澜沧-耿马地震的S波偏振及P波、S波振幅比变化特征

S-WAVE POLARIZATION AND VARIATION CHARACTERISTICS OF AMPLITUDE RATIO OF P-AND S-WAVES FOR THE LANCANG-GENGMA EARTHQUAKE

摘要:

本文通过对1988年11月6日云南澜沧-耿马7.6、7.2级强震前后S波偏振角的计算分析,得出大震前后U_SH-U_Sv的三种变化图象,这种变化特征具有一定的前兆意义。与此同时,对大震前后P波、S波最大振幅比值分布和S波偏振角空间分布进行研究发现,北纬22°57'可能是澜沧、耿马两地区介质差异的分界面。

Abstract:

Three variation patterns of U_SH-U_SV of the Nov. 6,1988, Lancang-Gengma earthquakes(M=7.6, 7.2)have been obtained through calculating and analysing the S-wave polarization angles before and after the earthquakes. The variation characteristics possess precursory meaning. Study on the distribution of maximum amplitude ratio of P-and Swaves and spatial distribution of S-wave polarization angles before and after the earthquakes shows the line of 22°57'north latitude may be the medium boundary between Lancang and Gengma areas.