Limited impact of the July 29, 2025 Kamchatka tsunami explained by the complex seismic rupture

On July 29, 2025, a great mega-thrust earthquake of magnitude Mw 8.8 occurred near the Kamchatka Peninsula, Russia, generating a local tsunami comparable to that of its larger 1952 (Mw 9.0) predecessor. In contrast, the 1952 event caused a larger tsunami on the far-field Pacific shorelines. In addition, the 2025 tsunami was also smaller than anticipated by the life-saving tsunami warning issued for the far-field Pacific shorelines (e.g., Japan, Hawaii, South America). Here, we investigate the tsunami source of the 2025 event by jointly inverting the SWOT (Surface Water and Ocean Topography) and DART tsunami data with the static coseismic deformation measured by InSAR and GNSS. The tsunami Green’s functions are computed by considering the Kurils-Japan subduction interface parameterised by means of triangular subfaults, and the JAGURS code that solves the nonlinear shallow water equations with Boussinesq terms and also takes into account seawater density stratification, elastic loading, and gravitational potential change. Geodetic Green’s functions, as well as the tsunami initial conditions, are computed through the analytical formulation proposed by Nikkhoo and Walter (2015) for triangular dislocations considering also the contribution of the horizontal displacement. The slip model obtained after the inversion using the Simulated Annealing algorithm, highlights a southwestern unilateral rupture whose pattern partially overlaps the 1952 source zone consistently with the stress that had enough time to build up again since 1952. We show that the smaller earthquake magnitude (Mw 8.8 vs 9.0) and the overall relatively deep slip generated smaller tsunami potential energy, thus explaining the moderate far-field impact. Conversely, some shallow tsunamigenic displacement, reaching the trench, explains the enhanced local run-up comparable to the 1952 run-up, despite the smaller 2025 earthquake magnitude. Finally, we show that our findings are supported by a comparison with tsunami sources and observations for the 2010 Mw 8.8 Maule (Chile), and the 2005 Mw 8.5 Nias (Indonesia) earthquakes.