汶川地震余震震源参数及地震动衰减与场地影响参数反演分析
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摘要
基于强震动观测台钻孔数据,统计得到了四川、甘肃地区20m深的浅硬土层场地平均剪切波速模型.通过与美国加州地区的波速模型对比,结合四川、甘肃地区地震预报的地壳模型,延拓剪切波速模型至40km.应用四分之一波长法计算了浅硬土层场地的平均场地放大系数.利用场地放大系数,消除13次余震中浅硬场地的台站场地响应,反演了龙门山断层上、下盘的介质品质因子以及13次余震的有效应力降.通过与普通土层场地的强震动记录对比,对浅硬土层场地的放大系数进行调整,得到了深厚土层场地的平均放大系数.
The average shear-wave velocity profile for shallow soil sites at a depth of 20 m is derived from the drilling data of strong motion stations in Sichuan and Gansu provinces.Combined with the profile of California and the crust model used in earthquake prediction study for Sichuan Province,the average shear-wave velocity profile is extended to 40 km.The site amplification factor for shallow soil sites is generated by using the quarter wave-length method.Then,the quality factors of different zones,the effective stress drop and kappa value at shallow soil sites are deduced from the Fourier amplitude spectra of 13 aftershocks of the Wenchuan earthquake.Due to different site effects,the strong motion data at deep soil sites show a large bias from the inverted model.According to the bias,the site amplification factor for deep soil sites is derived from revision of the site amplification factor for shallow soil sites.
The average shear-wave velocity profile for shallow soil sites at a depth of 20 m is derived from the drilling data of strong motion stations in Sichuan and Gansu provinces.Combined with the profile of California and the crust model used in earthquake prediction study for Sichuan Province,the average shear-wave velocity profile is extended to 40 km.The site amplification factor for shallow soil sites is generated by using the quarter wave-length method.Then,the quality factors of different zones,the effective stress drop and kappa value at shallow soil sites are deduced from the Fourier amplitude spectra of 13 aftershocks of the Wenchuan earthquake.Due to different site effects,the strong motion data at deep soil sites show a large bias from the inverted model.According to the bias,the site amplification factor for deep soil sites is derived from revision of the site amplification factor for shallow soil sites.
引文
华卫,陈章立,郑斯华.2009.2008年汶川8.0级地震序列震源参数分段特征的研究[J].地球物理学报,52(2):365--371.
雷建设,赵大鹏,苏金蓉,张光伟,李凤.2009.龙门山断裂带地壳精细结构与汶川地震发震机理[J].地球物理学报,52(2):339--345.
谈洪波,申重阳,玄松柏.2010.地壳分层与地壳厚度对汶川地震同震效应的影响[J].大地测量与地球动力学,30(4):29--35.
赵珠,范军,郑斯华,长谷川昭,堀内茂木.1997.龙门山断裂带地壳速度结构和震源位置的精确修订[J].地震学报,19(6):615--622.
Anderson J G,Hough S E.1984.A model for the shape of the Fourier amplitude spectrum of acceleration at highfrequencies[J].Bull Seism Soc Amer,74(5):1969--1993.
Atkinson G M,Mereu R F.1992.The shape of ground motion attenuation curves in Southeastern Canada[J].Bull SeismSoc Amer,82(5):2014--2031.
Boore D M,Joyner W B.1997.Site amplifications for generic rock sites[J].Bull Seism Soc Amer,87(2):327--341.
Chiou B,Darragh R,Gregor N,Silva W.2008.NGA project strong-motion database[J].Earthq Spectra,24(1):23-44.
Herrmann R B.1985.An extension of random vibration theory estimates of strong ground motion to large distance[J].Bull Seism Soc Amer,75(5):1447--1453.
Joyner W B,Warrick R E,Fumal T E.1981.The effect of quaternary alluvium on strong ground motion in the CoyoteLake,California,Earthquake of1979[J].Bull Seism Soc Amer,71(4):1333--1349.
Press W H,Teukolsky S A,Vetterling W T,Flannery B P.2005.Numerical Recipes in Fortran[M].New York:Cambridge University Press:678--682.
Silva W J,Li S,Darragh B,Gregor N.2000.Surface Geology-Based Strong Motion Amplification Factors for SanFrancisco and Los Angeles Areas[R].PEER Report,30--45.
Silva W J.1996.Description and validation of the stochastic ground motion model[R]∥A Report to EngineeringResearch and Applications Division Department of Nuclear Energy Brookhaven National Laboratory.Chapter3:1-8.
雷建设,赵大鹏,苏金蓉,张光伟,李凤.2009.龙门山断裂带地壳精细结构与汶川地震发震机理[J].地球物理学报,52(2):339--345.
谈洪波,申重阳,玄松柏.2010.地壳分层与地壳厚度对汶川地震同震效应的影响[J].大地测量与地球动力学,30(4):29--35.
赵珠,范军,郑斯华,长谷川昭,堀内茂木.1997.龙门山断裂带地壳速度结构和震源位置的精确修订[J].地震学报,19(6):615--622.
Anderson J G,Hough S E.1984.A model for the shape of the Fourier amplitude spectrum of acceleration at highfrequencies[J].Bull Seism Soc Amer,74(5):1969--1993.
Atkinson G M,Mereu R F.1992.The shape of ground motion attenuation curves in Southeastern Canada[J].Bull SeismSoc Amer,82(5):2014--2031.
Boore D M,Joyner W B.1997.Site amplifications for generic rock sites[J].Bull Seism Soc Amer,87(2):327--341.
Chiou B,Darragh R,Gregor N,Silva W.2008.NGA project strong-motion database[J].Earthq Spectra,24(1):23-44.
Herrmann R B.1985.An extension of random vibration theory estimates of strong ground motion to large distance[J].Bull Seism Soc Amer,75(5):1447--1453.
Joyner W B,Warrick R E,Fumal T E.1981.The effect of quaternary alluvium on strong ground motion in the CoyoteLake,California,Earthquake of1979[J].Bull Seism Soc Amer,71(4):1333--1349.
Press W H,Teukolsky S A,Vetterling W T,Flannery B P.2005.Numerical Recipes in Fortran[M].New York:Cambridge University Press:678--682.
Silva W J,Li S,Darragh B,Gregor N.2000.Surface Geology-Based Strong Motion Amplification Factors for SanFrancisco and Los Angeles Areas[R].PEER Report,30--45.
Silva W J.1996.Description and validation of the stochastic ground motion model[R]∥A Report to EngineeringResearch and Applications Division Department of Nuclear Energy Brookhaven National Laboratory.Chapter3:1-8.
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