Dominant Control of 3D Fault Geometry on the Seismogenic Environment of the Longmenshan Fault: Insights from Multi-Source Data-Constrained 3D Numerical Modeling of the Eastern Tibetan Plateau

In this study, we constructed a 3D viscoelastic finite element model of the lithosphere in the eastern Tibetan Plateau, incorporating fine-scale 3D fault geometries rigorously constrained by multi-source data. We quantitatively analyzed the seismogenic mechanisms and controlling factors of the Longmenshan Fault Zone (LMSFZ). The results indicate that: (1) Regional deformation is co-governed by the synergistic mechanism of "rigid blocking by the Sichuan Basin" and "kinematic decoupling along major strike-slip faults." (2) The 3D fault geometry serves as the primary factor controlling stress accumulation on the LMSFZ, following a physical control chain of "Geometry → Mechanical Response → Kinematic Characteristics." Vertically, the listric geometry results in a stratified feature of "deep-driving and shallow-locking"; along the strike, geometric variations dominate the mode transition from "thrust-strike-slip coupling" to "strike-slip dominance." (3) Seismic hazard assessment identifies a high-risk "unruptured asperity" near Dachuan in the southwestern segment, where the deep strain energy density is comparable to that of the Wenchuan earthquake nucleation zone. Conversely, the northeastern segment is characterized by a "low-resistance/slip-deficit" mode, indicating high long-term seismic hazard. Based on physically self-consistent heterogeneous continuum mechanical modeling, this study transcends the limitations of discrete surface observations. It achieves a transition from 2D surface projections to deep 3D continuous fields, providing a reliable physical basis for quantitatively unraveling the deep seismogenic mechanisms of faults.