A comparison of different fractal analyses for VHF electromagnetic emissions and their self-organization for the off-sea Miyagi-prefecture earthquake

Abstract

Abstract. The VHF electromagnetic noise intensity data at several stations in the Tohoku area of Japan during the period of a rather large (with magnitude of 7.2) earthquake (Miyagi-ken oki earthquake) taken place on 16 August 2005, are analyzed by means of different fractal analysis methods, including (1) spectral slope estimation, (2) multi-fractal detrended fluctuation analysis and (3) multi-fractal wavelet transform modulus maxima method. It seems to the authors that there is no definite analysis method for the analysis of any seismogenic phenomenon, so that the only way we have to take, is to apply different methods to the same data for the detailed comparison of the results. This comparison enables us to deduce the properties commonly observed by the above methods. Because the most important feature common to these three methods, is that significant changes in fractal scaling characteristics are observed just during the earthquake (mainly before the earthquake) only at one station of Kunimi. Finally, we can come to the definite conclusion on the self-organization of VHF emissions only at one station in the present case.

Fractal analysis for VHF electromagnetic noises and the identification of preseismic signature of an earthquake

“…There have already been proposed several methods for the multi-fractal analysis: extended multi-fractal detrended fluctuation analysis (MF-DFA) (Kantelhardt et al, 2002), wavelet transform modulus maxima (WTMM) (Muzy et al, 1993;Mallat and Hwang, 1992), etc. In order to confirm the reliability of the analysis results, we have utilized the above-mentioned two methods and have confirmed that these two methods have yielded consistent results (this will be presented elsewhere in Yonaiguchi et al, 2007). So, in this paper we present only the result by the MF-DFA (not standard, but extended).…”

Statistical features of seismoelectric signals prior to M7.4 Guerrero-Oaxaca earthquake (México)

“…Our conclusion is that these parameters, describing the dynamics of ULF geoelectrical data can be considered as good candidates to precursors of the Guerrero-Oaxaca EQ occurred in September 1995. On the other hand, although the possible geoelectric precursors suggested by us seem to be significant, they lack of isotropy just, as it was reported by Yonaiguchi et al (2007), for VHF electromagnetic emissions in Japan.…”

Generation of VHF radio emissions by electric discharges in the lower atmosphere over a seismic region

“…The distance to epicenters was several hundreds of kilometers, and therefore it was possible to register radiation if its source was located in the atmosphere at altitude of several kilometers. Yonaiguchi et al (2007) investigated the fractal character of VHF radiation on frequency 49.5 MHz, which occurred on the eve of an EQ (M¼7.2) on August 16, 2005. The observations were made on three stations in the nearby zone located at the distances in dozens of kilometers from the epicenter.…”