断层下方地壳分层结构对地震动模拟结果的影响研究
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摘要
考虑震源破裂过程的三维地震动数值模拟一般需将震源包含在计算区域中,这样的计算模型区域大,计算量大,尤其是对于断层埋深较大的情况。本文对破裂断层下地壳分层结构引起的反射波的影响进行了分析,分别对改变断层下方介质的密度和波速两个参数的模拟结果进行了对比,结果表明:断层下方地壳分层结构引起的反射波对地表观察点地震动时程的影响很小,可以忽略。因此进行三维地震动数值模拟可以不考虑断层下介质的影响,从而可以大大减小计算区域,提高计算效率。
Three dimensional seismic ground motion simulation considering source rupture process generally includes source in the computational domain,in which the computation region and amount are quite large,especially in the case of large buried depth of the fault.Analysis of the influences of reflected wave caused by the crust layered structure beneath fault has been made in this paper,and the simulation results are compared when medium density and wave velocity under the fault are changed respectively.The results show that the effect of reflected wave caused by the crust layered structure beneath fault on the ground motion of surface observation points is small and negligible.So we can ignore the effect of medium under the fault in 3D numerical simulation of strong ground motion,which will reduce the calculation region significantly and the calculation efficiency is improved as well.
Three dimensional seismic ground motion simulation considering source rupture process generally includes source in the computational domain,in which the computation region and amount are quite large,especially in the case of large buried depth of the fault.Analysis of the influences of reflected wave caused by the crust layered structure beneath fault has been made in this paper,and the simulation results are compared when medium density and wave velocity under the fault are changed respectively.The results show that the effect of reflected wave caused by the crust layered structure beneath fault on the ground motion of surface observation points is small and negligible.So we can ignore the effect of medium under the fault in 3D numerical simulation of strong ground motion,which will reduce the calculation region significantly and the calculation efficiency is improved as well.
引文
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[3]刘启方,李雪强.唐山大地震近场宽频带地震动模拟[J].地震工程与工程振动,2011,31(5):1-7.LIU Qifang,LI Xueqiang.Broad-band strong motion simulation of the great Tangshan earthquake[J].Journal of Earthquake Engineering and En-gineering Vibration,2011,31(5):1-7.(in Chinese)
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[5]丁海平,罗光财.地震动有限元模拟方法的精度验证[J].地震工程与工程振动,2010,30(6):38-42.DING Haiping,LUO Guangcai.Precision verification for finite-element method in ground motion simu-lation[J].Journal of Earthquake Engineer-ing and Engineering Vibration,2010,30(6):38-42.(in Chinese)
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[7]廖振鹏.工程波动理论导论[M].2版.北京:科学出版社,2002,44-53.LIAO Zhenpeng.Introduction to wave motion theories for engineering[M].2nd ed.Beijing:Science Press,2002:44-53.(in Chinese)
[8]Wells D L,Coppersmith K J.New relationships among magnitude,rupture length,rupture width,rupture area,and surface displacement[J].Bull.Seismol.Soc.Am.,1994,84(4):974-1002.
[9]Hanks T C,Kanamori H.A moment magnitude scale[J].Journal of Geophysical Research,1979,84(B5):2348-2350.
[10]Somerville P,Irikura K,Graves R,et al.Characterizing crustal earthquake slip models for the prediction of strong ground motion[J].Seism.Res.Lett.1999,70(1):59-80.
[11]Schmedes J,Archuleta R J.Near-source ground motion along strike-slip faults:insights into magnitude saturation of PGV and PGA[J].Bull.Seismol.Soc.Am.,2008,98(5):2278-2290.
[2]刘启方,金星,丁海平.复杂场地条件下震源参数对断层附近长周期地震动的影响[J].地球物理学报,2008,51(1):186-196.LIU Qifang,JIN Xing,DING Haiping.Effects of the source parameters on long period near-fault ground motion in the case of complex site condi-tion[J].Chinese Journal of Geophysics,2008,51(1):186-196.(in Chinese)
[3]刘启方,李雪强.唐山大地震近场宽频带地震动模拟[J].地震工程与工程振动,2011,31(5):1-7.LIU Qifang,LI Xueqiang.Broad-band strong motion simulation of the great Tangshan earthquake[J].Journal of Earthquake Engineering and En-gineering Vibration,2011,31(5):1-7.(in Chinese)
[4]盛俭,薄景山,佴磊,等.近断层地震动场预测——以长春市为例[J].地震工程与工程振动,2012,32(2):48-53.SHENG Jian,BO Jingshan,NAI Lei,et al.Forecast for near-fault ground motion field:Taking Changchun city as an example[J].Journal ofEarthquake Engineering and Engineering Vibration,2012,32(2):48-53.(in Chinese)
[5]丁海平,罗光财.地震动有限元模拟方法的精度验证[J].地震工程与工程振动,2010,30(6):38-42.DING Haiping,LUO Guangcai.Precision verification for finite-element method in ground motion simu-lation[J].Journal of Earthquake Engineer-ing and Engineering Vibration,2010,30(6):38-42.(in Chinese)
[6]许力生,陈运泰.震源时间函数与震源破裂过程[J].地震地磁观测与研究,2002,23(6):1-7.XU Lisheng,CHEN Yuntai.Source time function and rupture process of earthquake[J].Seismological and Geomagnetic Observation and Re-search,2002,23(6):1-7.(in Chinese)
[7]廖振鹏.工程波动理论导论[M].2版.北京:科学出版社,2002,44-53.LIAO Zhenpeng.Introduction to wave motion theories for engineering[M].2nd ed.Beijing:Science Press,2002:44-53.(in Chinese)
[8]Wells D L,Coppersmith K J.New relationships among magnitude,rupture length,rupture width,rupture area,and surface displacement[J].Bull.Seismol.Soc.Am.,1994,84(4):974-1002.
[9]Hanks T C,Kanamori H.A moment magnitude scale[J].Journal of Geophysical Research,1979,84(B5):2348-2350.
[10]Somerville P,Irikura K,Graves R,et al.Characterizing crustal earthquake slip models for the prediction of strong ground motion[J].Seism.Res.Lett.1999,70(1):59-80.
[11]Schmedes J,Archuleta R J.Near-source ground motion along strike-slip faults:insights into magnitude saturation of PGV and PGA[J].Bull.Seismol.Soc.Am.,2008,98(5):2278-2290.
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