“…Li (lqdzjybzx@126.com) has also been shown in multifractal research on seismic activity that the spectrum of generalised dimensions and the singularity spectrum display characteristic changes before large earthquakes (Caruso et al, 2006;Dimitriu et al, 2000;Nakaya, 2005;Roy and Padhi, 2007). Some results have confirmed that the decrease in fractal dimension, the steepening of curves in the generalised dimension spectrum and the broadening of the value range in the singularity spectrum, can be taken as indicators of an unstable state of an earthquake system before a large rupture (Carpinteri et al, 2009;Goltz, 1997;Kiyashchenko et al, 2004;Lee et al, 2008;Matcharashvili et al, 2000;Radulian and Trifu, 1991;Telesca et al, 2005;Telesca and Lapenna, 2006). However, there are some shortcomings in the research: the mono-fractal dimension is not sufficient to characterise heterogeneous fractals (Grassberger and Procaccia, 1984;Kentz and Schreiber, 1997), while the generalised dimension spectrum and singularity spectrum can only represent a global description of the scaling properties (Chhabra and Jensen, 1989;Grassberger, 1983).…”