陈婷,余海琳,章阳,等. 唐山地区三维b值分布特征研究[J]. 华北地震科学,2022, 40(1):34-40. doi:10.3969/j.issn.1003−1375.2022.01.006.
引用本文: 陈婷,余海琳,章阳,等. 唐山地区三维b值分布特征研究[J]. 华北地震科学,2022, 40(1):34-40. doi:10.3969/j.issn.1003−1375.2022.01.006.
CHEN Ting,YU Hailin,ZHANG Yang,et al. Research on the Three-dimensional b-value Distribution Characteristics in Tangshan Area[J]. North China Earthquake Sciences,2022, 40(1):34-40. doi:10.3969/j.issn.1003−1375.2022.01.006.
Citation: CHEN Ting,YU Hailin,ZHANG Yang,et al. Research on the Three-dimensional b-value Distribution Characteristics in Tangshan Area[J]. North China Earthquake Sciences,2022, 40(1):34-40. doi:10.3969/j.issn.1003−1375.2022.01.006.

唐山地区三维b值分布特征研究

Research on the Three-dimensional b-value Distribution Characteristics in Tangshan Area

  • 摘要: 搜集唐山及周边地区M7专项工作组(2002.1—2008.12)及中国地震台网中心(2009.1—2020.9)的震相报告,首先采用双差层析成像方法对地震进行重定位,然后采用K-K法对重定位后的地震事件去余震,最后采用“最近距离—最少事件”扫描方法扫描2012年5月28日河北唐山ML5.1地震和2020年7月12日河北唐山ML5.4地震发生前后唐山地区的平面和不同深度b值图像,分析2次地震发生前后唐山地区b值空间分布和演化规律,进一步探讨唐山地区中强震发生前后的应力演化特征。结果表明:重定位后震源深度更合理,不同深度b值图像比平面b值图像分布和演化都更为丰富,唐山ML5.1地震和ML5.4地震均发生在b值降低过程中。虽然唐山地区b值持续降低,代表着该区应力累计的逐渐增强,但该区浅部应力水平高于深部,表明发生更大地震的紧迫程度不强。

     

    Abstract: We collected the seismic phase reports of the M7 working groups (2002.1—2008.12) and the China Earthquake Networks Center (2009.1—2020.9) in Tangshan and its surrounding areas. Firstly, we relocate the earthquake using the double-difference tomography method. Then, we used the K-K method to remove aftershocks from relocated seismic events. Finally, the closest distance and least number of events scanning method was used to scan the plane and different depth b-value images of the Tangshan area before and after Tangshan ML5.1 earthquake in Hebei on May 28th, 2012 and Tangshan ML5.4 earthquake in Hebei on July 12th, 2020. We analyzed the spatial distribution and evolution of the b-value in Tangshan area before and after the occurrence of two earthquakes, and further explore the characteristics of stress evolution in the area before and after the occurrence of moderate and strong earthquakes in Tangshan area. The results show that the focal depth is more reasonable after relocation, and the distribution and evolution of b-value images of different depths were more abundant than the b-value images of plane. The Tangshan ML5.1 earthquake and Tangshan ML5.4 earthquake both occurred in the decreasing process of the b-value. Although the b-value in Tangshan area continued to decrease, which represented the gradual increase in stress accumulation, but the stress level in shallow is higher than in deep, the urgency of a larger earthquake is not strong at present.

     

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