Quantifying the effects of tsunamigenic factors during the 2025 Mw 8.8 Kamchatka earthquake

We investigate the influence of tsunamigenic factors (subsurface models, horizontal seafloor motion, and rupture kinematics) on tsunami source representation and tsunami features for the July 2025 Kamchatka M w 8.8 earthquake. Slip distributions of three USGS finite-fault models (versions V3, V4 and V5) were first compared. The best agreement was obtained for V3, with a maximum slip of approximately 14.5 m at 30 km depth. Based on V3, we progressively refined the tsunami source representation by incorporating vertical variations of elastic properties of the Earth (layered Earth model), horizontal seafloor motion, and kinematic earthquake rupture. The layered Earth model, compared with the uniform Earth model, increases horizontal displacement by 0.8 m (EW) and 0.4 m (NS), which, combined with steep near-source slopes, further raises surface uplift by 1.2 m (32%). Rupture kinematics amplifies coastal tsunami wave height and energy along the rupture direction and reduces it in the opposite direction. The tsunami presents fault-dimension-dependent peak periods (32–64 min). Simulated coastal tsunami heights indicate that minor variations in coseismic deformation can lead to differences between models exceeding 5% and 10% in 50% and 12% of nearshore coastal areas, respectively. These results indicate that realistic yet computationally efficient representations of tsunami sources are essential for improving both scientific understanding and hazard assessment. They also highlight the role of various tsunamigenic factors in controlling predictions of tsunami height and behavior, thereby guiding tsunami hazard assessments worldwide.