## 2 Materials and Methods
### Spaceborne SAR Data  
High-resolution COSMO-SkyMed and medium-resolution Sentinel-1 data were used in this study (Table 1). COSMO-SkyMed is a four-satellite constellation carrying onboard X-band SAR sensors (9.60-GHz frequency and approximately 3.1-cm wavelength); it was launched in 2007 and designed for both civil and military purposes [15]. A COSMO-SkyMed second-generation constellation is planned to operate in addition to the original constellation to guarantee operational continuity and to improve the revisit time of the system, whose first satellite was launched in 2019 and began operation in 2021. The sensors scan with different modes, allowing investigations of areas with different resolutions and sizes. In this work, we used a rare stack of 3 Spotlight 1 \(\times\) 1-m-resolution images (2 pre-earthquake and 1 post-earthquake) covering Norcia village and 8 ascending and descending StripMap 3 \(\times\) 3-m-resolution images (4 pre- and 4 post-event) covering the Norcia and Castellucio villages (Figure 1).  
Figure 1: Workflow of the approach carried out to evaluate the performance of Multi-resolution Satellite SAR Images for Post-Earthquake Damage Detection and Mapping.  
Sentinel-1 (European Space Agency) is a two-satellite constellation carrying onboard C-band SAR sensors (5.40-GHz frequency and approximately 5.55-cm wavelength), launched in 2014, and it is able to acquire SAR images with extremely variable resolutions and coverage swaths up to 400 km [21]. Specifically, the standard acquisition mode of Sentinel-1 is the Interferometric Wide Swath (IW), which is characterized by 250-km-wide images. One of the main advantages of Sentinel-1 is its short revisit time, at 6 days (or 12 days for specific regions of the planet) over the same area, considering both satellites, S1A and S1B. In this study, we used a stack of 4 ascending and 4 descending 20 m \(\times\) 5 m (4 pre- and 4 post-event) IW images (Figure 2).  
\begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline
**Acquisition** & **Geom.** & **Geom.** & **Geomol.** & **Swath Width** & **Look** & **Incidence** & **Polarization** & **Ascenting** & **Standard** \\
**Mode** & **Resol.** & **Resol.** & **Resol.** & **Angle** & **Angle** & & & **Time** \\ \hline Spotlight & 1 m \(\times\) 1 m & 0.5 m \(\times\) 0.7 m & 10 km \(\times\) 10 km & & 52.39\({}^{\circ}\) & VV & 31 August 2016 (04:58 UTC) & n.a. \\  & CSK & & & & & & 31 October 2016 (04:58 UTC) & \\ StripMap & & & & & & 5 October 2016 (04:41 UTC) & \\ HHMAGE & 3 m \(\times\) 3 m & 2.1 m \(\times\) 2.3 m & 40 km \(\times\) 40 km & & 29.35\({}^{\circ}\) & HH & 21 October 2016 (04:41 UTC) & \\  & CSK & & & & & 6 November 2016 (04:41 UTC) & \\  & & & & Right & & & 22 November 2016 (04:41 UTC) & \\  & IW & & & & & 20 October 2016 (04:41 UTC) & \\ Sentinel-1 & 20 m \(\times\) 5 m & 3.4 m \(\times\) 14 m & 250 km & & 43.81\({}^{\circ}\) & VV & 26 October 2016 (17:04 UTC)\({}^{-}\)S1A & \\  & & & & & & & 26 October 2016 (17:04 UTC)\({}^{-}\)S1B & \\  & & & & & & & 7 November 2016 (17:04 UTC)\({}^{-}\)S1A & \\ StripMap & & & & & & & 11 October 2016 (17:08 UTC) & \\ HHMAGE & 3 m \(\times\) 3 m & 2.1 m \(\times\) 2.2 m & 40 km \(\times\) 40 km & 26.58\({}^{\circ}\) & HH & 27 October 2016 (17:08 UTC) & \\  & CSK & & & & & 3 November 2016 (17:08 UTC) & \\  & & & & & & 19 November 2016 (17:08 UTC) & \\  & & & & & & 19 October 2016 (15:09 UTC)\({}^{-}\)S1B & \\  & & & & & & 25 October 2016 (05:19 UTC)\({}^{-}\)S1A & 6 days \\ Sentinel-1 & & & & & & & 6 November 2016 (05:19 UTC)\({}^{-}\)S1A & \\ \hline \hline \end{tabular}
\end{table}
Table 1: Description of the analyzed dataset (dates are in dd/mm/yyyy hh:mm UTC). The SAR images for each dataset have been acquired with the same acquisition condition and geometry.  
Figure 2: Footprints of the selected SAR datasets over Norcia and Castellucio towns.