Fractal analysis of the ground-recorded ULF magnetic fields prior to the 11 March 2011 Tohoku earthquake (M sub(W) = 9): discriminating possible earthquake precursors from space-sourced disturbances

The fractal characteristics of the ultra-low-frequency (ULF) magnetic field variations recorded prior to the Tohoku earthquake (EQ) with M sub(W) = 9 which happened on 11 March 2011 are studied in this article with the use of detrended fluctuation analysis and Higuchi fractal dimension algorithm. In...

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Bibliographic Details
Published in:Natural hazards (Dordrecht) 2017-01, Vol.85 (1), p.59-86
Main Authors: Potirakis, Stelios M, Hayakawa, Masashi, Schekotov, Alexander
Format: Article
Language:English
Subjects:
Algorithms
Earthquakes
Fractal analysis
Fractals
Magnetic fields
Mathematical analysis
Preprocessing
ULF
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Summary:The fractal characteristics of the ultra-low-frequency (ULF) magnetic field variations recorded prior to the Tohoku earthquake (EQ) with M sub(W) = 9 which happened on 11 March 2011 are studied in this article with the use of detrended fluctuation analysis and Higuchi fractal dimension algorithm. In the specific study, we use for our calculations only nighttime (LT = 3 a.m. plus or minus 2 h ) data because of their lowest contamination by industrial noise. A key aspect of our analysis is the investigation about any possible correlation of the ULF magnetic field variations or their calculated fractal characteristics with geomagnetic indices. Different preprocessing approaches are examined aiming at the minimization of any possible influences from global phenomena in the fractal analysis results, while in the same time retaining the scale-invariant character of ULF magnetic field variations after preprocessing. The obtained fractal analysis results imply locally driven change in the fractal characteristics of the ULF data prior to the Tohoku EQ, which is compatible with the change that has been reported prior to other large EQs.
ISSN:0921-030X
1573-0840
DOI:10.1007/s11069-016-2558-8