Curved Megathrust Geometry and Locking Heterogeneity Contributed to the Rupture of the 2025 Mw 8.8 Kamchatka Earthquake, as Inferred from Geodesy and Seismic Data.
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| Title: | Curved Megathrust Geometry and Locking Heterogeneity Contributed to the Rupture of the 2025 Mw 8.8 Kamchatka Earthquake, as Inferred from Geodesy and Seismic Data. |
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| Authors: | Sun, Guangtong1,2,3 (AUTHOR), Song, Ping1,2 (AUTHOR) songping@cidp.edu.cn, Zhang, Guohong1,2,3 (AUTHOR) |
| Source: | Remote Sensing. Jun2026, Vol. 18 Issue 11, p1803. 13p. |
| Subjects: | Subduction zones, Seismic surveys, Earthquake hazard analysis, Geodesy, Surface fault ruptures |
| Geographic Terms: | Kamchatka Peninsula (Russia) |
| Abstract: | Highlights: What are the main findings? The 2025 Mw 8.8 Kamchatka earthquake shows a NE-to-SW unilateral rupture (560 km, 200 s) with peak slip ~10 m at 15–30 km depth, jointly controlled by curved megathrust geometry and along-strike locking heterogeneity. High-frequency radiation migrated southwestward and concentrated at large-slip boundaries/structural segmentation zones, rather than peak-slip centers, indicating sensitivity to fault friction and geometric discontinuities. What are the implications of the main findings? A curved fault model (instead of planar segments) improves the accuracy of rupture process inversion and tsunami simulation for subduction zone megathrust earthquakes. The north–south magnitude contrast along the Kamchatka subduction zone is attributed to along-strike variations in locking strength, megathrust smoothness, and subducted submarine tectonic features, providing key constraints for regional seismic hazard assessment. On 29 July 2025, an Mw 8.8 megathrust earthquake occurred offshore of the southeastern Kamchatka Peninsula, ranking among the ten largest earthquakes worldwide since 1900. Due to observational limitations, the rupture characteristics of large earthquakes along the Kamchatka subduction zone and the north–south contrast in earthquake magnitudes remain poorly understood. In this study, we combine InSAR data, GNSS displacements, and teleseismic waveforms to investigate the spatiotemporal evolution of the 2025 mainshock by constructing a curved fault geometry with along-strike and downdip variations and applying finite-fault inversion together with back-projection analysis. The inversion results show that the mainshock was characterized by unilateral rupture propagating from northeast to southwest, with a rupture length of about 560 km, a duration of about 200 s, and dominant slip concentrated at depths of 15–30 km, with a peak slip of about 10 m. Slip was weak during the initial nucleation stage near the hypocenter, whereas the main slip patch was located within a strongly locked region in the southern segment, and the rupture accelerated rapidly after entering that region. The back-projection results indicate that high-frequency radiation mainly migrated southwestward and was concentrated along the boundaries of the large-slip region and possible structural segmentation zones. These results indicate that the rupture behavior of the 2025 mainshock was jointly controlled by curved megathrust geometry and along-strike locking heterogeneity. The north–south contrast in earthquake size along the Kamchatka subduction zone may result from the combined effects of stronger locking and smoother megathrust geometry in the south, versus more complex fault geometry and submarine tectonic features in the north. This study provides new constraints on rupture processes, seismic cycle behavior, and regional seismic hazard along the Kamchatka subduction zone, and offers important implications for understanding the mechanisms and magnitude potential of future great earthquakes in the Kamchatka region. [ABSTRACT FROM AUTHOR] |
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| Database: | Engineering Source |
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| Abstract: | Highlights: What are the main findings? The 2025 Mw 8.8 Kamchatka earthquake shows a NE-to-SW unilateral rupture (560 km, 200 s) with peak slip ~10 m at 15–30 km depth, jointly controlled by curved megathrust geometry and along-strike locking heterogeneity. High-frequency radiation migrated southwestward and concentrated at large-slip boundaries/structural segmentation zones, rather than peak-slip centers, indicating sensitivity to fault friction and geometric discontinuities. What are the implications of the main findings? A curved fault model (instead of planar segments) improves the accuracy of rupture process inversion and tsunami simulation for subduction zone megathrust earthquakes. The north–south magnitude contrast along the Kamchatka subduction zone is attributed to along-strike variations in locking strength, megathrust smoothness, and subducted submarine tectonic features, providing key constraints for regional seismic hazard assessment. On 29 July 2025, an Mw 8.8 megathrust earthquake occurred offshore of the southeastern Kamchatka Peninsula, ranking among the ten largest earthquakes worldwide since 1900. Due to observational limitations, the rupture characteristics of large earthquakes along the Kamchatka subduction zone and the north–south contrast in earthquake magnitudes remain poorly understood. In this study, we combine InSAR data, GNSS displacements, and teleseismic waveforms to investigate the spatiotemporal evolution of the 2025 mainshock by constructing a curved fault geometry with along-strike and downdip variations and applying finite-fault inversion together with back-projection analysis. The inversion results show that the mainshock was characterized by unilateral rupture propagating from northeast to southwest, with a rupture length of about 560 km, a duration of about 200 s, and dominant slip concentrated at depths of 15–30 km, with a peak slip of about 10 m. Slip was weak during the initial nucleation stage near the hypocenter, whereas the main slip patch was located within a strongly locked region in the southern segment, and the rupture accelerated rapidly after entering that region. The back-projection results indicate that high-frequency radiation mainly migrated southwestward and was concentrated along the boundaries of the large-slip region and possible structural segmentation zones. These results indicate that the rupture behavior of the 2025 mainshock was jointly controlled by curved megathrust geometry and along-strike locking heterogeneity. The north–south contrast in earthquake size along the Kamchatka subduction zone may result from the combined effects of stronger locking and smoother megathrust geometry in the south, versus more complex fault geometry and submarine tectonic features in the north. This study provides new constraints on rupture processes, seismic cycle behavior, and regional seismic hazard along the Kamchatka subduction zone, and offers important implications for understanding the mechanisms and magnitude potential of future great earthquakes in the Kamchatka region. [ABSTRACT FROM AUTHOR] |
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| ISSN: | 20724292 |
| DOI: | 10.3390/rs18111803 |
