Quantifying present-day strain rate of the southeastern Tibetan Plateau from high-resolution GNSS data: Implications for tectonic interactions and seismic hazards

Summary By leveraging a significantly expanded GNSS dataset (997 vectors, 335 new), we construct a high-resolution crustal strain rate model for the Southeastern Tibetan Plateau (SETP) that approximately doubles the resolution of previous studies. Our model delineates a prominent J-shaped high-strain zone that follows the Xianshuihe-Xiaojiang fault system (XXFS) and extends ∼600 km southwestward. This feature, combined with unsupervised Euler pole clustering (EPC) machine learning results, provides further evidence for a mid-to-lower crustal linkage between the XXFS and faults southwest of the Red River fault (RRF), suggesting the active XXFS is propagating across this ancient boundary (RRF) at depth. Within the SETP interior, our model reveals widespread extensional deformation characterized by a systematic clockwise rotation of its principal axes from north to south, alongside discrete rotational domains partitioned by major faults. Shear strain patterns within the SETP indicate that major strike-slip faults, predominantly sinistral, drive regional strain localization. Moreover, the close association between modeled high-strain zones and historical M ≥ 6 earthquakes suggests that our high-resolution model can serve as a refined, physically-based perspective for regional seismic hazard assessment.