FUZZY TEMPORAL FRACTAL DIMENSION OF SEISMIC ACTIVITY REGIONS ON NORTH-WESTERN SEISMIC ZONE
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摘要: 选用北西地震带1970年至1990年21年地震资料,对所发生地震的模糊时间分维结构进行了分析和研究。分别以二个月为-个单位和-年为-个单位计算了模糊时间维数Do并绘出以二个月Do随t变化和21年每年Do随t变化曲线。为了更好突出中强震选取了覆盖北西地震带6个面积相等小区,分别进行了模糊时间分维计算,求出每年6个Do来,再(1/6)ΣDo,计算出每年的平均Do来并绘出每-小区二个月Do随t变化和21年每年Do随t变化曲线。经计算可得以下结果。(1)多数较强地震之前Do明显降低。(2)六小区模糊时间分维Do随t变化特征可识别地震带不同区域活动性。(3)可划分未来发生较强震所在地区。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.-
Key words:
- fuzzy temporal fractal dimension /
- seismic zone /
- seismic activity
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[1] 1 冯德益.等.模糊自相似、模糊分数维及其在地震研究中的某些应用.见:分形理论 及其应用.成都:四川大学出版社, 1989.89
2 张永平,等.模糊分形与思维科学见分形理论及应用,成都:四川大学出版社, 1989.108
3 冯德益,等.大地震活动的模糊时间分维特征中国地震. 1991. 7 (4).
4 国家地震局分析预报中心.中国东部地震目录.1970年1991年.
5 国家地震局分析预报中心.全国地震月报目录数据库.1970年1991年. -
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