On the multi-fractal characteristics of the ULF geomagnetic field before the 1993 Guam earthquake

Abstract

Abstract. Ida et al. (2005) document significant changes in the multi-fractal parameters of the ULF geomagnetic field H component starting about one month before the 1993 Guam earthquake. According to the authors, these multi-fractal signatures can be considered as precursory signals of the Guam earthquake. As a consequence, they conclude that the multifractal analysis may have an important role in the development of short-term earthquake prediction capabilities. Since this and other similar reports have motivated the idea that earthquake prediction based on electromagnetic precursory signals may one day become a routine technique, the presumed precursors need to be validated through independent datasets. In this review the seismogenic origin of the multifractal magnetic signatures documented by Ida et al. (2005) before the 8 August 1993 Guam earthquake is seriously put into question. By means of the geomagnetic K p index, it is demonstrated that these multi-fractal parameter changes are normal signals induced by the variation of the global geomagnetic activity level.

Are there new findings in the search for ULF magnetic precursors to earthquakes?

“…[], many papers [see Hayakawa et al ., ; Hobara et al ., ; Ida et al ., ; Ida and Hayakawa , ; Smirnova et al ., ] have documented ULF magnetic changes preceding the Guam earthquake using different methods of analysis. Masci [, , , ] and Thomas et al . [], however, have shown that the magnetic changes identified prior to the Guam earthquake are not precursors.…”

“…However, we want to stress once again that evidence of the proposed relationship between magnetic anomalies and incoming earthquakes has never been provided. Conversely, in recent papers [see, e.g., Masci , , , , , , ; Thomas et al ., , ] the authors have demonstrated that many of the reported preearthquake ULF magnetic changes are invalid precursors of earthquakes.…”

“…The most commonly used methods to identify preearthquake ULF anomalies in geomagnetic field records are the so called spectral polarization ratio analysis [see, e.g., Hayakawa et al, 1996] and fractal analysis [Hayakawa et al, 1999]. Fractal anomalies preceding earthquakes have been extensively discussed and denied as precursors by Masci [2010Masci [ , 2013b and Masci and Thomas [2013a, 2013b, 2015b. Reports of precursory signatures in the spectral polarization ratio were proved invalid as well [see, e.g., Masci, 2011aMasci, , 2012aMasci, , 2012cMasci and Thomas, 2015b;Thomas et al, 2009b].…”

Comment on "Fractal analysis of ULF electromagnetic emissions in possible association with earthquakes in China" by Ida et al. (2012)

“…Ida et al (2012) criticized the findings of some of these papers, such as, Campbell (2009) and Thomas et al (2009a, b), but they did not provide any solid evidence in support of their weak criticism. Among these reviews, there are the studies by Masci (2010Masci ( , 2013, which demonstrated that the fractal analysis of the geomagnetic field in the ULF band is not a good indicator of an imminent earthquake. On the contrary, Ida et al (2012) referred to several papers that identified increases in the fractal dimension of the ULF geomagnetic field H component as earthquake precursors.…”

Review Article: On the relation between the seismic activity and the Hurst exponent of the geomagnetic field at the time of the 2000 Izu swarm

“…These studies led to a re-examination of many controversial observations of earthquake-related signals, which found that several methodologies used to identify magnetic precursors were invalid. Among these methods are magnetic polarization ratio (see Thomas et al, 2009b;Masci, 2011aMasci, , 2012a, fractal characteristics of the geomagnetic field components (see Masci, 2010Masci, , 2013aMasci and Thomas, 2013), and eigenvalues of the principal component analysis (see Masci, 2011b). Reports of ionospheric earthquake-related disturbances were also investigated (see Masci, 2012dMasci, , 2013bThomas et al, 2012).…”