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

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• 作者：Stelios M. Potirakis ; Masashi Hayakawa ; Alexander Schekotov
• 关键词：ULF magnetic fields ; Earthquake (EQ) ; Ionosphere ; Higuchi fractal dimension ; Detrended fluctuation analysis ; Seismo ; electromagnetics ; The 2011 Tohoku EQ ; Time series analysis ; Criticality ; Fractal analysis
• 刊名：Natural Hazards
• 出版年：2017
• 出版时间：January 2017
• 年：2017
• 卷：85
• 期：1
• 页码：59-86
• 全文大小：
• 刊物类别：Earth and Environmental Science
• 刊物主题：Natural Hazards; Hydrogeology; Geophysics/Geodesy; Geotechnical Engineering & Applied Earth Sciences; Civil Engineering; Environmental Management;
• 出版者：Springer Netherlands
• ISSN：1573-0840
• 卷排序：85

文摘

The fractal characteristics of the ultra-low-frequency (ULF) magnetic field variations recorded prior to the Tohoku earthquake (EQ) with M_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. ± 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.