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Title:: A Study on the Interpretation Ability of Near-field Strong Motion Records to the Rupture Process of the Wenchuan Earthquake

作者:: 尹得余¹; 刘启方²; 董云¹; 佘跃心¹; 武精科¹; 程永振¹; 张继华¹; 陈家瑞¹; (1.淮阴工学院建筑工程学院,江苏淮安 223001; 2.苏州科技大学土木工程学院,江苏苏州 215000)

Author(s):: YIN Deyu¹; LIU Qifang²; DONG Yun¹; SHE Yuexin¹; WU Jingke¹; CHEN Yongzhen¹; ZHANG Jihua¹; CHEN Jiarui¹; (1.Faculty of Architecture and Civil Engineering,Huaiyin Institute of Technology,Huai'an 223001,Jiangsu,China)(2.School of Civil Engineering of Suzhou University of Science and Technology,Suzhou 215011,Jiangsu,China)

Keywords:: Wenchuan earthquake; near-field strong motion records; inversion of rupture process; rupture sequence; Xiaoyudong fault

摘要:: 选用方位角覆盖较均匀的43个近场强震记录,通过基线校正、积分和滤波后得到速度时程。采用非负最小二乘法和多时间视窗技术,反演了2008年汶川地震破裂过程。研究表明:①所选43个近场台站记录对近乎平行的北川断层南段和彭灌断层的滑动分辨能力不同,所选记录能很好地分辨北川断层南段的滑动,而对彭灌断层的滑动分辨能力要差; ②为满足破裂后方区域台站合成记录的第二个波包,北川断层南段或彭灌断层需产生往破裂后方西南侧方向的破裂。综合考虑波形拟合残差及反演结果与地表破裂数据的吻合情况,得到可能的破裂顺序:破裂起始于北川断层南段深部低倾角位置,接着引起彭灌断层破裂,进而引起小鱼洞断层破裂,小鱼洞断层触发北川断层南段高倾角区域发生双侧破裂。

Abstract:: In this paper,43 near-field acceleration records with uniform azimuth coverage are selected.Then velocity records are obtained by baseline correction,record integral and record filtering.Non-negative least squares method and multi-time window technique are used to invert the rupture process of the 2008 Wenchuan earthquake.The following conclusions are obtained:(1)Forward testing shows that the slip resolution of the 43 near-field stations is different between the south section of the Beichuan fault and the Pengguan fault,which are nearly parallel.The selected records can distinguish the slip of the south section of the Beichuan fault,but the slip resolution of the Pengguan fault is worse.(2)In order to satisfy the second wave packet of stations in the area behind the rupture direction,the southern section of the Beichuan fault or the Pengguan fault needs to produce a rupture to the southwest direction.Considering the fitting residual of waveform and the coincidence of inversion results with surface rupture data,the possible rupture mode is as follows:the rupture started at the low dip angle in the south part of the Beichuan fault,which causes the rupture of the Pengguan fault,and then causes the rupture of the Xiaoyudong fault,which triggers the bilateral rupture of the high dip angle in the south part of the Beichuan fault.