Distribution of Manmade Low-Frequency Magnetic Noise in a Big Industrial City

Resumo

This paper deals with measurements of technogenic magnetic noise in the frequency range of 0.01–200 Hz carried out in the daytime within the central part of Yekaterinburg, the city’s bypass road, and the Yekaterinburg ring road. The equipment, measurement technique, and methods of data processing are described. On the basis of the results, the magnetic induction module was determined and a schematic map of the distribution of anthropogenic magnetic noise over the area of Yekaterinburg and in its surroundings was constructed. It is shown that magnetic noise is concentrated in the central regions of the city, and its amplitude can reach ~1500 nT. Within the regions near the ring road, magnetic noise decreases to 150 nT. Examples of records of anthropogenic magnetic noise created by power lines and electric trains of the underground are also given. They show that the amplitude of magnetic noise produced by these sources is much higher than the average intensity of magnetic noise in the central part of the city. We reveal that the amplitude of the vertical component of the magnetic noise, as a rule, is larger in comparison with the horizontal components.