## 1 Introduction  
Ground deformation is defined as the Earth's surface movement (gradual settling, sudden sinking, or uplift) due to the subsurface movement of Earth materials, which has become a common geological hazard that has caused potential threats to public safety, bringing about a series of harmful impacts [1; 2; 3; 4]. The ground deformation associated with horizontal deformation and the occurrence of ground failures is induced by natural or anthropogenic factors such as underground water withdrawal, long-term drought, and urban construction; however, their causes are puzzles worldwide [5]. Generally, the ground deformation caused by underground water withdrawal has been reported around the world; however, the ground deformations induced by artificial buildings are seldom shown [6], without even talking about the interactions between the natural factors and anthropogenic activities. During the past decades, the rapid urbanization, especially in modern and tourist cities, has increased the risk of ground deformation in China, which has led to the damage of urban infrastructures and endangered urban safety [7; 8; 9; 10]. Characterizing the ground deformations, exploring their causal factors, and predicting their changing tendency have important implications for making adaptive measures to reduce the potential dangers [11; 12]. Interferometric Synthetic Aperture Radar (InSAR) has been successfully applied to the research field of ground deformation in many countries, which has showed great capability to monitor subsidence disasters with high spatial and temporal resolution in the past decades [13; 14; 15; 16]. InSAR is a method that two radar scenes acquired in the same area at different times that could provide radar phase information. The InSAR technique can allow sub-centimeter-scale ground motion to be detected and measured in the form of phase-change interferograms, which can be applied to derive information about ground deformation [17]. However, the accuracy of InSAR measurement is commonly affected by the spatial-temporal decorrelation and atmospheric delay [18; 19]. Therefore, Persistent Scatter Interferometry (PS-InSAR) and Small Baseline Subset InSAR (SBAS-InSAR) are proposed to increase accuracy [20; 21; 22]. The SBAS-InSAR technology reduces not only the spatial and temporal decorrelation, but also phase unwrapping and atmospheric delay errors. Therefore, it could provide precise features for a time series of deformation [23; 24; 25; 26]. [PERSON] et al. [27] used the European Space Agency (ERS)--1/2 satellite radar data to detect large-scale deformation information in Rome, Italy, and then demonstrated the capability of the SBAS approach to retrieve related information from the low-resolution InSAR data, which has led to identify several sites affected by significant displacements. [PERSON] et al. [28] applied full-resolution SBAS technology to a wide range of ground deformation calculations, covering the 1992-2010 time interval in Rome, Italy, and detected possible deformations affecting historic buildings. Their results show the effectiveness of the two-scale multi-sensor SBAS-InSAR method in detecting and monitoring the displacements that affect historical and artistic monuments. [PERSON] et al. [29] obtained 20 I-band ALOS PALSAR images with the SBAS-InSAR method to generate a linear deformation rate map and obtain a time series of ground deformation. [PERSON] et al. [30] applied the Point Target (PT) SBAS-InSAR strategy to investigate coastal vertical land movements related to land reclamation in Shenzhen using the ENVISAT Advanced Synthetic Aperture Radar (ASAR), which is acquired through the ascending and descending orbit method. They found that the reclaimed land is experiencing significant coastal subsidence (up to 25 mm/year). [PERSON] et al. [31] investigated wide-area surface subsidence characteristics in Wuhan, China using 15 Sentinel-1A TOPS SAR images with the SBAS-InSAR technique.