Interseismic deformation rate of the Haiyuan fault system based on the modified SBAS method

Abstract

Radar interferograms are usually influenced by factors such as atmospheric artifacts, orbital errors, and terrain errors. It is difficult to reduce the influence by using the conventional small baseline subset (SBAS) method when determining the deformation rate. This study uses the adjustment model with systematic parameters to improve the conventional SBAS method and employs it to determine the interseismic deformation rate of the Haiyuan fault system, providing a data reference for exploring the locking depth, strain accumulation state, and potential seismic risk assessment of different segments of the Haiyuan fault system. The results are as follows: (1) the simulation experiment verifies the feasibility and robustness of the modified SBAS method. This method can effectively reduce the influence of residual signals such as atmospheric artifacts, orbital errors and terrain errors in the interferograms. The deformation rate map can be significantly improved; (2) the deformation rate field in the radar's Line of Sight (LOS) direction shows that there are obvious differences between the north and south sides of Haiyuan fault system, which is consistent with the characteristics of the left-lateral strike-slip movement of the Haiyuan fault system. The deformation rate field and profiles reflect the complex trends among different segments of Haiyuan fault system in detail. (3) the deformation rate of the Jingtai pull-apart basin is higher than that of the surrounding areas, possibly indicating strong regional activity, which provides a reference for studying the seismic risk of the Jingtai pull-apart basin; and (4) the interseismic deformation rate and profiles across the fault show that the middle section of the Lao Hu Shan (LHS) segment and the western and middle sections of the Haiyuan segment are locked.