内蒙古和林格尔地处鄂尔多斯块体北缘阴山地震带内，历史上6级以上强震频发。2020年3月30日和林格尔发生M_L4.5地震，打破了自2005年以来阴山地震带M_L4.0以上地震的长期平静。研究此次地震序列的发震构造对区域应力状态和地震危险性分析有重要作用，然而内蒙古地震台网台站较为稀疏，相对于华北其他地区地震监测能力较低，对和林格尔地震序列的分析造成不利影响。本文采用匹配定位检测方法（M&L）检测区域台网目录遗漏的微震，并对检测到的地震事件进行精定位。匹配定位方法共检测到序列中可定位的地震事件61个，约为台网目录的1.3倍，可定位地震约为台网目录的2.9倍。地震序列重定位结果中余震整体呈现NE向的分布，与使用CAP方法得到主震震源机制NE向节面走向基本一致，破裂为正断走滑型，显示和林格尔M_L4.5地震序列发震构造为NE走向、NW倾向的拉张性断层。结合计算结果和区域地震地质构造特征，认为M_L4.5地震序列发震构造为NE走向的岱海-黄旗海盆地南缘断裂。

Horinger of Inner Mongolia is located in the Yinshan seismic zone on the northern margin of the Ordos block,and in which strong earthquakes of magnitude 6 or above are frequent in history. A M_L4.5 earthquake in Horinger on March 30,2020 broke the long quiescence of earthquakes above M_L4.0 in the Yinshan seismic zone since 2005. The analysis of the seismogenic structure of the 2020 Horinger earthquake sequence is of great importance to the regional stress and seismic risk research. However,the stations around Horinger are sparse and earthquake monitoring capacity are relatively weak in comparison to other areas in North China,which has a negative impact on the analysis of the Horinger 2020 earthquake sequence. In this paper,we used Match and Locate method(M&L)to detect the micro-earthquakes missed in network catalog,relocated the earthquakes detected,and used Cut and Paste method(CAP)to calculate the mechanism of M_L4.5 earthquake. Using M&L we detected a total of 61 locatable earthquake events,which is about 1.3 times as much as that in the network catalog,and the number of locatable earthquakes is about 2.9 times as much as that in the network catalog. The relocation result shows that the epicenters of earthquake sequence are in NE direction distribution,which is basically consistent with the north-east plane of M_L4.5 earthquake mechanism obtained by CAP method. Considered the relocation result and source mechanism,the seismogenic structure of the 2020 Horinger earthquake sequence is a normal fault in NE strike direction and NW dip direction. Combined with regional seismic geological structure characteristics,we conclude that the seismogenic structure of the M_L4.5 earthquake sequence is the south margin fault of Daihai-Huangqihai Basin.

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内蒙古自治区地震局局长基金（2020JP01）、地震科技星火计划项目（XH21002Y、XH210501、XH21006）共同资助