| 汶川MS8.0级地震发生背景与过程的研究 |
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| 引用本文： | 陈章立,赵翠萍,王勤彩,华卫,周连庆,史海霞,陈翰林.汶川MS8.0级地震发生背景与过程的研究[J].地球物理学报,2009,52(2):455-463. |
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| 作者姓名： | 陈章立 赵翠萍 王勤彩 华卫 周连庆 史海霞 陈翰林 |
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| 作者单位： | 1.中国地震局，北京 100036;2.中国地震局地震预测研究所，北京 100036;3.中国地震台网中心，北京 100036 |
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| 摘 要： | 本文首先阐明汶川MS8.0级地震发生在由区域布格重力异常和地震震中分布所确定的武都—松潘—茂汶—汶川—泸定地震带上.汶川地震所在地段是地震前兆和中小地震（M≤7.0）的空白区，震前出现明显的孕震空区，MS8.0级地震发生在空区周围区域中小地震活动峰值之后的减少段里.地震的破裂超出孕震空区范围，空区内、外余震活动呈现出不同的衰减特征，依此将余震活动分为WS和NE两个区段.地震破裂过程、4级以上余震矩张量及震区应力场反演和余震应力降的测定结果表明，两个区域的位错、余震机制解和应力降及最大主应力的方〖JP2〗向等明显有别.根据这些特征和地震应力触发的研究，推测NE段地震的发生可能是〖JP〗由WS段主破裂的发生所触发.
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| 关 键 词： | 汶川8.0级地震 地震空区 序列衰减 分段性 应力触发 |
| 收稿时间： | 2008-12-5 |
| 修稿时间： | 2009-1-14 |
A study on the occurrence background and process of Wenchuan MS8.0 earthquake |
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| CHEN Zhang-Li,ZHAO Cui-Ping,WANG Qin-Cai,HUA Wei,ZHOU Lian-Qing,SHI Hai-Xia,CHEN Han-Lin.A study on the occurrence background and process of Wenchuan MS8.0 earthquake[J].Chinese Journal of Geophysics,2009,52(2):455-463. |
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| Authors: | CHEN Zhang-Li ZHAO Cui-Ping WANG Qin-Cai HUA Wei ZHOU Lian-Qing SHI Hai-Xia CHEN Han-Lin |
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| Institution: | 1.China Earthquake Administration, Beijing 100036, China;2.Institute of Earthquake Science， China Earthquake Administration, Beijing 100036, China;3.China Earthquake Networks Center, Beijing 100045, China |
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| Abstract: | In this paper, we firstly demonstrated that the MS8.0 earthquake occurred on the Wudu-Songpan-Maowen-Wenchuan-Luding seismic zone, which is delineated by the regional gravity anomalies and seismic activity. The main ruptured region of the earthquake was located on a segment that lacked strong earthquakes during the active seismic period, i.e. seismic gap. The seismic gap is very remarkable before the MS8.0 event and the main event occurred in the period of decreased seismicity outside the gap area. The rupture process extended towards NE direction and exceeded the seismic gap region. Seismicity in and out the gap show different active features, therefore the aftershock seismicity is divided into NE and WS segments by the author. Researches on source rupture process, moment tensor inversion of M≥4.0 aftershocks, stress field inversion, as well as the stress drops of aftershocks reveal that there exists significant difference between the two segments in slip distribution on the fault, focal mechanisms of aftershocks, stress drops, as well as direction of the tress field. According to those characteristics and study on the stress triggering, it is suggested that the seismicity on the NE segment may be triggered by the main rupture starting on WS segment. |
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| Keywords: | Wenchuan MS8 0 earthquake Seismic gap Decrease of the aftershock sequence Segmentation feature Stress triggering |
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