摘要
本文首先简要介绍了模糊分维的概念与确定方法。然后以中国华北、川滇、甘宁青地区,日本伊豆和日本海地区以及美国加利福尼亚地区的地震活动时间分布为例,研究了大地震活动的模糊时间分维特征,并用模糊分维划分强震活动的高潮期和探索强震前的中长期测震学前兆异常指标。结果表明,模糊分维数D_0呈趋势上升的时期为强震活动的高潮期;此外,据D_0随时间的变化曲线可以发现一些大地震前数年D_0先下降而后回升的中长期前兆异常变化。本文还研究了模糊集“大地震”的λ-截集的分维数D_0(λ),具体取λ=0.65和λ=0.8,并与模糊分维数D_0进行了对比分析。结果表明,D_0(λ)与D_0的总变化趋势相近,但一般说来D_0的应用效果更好。
The concept and determination of fuzzy fractal dimension were introduced briefly at first. Then, based on the distributions in time of large earthquakes occuring in North China, Sichuan-Yunnan, Gan-su-Ningxia-Qinghai of China, California of USA, Nihonkai, Izu of Japan as examples, the temporal characteristics of fuzzy fractal dimension of large earthquakes have been studied and applied to dividing the highly active periods of strong earthquakes, as well as to investigating the long-medium-term seismic precursors before strong earthquakes. The results obtained show that the periods in which the fuzzy fractal dimension D0 tendentiously increases are the highly active periods of strong earthquakes. Moreover, according to the variation curve of DO with respect to time we can discover the long-medium-term precursors reflected in decrease-increase anomalous variations of D0 before the strong earthquakes. Finally, the fractal dimensions D0 (λ) of λ -cut sets of the fuzzy set 'large earthquakes' were studied for λ = 0. 65 and 0. 8, and their comparative analysis with fuzzy fractal dimension D0 was made too. The results show that D0 is the most effective, and the effectiveness of D0 (0. 65) is the worst.
出处
《中国地震》
CSCD
北大核心
1991年第4期1-11,共11页
Earthquake Research in China
基金
地震科学联合基金
