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利用单键群分析方法 ,对 1 976年唐山和 1 989年大同地震前多学科前兆异常的时空群集特征进行了研究 .对 2次地震前兆的单键群构架的信源熵、平均键长和累积滑动频次进行了时空扫描 .结果表明 ,地震前单键群构架异常非常明显 ,并且可以分为 5个阶段 .1 975年 6月～ 1 976年 6月 (第 4阶段 )异常幅度变化最大 .震前 1个月(第 5阶段 )信源熵值进一步下降 ,平均键长变化维持在第 4阶段的水平 ,累积滑动频次增加 .异常的变化阶段可为地震的中短期预报提供判据 .最小信源熵的变化经历了一个由外围逐渐向未来地震区迁移的过程 ,根据这一特点可以追踪和确定地震危险区的范围
Using the single-bond group analysis method, the spatio-temporal cluster features of multi-disciplinary precursory anomalies before Tangshan and 1989 Datong earthquakes in 1976 are studied. The entropy, average bond length, The results show that the anomaly of single-bond swarm before earthquakes is very obvious and can be divided into five stages.From June 1975 to June 1976 (the fourth stage), the anomalous amplitude changes the most. The entropy of source decreases further in the first month (stage 5) before earthquake, and the average bond length changes remain at the level of stage 4, and the cumulative slip frequency increases. The abnormal change stage can provide criteria for medium and short term earthquake prediction. The change of source entropy has undergone a process of gradually migrating from the periphery to the future earthquake area. According to this feature, the scope of the earthquake danger area can be traced and determined