3D Coseismic Deformation and Slip Distribution Inversion of the 2024 Noto Mw 7.5 Earthquake

On 1 January 2024, a magnitude 7.5 earthquake struck Japan's Noto Peninsula. Thoroughly elucidating the seismic mechanism and tectonic activity characteristics of this event holds significant importance for assessing regional seismic hazard. Existing studies predominantly rely on ALOS-2 PALSAR-2 imagery and geodetic data, overlooking the unique role of optical remote sensing data in reconstructing horizontal displacement fields and the potential of Sentinel-1 intensity information for extracting azimuthal deformation. Consequently, this study comprehensively utilises multi-source remote sensing data from ALOS-2 PALSAR-2 and Sentinel-1/2. Employing Differential Interferometric Synthetic Aperture Radar (D-InSAR), Synthetic Aperture Radar Pixel Offset Tracking (POT), and Optical Image Correlation (OIC) techniques to obtain a high-precision co-seismic deformation field. This enabled the inversion of fault slip distributions, revealing earthquake rupture characteristics and stress effects. This study successfully obtained the complete three-dimensional co-seismic deformation field of the earthquake, revealing significant deformation characteristics both along the fault strike and in the normal direction. The slip distribution inversion results clarified the geometric parameters and motion characteristics of the primary rupture fault, demonstrating spatially concentrated slip distribution. Furthermore, analysis based on co-seismic Coulomb stress changes indicated a significant spatial correlation between co-seismic stress perturbations and aftershock distribution. This suggests that static stress triggering plays a dominant role in aftershock activity, while also identifying stress-loading zones with potentially high seismic hazard for the future. The application of multi-source remote sensing technology effectively compensates for the monitoring shortcomings of single techniques in regions with large deformation gradients. It significantly enhances the informational completeness and spatial continuity of the co-seismic deformation field, providing a reliable method for obtaining high-precision, multi-dimensional surface displacement data. The subsequent inversion of slip distribution and Coulomb stress analysis, based on multi-source deformation data, not only provided a detailed characterisation of the Noto earthquake's fault geometry and rupture behaviour but also further elucidated the triggering mechanisms and spatial control exerted by co-seismic stress perturbations on the aftershock sequence. These findings have deepened our understanding of the seismic rupture dynamics in this region and offer crucial insights for assessing post-seismic hazard risks and identifying potential precursory phenomena.