Frequency dependent attenuation function and fourier amplitude spectra of strong earthquake ground motion in California, 1995

This report presents the third generation of empirical equations for direct scaling at Fourier amplitude spectra of strong ground motion in California. Simultaneously we present a new, path and frequency dependent, attenuation function for spectral amplitudes versus distance between the causative fault and the recording station.; The results show major improvements in the empirical scaling equations relative to the former models from 1976 (first generation) and 1985 (second generation). These improvements were feasible because a) the number of strong motion recordings which could be used in the analysis grew to about 2000 (compared to 186 in mid 1970's and 55 in mid 1980's), and because b) of the detailed and systematic characterization of the recording sites by local geological and local soil site parameters.

本报告提出了适用于加利福尼亚地区强地面运动傅里叶振幅谱（Fourier amplitude spectra）直接标定的第三代经验公式。同时，本研究还提出了一种新的、与路径和频率相关的衰减函数，用于描述谱振幅随发震断层至观测台站之间距离的变化关系。研究结果表明，相较于1976年（第一代）和1985年（第二代）的原有模型，本次提出的经验标定公式实现了显著优化。本次优化得以实现的原因在于：其一，可用于分析的强震动记录数量从20世纪70年代中期的186条、80年代中期的55条增长至约2000条；其二，研究团队通过当地地质与场地土参数对观测台站进行了细致且系统的场地特征刻画。