Objectives The coseismic deformation field of 2017 Jiuzhaigou earthquake has been investigated by previous numerous studies. However, these studies most focus on the one-dimensional(1D) ground motion along the radar line of sight(LOS), thus resulting in anamorphic coseismic displacements.
Methods We construct high-quality three-dimensional(3D) coseismic deformation field using ascending and descending synthetic aperture radar(SAR) data from Sentinel-1A satellite with constraint of the elastic dislocation model to reflect the real movement patterns of 2017 Jiuzhaigou earthquake. Firstly, we use differential interferometry method to generate LOS coseismic deformation field with SAR images. Then, a two-step inversion algorithm is used to subdivide the fault plane, and obtain the geometric parameters and the optimal fault slip distribution. With constraint of this fault model, we take the variance component estimation approach to reconstruct 3D coseismic deformation field based on interferometric synthetic aperture radar(InSAR) measurements.
Results 3D coseismic deformation results show that the coseismic deformation field is dominated by horizontal displacement. In the north-south(N) direction, the maximum displacement of the hanging wall is －19.81 cm and 14.38 cm in the footwall. In the east-west(E) direction, the maximum displacement of the hanging wall is 18.37 cm for the northwestern, while that of the footwall is －7.84 cm for the Southeastern. In the vertical(U) direction, there is a little uplift in the northern of the fault and the maximum is about 3 cm.
Conclusions The derived north-south and east-west displacements are in good consistency of the global navigation satellite system investigations, indicating that combing InSAR measurements and elastic dislocation model to reconstruction 3D seismic deformation field is feasible and effective, which overcomes the problem of insufficient geodetic data and offers extensive future usage for measuring earthquake deformation.
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