# Review of Works Combining GNSS and InSAR in Europe
## 3 Temporal and Spatial Distribution of Scientific Production in Europe
### Field of Application
Next, there are 4 contributions associated with Spain concerning the monitoring of the Vallcebre landside [125], the Tena Valley [126; 127], which was affected by very slow landslides, and the Portalet landslide area [53]. In Slovenia, 3 works have been dedicated to the deformation monitoring of the Potoska Planina [128; 129; 130], while 2 peer-reviewed publications set in Malta deal with slow-moving coastal landslides [131] and landslide susceptibility modeling [132] of the Northwestern coast. Scientific contributions are also found investigating the Triesenberg-Triesen landslide in Liechtenstein [89], the Trifon Zarezan landslide in Bulgary [133], the ground deformation affecting the Choirkoitia UNESCO World Heritage site in Cyprus [134], the La Vallette landslide in France [135], the deformation phenomena that occurred in the Tatra Mountains in Slovakia [109], the ground deformation affecting Kulcs village in Hungary [136], and the investigation of the Grande da Pipa river basin in Portugal [67]. The analysis of tectonic movements (including pre-, sin-, and post-event movements) via GNSS and SAR is mainly concentrated in the seismic areas of Europe. The scientific contributions mainly come from Italy, with 16 publications, Greece and Iceland, with 5, and Romania, with 4. Italy constitutes a large representation due to the various seismic sequences that have occurred within the last 20 years, such as the 2009 L'Aquila earthquake [46; 137; 138], the 2012 Emilia Romagna earthquake [139], and the 2016 Central Italy  
Figure 4: Distribution of the scientific works dealing with the combined use of GNSS and SAR data according to the field of application. seismic swarm [21; 50; 140; 141; 142; 143], in addition to the old 1997 Colfiorito earthquake [42; 88]. Furthermore, in Italy, scientific publications on the investigation of the geodynamic processes active throughout the whole Italian territory [20] or focused on the Southeastern Po Plain [144] and the geodynamic movements of the Mount Etna [87] or the strain rate of the Hyblean Plateau [145] in Sicily were developed by exploiting a combination of GNSS- and InSAR-derived information. The scientific literature devoted to Greece has reported interesting research on the investigation of pre-earthquake deformation processes by examining GPS, DInSAR, MTInSAR, and ancillary data collected over Zakynthos Island [146]. In addition, the seismological analysis of the critical estimation of a future strong seismic event in the broader area of Cephalonia [82], the post-seismic investigation of a seismic sequence that occurred during the period of January-February 2014 [147] or a specific earthquake, such as the Lefkada involving the Cephalonia Transformation Fault (CTF), close to Cephalonia Island [81], and the post-seismic motion analysis of one of the most active extending grabens, the Corinthian Gulf [85], were collected. Iceland is represented by five contributions. One is the investigation of a M\({}_{\rm w}\) (moment magnitude) 6.5 earthquake that occurred in 2000 [71; 148]. The others are on the identification of extensional and interseismic deformation recorded in the Northern Vulcanic Zone [149], as well as the investigation of ground deformation close to geothermal power plants in Hengill due to the interaction of regional tectonics and volcanic deformation [150] and the post-seismic viscous relaxation in the Southern Iceland [151]. In the South Carpatians, Romania, crustal deformation was investigated by detecting small-magnitude tectonic processes [152], and GNSS data, combined with SAR interferometry, were adopted for the analysis of the abnormal seismic behaviors of Izvoarele-Galati and for the development of an early-warning system for marine geohazards along the Black Sea coast [153]. Furthermore, [PERSON] [154] combined geospatial information, i.e., GPS and SAR images, with in situ information to assess the seismic hazard associated with the Vrancea area in Romania.