Abstract: The Yutian M_S6.4 earthquake on June 26, 2020 in Xingjiang, China, occurred in the 2020 annual earthquake risk areas, and the medium-term forecasting is correct. One of the main basis is the quasi periodic characteristic of earthquakes with M_S≥6.0 in this area. The quantitative calculation by the Morlet wavelet transform showed that 11.7-year, 5.8-year and 79.5-year are the mainperiods, in which the former passed 90% confidence test, are the main periodic components. In this paper, we reviewed the characteristics of seismicity periodic spectrum before the M_S6.4 earthquake, discussed the effects of study region range, different parameters and different length of time series on the result stability of Morlet wavelet transform and its application in earthquake forecasting.

Key words: The Yutian M_S6.4 earthquake, Morlet wavelet transform, Periodic spectrum