Built-Up Strain and the Predictability of the July 29(30), 2025 Kamchatka Earthquake

The July 29(30), 2025 Kamchatka earthquake occurred only 73 years after the major November 4, 1952 event in the same subduction zone, highlighting the relatively short interval between two large ruptures in this segment. The 2025 earthquake (MW 8.8) ruptured approximately 480 km of the Kuril-Kamchatka Trench, generating a moderate tsunami with maximum recorded wave heights of ~4–5 m, smaller than expected for an event of this magnitude. Based on synthetic earthquake catalogs generated using stochastic modeling of background seismicity and ETAS-type aftershock sequences, the most likely location and depth of a future earthquake with MW ≥ 7.7 were identified as early as October 2024 in this region. Moreover, our prior calculations of accumulated seismogenic potential in this segment of the subduction zone, based on 28 years of continuous GNSS observations, indicated that an earthquake of this magnitude was indeed possible. GNSS-derived estimates of accumulated elastic strain indicate that the July 29(30), 2025 mainshock released the majority of the stored seismogenic potential, while large September 13 and 18, 2025 aftershocks likely redistributed stress along the subduction interface, partially releasing previously accumulated strain. Estimates of remaining seismogenic potential suggest that areas north of the 2025 rupture remain capable of producing large earthquakes (MW ≈ 8), emphasizing the importance of continuous geodetic and seismic monitoring, and demonstrating that combining long-term probabilistic seismic modeling with GNSS-based strain measurements can improve the anticipation of large earthquakes.