四川芦山M_s7.0地震震源机制解
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摘要
使用中国数字地震台网记录的区域和远震宽频带波形,通过频率域和时间域多步反演,研究四川芦山M_S 7.0地震基于点源模型的震源机制解和有限断层模型。考虑到使用不同波形资料类型、盆地效应及简化的一维速度模型等给反演震源参数带来的影响,经测试比较,结果表明:使用区域波形和本区域简化一维速度模型,波形拟合误差最小。此次地震表现为高倾角纯逆冲型事件矩心在水平方向上位于震中偏南西向约4.5 km,最佳波形拟合矩心深度约17 km,矩震级M_W约6.6。推断此地震大多数能量主要在震源偏南西约4.5 km处释放。
We employ multistep inversions in the frequency or time domain,to infer the point-source and finite-fault model of Lushan M_s 7.0 earthquake,mainly using regional and far broadband seismic waves recorded by the Chinese Digital Seismic Network.We take into account some factors,which could bring possible effects on the inverted result,consisting of different datasets,basin effect and simplified 1-D velocity models.The result indicates the misfit between observed waves and synthetics is better,if we use the regional waves and the 1-D velocity model in this studied area.This event occurs on a true rupture plane(strike =214°/dip = 47°/rake=96°),showing a high-angle thrust faulting.The horizontal centroid locates at nearly 4.5 km southwest of the epicenter(30.303°N,102.988°E),and the best-fitting centroid depth is about 17 km.The total scalar moment M_O,is retrieved with an average value of 1.16 ×10~(19)N ? m(or moment magnitude M_w 6.6).We speculate that most of energy could release at nearly 4.5 km southwest of the epicenter.
We employ multistep inversions in the frequency or time domain,to infer the point-source and finite-fault model of Lushan M_s 7.0 earthquake,mainly using regional and far broadband seismic waves recorded by the Chinese Digital Seismic Network.We take into account some factors,which could bring possible effects on the inverted result,consisting of different datasets,basin effect and simplified 1-D velocity models.The result indicates the misfit between observed waves and synthetics is better,if we use the regional waves and the 1-D velocity model in this studied area.This event occurs on a true rupture plane(strike =214°/dip = 47°/rake=96°),showing a high-angle thrust faulting.The horizontal centroid locates at nearly 4.5 km southwest of the epicenter(30.303°N,102.988°E),and the best-fitting centroid depth is about 17 km.The total scalar moment M_O,is retrieved with an average value of 1.16 ×10~(19)N ? m(or moment magnitude M_w 6.6).We speculate that most of energy could release at nearly 4.5 km southwest of the epicenter.
引文
房立华,吴建平,王未来,等.四川芦山M_S 7.0地震及其余震序列重定位研究[J].科学通报,2013,58(20):1 901—1 909.
房立华,吴建平,张天中,等.2011年云南盈江M_S 5.8地震及其余震序列重定位[J].地震学报,2011,33:262—267.
王卫民,郝金来,姚振兴.2013年04月20日四川芦山地震震源破裂过程反演初步结果[J].地球物理学报,2013,56(4):1 412—1 417.
吴为治,包丰,汪小厉,等.单台法研究澳大利亚Tennant Creek地区地震的震源深度和浅层结构[R].中国地球物理学会会议摘要,2012.
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许志琴,李化启,侯立玮,等.青藏高原东缘龙门山-锦屏造山带的崛起-大型拆离断层和挤出机制[J].地质通报,2007,26(10):1 262—1 276.
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):1 066—1 073.
张培震,闻学泽,徐锡伟,等.2008年汶川8.0级特大地震孕育和发生的多单元组合模式[J].科学通报,2009,54(7):944—953.
张勇,许力生,陈运泰.芦山4·20地震破裂过程及其致灾特征初步分析[J].地球物理学报,2013,56(4):1 408—1 411.
曾祥方,罗艳,韩立波,等.4月20日四川芦山M_S 7.0地震:一个高角度逆冲地震[J].地球物理学报,2013,56(4):1 418—1 424.
张勇,许力生,陈运泰.芦山4·20地震破裂过程及其致灾特征初步分析[J].地球物理学报,2013,56(4):1 408—1 411.
赵珠,范军,郑斯华,等.龙门山断裂带地壳速度结构和震源位置的精确修定[J].地震学报,1997,19:615—622.
Cesca S,Heimann S,Stammler K et al.Automated procedure for point and kinematic source inversion at regional distances[J],J Geophys Res,2010,115(6):1-24.
Custodio S,Cesca S.Heimann Fast kinematic waveform inversion and robustness analysis:Application to the 2007 Mw 5.9Horseshoe Abyssal Plain earthquake offshore southwest Iberia[J].Bull Seism Soc Am,2012,102(1).361—376.
