Abstract: Based on the principle of the “fixed radius method”,the temporal characteristics of D_q-q and f(a)-a spectra of the Heishan and Tuoji earthquake swarms have been preliminarily studied. The results show that two precursory swarms have different abnormal features. For Tuoji earthquake swarm, the value of D_q increases when q<0 and D_q value decreases when q>0. Meanwhile, the changing range of D_q value is wide and two ends of f(a) curve drop down, and the numerical distribution range of index a becomes wider and wider. The obvious abnormal precursors can not be found from temporal multifractal structure for Heishan earthquake swarm. The change of D_q-q curve is not obvious and distribution range of f(a)-a spectra is small. The reason of the difference between two earthquake swarms is also discussed in this paper.

Key words: Earthquake swarm, Multifractural, Dimension D_q, Scaling index spectra f(a)