## 2 Materials and Methods
### Local Areas Detection  
At present, the BAPA landslide and ground movements database, developed by the Department of Geology (University of Oviedo, Oviedo, Spain), covers the period 1980-2019, recording 2839 individual landslides. Information was classified in 105 data fields. Data accuracy of the spatial location and temporal occurrence of the landslides were evaluated and validated through field work. Moreover, the inventory included data about the source, the type of landslides, the triggering factor and the damage, costs and affected infrastructures, among others [46]. \begin{table}
\begin{tabular}{c c} \hline \hline
**Satellite** & **Sentinel-1** \\ \hline Sensor & A/B \\ Band & C \\ Wavelength & 5.55 cm \\ Acquisition mode & Wide Swath \\ Polarization & VV \\ SAR product & Single Look Complex \\ Acquisition orbit & Descending \\ Temporal period & 4 January 2018–5 February 2020 \\ Revisit period & 6–12 days \\ Resolution & \(14\times 4\) m \\ Incidence angle & \(39^{\circ}\) \\ Track & 154 \\ Number of SAR images & 113 \\ \hline
**Processing Parameters** & **PSIG** & **GEP** \\ \hline A-DInSAR technique & PSI & P-SBAS \\ Pixel Resolution & \(14\times 4\) m & \(90\times 90\) m \\ Pixel selection criteria & Amplitude & Coherence \\ Reference Point & \(-5.862760/43.364576\) & \(-5.8430905/43.368119\) \\ Used DEM & SRTM\_35\_04 (90\) m & SRTM\_1 arcsec (30 m) \\ Multilooking Factor & \(1\times 1\) (Azimuth \(\times\) Range) & \(5\times 20\) (Azimuth \(\times\) Range) \\ Applied Filter & LPS & APS \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Main acquisition parameters of the SAR satellite dataset used and principal processing parameters of both approaches. All the inventoried landslides present in the study area have been reviewed (Figure 2). A total of 232 landslide events were registered between 1980 and 2019 in the study area; 37.5% of them were classified as rockfalls, 14.2% as slides, 14.3% as flows, 1.7% were cracks, and 32.3% were undetermined instabilities (Figure 3). Different local areas have been selected in order to apply A-DInSAR techniques according to i) the BAPA database, by considering the spatial distribution of landslides, and ii) previous studies about cliffs on the Asturian coast [43; 44; 45]. In this way, historical landslides and other known terrain instabilities are taken into account for the interpretation of results. Moreover, new ground deformations associated with mass movements have been detected and studied using remote sensing. The selected local areas were as follow, from West to East (Figure 3):  
1. Salinas Town. With an area of 3.9 km\({}^{2}\), it is highly anthropized and urbanized, encompassing the urban centers of Arnao, Salinas, and La Vallina, among others. Its maximum altitude is 85 m, and the coastal orientation is towards the North. There are 72 mass movements recorded in the BAPA database in this sector. 2. Podes Peninsula. With an area of 2.8 km\({}^{2}\), it is a predominantly rural area, with very few buildings. Its maximum altitude is 75 m, and the coast orientation is towards the North. Only one mass movement is registered in the BAPA database. 3. Luanco Town. With an area of 8.1 km\({}^{2}\), it includes the urban area of Luanco, the rest being predominantly rural. Its maximum altitude is 90 m, and the predominant coastal orientation is towards the East and North. Nine mass movements are recorded in the BAPA database in this sector. 4. Candas Town. With an area of 7.5 km\({}^{2}\), it includes the urban area of Candas and other small villages. Its maximum altitude is above 100 m, and the predominant coastal orientation is towards the Northeast. There are 37 mass movements recorded in this sector. 5. Musel Port. With an area of 4.7 km\({}^{2}\), it is located to the West of the city of Gijon. It is the most important and critical port infrastructure of Asturias. Its maximum altitude is 120 m, and the predominant coastal orientation is towards the East. Thirteen mass movements are recorded in this sector. 6. Penarrubia Beach.