Domingues A,Cust6dio S,Cesca S.Waveform inversion of small-to-moderate earthquakes located offshore southwest Iberia[J].Geophys J Int,2013,192(1):248-259.
Friederich W,Dalkolmo J.Complete synthetic seismograms for a spherically symmetric Earth by a numerical computation of the Green's function in the frequency domain[J].Geophys J Int,1995,122:53—550,
Heimann S.A robust method to estimate kinematic earthquake source parameters[D].University of Hamburg,Hamburg,Germany,2011,161.
Hartzell S,Liu P,Mendoza C et al.Stability and uncertainty of finite-fault slip inversions:Application to the 2004Parkfield,California,earthquake[J].Bull Seism Soc Am,2007,97(6):1 911-1 934.
Mai P M,Monelli D,Festa G et al.Earthquake source inversion blindtest:Initial results and further development[R].Eos Trans AGU,2007,88(52),Fall Meet Suppl,Abstract S53C-08.
Vavryuk,K(u|¨)hn D.Moment tensor inversion of wavefor Ms:a two-step time-frequency approach[J].Geophysical Journal International,2012,190,1 761-1 776.
Wang R J.A simple orthonormalization method for stable and efficient computation of Green's function[J].Bull Seism Soc Amer,1999,89(3):733-741.
房立华,吴建平,张天中,等.2011年云南盈江M_S 5.8地震及其余震序列重定位[J].地震学报,2011,33:262—267.
王卫民,郝金来,姚振兴.2013年04月20日四川芦山地震震源破裂过程反演初步结果[J].地球物理学报,2013,56(4):1 412—1 417.
吴为治,包丰,汪小厉,等.单台法研究澳大利亚Tennant Creek地区地震的震源深度和浅层结构[R].中国地球物理学会会议摘要,2012.
许志琴,侯立玮,王宗秀,等.中国松潘-甘孜造山带的造山过程[M].北京:地质出版社,1992.
许志琴,李化启,侯立玮,等.青藏高原东缘龙门山-锦屏造山带的崛起-大型拆离断层和挤出机制[J].地质通报,2007,26(10):1 262—1 276.
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):1 066—1 073.
张培震,闻学泽,徐锡伟,等.2008年汶川8.0级特大地震孕育和发生的多单元组合模式[J].科学通报,2009,54(7):944—953.
张勇,许力生,陈运泰.芦山4·20地震破裂过程及其致灾特征初步分析[J].地球物理学报,2013,56(4):1 408—1 411.
曾祥方,罗艳,韩立波,等.4月20日四川芦山M_S 7.0地震:一个高角度逆冲地震[J].地球物理学报,2013,56(4):1 418—1 424.
张勇,许力生,陈运泰.芦山4·20地震破裂过程及其致灾特征初步分析[J].地球物理学报,2013,56(4):1 408—1 411.
赵珠,范军,郑斯华,等.龙门山断裂带地壳速度结构和震源位置的精确修定[J].地震学报,1997,19:615—622.
Cesca S,Heimann S,Stammler K et al.Automated procedure for point and kinematic source inversion at regional distances[J],J Geophys Res,2010,115(6):1-24.
Custodio S,Cesca S.Heimann Fast kinematic waveform inversion and robustness analysis:Application to the 2007 Mw 5.9Horseshoe Abyssal Plain earthquake offshore southwest Iberia[J].Bull Seism Soc Am,2012,102(1).361—376.
Domingues A,Cust6dio S,Cesca S.Waveform inversion of small-to-moderate earthquakes located offshore southwest Iberia[J].Geophys J Int,2013,192(1):248-259.
Friederich W,Dalkolmo J.Complete synthetic seismograms for a spherically symmetric Earth by a numerical computation of the Green's function in the frequency domain[J].Geophys J Int,1995,122:53—550,
Heimann S.A robust method to estimate kinematic earthquake source parameters[D].University of Hamburg,Hamburg,Germany,2011,161.
Hartzell S,Liu P,Mendoza C et al.Stability and uncertainty of finite-fault slip inversions:Application to the 2004Parkfield,California,earthquake[J].Bull Seism Soc Am,2007,97(6):1 911-1 934.
Mai P M,Monelli D,Festa G et al.Earthquake source inversion blindtest:Initial results and further development[R].Eos Trans AGU,2007,88(52),Fall Meet Suppl,Abstract S53C-08.
Vavryuk,K(u|¨)hn D.Moment tensor inversion of wavefor Ms:a two-step time-frequency approach[J].Geophysical Journal International,2012,190,1 761-1 776.
Wang R J.A simple orthonormalization method for stable and efficient computation of Green's function[J].Bull Seism Soc Amer,1999,89(3):733-741.
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