Objectives The coseismic surface three-dimensional (3D) deformation field is the most intuitive description of the surface deformation caused by earthquakes in real space. In the study of seismic deformation, the recovery of coseismic surface 3D deformation field is of great significance. In view of the shortcomings and defects of the current coseismic 3D deformation calculation method, a coseismic surface 3D deformation field joint calculation method considering deformation gradient is proposed.
Methods First, we use the deformation gradient information to decompose the deformation region obtained by interferometric synthetic aperture radar (InSAR) into disjoint subregions with approximately equal deformation gradient. Then, according to the number of observations in the sub-region, the weighted least square (WLS) method or InSAR 3D deformation calculation method based on stress-strain model (SM) and variance component estimation (VCE) are selected to obtain 3D deformation field of the coseismic surface.
Results Compared with the traditional WLS and SM-VCE methods, the results of simulation experiments and actual earthquake examples show that the deformation gradient information can effectively restore the surface 3D deformation of the earthquake rupture zone and obtain more complete and reliable 3D deformation field of the coseismic surface.
Conclusions This proposed method can avoid the defect that the traditional SM-VCE method cannot identify the differential deformation information on both sides of the fault in the cross-fault area, and make up for the lack of adjacent point information in the traditional WLS solution method.
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