影响面波勘探精度的因素探讨

Approach to the Factors Effecting on Exploration Precision of Surface Wave

分析了影响面波勘探精度的主要因素 ,针对计算面波相速度的精度问题 ,讨论了常用测量台间面波相速度方法的优缺点及其适用范围 ,并提出通过测量台间格林函数进行相位校正 ,以得到两台之间的精确相位。以合成的高频理论地震图作为记录信号 ,并在理论地震图上叠加了 2 0 %的随机噪声 ,利用这些方法分析理论信号 ,数字实验表明 :在相干频率范围内 ,格林函数方法能够精确测量台间相速度 ,而互相关法和窄带通滤波互相关法所得结果较为离散。以此方法对一个排列的实测地震面波信号进行处理 。

The main factors effecting on exploration precision of surface wave are analyzed in the light of calculation of phase velocity of surface wave; the merits and demetits of common computing methods for phase velocity between stations and their applied range are discussed and calculation of interstation Green's function for correcting phase is put forward to get the precise phase difference between two stations. Some methods, in which synthesized theoretical seismogram of high frequency is taken as record signal and 20% random noise is superimposed on the seismogram, are used to analyze the theoretical seismogram. The digital experiment shows that in the correlating frequency range, Green's function method can measure precisely interstation phase velocity, but the results obtained by correlation and narrow band-pass filtering correlation methods are more dispersed. The Green's function method is used to an array of observed surface wave signals and velocity structure of shear wave beneath the array is obtained.