On the dynamics and structure of Earth’s oscillations in December 2004 from seismic gravimeter observations in St. Petersburg

The paper describes phenomena of large-scale deformations, in particular, long-term deformation, observed on the planet during December 1–12, 2004, before a cycle of enhanced seismic activity. The spectrum of seismic vibrations with periods of 1 to 9 hr is calculated. A high correlation is established between the frequency distribution of significant vibrations recognizable in this spectrum and vibrations that should be excited most frequently in accordance with the statistical spectrum of the seismogravitational oscillations of the Earth.