Observation and Study on High Resolution Deformation and Strain Field Characteristics of the Bayan Har Block in the Central Tibetan Plateau

The Bayan Har block, located in the central part of the Tibet Plateau, is a key region characterized by intense tectonic activity and frequent major earthquakes within the plateau. It also serves as a crucial pathway for the eastward extrusion of the Tibet Plateau and continental shortening deformation. Systematically characterizing the current deformation and strain distribution of this block holds significant scientific value for understanding the plateau's tectonic deformation mechanisms and potential seismic hazards. Utilizing Sentinel-1 satellite data from 2015-2025 and integrating GNSS data, we obtained high-resolution three-dimensional deformation and strain rate fields for the Bayan Har block. The results reveal that the east-west component of the 3D velocity field exhibits significant cross-fault velocity discontinuities and gradients near the East Kunlun Fault, Xianshuihe Fault, and some secondary faults, reflecting the dominant deformation features of the overall eastward escape of the Bayan Har block and its boundary strike-slip faults. The north-south component is relatively smooth, primarily reflecting block-scale differential motion and GNSS interpolation constraints. The vertical component is dominated by slow subsidence, with localized patchy anomalies closely related to non-tectonic signals such as permafrost, hydrology, and surface processes. Current strain in the Bayan Har block is significantly concentrated along its boundaries and several major strike-slip fault zones. High shear strain rate belts spatially coincide with large faults like the East Kunlun and Xianshuihe faults, while areal strain rates reveal a mixed tectonic environment dominated by compression around strike-slip faults, with localized extension. Given that the InSAR observation period includes postseismic recovery processes from strong earthquakes such as the 2001 Kunlun Mountains and 2021 Maduo events, the high strain rates and pronounced cross-fault gradients along the faults reflect the combined effects of transient postseismic deformation and interseismic steady-state locking.