2017年四川九寨沟M_S7.0地震的强地面运动模拟
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摘要
2017年8月8日发生的九寨沟M_S 7.0地震,是中国近10年来发生的强震之一,造成了大量建筑破坏、人员伤亡和经济损失,强震台网记录到的最大峰值加速度为0.19g。本文采用Wang等(2015)提出的改进有限断层法模拟了这次地震中部分台站的加速度时程。首先,选取合适的震源模型和输入参数,通过对比模拟结果和地震记录,估计这次地震的应力降大约为4.0MPa,与王宏伟等(2017)的分析结果基本一致。与EXSIM(Motazedian等,2005)方法相比,Wang等(2015)的方法得到的结果在频域上与实际地震记录更相符。同时,合成了强震台站以及断层附近网格点的加速度时程,模拟结果的时程和反应谱与实际记录整体上较为符合,震中附近的PGA分布与震中烈度区基本一致,验证了本文结果的有效性。本文合成的地震动可以为该地区的灾后抗震设计提供一定依据。
The August 8, 2017 Jiuzhaigou M_S 7.0 earthquake is one of the strong earthquakes occurred in China during the last decade. This earthquake has caused a large amount of building damage, casualties and economic loss. The maximum PGA recorded by the seismic network is 0.19 g. In this paper, the acceleration time histories at several strong-motion stations are simulated using an improved stochastic finite-fault method proposed by Wang et al.(2015). First, we selected proper source model and input parameters. Through the comparison between simulation results and seismic records, we estimate that the stress drop of this seismic event is as 4.0 MPa, which is generally consistent with the analytical result reported in literature. Compared with the EXSIM method(Motazedian et al., 2005), the results obtained by using the Wang's method(2015) have better agreement with the seismic records in the frequency domain. Then we generated acceleration time histories at several strong-motion stations and grid points surrounding the fault. Through the simulation, we found that the synthetic time series and response spectra are in generally good agreement with the recorded motions, and distribution of synthetic PGA close to the epicenter is consistent with the maximum intensity area, suggesting the effectiveness of the results. The synthetic ground motions could provide reliable basis for the post-disaster seismic design in this region.
The August 8, 2017 Jiuzhaigou M_S 7.0 earthquake is one of the strong earthquakes occurred in China during the last decade. This earthquake has caused a large amount of building damage, casualties and economic loss. The maximum PGA recorded by the seismic network is 0.19 g. In this paper, the acceleration time histories at several strong-motion stations are simulated using an improved stochastic finite-fault method proposed by Wang et al.(2015). First, we selected proper source model and input parameters. Through the comparison between simulation results and seismic records, we estimate that the stress drop of this seismic event is as 4.0 MPa, which is generally consistent with the analytical result reported in literature. Compared with the EXSIM method(Motazedian et al., 2005), the results obtained by using the Wang's method(2015) have better agreement with the seismic records in the frequency domain. Then we generated acceleration time histories at several strong-motion stations and grid points surrounding the fault. Through the simulation, we found that the synthetic time series and response spectra are in generally good agreement with the recorded motions, and distribution of synthetic PGA close to the epicenter is consistent with the maximum intensity area, suggesting the effectiveness of the results. The synthetic ground motions could provide reliable basis for the post-disaster seismic design in this region.
引文
王宏伟,任叶飞,温瑞智,2017.2017年8月8日九寨沟MS 7.0地震震源谱及震中区域品质因子.地球物理学报,60(10):4117-4123.
王卫民,何建坤,郝金来等,2017.2017年8月8日四川九寨沟7.0级地震震源破裂过程反演初步结果.中国科学院青藏高原研究所.(2017-08-09).http://www.itpcas.ac.cn/xwzx/zhxw/201708/t20170809_4840737.html.
喻烟,2012.汶川地震区地震动估计经验模型.哈尔滨:中国地震局工程力学研究所.
中国地震局,2017.中国地震局发布四川九寨沟7.0级地震烈度图.(2017-08-12).http://www.cea.gov.cn/publish/dizhenj/464/478/20170812211337414565961/index.html.
Atkinson G.M.,Boore D.M.,1995.Ground-motion relations for eastern North America.Bulletin of the Seismological Society of America,85(1):17-30.
Beresnev I.A.,Atkinson G.M.,1997.Modeling finite-fault radiation from theωn spectrum.Bulletin of the Seismological Society of America,87(1):67-84.
Boore D.M.,1983.Stochastic simulation of high-frequency ground motions based on seismological models of the radiated spectra.Bulletin of the Seismological Society of America,73(6):1865-1894.
Boore D.M.,Joyner W.B.,1997.Site amplifications for generic rock sites.Bulletin of the Seismological Society of America,87(2):327-341.
Motazedian D.,Atkinson G.M.,2005.Stochastic finite-fault modeling based on a dynamic corner frequency.Bulletin of the Seismological Society of America,95(3):995-1010.
Sun X.D.,Tao X.X.,Duan S.S.,et al.,2013.Kappa(k)derived from accelerograms recorded in the 2008Wenchuan mainshock,Sichuan,China.Journal of Asian Earth Sciences,73:306-316.
Wang G.X.,Ding Y.,Borcherdt R.,2015.Simulation of acceleration field of the Lushan earthquake(MS 7.0,April20,2013,China).Engineering Geology,189:84-97.
王卫民,何建坤,郝金来等,2017.2017年8月8日四川九寨沟7.0级地震震源破裂过程反演初步结果.中国科学院青藏高原研究所.(2017-08-09).http://www.itpcas.ac.cn/xwzx/zhxw/201708/t20170809_4840737.html.
喻烟,2012.汶川地震区地震动估计经验模型.哈尔滨:中国地震局工程力学研究所.
中国地震局,2017.中国地震局发布四川九寨沟7.0级地震烈度图.(2017-08-12).http://www.cea.gov.cn/publish/dizhenj/464/478/20170812211337414565961/index.html.
Atkinson G.M.,Boore D.M.,1995.Ground-motion relations for eastern North America.Bulletin of the Seismological Society of America,85(1):17-30.
Beresnev I.A.,Atkinson G.M.,1997.Modeling finite-fault radiation from theωn spectrum.Bulletin of the Seismological Society of America,87(1):67-84.
Boore D.M.,1983.Stochastic simulation of high-frequency ground motions based on seismological models of the radiated spectra.Bulletin of the Seismological Society of America,73(6):1865-1894.
Boore D.M.,Joyner W.B.,1997.Site amplifications for generic rock sites.Bulletin of the Seismological Society of America,87(2):327-341.
Motazedian D.,Atkinson G.M.,2005.Stochastic finite-fault modeling based on a dynamic corner frequency.Bulletin of the Seismological Society of America,95(3):995-1010.
Sun X.D.,Tao X.X.,Duan S.S.,et al.,2013.Kappa(k)derived from accelerograms recorded in the 2008Wenchuan mainshock,Sichuan,China.Journal of Asian Earth Sciences,73:306-316.
Wang G.X.,Ding Y.,Borcherdt R.,2015.Simulation of acceleration field of the Lushan earthquake(MS 7.0,April20,2013,China).Engineering Geology,189:84-97.