以2001年以来2次8级地震和2010年4月青海玉树M7.2地震为例,分析了Rt值在强震前后随时间和空间异常变化特征,同时对综合参量的预测效能进行了检验.结果表明:在强震前Rt值大都出现明显的异常降低过程.在地震综合参数异常和强震关系的研究中,利用地质构造块体约束研究的区域,可以较为清晰地看到强震前后地震活动性异常特征的重现性.%Eight earthquakes with magnitude equal to 7 and more have occurred within the Kunlun-Bayan Har block since 1970. It reveals the exceptionally severe earthquake activity in the block in recent years. In order to investigate the characteristics of abnormal variation in the seismicity of the block, a synthesized seismicity parameter is introduced to generally depict the state of earthquake activity, denoted by R,, and the characteristics of R, before strong earthquakes in the block is examined systematically. The characteristics of the spacial distribution of R, is obtained by taking a point on a tectonic fault as the center of the scanning region. In this study the two earthquakes with Ms 8. 0 or over and the Ms 7.1 Yushu earthquake in Qinghai, China on April 14, 2010 are taken as the examples to analyze the characteristics of the spacial and temporal abnormal variation in R, value showing before the occurrence of them, and the effect of prediction of R, value is tested. The results show that Rt value decreased obviously prio to the three events. When the tectonic block is taken as the research region in the study of the relationship between R, value and strong earthquakes, the reproducibility of the characteristics of abnormal seismicity prior to the occurrence of the strong earthquakes can be seen clearly.
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