Simple unilateral rupture of the great M_w 8.8 2025 Kamchatka earthquake.

On 29 July 2025, a moment magnitude (Mw) 8.8 great earthquake ruptured along offshore southern Kamchatka, with the aftershock region overlapping that of a 1952 Mw 8.8 to 9.0 event. Like 1952, the 2025 event nucleated at the northeastern end of the rupture, preceded by intense foreshock activity. Joint inversion of teleseismic and InSAR (Interferometric Synthetic Aperture Radar) data for the space-time slip distribution, with validation by means of forward modeling of deep-water tsunami recordings, revealed a southwestward elongated large-slip patch on the curved plate boundary. A slip of up to 14 meters was located offshore southern Kamchatka and Paramushir Island. The 1952 earthquake generated stronger tsunami signals in Hawaii, indicating a different slip distribution. Peak slip in 2025 exceeded the maximum slip deficit accumulated since 1952. Observations of volcanic eruptions after multiple great earthquakes in Kamchatka provide compelling evidence of earthquake-volcano interactions. Editor's summary: In late July 2025, a moment magnitude 8.8 earthquake struck off the Kamchatka Peninsula coast in Russia, sparking a trans-Pacific tsunami and triggering volcanic activity in the region. The event highlighted how the recurrence of great earthquakes may not follow regular patterns. Liu et al. combined teleseismic and satellite data with deep-water tsunami recordings to estimate the slip history for the 2025 event. Peak slip was greater than for the similarly located 1952 earthquake despite generating a weaker tsunami. Variable recurrence and slip distributions in this region suggest complex strain release patterns that may heighten seismic risk. —Angela Hessler [ABSTRACT FROM AUTHOR]