Yabuki&Matsu’ura方法在汶川M_W7.9地震反演中的应用
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摘要
2008年5月12日,青藏高原东缘龙门山断裂带发生汶川MW7.9地震,该地震使得北川—映秀断裂、灌县—江油断裂发生了同震破裂。本文主要利用震后通过复测获得的GPS同震形变场,采用Yabuki&Matsu’ura反演计算方法和分段平面断层模型,反演了地震同震滑动分布。结果表明:映秀—北川主破裂带的断层错动,在映秀附近以逆冲滑动为主,而在北川以北,其走滑运动明显大于逆冲,这一结果与震后地质调查结果与通过地震波研究获得的断层破裂特征相一致;反演得到的最大滑动量达到9.3m和9.6m,分别对应于这次地震中地表破坏最为严重的北川和映秀地区;由所获得的滑动分布计算的地震矩为8.07×1020 N.m,对应的震级为MW7.9。研究结果初步显示,Yabuki&Matsu’ura反演方法可适用在内陆地震断层反演计算中。
On May 12,2008,the great Wenchuan earthquake occurred on the Longmenshan belt,which is located at the eastern margin of the Tibetan Plateau,rupturing the Beichuan-Yingxiu and Guanxian-Jiangyou faults.We apply Yabuki&Matsu'ura's inversion method to estimate the co-seismic slip distribution of thhis earthquake from GPS data.The whole fault model is divided into four sub-faults during our inversion.Our results show that the slips caused by the great earthquake are characterized mainly by thrust motion near Yingxiu,the south segment of the Yingxiu-Beichuan fault;the dextral components are apparently larger than thrust slips at the north segment of the fault.Our estimations agree well with the results of geologic survey and the characteristics of rupturing.The estimated slips have two high-slip concentrations up to 9.6 m and 9.3 m,located respectively near the Yingxiu town and Beichuan city,which suffered the greatest fatalities and structure damages during the earthquake.The total moment released by the great earthquake is about 8.07×1020 N·m,corresponding to an earthquake with magnitude of MW7.9.Our study shows that Yabuki&Matsu'ura's inversion method is suitable to estimate the fault slip model in mainland China.
On May 12,2008,the great Wenchuan earthquake occurred on the Longmenshan belt,which is located at the eastern margin of the Tibetan Plateau,rupturing the Beichuan-Yingxiu and Guanxian-Jiangyou faults.We apply Yabuki&Matsu'ura's inversion method to estimate the co-seismic slip distribution of thhis earthquake from GPS data.The whole fault model is divided into four sub-faults during our inversion.Our results show that the slips caused by the great earthquake are characterized mainly by thrust motion near Yingxiu,the south segment of the Yingxiu-Beichuan fault;the dextral components are apparently larger than thrust slips at the north segment of the fault.Our estimations agree well with the results of geologic survey and the characteristics of rupturing.The estimated slips have two high-slip concentrations up to 9.6 m and 9.3 m,located respectively near the Yingxiu town and Beichuan city,which suffered the greatest fatalities and structure damages during the earthquake.The total moment released by the great earthquake is about 8.07×1020 N·m,corresponding to an earthquake with magnitude of MW7.9.Our study shows that Yabuki&Matsu'ura's inversion method is suitable to estimate the fault slip model in mainland China.
引文
[1]徐锡伟,闻学泽,叶建青,等.汶川MS8.0地震地表破裂带及其发震构造[J].地震地质,2008,30(3):597-629.
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[3]赵翠萍,陈章立,周连庆,等.汶川MW8.0地震震源破裂过程研究[J].分段特征.科学通报,2009,54(22):3 475-3 482.
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[5]王敏.基于GPS同震位移场约束反演2008年5.12汶川大地震破裂空间分布[J].地球物理学报,2009,52(10):2 519-2 525.
[6]许才军,刘洋,温扬茂.利用GPS资料反演汶川MW7.9地震滑动分布[J].测绘学报,2009,38(3):195-201.
[7]Shen Z K,Sun J,Zhang P,et al.Slip maxima at fault junctions and rupturing of barriers during the2008Wenchuan earthquake[J].Nature Geoscience,2009,2(10):718-724.
