Abstract: Surface subsidence has the characteristics of time persistence and spatial expansion. The spatio-temporal characteristics of surface subsidence with time series, wide coverage and high accuracy prevent the potential harm caused by surface subsidence. This paper utilizes SBAS-InSAR and Sentinel-1A images (from April 2017 to February 2021) to monitor surface subsidence in Xining city. The results suggest that the surface deformation in Xining city has the trend of stable urban deformation, obvious local regional subsidence and slow uplift. The subsidence rate of three obvious subsidence areas (subsidence area Ⅰ in the east of the city, subsidence area Ⅱ in the west of the city and subsidence area Ⅲ in the north of the city) is approximately 20~35 mm/a. The driving factors of the subsidence are attributed to the collapsible loess stratum in the subsidence area, which has the bearing characteristics of fragile soil structure. Under the combined action of the self-weight stress of the covering soil layer and the additional stress of buildings. After the soil is soaked by water, the structural performance of the soil is rapidly damaged. The soil layer will have significant additional subsidence, and its strength will be rapidly reduced, so as to cause uneven subsidence of buildings.

Key words: SBAS-InSAR, time-series analysis, monitoring subsidence, driving factors