DETECTION AND ESTIMATION OF THE SLICHTER MODE IN LONG-TERM STRAIN DATA

¹Sternberg Astronomical Institute, Lomonosov Moscow State University, Moscow, Russia

²Vladikavkaz Scientific Center of the Russian Academy of Sciences, Vladikavkaz, Republic of North Ossetia–Alania, Russia

*e-mail: vmilyukov@yandex.ru

Abstract. An analysis of the long-term (more than 15 years) strain data measured with the Baksan laser interferometer-strainmeter with a measuring arm length of 75 m of the Sternberg Astronomical Institute, Lomonosov Moscow State University in the Elbrus region, North Caucasus was performed to search for the Slichter mode (the longest period of the Earth's free oscillations ₁S₁). The asymptotically optimal algorithm for data analysis developed by the authors taking into account the properties of seismic noise and mode features, including the parameters of its splitting, was applied to detect and estimate the Slichter mode. The hypothesis of continual mode excitation has been verified. The most probable periods of the Slichter mode and the values of the splitting parameter have been determined; the statistical reliability of the detection has also been estimated.

Keywords: Earth's core, Earth’s free oscillations, Slichter mode, laser interferometer-strainmeter, asymptotically optimal algorithm.

About the authors

MILYUKOV Vadim Konstantinovich – Sternberg Astronomical Institute, Lomonosov Moscow State University. Russia, 119234, Moscow, Universitetsky av., 13; Vladikavkaz Scientific Center of the Russian Academy of Sciences. Russia, Republic of North Ossetia–Alania, 362027, Vladikavkaz, Markusa st., 22. E-mail: vmilyukov@yandex.ru

VINOGRADOV Mikhail Petrovich – Sternberg Astronomical Institute, Lomonosov Moscow State University. Russia, 119234, Moscow, Universitetsky av., 13. E-mail: rospak@inbox.ru

MIRONOV Alexey Pavlovich – Sternberg Astronomical Institute, Lomonosov Moscow State University. Russia, 119234, Moscow, Universitetsky av., 13; Vladikavkaz Scientific Center of the Russian Academy of Sciences. Russia, Republic of North Ossetia–Alania, 362027, Vladikavkaz, Markusa st., 22. E-mail: almir@physics.msu.ru

MYASNIKOV Andrey Vladimirovich – Sternberg Astronomical Institute, Lomonosov Moscow State University. Russia, 119234, Moscow, Universitetsky av., 13. E-mail: andrey0405@mail.ru

Cite this article as: Milyukov V.K., Vinogradov M.P., Mironov A.P., Myasnikov A.V. Detection and estimation of the Slichter mode in long-term strain data, Geofizicheskie Protsessy i Biosfera (Geophysical Processes and Biosphere), 2020, vol. 19, no. 4, pp. 143–152 (in Russian). https://doi.org/10.21455/gpb2020.4-10

English version: Izvestiya, Atmospheric and Oceanic Physics, 2020, vol. 56, iss. 11. ISSN: 0001-4338 (Print), 1555-628X (Online). https://link.springer.com/journal/volumesAndIssues/11485