Abstract: The Sagaing fault, situated within Myanmar, serves as the right-lateral strike-slip boundary between the Burma microplate and the Sunda plate. As a major structure accommodating the oblique convergence between India and Sunda, its kinematic characteristics are critical for seismic potential analysis. This study utilizes dense GPS observations from Myanmar and adjacent regions (1998—2024) to construct a horizontal velocity field referenced to the Sunda Plate through high-precision processing and ITRF framework alignment. Integrated with strain rate inversion via the VISR method, we systematically reveal the deformation characteristics and dynamic mechanisms of the Sagaing fault. The key findings include: ① The fault exhibits dominantly right-lateral strike-slip motion. The western block moves northwestward at 10~40 mm/a, while the eastern block shifts westward at <10 mm/a, forming a prominent velocity gradient zone. A velocity jump of 8~10 mm/a near Mandalay (~22°N) indicates deep fault locking, marking a critical segment for strain accumulation and major earthquake preparation. ② The strain rate analysis demonstrates that the northern segment (>21°N) undergoes shear-compression composite deformation, with a maximum compressive strain rate of -90×10^-9 /a, correlating with historical seismic clusters. The central segment (18°N~21°N) hosts localized secondary strain concentration zones (e.g., an elliptical anomaly at 21°N, 97°E), reflecting complex internal strain partitioning. The southern segment (<21°N) exhibits steady strike characteristics, evidenced by dilatational strain rates (-30×10^-9 /a~10×10^-9 /a) and seismicity, modulated by Andaman Sea expansion. ③ Maximum shear strain rates (>120×10^-9 /a) align spatially with historical large earthquakes (e.g., the 2012 Thabeikkyin M_W6.8 earthquake and the 2025 Mandalay M_S7.9 earthquake), confirming the control of high-strain gradients on seismogenesis. ④ The deformation patterns of the Sagaing Fault reveal the dynamic equilibrium between westward extrusion of the Burma microplate and boundary confinement under oblique Indian-Sunda plate convergence. The spatial correlation between velocity gradient discontinuities in the northern segment and historical seismic gaps establishes critical kinematic constraints for identifying both locked segments and regions of elevated seismic risk. Future research should prioritize quantifying strain accumulation rates within the northern locked segments (particularly the Sagaing and Meiktila segments) while systematically evaluating the seismic potential of secondary fault systems in the central segment.

Key words: GPS, Sagaing Fault, Velocity field, Crustal deformation