天津某环境背景噪声分析  

Analysis of one ambient seismic noise in Tianjin

作　　者：李晔[1] 郭巍[1] 许可[1] 曹付阳 马超群 徐小远[1] Li Ye;Guo Wei;Xu Ke;Cao Fuyang;Ma Chaoqun;Xu Xiaoyuan(Tianjin Earthquake Agency,Tianjin 300202,China)

机构地区：[1]天津市地震局,天津300202

出　　处：《地震科学进展》2024年第6期389-395,406,共8页Progress in Earthquake Sciences

基　　金：天津市地震局局内科研项目(Zd202205)资助。

摘　　要：连续波形检查中发现,天津尔王庄(EWZ)等台明显受到某未知噪声的干扰,且EWZ台受影响程度最大,此噪声常年如此,不随昼夜时间发生变化,且已存在多年。长期观测还发现,此噪声每年会有几天观测不到,但时间并不确定。与通常的环境背景噪声不同,此噪声具有一些固定特征。本文对其从本身特征、影响范围、频谱特性、对地震的影响等几个方面进行了研究。研究表明,噪声不受天气、季节等自然因素影响,具有随距EWZ台距离增大而振幅变小的变化特征,其主要频率范围在1~2 Hz之间。噪声的影响范围较广泛,可被周围12个台站记录到,最远到达YGZ台,距离EWZ台约58 km。通过偏振分析,发现噪声的传播具有特定的方向性,初步判断此噪声具有固定源噪声的特点。此噪声会对地震记录造成影响,使震相拾取率降低,甚至完全淹没在噪声中,通过带阻频率滤波会有所改善。During checking continuous waveform record,it was found that some stations of Tianjin such as EWZ were significantly affected by one unknown noise,and EWZ station was the most seriously affected.Long term observations had also found that this noise cannot be observed for uncertainly several days each year.This noise was all year round and did not change with day and night time,and it had been existed for many years.This noise was different from typical environmental background noise and had some fixed characteristics.This article studied the noise from several aspects such as its own characteristic,its coverage of influence,spectral characteristics,and impact on earthquake records.The research has shown that the noise was not affected by natural factors such as weather and season,and had a characteristic of amplitude decreasing as the distance increasing from EWZ station.The main frequency of this noise ranged 1~2 Hz.The impact of noise was relatively wide and it can be recorded by 12 surrounding stations,with YGZ station being the farthest and approximately 58 km away from EWZ station.Through polarization analysis,it was found that the propagation of noise had a specific directionality,so it is preliminary judged that this noise had the characteristic of fixed source noise.This noise will have an impact on seismic records,reducing the seismic phase pickup rate,and even completely submerging it in the noise.Frequency filtering can improve it.

关 键 词：噪声源 时频域特性 影响范围 偏振分析 滤波 

分 类 号：P315.61[天文地球—地震学]