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

• Main Author: F. Masci
• Format: Article
• Language: English
• Published: Copernicus Publications 2013-01-01
• Series: Natural Hazards and Earth System Sciences
• Online Access: http://www.nat-hazards-earth-syst-sci.net/13/187/2013/nhess-13-187-2013.pdf

Ida et al. (2005) document significant changes in the multi-fractal parameters of the ULF geomagnetic field <i>H</i> 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 multi-fractal 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 multi-fractal 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 Σ<i>K</i><sub>p</sub> index, it is demonstrated that these multi-fractal parameter changes are normal signals induced by the variation of the global geomagnetic activity level.