地震研究

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。

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.

引言
1 数据的选取处理和模型参数
2 断层破裂方式
3 近场记录对2条平行断层滑动的分辨能力
4 反演结果
5 结论

图1 汶川地震地表破裂、震中和所选台站位置<br/>Fig.1 The locations of surface rupture,epicenter and stations used in this study of the Wenchuan earthquake

图1 汶川地震地表破裂、震中和所选台站位置
Fig.1 The locations of surface rupture,epicenter and stations used in this study of the Wenchuan earthquake

图2 破裂后方11个台站三分向加速度和速度记录(蓝线为第2个波段,字母和数台站和记录最大值)<br/>Fig.2 Three-component acceleration and velocity records of 11 stations are located behind the rupture direction.(Blue lines denote the second wave packet,letters and numbers denote stations and the maximum value of records)

图2 破裂后方11个台站三分向加速度和速度记录(蓝线为第2个波段,字母和数台站和记录最大值)
Fig.2 Three-component acceleration and velocity records of 11 stations are located behind the rupture direction.(Blue lines denote the second wave packet,letters and numbers denote stations and the maximum value of records)

表1 断层参数<br/>Tab.1 The parameters of fault model

表1 断层参数
Tab.1 The parameters of fault model

图3 汶川地震三维曲面断层模型<br/>Fig.3 The 3D curved fault model of the Wenchuan earthquake

图3 汶川地震三维曲面断层模型
Fig.3 The 3D curved fault model of the Wenchuan earthquake

表2 一维地壳速度模型<br/>Tab.2 1D crustal velocity model

表2 一维地壳速度模型
Tab.2 1D crustal velocity model

表3 算例1和2中输入模型参数和反演结果<br/>Tab.3 Parameters of input models and inversion results of examples 1 and 2

表3 算例1和2中输入模型参数和反演结果
Tab.3 Parameters of input models and inversion results of examples 1 and 2

图4 算例1结果输入模型(a),北川断层南段结果(b)和彭灌断层结果(c)<br/>Fig.4 The result of example 1.input model(a),result of south Beichuan fault(b),result of Pengguan fault(c)

图4 算例1结果输入模型(a),北川断层南段结果(b)和彭灌断层结果(c)
Fig.4 The result of example 1.input model(a),result of south Beichuan fault(b),result of Pengguan fault(c)

图5 算例2结果输入模型(a),彭灌断层结果(b)和北川断层南段结果(c)<br/>Fig.5 The result of example 2.input model(a),result of Pengguan fault(b),result of south Beichuan fault(c)

图5 算例2结果输入模型(a),彭灌断层结果(b)和北川断层南段结果(c)
Fig.5 The result of example 2.input model(a),result of Pengguan fault(b),result of south Beichuan fault(c)

表4 3种破裂方式断层面上地震矩和最大位错<br/>Tab.4 The maximum slip values and moment of three rupture modes

表4 3种破裂方式断层面上地震矩和最大位错
Tab.4 The maximum slip values and moment of three rupture modes

图6 破裂方式1(a)、2(b)和3(c)断层面滑动量和滑动方向分布<br/>Fig.6 Slip value and direction of rupture mode for 1(a),2(b)and 3(c)

图6 破裂方式1(a)、2(b)和3(c)断层面滑动量和滑动方向分布
Fig.6 Slip value and direction of rupture mode for 1(a),2(b)and 3(c)

图7 破裂方式1,2和3东西(a)、南北(b)和垂直向(c)合成速度记录与观测速度记录比较<br/>Fig.7 Comparison of synthetic and observed waveforms for EW(a),NS(b)and UD(c) of rupture modes 1,2 and 3

图7 破裂方式1,2和3东西(a)、南北(b)和垂直向(c)合成速度记录与观测速度记录比较
Fig.7 Comparison of synthetic and observed waveforms for EW(a),NS(b)and UD(c) of rupture modes 1,2 and 3

