空气中声波在井下地震计记录强度的特征分析

摘要

基于理论地震图,分别探讨台站埋深、S波速度以及衰减结构对井下地震计噪声强度的影响,发现当台站深度小于参考深度即S波速度与声波速度相等的深度时,声波转换波/P波振幅比随深度变化较小;而当台站深度大于参考深度时,声波转换波/P波振幅比随深度指数下降.利用2015年天津爆炸事件在井下地震计记录的波形,分析井下地震计噪声强度的变化特征,其结果与基于理论地震图的结果一致.%In this paper,based on synthetic seismograms,the effects of receiver depth,S wave velocity and attenuation structure on noise level are investigated.We find that the amplitude ratio of converted acoustic wave and P wave decreases exponentially with depth,when the receiver is deep enough and where S wave velocity is larger than acoustic wave velocity.Combined with the borehole seismic data of the 2015 Tianjin explosions,features of noise level are further discussed and examined,showing consistency with the characteristics of synthetic data.