| The Longnan MS5.5 Earthquake on September 12, 2008: A Very Shallow Event Probably Triggered by the Wenchuan Earthquake |
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| 作者姓名： | LUO Xinyu ZENG Xiangfang DONG Peiyu ZHOU Yong WEI Xing CHENG Huihong |
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| 作者单位： | School of Earth and Space Sciences, University of Science and Technology of China, Hefei 230026, China,State Key Laboratory of Geodesy and Earth''s Dynamics, Institute of Geodesy and Geophysics, Chinese Academy of Sciences, Wuhan 430077, China,Hubei Earthquake Agency, Wuhan 430071, China,Department of Earth and Space Sciences, Southern University of Science and Technology, Shenzhen 518055, China;School of Geodesy and Geomatics, Wuhan University, Wuhan 430072, China,China Earthquake Networks Center, Beijing 100045, China,State Key Laboratory of Geodesy and Earth''s Dynamics, Institute of Geodesy and Geophysics, Chinese Academy of Sciences, Wuhan 430077, China;CAS Key Laboratory of Computational Geodynamics, University of Chinese Academy of Sciences, Bejing 100049, China |
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| 基金项目： | This project is sponsored by the State Key Laboratory of Geodesy and Earth''s Dynamics, Institute of Geodesy and Geophysics, Chinese Academy of Sciences (SKLGED2018-4-1-E) and China MOST 973 Program(2014CB845901). |
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| 摘 要： | The 2008 Wenchuan earthquake has a significant impact on the seismicity of nearby regions. The Longnan earthquake which occurred on September 12,2008 in Gansu Province was out of the aftershock zone. Reliable source parameters are essential for understanding the seismogenic process of this earthquake. Therefore,three approaches are adopted to study the source parameters of this event. The focal mechanism is obtained with the g CAP method that takes non-Double-Couple(non-DC)component into account. The two fault planes are NP1:150°/45°/81° and NP2:342°/45°/98°,while the non-DC component is about 53%. The focal depth is 1. 6 km,which indicates the Longnan earthquake is a shallow event. Furthermore,this result is also in good agreement with results obtained with two other approaches:amplitude spectra of Rayleigh wave and surface displacement from In SAR measurement. To analyze the cause of the event,coulomb failure stress change caused by the Wenchuan earthquake on the Longnan earthquake fault plane is calculated. The result shows that coulomb stress change is 30 k Pa around the Longnan earthquake hypocenter,which exceeds the typical triggering threshold of 10 k Pa. The research indicates that the Wenchuan earthquake probably promote the happening of the Longnan earthquake.
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| 关 键 词： | Longnan earthquake Source parameter Rayleigh wave amplitude spectra Surface displacement Coulomb failure stress |
| 收稿时间： | 2019/4/5 0:00:00 |
| 修稿时间： | 2019/8/3 0:00:00 |
The Longnan MS5.5 Earthquake on September 12, 2008: A Very Shallow Event Probably Triggered by the Wenchuan Earthquake |
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| LUO Xinyu,ZENG Xiangfang,DONG Peiyu,ZHOU Yong,WEI Xing,CHENG Huihong.The Longnan MS5.5 Earthquake on September 12, 2008: A Very Shallow Event Probably Triggered by the Wenchuan Earthquake[J].Earthquake Research in China,2019,33(3):403-417. |
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| Authors: | LUO Xinyu ZENG Xiangfang DONG Peiyu ZHOU Yong WEI Xing and CHENG Huihong |
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| Institution: | School of Earth and Space Sciences, University of Science and Technology of China, Hefei 230026, China,State Key Laboratory of Geodesy and Earth''s Dynamics, Institute of Geodesy and Geophysics, Chinese Academy of Sciences, Wuhan 430077, China,Hubei Earthquake Agency, Wuhan 430071, China,Department of Earth and Space Sciences, Southern University of Science and Technology, Shenzhen 518055, China;School of Geodesy and Geomatics, Wuhan University, Wuhan 430072, China,China Earthquake Networks Center, Beijing 100045, China and State Key Laboratory of Geodesy and Earth''s Dynamics, Institute of Geodesy and Geophysics, Chinese Academy of Sciences, Wuhan 430077, China;CAS Key Laboratory of Computational Geodynamics, University of Chinese Academy of Sciences, Bejing 100049, China |
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| Abstract: | The 2008 Wenchuan earthquake has a significant impact on the seismicity of nearby regions. The Longnan earthquake which occurred on September 12, 2008 in Gansu Province was out of the aftershock zone. Reliable source parameters are essential for understanding the seismogenic process of this earthquake. Therefore, three approaches are adopted to study the source parameters of this event. The focal mechanism is obtained with the gCAP method that takes non-Double-Couple (non-DC) component into account. The two fault planes are NP1:150°/45°/81° and NP2:342°/45°/98°, while the non-DC component is about 53%. The focal depth is 1.6km, which indicates the Longnan earthquake is a shallow event. Furthermore, this result is also in good agreement with results obtained with two other approaches:amplitude spectra of Rayleigh wave and surface displacement from InSAR measurement. To analyze the cause of the event, coulomb failure stress change caused by the Wenchuan earthquake on the Longnan earthquake fault plane is calculated. The result shows that coulomb stress change is 30kPa around the Longnan earthquake hypocenter, which exceeds the typical triggering threshold of 10kPa. The research indicates that the Wenchuan earthquake probably promote the happening of the Longnan earthquake. |
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| Keywords: | Longnan earthquake Source parameter Rayleigh wave amplitude spectra Surface displacement Coulomb failure stress |
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