| 考虑震源破裂方向的地震动衰减模型 |
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| 引用本文： | 刘汉兴,汪素云.考虑震源破裂方向的地震动衰减模型[J].地震学报,1989,11(1):24-37. |
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| 作者姓名： | 刘汉兴 汪素云 |
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| 作者单位： | 国家地震局地球物理研究所 |
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| 摘 要： | 本文基于Haskell的3源辐射谱模型,加上介质非弹性吸收项,几何扩散项和自由面放大效应,推演出峰值加速度和均方根加速度表达式。据此,建议一种考虑震源破裂方向的地震动衰减模型。用Morgan Hill和Imperial Valley两地震的峰值加速度资料,单震级统计分析结果表明,文中建议的地震动衰减模型是合理的。与Joyner和Boore所用的衰减模型相比较,剩余标准差可减少0.1——0.2。本文所考虑的震源破裂的地震动衰减模型,可分别用于不同断层类型的地震,如单侧和双侧走滑型地震及倾滑型地震,分别建立地震动衰减关系,进行地震危险性分析。文章最后给出了美国西部考虑震源破裂方向的地震动峰值加速度和均方根加速度的衰减关系。
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| 关 键 词： | 震源破裂方向 地震动衰减模型 方向性函数 地震动参数 空间分布形状 |
A GROUND MOTION ATTENUATION MODEL DEPENDENT ON THE RUPTURE DIRECTION OF SEISMIC SOURCE |
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| Affiliation: | Institute of Geophysics, State Seismological Bureau |
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| Abstract: | In this paper,the expressions of peak ground motion acceleration and r. m. s acceleration have been derived,based on the Haskell's co-cube radiated spectrum of source model,plus the terms of anelastic attenuation,geometrical spreading and enlargement factor of free surface. Then,a ground motion attenuation model depsndent on the rupture direction of the seismic source from the expressions has been recommended. The formula is as the following: In (a) = C0+ C1Mw+ C21nR+ C3R+C41n(D())+C5d()+C6S Where a is a parameter of peak acceleration or RMS acceleration for the directivity functions of D() and d(),respectively.The results of uni-magnitude regressions indicated that the model proposed in this paper is more adequate than the euqi-distance circle model,utilizing the acceleration data of the Morgan Hill and Imperial Valley earthquakes which abound with ground motion records. Standard deviations may be reduced by 0.1 to 0.2,compiring the model developed in this paper with the conventional attenuation model,for instance,the Joyner and Boore's model. The ground motion attenuation model dependent on rupture direction of seismic source developed in this paper may be applied to earthquakes with different patterns of faults,for example,to unilateral or bilateral strik-slip and dip-slip rupture and reverse rupture patterns. The inadequacy of the circle distribuation of Cornell's piont source model and the narrow-long ellipse distribua-tion of fault rupture model with equi-distance also may be improved. Finally,The formulas of PGA and RMS accelerations attenuation dependent on the rupture direction of the seismic source are presented for the Western United States. |
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