GEOPHYSICAL RESEARCH, 2020, vol. 21, no. 4, pp. 5-20. https://doi.org/10.21455/gr2020.4-1

UDC 537.86

Abstract  References   Full text (in Russian)

MEASUREMENTS OF THE NATURAL ELECTROMAGNETIC BACKGROUND AT KAMCHATKA: ABOUT THE POSSIBILITY OF REGISTRATION OF GEOMAGNETIC DISTURBANCES FROM SUCH A DANGEROUS EVENT AS TSUNAMI

S.V. Korobkov, Yu.V. Shlyugaev, P.A. Mikryukov, M.E. Gushchin, E.A. Mareev

Institute of Applied Physics of the Russian Academy of Sciences, Nizhny Novgorod, Russia

Abstract. Electromagnetic fields induced by the movement of a conductive water mass in the Earth's Permanent Magnetic Field (EPMF) are used to measure currents and waves in the ocean, and can in principle be used to build tsunami early warning systems. Regardless of the specific technical solution, the sensitivity and reliability of an electromagnetic tsunami recorder is determined by the actual level of natural electromagnetic background in the frequency range of 1·10–4 to 1 Hz. This paper presents the results of the study of natural electromagnetic background in the tsunamigenic region of Russia – on the Kamchatka Peninsula. Using modern broadband induction magnetometers, for the first time in the region, measurements of alternating electromagnetic fields in a frequency range that cover six orders of magnitude have been performed. Measurements of horizontal components of alternating magnetic and electric fields were made during a month at different levels of geomagnetic disturbance. Based on the data obtained, qualitative and quantitative recommendations have been formulated for the application of advanced magnetometric tools for recording tsunami waves in the coastal zone. It was found that the level of background noise in Kamchatka is comparable to or exceeds the expected amplitude of electromagnetic signals from tsunami waves in the bottom region. Since the electromagnetic field induced by the tsunami wave is localized near the hydrophysical disturbance front, and the geomagnetic variations due to ionospheric and magnetospheric processes are large scale, differential signal processing from a pair of points containing identical sets of vector magnetometers has been proposed to compensate for the background and increase the signal-to-noise ratio when recording tsunami-wave events.

Keywords: magnetometer, magnetic hydrodynamics, tsunami, monitoring systems.

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