典型干扰环境中的大地电场优势方位角应用探讨

Application of dominant azimuth of the telluric field in a typical interference environment

高压直流输电故障、地电暴、地电阻率观测人工供电、地铁等通常会对地电场观测带来较大干扰,对观测资料的应用、地震异常信息的提取识别等带来了很大困扰。选取陵阳、瓜州等13个观测系统较好的地电场台站,基于大地电场岩体裂隙水(电荷)渗流(移动)模型,计算实际观测中这些典型干扰下各场地大地电场优势方位角α的变化情况。结果表明:通常的地电暴、高压直流输电、地电阻率观测人工供电、城市轨道交通等干扰,计算的α值受影响不明显,但持续多日的大幅度、剧烈干扰可能导致部分场地出现影响。通过对2018年9月陕西宁强MS5.3震例分析,其结果表明复杂环境中周边场地强震前的α值异常可能也显著。研究结果对地电场数据应用可能有一定参考意义。

HVDC transmission faults, geoelectric storms, geoelectric resistivity observations, artificial power supplies, and subways usually interfere significantly with geoelectric field observations, thus causing great trouble to the application of observation data and the extraction and identification of seismic anomaly information. Thirteen geoelectric field stations with good observation systems, such as Lingyang and Guazhou stations, were selected for analysis in this paper. Based on the seepage(movement) model of rock fissure water(charge) in the telluric field, the change of dominant azimuth α of the telluric field at each station under typical interference was calculated. Results show that the effect of usual interference on the calculated value of α is not obvious. However, severe interference with large amplitude lasting for many days may have impacts on some sites. The analysis results of the Ningqiang MS5.3 earthquake in Shaanxi Province on September 2018 show that the anomaly of α in the surrounding sites may be remarkable before a strong earthquake under complex conditions. The results of this research may have some reference significance for the application of geoelectric field data.