In this study,the Diebu,Gansu M_S5.9 earthquake,which occurred on January 8,1987,was regarded as the symbolical earthquake based on the review of the "activity in quiescence" and "quasi-activity in quiescence" methods and the analysis of the 10-year seismic risk area in the North-South seismic belt designated by the State Seismological Bureau in 1989. Then three places in the northern section of the North-South seismic belt,where earthquakes with magnitudes in the range of 6~7 may occur,were identified using the time scale of mid-long term prediction,one of which is the Jiuzhaigou area in Sichuan Province. Based on the discussions of some problems in the mid-long term prediction,the following conclusions are derived:(1) The Jiuzhaigou M_S7.0 earthquake verifies that "activity in quiescence" is a feasible method to predict earthquakes,and the method has been optimized in this study. (2) Based on the "activity in quiescence" method and the analysis of the 10-year seismic risk area in the North-South seismic belt,the precursors can be distributed into quiet and active periods,and the precursors in the quiet period may be more significant in predicting earthquakes.