Interpreting the crustal deformation and the spatial distribution of major earthquakes in the northeastern Tibetan Plateau using an enhanced block model

SUMMARY Determining the precise pattern of crustal deformation enhances our comprehension of crustal deformation traits and the significant earthquakes. By incorporating 21 additional continuous Global Navigation Satellite System (GNSS) stations along with existing ones, we generated an updated GNSS velocity field for the northeastern Tibetan Plateau. Using the back-slip dislocation model, we calculated the average slip rates of three major active faults: the Haiyuan fault, the Liupanshan fault and the Helanshan fault. Our findings indicated that the regional crustal movement does not conform to the equilibrium principles typically associated with the triple junction-like tectonics. This suggests the existence of a newly active tectonic belt within the Longxi block. Consequently, we proposed a revised block model that incorporates a right-lateral shear zone within the Longxi block to account for the observed crustal deformation in the northeastern Tibetan Plateau. Our study indicates that the right-lateral shear zone significantly contributes to the northeastward expansion of the Tibetan Plateau, accounting for approximately 82 per cent of strain accumulation, while the remaining 18 per cent accumulates along the Liupanshan fault. The revised block model emphasizes the pivotal role of the Haiyuan fault and the right-lateral shear belt as the key tectonic factors shaping the crustal deformation pattern. Our result enables a comprehensive understanding of both the spatial variations observed in the GNSS velocity field and the spatial distribution of significant earthquakes in the region.