Analysis of that influence of the observation mode of seismic station on the background noise
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摘要: 重庆地区三个地震台站经改造后,台基类型由深坑观测改变为地表观测。分别计算三个台站改造前后的噪声功率谱密度(PSD)及相应的概率密度函数(PDF),通过噪声功率谱平均噪声曲线,评估三个台站台基背景噪声变化情况。计算结果表明,虽受到2020年新冠肺炎疫情影响,台站背景噪声水平有所下降,但三个改造台站环境噪声水平却有所增加,尤其在2 Hz以上的频段,其中合川云门台(YUM)最大增加9 dB,开县临江台(LIJ)增加最大幅度为10 dB,忠县善广台(SHG)增大幅度为4 dB。目前,三个台站1—20 Hz频带范围内环境噪声水平仍符合观测规范要求,但改变台基观测方式后,传感器接收到人为干扰噪声信号更丰富。因此,开展地震台站建设、改造施工要慎重改变台基观测方式。Abstract: Three seismic stations in Chongqing area have been reconstructed, the type of station base is changed from deep pit observation to surface observation. The PSD and the PDF of the three stations before and after reconstruction were calculated respectively, the noise power spectrum is used to average the noise curve to evaluate the background noise variation of the three stations. The calculation results show that, excluding the impact of the epidemic situation of COVID-19 epidemic, the environmental noise level of the three reconstructed stations still increased, pecially in frequency bands above 2 Hz. The maximum increase of YUM Station is 9 dB, LIJ Station in is 10 dB, and SHG Station is 4 dB. But the overall environmental noise level between 1—20 Hz bands of the three stations still meets the requirements of the observation specifications. However, after changing the observation mode of the station base, the components of the noise signal received by the station change significantly, especially the human activity related noise, so when carry out the construction and reconstruction of seismic stations, it is necessary to carefully change the observation mode of the station base.
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表 1 台站基本信息
Table 1. Information of the stations
台站名称 观测设备信息 地震计墩改造情况 改造日期 地震计型号 数采型号 频带范围 改造前相对
地面深度/m改造后相对
地面高度/m实际增加
高度/m合川云门台 DS-4A TD-324CI 2 s—50 Hz 3.0 0.5 3.5 2019.12.13 忠县善广台 DS-4A TD-324CI 2 s—50 Hz 4.0 0.3 4.3 2020.03.11 开县临江台 DS-4A TD-324CI 2 s—50 Hz 2.3 0.6 2.9 2020.03.17 垫江新民台 GL-S60 EDAS-24GN 60 s—50 Hz 3.0 0.5 3.5 未改造 -
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