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ISSN 2096-7780 CN 10-1665/P

许英才, 曾宪伟. 吴忠—灵武地区地震活动性与强震危险性分析[J]. 地震科学进展, 2020, (10): 1-12. DOI: 10.3969/j.issn.2096-7780.2020.10.001
引用本文: 许英才, 曾宪伟. 吴忠—灵武地区地震活动性与强震危险性分析[J]. 地震科学进展, 2020, (10): 1-12. DOI: 10.3969/j.issn.2096-7780.2020.10.001
Yingcai Xu, Xianwei Zeng. The earthquake activity and strong earthquake risk analysis of Wuzhong-Lingwu region[J]. Progress in Earthquake Sciences, 2020, (10): 1-12. DOI: 10.3969/j.issn.2096-7780.2020.10.001
Citation: Yingcai Xu, Xianwei Zeng. The earthquake activity and strong earthquake risk analysis of Wuzhong-Lingwu region[J]. Progress in Earthquake Sciences, 2020, (10): 1-12. DOI: 10.3969/j.issn.2096-7780.2020.10.001

吴忠—灵武地区地震活动性与强震危险性分析

The earthquake activity and strong earthquake risk analysis of Wuzhong-Lingwu region

  • 摘要: 通过吴忠—灵武地区现有的地震活动性资料,并结合该区域过去的几次中强震震例和已有的研究结果,本文梳理与总结了中强震前该区域地震活动乃至中国大陆大震活动的时空特征,而且基于最小完整性震级分析了1970—2019年该区域中小地震的地震活动性特点。综合认为,吴忠—灵武地区中强震的广义前震和中小地震的活动性具有较为鲜明的特征,中强震发生前1—2年内该区域及邻区形成ML2.0以上地震集中区或其西北方向的阿左旗腰坝区域大都出现ML3.0以上信号震,而且一年前其主震的广义前震的确比较发育,存在一定程度的地震增强;地震序列统计分析表明,该区域的多重共轭构造可能是其主要原因,其多震型、双震型和震群型占有相对较高的比例。另外,从大形势角度来看,过去大部分5级以上中强震发生的主导因素很可能由华北地块主导的强震活跃幕引起,该区域的强震危险性不仅仅和局部特殊构造特征、区域前震活动变化有关,更重要的是,华北—东北亚地块大震活动对其也起到了较大的影响作用,相比而言,青藏高原、龙门山断裂带及祁连山构造带等区域的大震活动对吴忠—灵武地区中强地震触发影响不显著,而且吴忠—灵武地区的中强地震活动和华北—东北亚地块的大震活动可能存在一定的构造响应。

     

    Abstract: Based on the existing seismic activity data, past moderate-strong earthquake cases and the foregoing researches in Wuzhong-Lingwu area, this paper summarizes the moderate-strong earthquake sequence, the seismic activity before the mainshock and temporal and spatial features of major earthquakes in mainland China. Characteristics of small and moderate earthquake activity are analyzed based on minimum magnitude of completeness during 1970—2019. The generalized foreshock of moderate-strong earthquake and the small-moderate earthquake activity have many marked features. It reveals that 1 to 2 years before moderate-strong earthquakes, the regional earthquake concentration with ML≥2.0 was formed in the Wuzhong-Lingwu area and its vicinity. The signal earthquake with ML≥3.0 mostly appeared in the AzuoqiYaoba area which is in the northwest of Wuzhong-Lingwu area. The generalized foreshock was actually abundant before mainshock occurred, existing some degree of earthquakes intensify. Statistical analysis of the earthquake sequence shows that the multiple mainshock type, double-shock type and swarm type take a greater proportion and the multiple conjugate tectonics is probably the main reason. Besides, from large seismic situation perspective, the leading factor of most previous moderate-strong earthquake with M≥5 is probably caused by strong earthquakes active period of the North China block, and the high earthquake risk of the area has close connection not only with local special tectonic and regional foreshock activity, but also with the effect of major earthquakes activity from North China block to Northeast Asia block. In comparison, the major earthquakes activity of Tibetan plateau, Longmenshan fault zone, Qilianshan structure belt and other areas have no obvious effect on triggering moderate-strong earthquake in Wuzhong-Lingwu area, and there may be tectonic response between moderate-strong earthquake in Wuzhong-Lingwu area and major earthquakes activity from North China block to Northeast Asia block.

     

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