Three-dimensional deformation velocity field and kinematic characteristic of the middle and east parts of Haiyuan fault zone from InSAR and GPS observations

Three-dimensional deformation velocity field can reveal fine characteristics of surface deformation, and provide data support for the research on crustal motion mechanism and seismic hazard. In this study, the ascending and descending InSAR deformation velocity fields in the middle and east parts of Haiyuan fault zone are firstly obtained with Sentinel-1A data and SBAS InSAR technology. Then, by combining with GPS observations, the three-dimensional deformation velocity field is extracted and analyzed. Finally, the locking depths and deep slip rates at different locations are inverted by using the classical two-dimensional screw dislocation model, and the max-imum shear-strain rate is investigated. The results indicate that there are significant differences in the InSAR deformation velocity field between both sides of the middle and east parts of Haiyuan fault zone. The east-west deformation velocity field clearly reveals the left -lateral strike-slip characteristic of the fault zone. The northward movement gradually changes to southward movement from northwest to southeast. The vertical deformation velocity field displays significant differences on both sides of the section between MMSF and the middle of LHSF, and the middle and eastern of HYE fault. For LHSF, the locking depth and deep slip rate are 9.7 km and 4.9 mm/a; for HYW fault, they gradually decrease from west to east, with the locking depths of 6.4 km, 3.6 km and 3.2 km, respectively, and the deep slip rates of 5.5 mm/a, 4.2 mm/a and 3.8 mm/a, respectively; for HYM fault, they are 7 km and 4.7 mm/a; for HYE fault, they are 5.8 km and 3.6 mm/a. There are two obvious extreme regions of maximum shear-strain rate along the fault strike. This study can provide a reference for investigating the mechanism of regional uplift and extension and seismic hazard.(c) 2022 COSPAR. Published by Elsevier B.V. All rights reserved.