POSSIBLE TRIGGERS OF THE GREAT KAMCHATKA EARTHQUAKE 29.07.2025, Mw 8.8

Abstract

Seismic and geodetic observations preceding major earthquakes are important sources of information about the deformation processes occurring in the vicinity of the future earthquake hypocenter. The article presents the results of estimates of the possible contribution of static and dynamic deformations induced by large foreshocks to the initiation of the Kamchatka great earthquake on 07/29/2025, M_w 8.8. The results of calculating the values of variations in the Coulomb stress field on the plane corresponding to the mechanism of the main shock and main foreshocks, as well as shear dynamic stresses and deformations in seismic waves emitted during movements in the foci of the considered sequence of events, are presented. The estimates showed that the values of dynamic stresses and deformations affecting the hypocenter zones of the main foreshocks and the main shock from earlier events could reach values σ_d ~ 3 MPa, deformation ε ~ 10^-4; variations in Coulomb stresses reached several bars. The calculation results indicate that the likely trigger of the Kamchatka great event was a sequence of earthquakes that occurred over the past 10 days in the vicinity of ~ 50 km from the hypocenter of the main shock.