Kilometer-resolution three-dimensional crustal deformation of Tibetan Plateau from InSAR and GNSS

Located at the forefront of the collision between the Indian and Eurasian Plates, the Tibetan Plateau experiences intense crustal movement. Traditional ground-based geodetic monitoring, such as GNSS and leveling, is challenging, due to factors such as high altitude and harsh climate, making it difficult to accurately determine a high-resolution crustal deformation field of the plateau. Unaffected by ground observation conditions, InSAR technique has key advantages for obtaining extensive and high-resolution crustal deformation fields. This makes it indispensable for crustal deformation monitoring on the Tibetan Plateau. This study used Sentinel-1 data from 2014 to 2020 to compute the ascending and descending InSAR deformation fields for the Tibetan Plateau. This was conducted with a measurement accuracy of approximately 3 mm/yr. Building upon this, we integrated InSAR and GNSS data to yield kilometer-resolution three-dimensional(3D) crustal deformation and strain rate fields for the Tibetan Plateau. A spherical wavelet analysis was used to decompose the 3D deformation field and separate the nontectonic crustal deformation to increase the strength of the tectonic deformation signal. Short-wavelength(<110 km) deformations match the distribution of fault movement, post-seismic deformations, and other non-tectonic factors. Long wavelength(>110 km) deformation mainly results from subsidence in the central plateau and uplifts along the Himalayan Arc. This indicates that the Tibetan Plateau may have stopped the entire uplift and entered a local collapse stage. Furthermore, the deformation fields at different spatial scales reveal that the plateau exhibits discontinuous deformation in short wavelengths and continuous deformation in long wavelengths. The findings of this study contribute to resolving the controversy between the Block and Continuum Deformation models of the Tibetan Plateau.