Kate E. Allstadt William D Barnhart Samantha Ann Clapp Paul S. Earle Dara Elyse Goldberg Alex R. Grant Matt Herman Kishor S. Jaiswal Sara K. McBride Adam T. Ringler Max Schneider Eric M. Thompson Nicholas van der Elst David Wald Dun Wang Charles Worden William L. Yeck Harriet Zoe Yin 2026 <p><span>The 29 July 2025 <i>M</i>_w</span><span>&nbsp;8.8 Kamchatka, Russia, earthquake was the sixth largest instrumentally recorded earthquake. This event was seismically well observed at regional and teleseismic distances, but publicly available near‐source data were sparse at the time of the event, presenting unique challenges for rapid source and impact characterization. The U.S. Geological Survey (USGS) National Earthquake Information Center provides global real‐time monitoring for earthquakes, including rapid response information products that estimate source characteristics, shaking, and the resulting impacts. We describe the USGS rapid response earthquake information products following the Kamchatka event and discuss their implications for ongoing hazards in the region. We describe potential improvements to our response workflows motivated by this event, including more rapid constraints on source geometries and the automated selection of fault geometries for finite‐fault inversions. The rapid response products together support the interpretation of a unilateral southwestward rupture with significant slip on the southwestern end of the rupture extent. The <i>M</i>_w</span><span>&nbsp;8.8–9.0 event in 1952, which ruptured a comparable extent of the Kuril–Kamchatka subduction interface, has many similarities to the 2025 rupture. This illustrates that slip deficits may remain following great earthquakes and highlights the usefulness of comparative studies between historic and modern events.</span></p> application/pdf 10.1785/0320250038 en Seismological Society of America Rapid characterization of the 2025 Mw 8.8 Kamchatka, Russia earthquake article