地电场观测可靠性分析——基于瓜州台的解析研究

Reliability Analysis of a Geoelectric Field Observation:A Case Study of Guazhou Station

应用时间序列的时频域分析方法处理了瓜州台两种地电场仪器型号的长程观测数据,分析了该台地电场观测质量和数据可靠性。结果如下:(1)同方向长短极距测道观测数据的相关系数R基本上均优于0.9,差值D优于1 mV/km,表明该台长短极距测道观测的地电场变化高度吻合;(2)计算了2015年2月和2019年2月两种仪器观测的地电场最大日变化幅度A,不同仪器之间不同时段的长、短极距测道A的比值接近1;(3)2014—2016年该台SN向、EW向观测数据的FFT频谱均显示12 h、8 h、24 h的优势周期,与中国大陆地电场日变化的优势周期一致。上述结果表明:瓜州台地电场观测资料可靠准确,能满足对地震预测和地球电磁场监测及研究的需求。

In this study,observation data of two different instruments at Guazhou station were processed through time-frequency analysis methods,and the reliability of the geoelectric field observation data of Guazhou station for many years was evaluated.The following conclusions are drawn:(1)The correlation coefficient of the long and short dipoles in the same direction is basically above 0.9,and the difference value is below 1 mV/km.(2)The comparison and analysis results of the two instruments in February 2015 and February 2019 show that the maximum diurnal variation ratio of the long dipole to the short dipole in different periods is close to 1.This finding indicates that the device system,observation environment,and electrical structure of the observation site have been in a stable state for a long time.(3)The frequency spectra of FFT in the north-south and east-west directions from 2014 to 2016 show dominant periods of 8,12,and 24 h.Generally,the observation data recorded by the two instruments at Guazhou station are basically reliable and can meet the requirements of earthquake prediction and electromagnetic field monitoring.