Purpose. The purpose of this study is to investigate the statistical characteristics of the background microseismic field recorded by horizontal unequal-arm laser strainmeters and to assess deviations of the data from a normal distribution.

Methods and Results. The study involved data from two laser strainmeters developed using modern laser-interferometry techniques and installed at the Cape Shults Marine Experimental Station of POI FEB RAS (Primorsky Krai). The analysis focused on microdeformations of the Earth’s crust upper layer measured by laser strainmeters with measuring arm lengths of 52.5 m (North – South orientation) and 17.5 m (West – East orientation). The microseismic noise field was statistically analyzed using data from these laser-interferometric devices for 2019–2020. The considered frequency range (0.05–0.5 Hz) includes microseisms generated by both terrestrial and marine processes (wind and swell waves). The statistical properties of the signals were comprehensively analyzed, including evaluation of skewness and kurtosis coefficients. Deviations from normal distribution were identified, and the Gram-Charlier series, which demonstrated the best correlation with empirical data, was applied to describe the probability density function. Kurtosis was predominantly positive for both components, indicating a high likelihood of large-amplitude outliers.

Conclusions. The performed analysis enabled quantitative assessment of background signal deviations from normal distribution and revealed their key statistical features. These results are crucial for analyzing microseismic background characteristics, as deviations from normality facilitate the study of physical mechanisms underlying the generation and interaction of oceanic, atmospheric and lithospheric processes.