%0 Journal Article
%T Fractal analysis of ULF electromagnetic emissions in possible association with earthquakes in China
%A Y. Ida
%A D. Yang
%A Q. Li
%A H. Sun
%A M. Hayakawa
%J Nonlinear Processes in Geophysics (NPG)
%D 2012
%I Copernicus Publications
%X The long-term data (during the period of 1 March 2003 through 31 December 2006) of ULF geomagnetic variations observed at Kashi station (geographic coordinates: 39.5กใ N, 76.0กใ E) in China have been used to investigate the long-term variation of fractal dimension of ULF emissions. We have studied the changes in fractal dimension in association with several earthquakes around the observation station. It is then found that a significant change (or decrease) in the fractal dimension of the Z component took place before the 1 September 2003 earthquake, which lends a further support to our previous finding based on our improved polarization analysis for the same earthquake. The results obtained are discussed in the contexts of a few aspects (detectability of seismogenic emissions, comparison with previous results by other analysis methods, the importance of fractal analysis in the nonlinear process of the lithosphere and earthquake prediction).
%U http://www.nonlin-processes-geophys.net/19/577/2012/npg-19-577-2012.html