泰安地震台GM-4仪观测中台阶干扰分析

Reason for the steps in the GM-4 fluxgate magnetometer observation at Taian Seismic Station

自2008年12月以来,泰安地震台的地磁观测数据在Z分量一直存在一种出现时间和持续时间长度均不规则的小幅度台阶干扰。分析此种干扰的特点,在泰安地震台的相对记录室、绝对观测室和山洞等不同场地进行实地对比观测试验,确定干扰仅出现在相对记录室,应属于供电干扰。通过排查分析,最终确定照明电路是导致该干扰的原因。

There has been disturbances of small steps in the vertical component （Z component） of the geomagnetic observation at Taian Observatory since December 2008 with no repetition in the occurring time and the lasting period. Based on the review of the characteristics of the disturbances, we carried out comparison observation with another instrument of different type in addition to the running GM-4 magnetometer. The comparison results showed that this kind of disturbances appeared only in the variometer room. After estimating each part of the electronic circuitry, the illuminating circuitry was cut off and the steps never showed up later. Something in the illuminating circuitry seemed to be the reason for the steps in the magnetic observation.