Abstract: By selecting 21 years' seismic data along the North-western zone from 1970 to 1990, the fuzzy temporal fractal dimensions (Do) of the earthquakes occurred during the period are analysed and studied. The fuzzy temporal fractal dimensions are calculated in this paper on 2-month and 1-year basis respectively and the curves are plotted to show the Do~variation with time t in every 2-month as well as every year during the studied 21 years. To be more outstanding for moderately-strong earthquakes,the fuzzy temporal fractal dimensions of the earthquakes are calculated respectively by selecting 6 small equal areas civering the north-western seismic zone so as to obtain 6 Do in every year, then 1/6 ΣDo and the curves are plotted to show the Do~variation with time t in every 2 months as well as every year during the studied 21 years for each small area. The calculated results are as follows:
1. The Do decreases before most of strong earthquakes.
2. Based on the variations of fuzzy temporal fractal dimentions with time t in the 6 small areas, the activity of each area of the seismic zone may be recognized.
3. The regions of the coming strong earthquakes can be determined.