## 1 Introduction  
Due to changes in ground water level, soil physical properties, atmospheric temperatures, wind power, light intensity, and the load and structure of the buildings themselves, high-rise buildings often produce different deformations, including vertical settlement, horizontal displacement, inclined deformation, deflections, and cracks. If the deformation is within a certain range, it can be regarded as a normal phenomenon, but if it exceeds the building bearing capacity, it will reduce the life of buildings, and even endanger their safety. Therefore, the stability and reliability of buildings have become the focus of attention [1; 2; 3; 4; 5]. Only by observing the deformation of high-rise buildings regularly and studying their deformation laws can we reasonably predict the degree and mode of their future changes. Then, we can take timely preventive and aftercare measures to ensure the safe use of buildings, and protect the safety of human lives and property. Shenzhen, located in the south-central coastal area of Guangdong Province, China, is a bridge between Hong Kong and the mainland of China. Its \"National Central cities Index\" ranks fourth in China, and it is rated as a first-tier city in the world by Globalization and World Cities (GaWC). The Futian District of Shenzhen is a large central business district led by the new Shenzhen Convention and Exhibition Center, where several high-riseoffice buildings are gathered and serve as the main population gathering places. With the rapid growth in population and economy in Shenzhen, extensive human activities have caused an increase of subsidence related hazard [6; 7; 8; 9; 10], thereby bringing great harm to surface buildings. Especially, the uneven deformation of high-rise buildings has had a great impact on the safety of buildings. Synthetic Aperture Radar Interferometric (InSAR) technology has the advantage of wide range observation, high precision measurement (millimeter level), and high resolution. It also has gradually become an effective tool for urban surface subsidence monitoring and geological hazard surveys [11; 12]. In particular, the latest high-resolution radar observation satellites (TerraSAR-X, COSMO_SkyMed, ALOS2, etc.) provide unprecedented high spatial resolution and high-quality images [13], giving us the ability to obtain deformation information for a single building, and setting off an upsurge in urban research [14; 15; 16; 17]. From the application of InSAR, land subsidence has been observed all over the world, including Beijing [18], Shanghai [19], Bangkok [20], Mexico City [21], Phoenix [22], and Jakarta [23]. The causes of settlement are different, but their effects are mostly the same. Surface deformation easily destroys buildings and production facilities, hinders construction and resource development, and even causes seawater irrigation. Therefore, continuous monitoring of land subsidence, especially in populous areas like Shenzhen, is of great significance. Several studies have been carried out in Shenzhen. In [24], the authors combined the interferograms of different tracks to estimate the linear rate map and time series in the Pearl River Delta region, which has a higher time resolution than a single track. In order to study the land subsidence related to reclamation, [PERSON] proposed a small baseline subset InSAR method based on a point target (PT). This new method can not only select high density points but also produce reliable InSAR measurements with full spatial resolution [25]. Another study focused on the effects of external digital elevation model (DEM) on the PS-InSAR results in Shenzhen in several different SAR datasets [26]. Recently, some scholars have become interested in the long-term settlement monitoring and interpretation of the deformation signals in Shenzhen. They have used different InSAR methods to invert the ground deformation, analyze the spatial and temporal characteristics of displacement, and explore the role of human activities on surface evolution [27; 28].