Large‐Scale Deformation, Strain Characteristics, and Locking Distribution of the Qilian‐Haiyuan Fault System

Abstract The Qilian‐Haiyuan fault system is the main tectonic boundary of the northeastern Tibetan Plateau, controlling the regional tectonic deformation and seismic activity. Extensive Sentinel‐1 SAR data (2014–2021) are used to map the regional tectonic deformation, strain distribution, and locking along primary and secondary faults. We firstly use SAR images on five ascending and six descending tracks to obtain the large‐scale displacement rate fields by InSAR time series analysis. We calculate high‐resolution east‐west, vertical velocity fields, and horizontal strain rate fields by combining GNSS horizontal velocities. Additionally, we invert kinematic parameters of fault locking based on 2D elastic dislocation models, and explore the spatiotemporal evolution of creep rates on the Laohushan segment and its relationship with nearby earthquakes. We show that there are two spatially separated high‐strain zones, one along the Tianzhu Gap and the 1920 Haiyuan earthquake rupture zone, and the other along the North Qilian fault. Creep rate of the eastern Laohushan segment has been decreasing over the past three decades, from ∼10 mm/yr to ≤2 mm/yr. We argue that the creep may be modulated by co‐ and post‐seismic stress perturbations imparted by two ∼ M6 earthquakes in Jingtai in 1990 and 2000.