Megathrust Earthquake off the Eastern Coast of Kamchatka on July 30, 2025

Abstract The results of studying the megathrust earthquake (Mw = 8.8) that occurred on July 30, 2025 in the Pacific Ocean off the eastern coast of the Kamchatka Peninsula are presented. Ground motions with Community Internet Intensity (CII) ranging from 4.8 to 8.5 were felt in Kamchatka Krai and on Paramushir Island of Sakhalin oblast. Several buildings were damaged. The triggered tsunami caused inundation and damage to a number of facilities in Severo-Kurilsk (Paramushir Island) and on Shumshu Island. The high-frequency source-related acceleration spectrum (A0 = 1.26 × 1020 N m/s2) is reconstructed based on seismic recordings and macroseismic data and the role of high slip areas (asperities) on a fault plane in generating strong ground motion is determined. The obtained results provide in part an explanation for the contrast between the high magnitude of the event and a moderate level of seismic impacts and a relatively low degree of destruction. The average recurrence interval between the megathrust earthquakes (Mw ≥ 8.5) in the Kamchatka segment of the subduction zone is 57.6 ± 21.6 years.