景泰地区Q值变化特征及其原因初探

THE CHARACTERISTICS OF Q VALUE CHANGES IN JINGTAI AREA AMD PRELIMINARY STUDY OF ITS REASON

摘要:

本文利用兰州有线传输台网的资料,首先用两次地震的频谱比确定了景泰地区地震震源谱的高频衰减趋势,其形式为ω^-2,然后用试错法测得了景泰地区的Q_p、Q₃值。研究发现,1990年10月20日景泰地震前,从1988年开始,其震中至各台站间所有路径上介质的Q_p、Q₃值皆明显高于震后并高于参考值(1984-1985年介质的Q值)。本文还将景泰地区Q值与我国其它地区Q值进行了对比,最后用组合模式从理论上讨论了景泰地区Q值变化的原因。

Abstract:

In this paper, firstly, we determined the high frequence attenuation tendency(ω^-2)of P and S waves of the source in Jingtai area using spectral ratio of two events, utilizing the data of the wired transmission network of Lanzhou; and then measured Q_p and Q₃ values with the method, of trial and error. It,showed that the Q_p and Q₃ values (from 1988 to Oct. 1990) of medium on all paths between the mainshock source(Ms=6.2) in Jingtai on Oct. 20 1990 and each station before the mainshock are obviously, higher than those of after the major earthquake and the reference values (Q values of media from, 1984 to 1985). This paper also compared the Q values in Jingtai area with the ones in other places of china. Finally, the reasons of the changes of Q values were discussed physically by using the combination model.