Analysis of the 2025 Kamchatka, Russia earthquake sequence: Preliminary results
Kazuyoshi Z. Nanjo, Joe Yazbeck, & John B. RundleSubmitted September 7, 2025, SCEC Contribution #14697, 2025 SCEC Annual Meeting Poster #TBD
We studied seismicity before and after the July 29, 2025, M8.8 earthquake striking offshore the Kamchatka peninsula in Russia, using the ANSS earthquake catalog (M>=4.5). This earthquake occurred in a seismically active region along the Kuril-Kamchatka trench, where the Pacific plate subducts beneath the North American plate.
The spatial extent of the aftershock area of the 2025 M8.8 earthquake roughly overlapped with that of the 1952 M9.0 earthquake, the largest recorded event in the Kamchatka section of the subduction zone. In details, the areas of large co-seismic slip of the M8.8 event (USGS 2025) were located at shallow segments of the Kamchatka section while those of the M9.0 event (Johnson and Satake 1991) were located at deep segments of it. Results imply that the 2025 rupture was complementary to the 1952 rupture, not re-rupture of the 1952-type event.
The zones of low seismicity rates prior to the M8.8 event remarkably coincided with the locations of large co-seismic slip of the M8.8 event, implying that the zones were fully coupled between the plates before the occurrence of the M8.8 event. Locally, seismic activation near the future hypocenter started at the moment of the July 20, 2025 M7.4 earthquake. Statistical ETAS modeling was conducted for earthquake data since 2014, showing that local comparable seismic activation has not been observed in the preceding decade. We further found that the overall activation was due to enhancement of clustering activity, rather than background activity.
The same statistical modeling was conducted for earthquake data since 1975, showing that another seismic activation due to enhanced clustering activity began around May 2013. In short, seismic activation occurred twice near future M8.8 hypocenter.
Recent observation showed that seismic activation associated with enhanced clustering activity preceded the 2023 Kahramanmaras, Turkey earthquake (Kwiatek et al. 2023; Nanjo et al. 2025). Our results add to the accumulating evidence that some large earthquakes display such seismic activation that may be a preparation process that can be monitored for future large earthquakes.
Key Words
2025 Kamchatka earthquake, Seismic activation, Statistical modeling
Citation
Nanjo, K. Z., Yazbeck, J., & Rundle, J. B. (2025, 09). Analysis of the 2025 Kamchatka, Russia earthquake sequence: Preliminary results. Poster Presentation at 2025 SCEC Annual Meeting.
Related Projects & Working Groups
Plate Boundary System (PBS)
