Geometric Structural Characteristics and Tectonic Significance of the Litang Fault Zone, Southeastern Margin of the Tibetan Plateau

The Litang fault zone is an important seismogenic structure along the southeastern margin of the Tibetan Plateau. It caused the M7¼ earthquake in Litang in 1948 AD. The fault zone intersects the Sichuan–Tibet transportation corridor and poses a serious risk to its safe operation. This study, utilizing high-resolution remote sensing interpretation, field geological verification, UAV photogrammetry, UAV LiDAR, paleoearthquake trench excavation, and AMS ¹⁴C and OSL dating methods, reveals the geometric structure, slip rates, paleoearthquake sequence, and earthquake rupture segmentation of the Litang fault zone; analyzes the rupture distribution range of the 1729 AD Litang earthquake and estimates its magnitude. The study indicates that the Litang fault zone is a relatively immature strike-slip fault, which has developed as a new active fault zone within the Northwestern Sichuan sub-block during the southeastward material migration of the southeastern margin of the Tibetan Plateau. This reflects a transformation in the deformation model of the Northwestern Sichuan sub-block crust from the ‘Rigid Block’ model to the ‘Continuous Deformation’ model.