估计近场地震动的统计—经验格林函数法

本文提出统计-经验格林函数法,用以估计缺乏小震记录场点在大震时的地震动时程。统计-经验格林函数的富里哀幅值谱从其它类似场地获得的小震记录的富里哀谱的衰减关系中得到,其相位谱则直接取自小震记录的相位谱。本文分别用经验格林函数法和统计-经验格林函数法,用迁安台记录到的1976年唐山地震的三次余震(M_L 5.8、M_L 5.7和M_L 5.4)的加速度记录,合成唐山地震的最大余震滦县地震(M_s 7.1)时迁安台的加速度时程曲线,合成结果说明了所提方法的可行性。

STATISTICAL-EMPIRICAL GREEN'S FUNCTION METHOD FOR ESTIMATING NEAR-FIELD EARTHQUAKE GROUND MOTIONS

A statistical-empirical Green's function method is proposed for estimating near-field earthquake ground motions. The method can be applied to the estimation of ground motions at sites where there are no observed small earthquake records for use as empirical Green 's functions. The method requires only some small-earthquake records, which are more easily obtainable than large- earthquake records, for regression analysis of Fourier amplitude spectra. Hence, the method does not need any extrapolation as does the usual attenuation regression analysis. In order to facilitate method application, the Fourier phase spectrum of the observed records is used directly in this method. Six records of three aftershocks of the 1976 Tangshan earthquake (ML 5. 8 , ML 5. 7 and ML 5. 4 ) recorded at Qiannan station were used to generate statistical-empirical Green's functions. The strong ground motions at Qianan station during the largest aftershock (Ms 7.1) of the Tartgshan Earthquake were synthesized. The synthesized results confirm the reliability of the proposed method.