Abstract:Numerous deep fault zones have developed in the northeastern Tibetan Plateau, which is the convergence zone of the active Tibetan block, the stable Alashan block, the stable Ordos block, and the stable South China block. Among these fault zones, the Haiyuan fault zone, in which two M8 and several M7 earthquakes have occurred, is one of the most active. Presently, it still controls the activities of strong earthquakes nearby. In this study, based on ISCE and the StaMPS platform, and 72 Sentinel-1 synthetic aperture radar (SAR) images, we monitored the surface deformation of the Haiyuan fault zone by the persistent scatter-interferometric synthetic aperture radar (PS-InSAR) technique, calibrated the initial InSAR result with the GPS velocity field, and finally obtained the annual mean deformation velocity of the Haiyuan fault zone from March 2017 to June 2020. The results revealed the following: (1) The deformation rate on the north and south sides of the Haiyuan fault zone was quite different, which was consistent with the movement characteristics of left-lateral strike-slip faults. (2) The Maomaoshan fault and the western Laohushan fault were locked, and the middle eastern Laohushan fault was fairly active; here, we observed creep deformation. The Haiyuan seismic rupture zone was in a healing state. (3) The creep deformation at the middle eastern Laohushan fault is the most significant section in the northeast margin of the Qinghai Tibet Plateau. We infer that the creeping may be associated with the two M6 earthquakes that happened in Jingtai in 1880 and 1990.