Figure 1: The three variation stages of the generalized dimension spectrum and singularity spectrum before 22 April 1974 Liyang earthquake (M5.5). (a) and (d) show the generalized dimension spectrum and singularity spectrum two years prior to this earthquake, respectively; (b) and (e) show the generalized dimension spectrum and singularity spectrum seven months prior to this earthquake, respectively; (c) and (f) show the generalized dimension spectrum and singularity spectrum four months prior to this earthquake, respectively. The curve of the generalized dimension spectrum in Figure 1(b) is steeper than the two others, and the value range of the singularity spectrum in Figure 1(e) is broader than the two others. 
