近断层地震时-频谱特性小波变换分析

Wavelet transform analysis for the time-frequency spectrum characteristics of near-fault ground motions

借助小波变换,研究汶川地震(Wen Chuan earthquake,2008)什邡八角台站加速度记录的局部谱密度分布特点.通过对小波分量的重构来解析加速度脉冲,发现地震能量富集于中、高频段内,在时域上存在显著的能量双峰,地震波长周期成分并不明显.对美国洛杉矶北岭地震(Northridge earthquake,1994)Sylmar-OliveView台站加速度记录进行研究,通过循环移位操作来分离低频加速度脉冲,发现低频加速度脉冲对长周期结构的破坏作用更显著.因此,借助小波方法研究近断层地震独具优势,可为相关领域的抗震研究提供新思路.

Through wavelet transform method,the local spectral density of acceleration records obtained from Shifang Bajiao station（Wenchuan earthquake,2008） are analyzed,and the acceleration pulse is parsed by wavelet vector reconstruction.It shows that seismic energy is gathered near high frequency band,and there is significant energy twin peaks in the time domain.Meanwhile,long-period components of the earthquake adjacent to the fault are not obvious.Acceleration record of Sylmar-Olive View station（Los Angeles Northridge earthquake,1994） is also studied,and low-frequency acceleration pulse is detached through the cyclic shift operation.It turns out that the low-frequency acceleration pulse is more destructive to the long-periodic structure.The wavelet method has great advantages of analyzing the near-fault ground motions,and it can provide new ideas in the related area of anti-seismic research.