【摘要】 利用单健群分析方法研究了2013年7月22日岷县漳县6.6级地震前地震空间相关长度增长现象。结果表明,从2011年下半年开始主震周围区域地震空间相关长度明显增长。利用这种特征对可能的大震危险区进行网格式搜索,至少可以对未来强震发生的地点进行初步预测。更多还原

【Abstract】 The seismic correlation lengths prior to the Minxian-Zhangxian earthquake occurring on July 22,2013,have been studied using the single-link cluster analysis(SLC)method.The catalogs used were downloaded from the China Earthquake Data Center(CEDC;http://data.earthquake.cn/data/).Earthquakes that occurred during the five years prior to the main shock until its origin time were located in an area centered on the main shock(34.5N°,104.11°E)with a range of 32°～37°,102°～107°.We selected 2.5(ML)as the minimum magnitude and verified the completeness of the catalogs prior to the mainshock using the Gudengberg formula,which showed good results above magnitude ML=2.5.The result shows that an increase in correlation length for moderate-sized earthquakes was observed nearly 1.5years before the main shock and can be fitted well by the power law.For the preparation and occurrence stage of the earthquake process characterized as a self-organized critical phenomenon,direct testing for the increase in spatial correlation lengths prior to large earthquakes is an independent approach used to detect critical point behavior in observed seismicity.The results of this study show that the self-organized critical point characteristic was been observed prior to the Minxian-Zhangxian MS6.6 earthquake.The results from the many earthquake examples indicate that the increase in seismic correlation length by the power law represents a physical process of critical-point characteristics in the source area in preparation of the main earthquake.In a future work,the grid search technique is applied to systematically extract a region of increased correlation length from a dataset.Estimates for the epicenter of an expected mainshock may be then obtained from the results of the grid search.更多还原