |
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| Zusammenfassung |
| An extremely large earthquake (with magnitude of 8.2) happened on
8 August 1993 near the Guam island, and ultra-low-frequency (ULF) (frequency
less than 1 Hz) electromagnetic fields were measured by 3-axis induction
magnetometers at an observing station (with the epicentral distance of 65 km)
with sampling frequency of 1 Hz. In order to study electromagnetic signature
of prefracture criticality, we have undertaken the fractal (mono-fractal)
analysis by means of the Higuchi's method for the ULF data during the 1993
Guam earthquake. Then, it is found that the fractal dimension exhibits five
maxima 99, 75, 52, 21, and 9–4 days before the earthquake main shock, which
suggests the ULF electromagnetic signature of nonlinear evolution (in the
sense of self-organized criticality) taking place in the lithosphere just
before the 1993 large Guam earthquake. That is, there take place step-like
changes in the lithosphere during the long-term of the order of several
months before the main shock. |
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