我国东南地区π_g波的频散特征

DISPERSION CHARACTERISTIC OF THE π_g WAVE IN SOUTHEASTERN CHINA

本文利用1987年8月在江西省寻乌发生的三次5.0级以上地震的记录资料,讨论了我国东南地区π_g波的传播特征。结果表明:π_g波的初至波速为6.00km/s,与Press的结果相近;π_g波有明显的频散特征,其卓越周期为0.6—0.8秒,较多表现为正常频散,同时也有少量表现为反常频散,由π_g波的波数及波峰的水平合成矢量得到的振幅辐射图象,基本上与弱非均匀介质辐射图象相近;π_g波各波数水平到时与垂直到时存在明显的到时差。

Using the data of the three earthquakes (M_L>5.0) which occurred in Xunwu, Jiangxi Province in August 1987, we have discussed a travel characteristics of the π_g wave in Southeastern China. The results show that, The first velocity is 6.0km/s, it is close to Press's results; the π_g wave has shown normal dispersion, and a few are no-normal dispersion; its paramount period is 0.6-0.8 second. Using the composite amplitude of horizontal component of the π_g wave, we have obtained the radiation pattern of the π_g wave, it is basically close to radiation pattern in weak heterogeneous medium. There is the D value of time of incidence (Phase Shift) between horizontal time and vertical time of the π_g wave number.