Source Process of the 2025 Mw 8.8 Kamchatka Peninsula, Russia, Earthquake Revealed by Backprojection and Waveform Inversion

Abstract The 2025 Mw 8.8 Kamchatka Peninsula, Russia, earthquake occurred 73 yr after the 1952 Mw 9.0 event, and their source areas may partially overlap. To understand the earthquake cycle in the Kuril–Kamchatka region, we investigated the spatiotemporal evolution of the 2025 event using backprojection (BP) analysis and teleseismic waveform inversion. BP analysis of teleseismic P waves indicated a total duration of ∼180 s and an average rupture propagation velocity of 2.2 km/s. Using these constraints, waveform inversion of teleseismic P and SH waves revealed a main slip region located 110–290 km southwest of the hypocenter near the trench, with an average slip of 12.3 m. The northeastern part of the main slip region may correspond to the recurrence of the 1841 M ∼ 9 earthquake. In contrast, the southwestern part of the 2025 main slip region may overlap the main slip region of the 1952 earthquake, and the estimated slip substantially exceeds that expected from 73 yr of strain accumulation, suggesting dynamic overshoot induced by the major rupture in the northeastern part.