基于PPSD方法的广东阳江小孔径井下型地震监测台阵环境地噪声计算与分析

选取2014—2018年广东阳江小孔径井下型地震监测台阵记录的连续波形三分量seed观测数据,使用概率功率谱密度(Probabilistic Power Spectral Densities,以下简称PPSD)方法,对该地震监测台阵所属10个子台进行环境地噪声计算,统计数据月连续率和年连续率;通过PPSD计算获得每小时、每天、每月、每年、5年的环境地噪声结果;汇总结果并分析环境地噪声稳定性和异常性。结果显示:①各子台这5年的环境地噪声水平稳定,说明其井下台基变化和仪器运行稳定,井下观测手段能够避免地面生产生活等人为干扰,解决了因城镇长期建设发展破坏地震监测环境的难题;②存在靠近海边的子台易受台风严重干扰、无线网桥通信方式的子台数据连续率较差、仪器垂直分量相对容易出现运行异常、井下设备故障维修周期较长等问题。

Calculation and Analysis of Environment Ground Noise Based on the PPSD Method for Yangjiang Guangdong Small Aperture Borehole Seismic Array

Based on the Probabilistic Power Spectral Densities(PPSD)method,the environment ground noise of ten sub-stations of Yangjiang Guangdong small aperture seismic array is calculated,the total archived continuous three-component seed data of five years from 2014 to 2018 are used.The monthly and annual continuity rates of those data is calculated.The results of environment ground noise were obtained by PPSD calculation for every hour,every day,every month,every year and five years.The results are summarized to analyze the stability and anomaly of environment ground noise.The results show that the environment ground noise level of each sub-station is stable in the past five years,which indicates that the change of underground platform foundation and the status of instrument operation are stable.The underground observation can avoid the human interference of production and activity on the ground,and solve the problem that the long-term construction and development of cities which destroy the environment of earthquake monitoring.But there also have some problems such as the sub-stations close to the sea are susceptible to the typhoon interference,the poor data continuity rate of sub-stations in wireless bridge communication mode,vertical component of instrument is relatively easily to abnormal situation,long maintenance period of underground equipment broken,etc.