地震前兆地声信号的低频特征

Low Frequency Characteristics of Precursory Seismic Acoustic Signal

阐述大地震前低频地声的波形和频谱的特征．论述了震前低频地声的形成及声波传播规律，指出震前低频地声具有近场穿透能力、信息可靠及易于提取和接收等优点，是探索近场地震短期前兆信息的重要手段．频谱分析结果表明，震前低频地声异常的频谱大多集中在０～２００Ｈｚ的低频段，观察表明，近场地震发生前低频地声异常信息强烈．

An exposition is given to the low frequency characteristic of earth sound as a seismic precursor,chiefly the characteristic of waveform and frequency spectrum.As indicated by observed results,prior to the occurrence of near field earthquake,low frequency earth sound becomes exceptional intensive in information.The authors discuss here the formation of precusory seismic acoustic signal and the rule of sound wave propagation;and point out such advantages of low frequency earth sound as near field penetrating power,reliable information,and easy of abstracting and receiving.Precusory low frequency earth sound is the important means for probing into short term precusory infomation of near field earthquake.As indicated by results of spectral analysis,abnormal frequency spectrum of precusory low frequency earth sound mostly centers on the low frequency band of 0～200 Hz.