Crustal Movements and Deformations in Relation to Seismicity in Continuation of the Preparation Period of the Kamchatka Megathrust Earthquake (2020–2025)

This study presents the results of a spatiotemporal analysis of crustal movements and deformations obtained by processing regional GNSS network data for a five-year period prior to the 2025 Kamchatka megaquake. The control network consisted of twenty-two continuously operating GNSS stations. Station spacing varied from 100 to 2500 km. An assessment was made of the sparse regional network’s response capabilities to the preparation of one of the strongest seismic events in history. Kinematic models were obtained for the evolution of internal displacement deficits, horizontal shear strains, and dilatation. The area of accumulated displacement deficit is regularly distributed along the Kuril–Kamchatka Trench, demonstrating resistance to the unidirectional northwestward translational motion of the Pacific tectonic plate. The evolution of total shear strain is consistent with the hypothesis of a possible triggering effect on the mature seismic source of the Kamchatka megathrust. The spatial distribution of accumulated dilatational strain reflects regional tectonic features previously identified by geophysical and geological studies. The results demonstrate the effectiveness of using sparse continuous GNSS observation networks to assess general regional geodynamic and tectonic trends in preparation of the 2025 Kamchatka megathrust.