Figure: Great earthquakes and their interaction with volcanoes along the southern Kamchatka subduction zone.

Supported by the National Natural Science Foundation of Young Scientist Fund (Grant No. 42222403) and other programs, Prof. Chengli Liu and Prof. Xiong Xiong from China University of Geosciences (Wuhan), together with their collaborators, have made new progress in the study of large earthquake rupture processes. Their research paper entitled “Simple unilateral rupture of the great Mw 8.8 2025 Kamchatka earthquake” was published online in Science on February 19, 2026.

Paper link: https://www.science.org/doi/10.1126/science.aeb8232

The nucleation process, rupture mechanisms, energy-release characteristics of great subduction-zone earthquakes, and their potential influence on volcanic systems remain fundamental scientific questions in seismology. On July 29, 2025, a great Mw 8.8 earthquake occurred offshore of the southern Kamchatka Peninsula, ranking as the seventh-largest earthquake globally since 1900. This event occurred at nearly the same location as the 1952 Kamchatka earthquake (Mw 8.8–9.0), providing a rare opportunity to comparatively investigate the nucleation processes and rupture patterns of great earthquakes.

Using a joint analysis of seismic, geodetic, and tsunami observations, the research team reconstructed the detailed spatiotemporal rupture process of the Mw 8.8 event. The results reveal a simple and highly concentrated unilateral rupture pattern. The rupture initiated at the northeastern end of the fault and propagated unilaterally toward the southwest, forming a narrow rupture zone approximately 250 km long with a maximum slip of about 14 m. In contrast to many earthquakes of comparable magnitude, shallow near-trench slip was limited, with most rupture concentrated at intermediate depths along the megathrust. Further analysis shows that two unusually active foreshock sequences occurred within the year preceding the Mw 8.8 mainshock. Their clear spatiotemporal migration patterns indicate progressive stress accumulation leading to the eventual triggering of the main rupture, providing key observational constraints on the nucleation stage and initiation mechanisms of great subduction-zone earthquakes. The slip distribution also indicates that local maximum slip exceeded the theoretical slip deficit accumulated since 1952, suggesting that the Kamchatka subduction-zone may currently be in a “super-earthquake cycle”. In this scenario, long-term tectonic strain is released over several centuries through multiple partial ruptures and episodic large earthquakes, rather than a single complete rupture. Following the Mw 8.8 mainshock, several active volcanoes in Kamchatka erupted or exhibited increased activity. Calculations of coseismic rock pressure changes suggest that the earthquake significantly perturbed the regional magmatic system, providing new evidence for earthquake–volcano interactions.

This study deepens our understanding of the rupture mechanisms of great subduction-zone earthquakes and provides important scientific insights for tsunami hazard assessment, long-term seismic hazard analysis, and volcanic monitoring and early warning.