Bipartite rupture in the 2025 Dingri earthquake indicates normal conjugate faulting during orogenic collapse

Normal faulting in the southern Tibetan rift system reflects ongoing orogenic collapse. Here we use multisensor InSAR (Lutan-1, Sentinel-1 and ALOS-2) to map deformation from the 2025 MW 7.0 Dingri earthquake and to invert fault geometry and slip for the main rupture and a geodetically inferred west-side slip episode. The mainshock exhibits bimodal slip on steeply dipping conjugate faults (dip ≥55°). The west-side episode is equivalent to MW ~6.0 and involves two oppositely dipping segments, including deeper reactivation of the fault that ruptured in the 2020 MW 5.6 Dingri earthquake. Numerical dynamic-rupture simulations indicate that, under the adopted friction and stress conditions, static and dynamic stress perturbations alone are unlikely to generate MW ~6 slip on the west-side structure, implying additional weakening or near-critical prestress. Larger fault-bounded volumes host larger slip, highlighting the role of connectivity and mechanical heterogeneity in seismic hazard assessment. Multisensor InSAR and dynamic rupture simulations suggest the Mw 7.0 Dingri earthquake in southern Tibet involved bimodal slip on steep conjugate faults, with the west-side episode requiring near-critical prestress or additional weakening.