若羌测震台背景噪声分析

Analysis of background noise of Ruoqiang Seismic Station

若羌测震台属国家测震台,为了评估该台站背景噪声水平,采用Welch平均周期法,对2009—2019年共11年近5000条小时波形数据进行功率谱计算,分析异常噪声特征。同时,绘制该台站11年无断记数据概率密度函数图,分析整体噪声水平。分析发现:①若羌测震台受持续增加的人类活动影响,背景噪声水平不断升高;②受气压影响,水平向噪声水平明显高于垂直向;③2017年后,若羌测震台功率谱密度曲线在频率10 Hz附近出现高频异常,应为米兰河水库运行造成的固有干扰。

Ruoqiang Seismic Station is a national station.In order to evaluate the noise level of Ruoqiang Seismic Station in the past 11 years,this paper uses the Welch average period method to calculate the power spectrum of nearly 5000 pieces of seismic data with a length of 1 hour that are observed from 2009 to 2019 at Ruoqiang Seismic Station to analyze the characteristics of abnormal noise.At the same time,the probability density function diagram of the 11-year uninterrupted data at Ruoqiang Seismic Station is drawn and the overall noise level of Ruoqiang Seismic Station is analyzed.The following understandings have been obtained:①Subjected to increasing human activities,the background noise level of the Ruoqiang Seismic Station continues to rise;②Affected by air pressure,the noise level in the horizontal component is obviously higher than that in the vertical component;③After 2017,a high-frequency anomaly appeared near 10 Hz at Ruoqiang Seismic Station,which is an inherent interference caused by reservoir construction.