Objectives This study aims to investigate the deep tectonic characteristics and seismogenic environment of the 2025 Dingri Ms 6.8 earthquake in Tibet. By analyzing crustal density structures and dynamic processes using gravity data, the research seeks to enhance understanding of seismic activity patterns in the region. Specifically, it focuses on deciphering how Indian-Eurasian plate interactions, combined with intraplate deformation, contribute to the formation of seismogenic zones. The findings aim to provide critical insights for improving regional earthquake hazard assessment and mitigation strategies in the seismically active southern Tibetan Plateau.

Methods The research utilizes the XGM2019e global gravity field model and shuttle radar topography mission 3 digital elevation data to compute Bouguer gravity anomalies. Gravity isostatic equilibrium analysis, based on the Airy model, is applied to evaluate crustal balance and derive Moho depths. Wavelet multi-scale decomposition is employed to separate gravitational signals at different depths, enabling identification of shallow and deep-seated density anomalies. A three-dimensional crustal density inversion, constrained by CRUST1.0 model data, is performed to resolve fine-scale density variations. These methods collectively allow for a comprehensive analysis of crustal structure, fault activity, and material migration processes.

Results Key results reveal pronounced negative Bouguer gravity anomalies (-653 to -101 mGal) in the epicentral region, indicative of thickened crust and significant crustal heterogeneity. Wavelet analysis identifies active north-south trending faults, such as the Dengmecuo Fault, as zones of high gravitational gradient, coinciding with aftershock clusters. Gravity isostatic equilibrium calculations show disequilibrium along north-south faults, with large negative residual forces (-20 to -10 MPa), suggesting ongoing crustal sinking and mantle-crust interactions. Three-dimensional density inversion highlights north-south oriented high-density anomalies in the upper crust, corroborating east-west extensional deformation driven by plate convergence. The seismogenic zone at 10 km depth exhibits mixed high/low density structures, aligning with fault zones and stress accumulation areas.

Conclusions The study concludes that the Dingri earthquake was triggered by complex interactions between Indian-Eurasian plate collision and intraplate east-west extension. The persistent northward extrusion of the Indian Plate induces deep material migration, creating structural weaknesses along north-south faults. These faults, in a state of disequilibrium, facilitate stress accumulation and sudden release, leading to seismic events. The identified high-density anomalies in the crust reflect tectonic stretching and gravitational instability, further enhancing seismic potential. These findings underscore the importance of integrating multi-scale gravity analysis with structural geology to unravel seismogenic mechanisms in collision zones. The results provide a scientific basis for refining earthquake hazard models and developing targeted mitigation strategies in southern Tibet.