[8]Wang Q,Qiao X J,Lan Q G,et al.Rupture of deep faults in the 2008 Wenchuan earthquake anduplift of the Longmen Shan[J].Nature Geoscience,2011,4(9):634-640.
[9]Tong X,Sandwell D T,Fialko Y.Coseismic slip model of the 2008 Wenchuan earthquake derivedfrom joint inversion of interferometric synthetic aperture radar,GPS,and field data[J].J geophysRes,2010,115(B04314).
[10]张培震,徐锡伟,闻学泽,等.2008年汶川8.0级地震发震断裂的滑动速率、复发周期和构造成因[J].地球物理学报,2008,51(4):1066-1073.
[11]李勇,黄润秋,周荣军,等.龙门山地震带的地质背景与汶川地震的地表破裂[J].工程地质学报,2009,17(1):3-18.
[12]Yabuki T,Matsu′ura M.Geodetic data inversion using a Bayesian information criterion for spatialdistribution of fault slip[J].Geophysical Journal International,1992,109(2):363-375.
[13]Akaike H.Likelihood and the Bayes procedure[J].Trabajos De Estadistica Y De Investigacion Op-erativa,1980,31(1):143-166.
[14]Lawson C L.&Hanson,R J.Solving Least Squares Problems[M].Prentice-Hall,EnglewoodCliffs,N J.1974.
[15]Maruyama T.Statical Elastic Dislocation in an Infinite and Semi-Infinite Medium[J].Bulletin of theEarthquakes Research Institute,1964,42(1):289-368.
[2]王卫民,赵连锋,李娟,等.四川汶川8.0级地震震源过程[J].地球物理学报,2008,51(05):1 403-1 410.
[3]赵翠萍,陈章立,周连庆,等.汶川MW8.0地震震源破裂过程研究[J].分段特征.科学通报,2009,54(22):3 475-3 482.
[4]张勇,冯万鹏,许力生,等.2008年汶川大地震的时空破裂过程[J].中国科学:D辑,2008,38(10):1 186-1 194.
[5]王敏.基于GPS同震位移场约束反演2008年5.12汶川大地震破裂空间分布[J].地球物理学报,2009,52(10):2 519-2 525.
[6]许才军,刘洋,温扬茂.利用GPS资料反演汶川MW7.9地震滑动分布[J].测绘学报,2009,38(3):195-201.
[7]Shen Z K,Sun J,Zhang P,et al.Slip maxima at fault junctions and rupturing of barriers during the2008Wenchuan earthquake[J].Nature Geoscience,2009,2(10):718-724.
[8]Wang Q,Qiao X J,Lan Q G,et al.Rupture of deep faults in the 2008 Wenchuan earthquake anduplift of the Longmen Shan[J].Nature Geoscience,2011,4(9):634-640.
[9]Tong X,Sandwell D T,Fialko Y.Coseismic slip model of the 2008 Wenchuan earthquake derivedfrom joint inversion of interferometric synthetic aperture radar,GPS,and field data[J].J geophysRes,2010,115(B04314).
[10]张培震,徐锡伟,闻学泽,等.2008年汶川8.0级地震发震断裂的滑动速率、复发周期和构造成因[J].地球物理学报,2008,51(4):1066-1073.
[11]李勇,黄润秋,周荣军,等.龙门山地震带的地质背景与汶川地震的地表破裂[J].工程地质学报,2009,17(1):3-18.
[12]Yabuki T,Matsu′ura M.Geodetic data inversion using a Bayesian information criterion for spatialdistribution of fault slip[J].Geophysical Journal International,1992,109(2):363-375.
[13]Akaike H.Likelihood and the Bayes procedure[J].Trabajos De Estadistica Y De Investigacion Op-erativa,1980,31(1):143-166.
[14]Lawson C L.&Hanson,R J.Solving Least Squares Problems[M].Prentice-Hall,EnglewoodCliffs,N J.1974.
[15]Maruyama T.Statical Elastic Dislocation in an Infinite and Semi-Infinite Medium[J].Bulletin of theEarthquakes Research Institute,1964,42(1):289-368.
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