# Review of Works Combining GNSS and InSAR in Europe
## 4 Temporal and Spatial Distribution in Italy  
A more specific analysis of the temporal and spatial distribution of previous studies, as well as within the field of application, was conducted focusing on the Italian literature, since Italy is the most represented country, accounting for the 47 published scientific contributions on the integrated use of GNSS and InSAR data. The highest number of scientific contributions is recorded in Emilia-Romagna and Umbria, which are two regions where tectonic, seismic, subsidence, and landslide events were analyzed (Figure 6). Despite the higher number of articles, books, and conference proceedings with case studies performed over the Italian territory, not all the regions are covered. In fact, six Italian regions do not exhibit any phenomena investigated by either GNSS or SAR data. One article [20] took into consideration the entire Italian territory using both techniques  
Figure 6: Spatial distribution per region in Italy. to study Earth surface deformation to provide the displacements with respect to different ground point position components. In the Valle d'Aosta Region, in Northwestern Italy, a large landslide in a high alpine environment was studied by GNSS, InSAR, and GB-InSAR remote sensing data to reduce uncertainties. The joint combination of these techniques provided a comprehensive view of the deformation field of the landslide [39]. Landslide investigations are also identified in the Umbria Region, central Italy, for the analysis and monitoring of the slow-moving Assisi landslide [23; 52]. The geodetic and interferometric products of four deep-seated landslides reactivated by the excavation of a double road tunnel that induced deformation were monitored in the Northern Apennine [123], while the same type of data was used in the Arno River basin, Tuscany Region, to update previous hazards and risk map realized by [124], [PERSON], et al. [202]. The highest number of applications, 15 in total, is represented by subsidence phenomena investigations. Seven scientific contributions on this theme, i.e., 2 peer-reviewed articles, 2 book chapters, and 3 conference proceedings, target the Emilia-Romagna Region, central Italy, 4 of which are specifically on the Po Plain. Only one is focused on the Tuscany Region, central Italy, more specifically in the Firenze-Prato-Pistoia Plain [100], as one on the Sibari Plain in the Calabria Region, South Italy [101], and on the plain that lies between the Tagliamento and Isonzo Rivers in the Friuli-Venezia Giulia Region, North-East of Italy [99]. The remaining 5 scientific contributions focus on the vertical deformation of the Venice lagoon [41; 43; 97; 98] or, more generally, on the subsidence phenomenon affecting the North Adriatic Sea [45]. The high number of scientific contributions sourced from the Umbria Region, central Italy, resulted from the Assisi landslide analysis and monitoring, as well as the investigation of the earthquakes that occurred in 1997, 2009, and 2016 involving Umbria and the neighboring regions. In total, 16 contributions targeted the investigation of tectonic and seismic investigations. In contrast to the landslide or subsidence investigations, the seismic analyses typically involved more than one region as earthquakes affect larger regions. For this reason, 4 articles and one conference proceeding focus on more than one region of central Italy. The 2009 L'Aquila earthquake, Abruzzo Region, was also represented in an article and in a book chapter analyzing the coseismic rupture [46] and slip distribution [138] concentrating the study area close to the epicenter. The 2012 Emilia-Romagna Region, instead, did not have relevant effects on the boundary regions. One of these contributions addresses the modeling of the influence of fluids and pore-pressure changes on surface displacements and on the Coulomb Failure Function (CFF) in the co-seismic and post-seismic period related to the 2012 mainshock [139]. [PERSON] et al.