## 4 Conclusions  
Recent developments in the acquisition of satellite interferometric data allow their integration to more traditional methods for Structural Health Monitoring purposes, providing additional insights that are often not available from in situ sensors and ensuring high spatial and temporal coverage. However, there are still some challenges related to their application because of the differences in the data gathered compared to the traditional on-site data. The new kind of data requires the development of optimal representation techniques that may be used to identify anomalous behavior necessary to provide an interpretation and carry out damage identification. Therefore, this paper explores different approaches; the first one is the representation of direct quantities, such as the velocity along the LOS of the satellite, which allows the identification of slow territorial-scale phenomena, such as subsidence. A second representation concerns the indirect quantities of entropy and energy, which allows modeling the behavior of a system (e.g., single building, building complex, monumental structure). These approaches are used to identify the effects of subsidence induced by the excavation of a new subway line in the urban area of Rome. In detail, the first representation highlights the presence of subsidence in the track's proximity. The second one studies the effects on a smaller observation scale and identifies the outliers. The entropy-energy representation is compared to the LOS velocity to validate the results. It is observed that the points subjected to subsidence are distributed on a low-entropy and high-energy branch  
Figure 24: Fitting parameters of the entropy-energy dispersions in the two periods for the Colosseum: (**a**) parameters of the mean model; (**b**) parameters of the standard deviation model. and are mainly characterized by low uncertainty, which can be interpreted as the signal of an actual movement. In addition, the paper compares results obtained from two periods, before and after the start of excavation, studying parameter changes in the curve-fitting process. It highlights an evident variation in the signal response, especially in the variance parameters, indicating the presence of effects induced by tunnel construction. The same procedure, applied to the Colosseum case study, does not show significant changes in the behavior of this monument, which was an expected result, given that its area had not been subjected to tunnel excavation during the analysis period. Furthermore, the ability of the entropy-energy representation to be applied to monumental structures is demonstrated, identifying the presence of outliers, i.e., points that should be further investigated, as they could also be related to anomalous structural and non-structural processes. Further studies are required to provide an objective interpretation of the outliers from the structural point of view. Nevertheless, future developments and the continuous increase in the quality of satellite data may allow the practical application of such information for SHM, leading to a low-cost, automated process for the study of large urban areas. Conceptualization, G.D., M.C., E.L., G.M., C.S. and R.C. ; methodology, G.D., M.C., E.L., G.M., C.S. and R.C. ; software, G.D., M.C., E.L., G.M., C.S. and R.C. ; validation, G.D., M.C., E.L., G.M., C.S. and R.C. ; formal analysis, G.D., M.C., E.L., G.M., C.S. and R.C. ; investigation, G.D., M.C., E.L., G.M., C.S. and R.C. ; resources, G.D., M.C., E.L., G.M., C.S. and R.C. ; data curation, G.D., M.C., E.L., G.M., C.S. and R.C. ; writing--original draft preparation, G.D.; writing--review and editing, G.D., M.C., E.L., G.M., C.S. and R.C. ; visualization, G.D., M.C., E.L., G.M., C.S. and R.C. ; supervision, M.C., E.L., G.M., C.S. and R.C. ; project administration, M.C., E.L., G.M., C.S. and R.C. ; funding acquisition, R.C. All authors have read and agreed to the published version of the manuscript.