Seismogravitational oscillations and a change in the Earth’s rotation rate in a period range from 1 to 5 h in December 2004

The observations carried out using a seismogravimeter in St. Petersburg simultaneously with the variations of the Earth’s rotation rate determined based on the results of observations with radiotelescopes located at large distances from each other at the surface of the Earth are compared with each other. It is found that the simultaneous observations agree with each other in the daily variation dynamics. It is also found that the distribution of spectral components along the frequency axis in the spectra of these observations in a period range from 1 to 5 h corresponds to a long-known distribution of frequencies at which the Earth’s oscillations arise most often. It is also shown that the spectra in a period range from 1 to 5 h obtained in different years using the astronomical data, the superconducting gravimeter observations, and the seismogravimeter observations at points located at large distances from each other agree with each other very well. Individual oscillation components have comparable amplitudes and may not be of a tidal nature. An explanation that allows one to examine the entire body of obtained results from a unified perspective is proposed.