陈桂华,徐锡伟,于贵华,等.2009.2008年汶川MS8.0地震多断层破裂的近地表同震滑移及滑移分解[J].地球物理学报,52(5):1384-1394.
陈九辉,刘启元,李顺成,等.2009.汶川MS8.0地震余震序列重新定位及其地震构造研究[J].地球物理学报,52(2):390-397.
邓起东,陈桂华,朱艾斓.2011.关于2008年汶川MS8.0地震震源断裂破裂机制几个问题的讨论[J].中国科学:地球科学,41(11):1559-1576.
贺鹏超,沈正康.2014.汶川地震发震断层破裂触发过程[J].地球物理学报,57(10):3308-3317.
胡幸平,俞春泉,陶开,等.2008.利用P波初动资料求解汶川地震及其强余震震源机制解[J].地球物理学报,51(6):1711-1718.
黄媛,吴建平,张天中,等.2008.汶川8.0 级大地震及其余震序列重定位研究[J].中国科学:地球科学,38(10):1242-1249.
钱琦,韩竹军.2010.汶川MS8.0级地震断层间相互作用及其对起始破裂段的启示[J].地学前缘,17(5):84-92.
王鹏,刘静.2014.断层横向构造在逆冲型地震破裂中的作用-以汶川地震小鱼洞断层为例[J].地球物理学报,57(10):3296-3307.
王卫民,赵连锋,李娟,等.2008.四川汶川8.0级地震震源过程[J].地球物理学报,51(5):1403-1410.
徐锡伟,陈桂华,于贵华,等.2010.2008.5·12汶川地震地表破裂基本参数的再论证及其构造内涵分析[J].地球物理学报,53(10):2321-2336.
徐锡伟,闻学泽,叶建青,等.2008.汶川MS8.0地震地表破裂带及其发震构造[J].地震地质,30(3):597-629.
尹得余,刘启方,刘畅,等.2018.基于近场强震记录和同震位移的汶川地震破裂过程[J].地震地质,40(3):698-717.
尹得余.2017.汶川地震破裂过程联合反演及高频辐射研究[D].哈尔滨:中国地震局工程力学研究所.
于彦彦.2016.三维沉积盆地地震效应研究[D].哈尔滨:中国地震局工程力学研究所.
张勇,冯万鹏,许力生,等.2008.2008年汶川大地震的时空破裂过程[J].中国科学:地球科学38(10):1186-1194.
赵静,任金卫,江在森,等.2018.龙门山断裂西南断闭锁与变形特征[J].地震研究,41(2):216-225.
朱艾斓,徐锡伟,刁桂苓,等.2008.汶川MS8.0 地震部分余震重新定位及地震构造初步分析[J].地震地质,30(3):759-767.
Hartzell S H,Heaton T H.1983.Inversion of strong ground motion and teleseismic waveform data for the fault rupture history of the 1979 Imperial Valley,California,earthquake[J]Bull.Seismol.Soc.Am,73(6):1553-1583.
Hartzell S,Liu P C,Mendoza C,et al.2007.Stability and uncertainty of finite-fault slip inversions:application to the 2004 Parkfield,California,Earthquake[J].Bull Seismol Soc Amer,97(6):1911-1934.
Hartzell S,Mendoza C,Ramirez-Guzman L,et al.2013.Rupture History of the 2008 MW7.9 Wenchuan,China,Earthquake:Evaluation of Separate and Joint Inversions of Geodetic,Teleseismic,and Strong-Motion Data[J].Bull Seismol Soc Amer,103(1):353-370.
Hubbard J,Shaw J H,Klinger Y.2010.Structural Setting of the 2008 MW7.9 Wenchuan,China,Earthquake[J].Bulletin of the Seismological Society of America,100(5B):2713-2735.
Hubbard J,Shaw J H.2009.Uplift of the Longmen Shan and Tibetan plateau,and the 2008 Wenchuan(M7.9)earthquake[J].Nature,458(7235):194.
Shen Z K,Sun J B,Zhang P Z,et al.2009.Slip maxima at fault junctions and rupturing of barriers during the 2008 Wenchuanearthquake[J].Nature geosciences,2(10):718-724.
Wu C C,Dreger D,Kaverina A.2001.Finite-Source Modeling of the 1999 Taiwan(Chi-Chi)Earthquake Derived from a Dense Strong-Motion Network[J].Bull Seismol Soc Amer,91(5):1144-1157.
Zhang P Z,Wen X Z,Shen Z K,et al.2010.Oblique,High-Angle,Listric-Reverse Faulting and Associated Development of Strain:The Wenchuan Earthquake of May 12,2008,Sichuan,China[J].Annu Rev Earth Planet,38(1):353-382.

备注

引言

1 数据的选取处理和模型参数

2 断层破裂方式

3 近场记录对2条平行断层滑动的分辨能力

4 反演结果

5 结论

期刊信息