# Characterizing Micro-Displacements on Active Faults in the Gobi Desert with Time-Series InSAR
## 5 Conclusions  
This research investigates the vertical (\(\mathrm{D_{U}}\)) and eastward horizontal (\(\mathrm{D_{E}}\)) deformation of a convergent wrench fault zone in the Jiujing region in Beishan, China, and successfully demonstrates a new approach to mapping and characterising unidentified active faults in large rural areas. This improves the understanding of overall tectonic regimes. The maximum deformation pattern (\(\mathrm{D_{MAX}}\)) is consistent with the maximum in situ compressive stress field. Based on the method of orthogonal decomposition and the measured eastward (\(\mathrm{D_{E}}\)) deformation, \(\mathrm{D_{MAX}}\) and \(\mathrm{D_{N}}\) are estimated and used to trace active fault lines along discontinuities and characterise previously unknown faults through the relative movements of footwall and hanging wall blocks. This research found that:  
1. [label=(0)]
2. Faults, such as F\({}_{16}\)-, F\({}_{17}\), F\({}_{18}\) and F\({}_{20}\)-, which had previously been interpreted as inactive, are still displacing vertically. 3. Furthermore, previously unidentified faults (F\({}_{\mathrm{a}}\), F\({}_{\mathrm{b}}\), F\({}_{\mathrm{c}}\), F\({}_{\mathrm{g}}\), F\({}_{\mathrm{i}-1}\), F\({}_{\mathrm{i}-2}\), F\({}_{\mathrm{i}-1}\), F\({}_{\mathrm{i}-2}\), F\({}_{\mathrm{m}}\), F\({}_{\mathrm{n}}\), and F\({}_{\mathrm{o}}\)) were mapped and their displacements characterised. The antittic strike-slip faults F\({}_{\mathrm{m}}\), F\({}_{\mathrm{n}}\), F\({}_{\mathrm{o}}\), and F\({}_{\mathrm{g}}\) with high angle-to-wrench strike are expected to shear dextrally due to NE compression; meanwhile, the synthetic strike-slip faults F\({}_{\mathrm{a}}\), F\({}_{\mathrm{b}}\), and F\({}_{\mathrm{i}-2}\) that are supparallel to the wrench fault strike tend to rotate anticlockwise, showing sinistral shearing properties. 4. There is no significant difference in deformation between the two sides of boundary faults (F\({}_{\mathrm{1}}\) and F\({}_{\mathrm{6}}\)), and these are therefore considered to be inactive. 5. Our results are consistent with the existing geodynamic model of a convergent wrench fault zone affected by NE compression, with crustal shortening in the NE-SW direction and NW-SE elongation, providing additional confidence that the PSI data discriminates patterns of active tectonic fault movement in this area. 6. Finally, vegetation, groundwater recharge, surface sediments accumulation, and granite erosion are shown to have only localised or negligible impacts on surface deformation. These discoveries confirm PSI as a powerful and effective tool to trace the undiscovered active faults and monitor micro-scale movements on existing faults that were previously considered to be inactive. This study involves only the use of persistent point scatterers, which, in this arid region, has proven very effective. Through the future employment of distributed scatterers, the detection of micro-scale fault movements could be extended to more temperate and more populated regions where seismic hazard in intraplate regions is poorly quantified. This research has also improved the understanding of the local stress regimes in Jiujing, which could greatly benefit the ongoing GDF siting investigation in this region of China. When these sub-millimetre-scale movements are considered over timescales of up to 100,000 years, they represent tens to hundreds of meters of displacement. Such significant and potentially hazardous displacements are important to the radioactive waste disposal agenda. Therefore, the newly identified active deformation along faults within the granite pluton should form part of the long-term safety case assessment for any future siting investigation.