摘要
本文根据广义分维方法,分析计算了1972年以来福建及其周边地区M_L≥5. 0级地震、台湾地区 Ms≥7. 0级地震前后小震活动广义时间分维(D_t)和广义空间分维(D_s)的变化特征。结果表明,闽台两地中强震前普遍存在着 D_t、D_s的低值异常,福建地区中强震前2a左右完成降维过程,而台湾地区则在强震前1a左右结束异常。通过对降维特征的分析提出了:中强震前D_t、D_s曲线至少有一条低于震前数年的一倍均方误差线,而另一条曲线则同步低于均值线作为异常判断标准。实际应用说明了广义时空分维能较好地反映闽台两地的中短期地震活动趋势,对两地区地震活动数学模型的建立进行了有益的探索。
This paper,uses the generalized fractal dimension method to analyze the changes of gen eralized temporal (D_t) and spatial (D_s) fractal dimension of small seismic events around the epicenter before and after earthquakes of larger than 5. 0 in ML value in Fujian and of larger than 7. 0 in Ms value in Taiwan. The results show that low value anomaly of D_t and D_s is widely detected before mid-strong earthquakes. The course of the low value anomaly was fin ished two years before mid-storng earthquakes in Fujian area and one a before mid-storng earthquakes in Taiwan area. The analysis of the lowering charcteristics of the generallied fractal dimension show at least that one of the both D_t and D_s curves is lower than several year's standard square error line before earthquake, meanwhile, the other synchronously lower than average value line. It can be used as a standard of anomaly identification. The results indicate that the generalized temporal and spatial fractal dimension method can well re flect Fujian and Taiwan's seismic tendency in intermediate and short terms.
引文
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