| 2013年三台MS4.7地震震源机制及发震构造研究 |
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| 引用本文： | 刘岁海,吕锦雄,赵学钦,张刚,文明如.2013年三台MS4.7地震震源机制及发震构造研究[J].地震学报,2021,43(6):716-729. |
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| 作者姓名： | 刘岁海 吕锦雄 赵学钦 张刚 文明如 |
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| 作者单位： | 中国四川绵阳621010 西南科技大学环境与资源学院;中国广西桂林541004 桂林海林工程勘察有限公司;中国四川绵阳622650 绵阳市安州区应急管理局 |
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| 基金项目： | 国家自然科学基金青年基金（41672206，41704105）和绵阳市防震减灾局科技计划项目（15ZH0011）联合资助 |
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| 摘 要： | 2013年2月19日四川省绵阳市三台县发生MS4.7地震，震中位于四川盆地中部基底断裂绵阳—三台—大足断裂与蒲江—三台—巴中断裂的交会区域。基于地震目录、震相报告和波形等资料，对地震序列进行重定位，采用近远震联合波形反演求解主震震源机制，结合野外地质调查对该地震的发震构造进行分析。余震序列重定位的空间展布方向为NW-SE向，与节面Ⅰ走向吻合，认为此次地震发震断裂走向为NW?SE，倾向为NE，且破裂面近于直立，发震断层在近NS向的近水平挤压应力作用下作右旋走滑错动。实地调查中未见地表破裂及地表断层行迹，认为发震构造为一隐伏断裂。重定位及通过近远震联合反演所得震源深度分别为21.6和19 km，震源深度反映震源区位于上地壳底部的低速层内。此次地震可能是汶川地震造成的区域构造应力场改变与调整过程中，四川盆地川中地块内隐伏于前震旦纪结晶基底中的高角度断裂重新活动的结果。
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| 关 键 词： | 三台MS4.7地震 震源机制 发震构造 隐伏性断裂 |
| 收稿时间： | 2020-12-22 |
Study on earthquake focal mechanism and seismogenic structure of the Santai MS4.7 earthquake in 2013 |
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| Liu Suihai,Lü Jinxiong,Zhao Xueqin,Zhang Gang,Wen Mingru.Study on earthquake focal mechanism and seismogenic structure of the Santai MS4.7 earthquake in 2013[J].Acta Seismologica Sinica,2021,43(6):716-729. |
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| Authors: | Liu Suihai Lü Jinxiong Zhao Xueqin Zhang Gang Wen Mingru |
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| Affiliation: | 1.Southwest University of Science and Technology，Sichuan MianYang 621010，China2.Guilin Hailin Engineering Investigation Co.，Ltd.，Guangxi GuiLing 541004，China3.Emergency Management Bureau of Mianyang Anzhou，Sichuan MianYang 622650，China |
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| Abstract: | Santai MS4.7 earthquake occurred in Mianyang city, Sichuan Province on February 19, 2013. The epicenter located in an intersection area which combined the basement fracture in central Sichuan basin, the Mianyang-Santai-Dazu fracture and the Pujiang-Santai-Bazhong fracture. Based on the earthquake catalogue, seismic phase report and waveform data, we relocated the earthquake sequence, and solved the focal mechanism of the main earthquake by joint inversion of local and teleseismic waveforms, and also studied the seismogenic structure of the Santai MS4.7 earthquake according to the field geological survey. The spatial distribution direction of the relocated aftershock sequence is NW-SE and it highly fitted with the nodal plane I of the focal mechanism, the seismogenic structure of the earthquake can be considered as strike NW-SE, dip NE, and rupture plane is nearly vertical, and the seismogenic fracture was dextral strike-slip dislocation by the proximately horizontal confining pressure in the direction of nearly NS. During the field survey, any fracture marks nor surface ruptures can be obviously found, hence the seismic structure is concluded as a buried fault. The focal depths are 21.6 and 19 km respectively through the relocation and joint inversion of local and teleseismic waveforms. The focal depth reflects that the location of the source area is in the low-velocity layer which is in the bottom of the upper-crust. This earthquake is caused during the adjusted and changed process of the tectonic stress field caused by Wenchuan earthquake, and it is the result of the reactivation of the high-angle fault concealed in the Presinian crystalline substrate in middle-block of Sichuan basin. |
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