ON ANISOTROPY OF THE EFFECTIVE CURRENT STRUCTURE IN THE PREPARATION ZONE FOR THE JULY 29, 2025, Mw 8.8 EARTHQUAKE OFF THE COAST OF KAMCHATKA

The present paper deals with the use of a probabilistic spectral analysis in the study of statistical properties of the variations in Z-component of electromagnetic field during 14 days prior to the July 29, 2025, M 8.8 earthquake which struck off Kamchatka. Additional analysis has been made on similar data for 9 days after the event. The analysis showed persistent differences in the statistical structure of geomagnetic variations at four spatially spaced magnitovariational stations. The persistence of differences is evidenced by the fact that they re-arise during the variation of processing parameters (N₁, M, h). The results obtained are consistent with the model of directed (anisotropic) effective current structure forming in the earthquake preparation zone. A simple geometric assessment based on the Biot – Savart – Laplace Law yields angular orientations comparable with an axial direction of seismic zone. The revealed differences do not correlate with the level of moderate geomagnetic activity of the period considered and may reflect large-scale anisotropy of magnetic response in the pre-seismic interval. The proposed approach is oriented at the analysis of statistical structure of geomagnetic variations and can be used to identify spatial features of strong earthquake preparation process. Further testing of the method on independent events is required to assess its practical applicability.

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