Synchronization of seismoacoustic emission with deformation of the Earth’s upper crust

Abstract

Long-term geoacoustic observations revealed an explicit synchronization in the Earth’s upper crust between the amplitude of acoustic noise at a frequency of 28‐35 Hz, which is related to seismoacoustic emission (SAE), and the calculated value (a squared rate of variation in the volume strain of the earth’s crust due to solar gravitation [1]). A joint study of these two processes, the observed SAE, and the calculated tidal deformation established that the average background seismic noise has a relatively high correlation coefficient (0.6‐0.8) with a solar component of tidal deformation (SD), but lacks stable correlation with the lunar component of tidal deformation (LD) or total deformation due to lunar‐solar tide (LSD). We found out previously that variation in SAE intensity within the mentioned frequency band at a depth of about 2000 m has good agreement (in terms of amplitude and phase) with the rate of variation in lunar‐solar disturbance of gravity [2]. As a result of a posteriori detailed analysis of data obtained in 1988 in a borehole at a depth of 390 m [3], the SAE intensity was found to have the best correlation with the sum of squared rates of variations in volume strain due to solar and lunar gravitation components (LD + SD), i.e., with the total power of the Earth’s tide. It is evident from the cited data that correlation coefficients of SAE intensity and calculated power of individual components of the tidal process in the Earth’s crust are rather significant for LD and SD components, but the correlation coefficient with the squared rate of deformation due to total lunar‐solar gravitation (LSD) yields negative values. This is evident from the following correlation coefficients between SAE and components, as follows: