SOURCES OF HUMAN-INDUCED MAGNETIC NOISE IN THE URBANIZED TERRITORIES

D. S. Tyagunov^a,#

^aInstitute of Geophysics, Ural Branch of the Russian Academy of Sciences, ul. Amundsena 100, Yekaterinburg, 620016, Russia
^#E-mail: tds-07@mail.ru

The article presents the research results on the intensity of sources of urban human-induced magnetic noise in the frequency range of 0.01–200 Hz, conducted in the daytime within Yekaterinburg. The magnetic induc-tion module of magnetic noise sources is determined on the basis of these measurements. The equipment, methods of measurement and processing of results are described. The sources of human-induced magnetic noise were subdivided into primary and secondary ones according to the importance of their contribution to the total magnetic noise in the city. The primary sources of human-induced magnetic noise of low frequen-cies include sources that create their own electromagnetic field (power lines, moving electromagnetic and fer-romagnetic sources). Thes secondary sources of human-induced magnetic noise of low frequencies include sources, which transform the electromagnetic field influencing them into the secondary magnetic field, which folds with the primary sources (effects and phenomena of electromagnetic induction and self-induc-tion in metallic non-magnetic conductors when moving them in an external magnetic field). It is shown that large values of the amplitude of human-induced magnetic noise within the city arise mainly due to primary sources, magnetic noise from which in the investigated frequency range can be 1000 nTl and more, especially in the “peak hours” and also at small distances from the source. With increasing distance from the source the amplitude of the magnetic noise is rapidly reduced to an average level (200–300 nTl) for this section of the city. The induction effects in metallic conductors and the movement of non-magnetic metallic conductors in the magnetic field have the least impact on the overall urban magnetic noise and are only manifested at a rel-atively small distance. The amplitude of the recorded magnetic field signal from such sources of magnetic noise from peak to peak is up to 100 nTl.

Key words: human-induced magnetic noise, magnetic induction, industrial interference, electromagnetic field

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