# Ground Displacement in East Azerbaijan Province, Iran, Revealed by L-band and C-band InSAR Analyses
## 6 Conclusions  
Tabriz and Shabestar basins have experienced ground subsidence for several years, mainly due to heavy water extraction for industrial and agricultural activities, as reported in several previous studies [13; 42; 43; 44]. All of the previous studies presented results of ground subsidence for the years before 2010 using C-band datasets such as ENVISAT tracks 49 and 92. As a fresh step in this study, we presented the ground subsidence rate using the L-band PALSAR-2 dataset. The SBAS results demonstrated that roads and railways are at immediate risk of ground subsidence, in which the maximum vertical subsidence rate for the roads and railway inside the ALOS-2 footprint is \(-81\) and \(-56\) mm/year, respectively. As shown in PCA results, the existence of long-term subsidence (i.e., PC1) in the study area could cause serious damage to the infrastructure. The SBAS ground subsidence rates were compared with the Sentinel-1 ground subsidence map. The displacement rates of both maps for the settlement zones showed a similar pattern and relatively close displacement rates. We concluded that the main urban area in Tabriz is stable according to Figure 7a,b. However, the displacement rates, piezometric measurements, and field observations suggest progressive land subsidence during 2015-2020. We also conclude that in the absence of geodetic measurements, the combination of SBAS and PCA can provide us with an opportunity to extract seasonal and long-term motions using PC loadings and scores. However, with regard to the similarity of PC2 and PC3, a question remains about whether the secular motions and noises are separated appropriately or not. Independent component analysis (ICA) could be conducted in the future to quantify the behavior of PC2 and PC3. This study mainly compared the SBAS vertical rate for 10 locations of piezometric data without in-depth quantitative analysis. Further geological and geotechnical data from boreholes in different locations could reveal more aspects of ground subsidence in the future.  
Conceptualization, S.K. and M.M.; methodology, S.K. and M.M.; software, S.K.; validation, S.K.; formal analysis, S.K.; investigation, S.K. and M.M.; resources, S.K.; data curation, S.K.; writing--original draft preparation, S.K.; visualization, S.K.; supervision, S.K. and M.M.; writing--review and editing, M.M.; project administration, S.K. and M.M.; funding acquisition M.M. All authors have read and agreed to the published version of the manuscript.  
This study was funded by the Japan Society for the Promotion of Science (JSPS) Grants-in-Aid for scientific research (KAKENHI) number 20H02411. The first author is supported by the University of Tabriz.  
The authors would like to express their gratitude to the European Space Agency (ESA) and the Japan Aerospace Exploration Agency for providing PALSAR-2 ALOS-2 data through the JAXA working group. The underground water data were provided by the regional water organization (RWO). The authors would like to appreciate Eng. [PERSON] for field investigations in Tabriz and Shabestar basins.  
The authors declare no conflict of interest. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript, or in the decision to publish the results.