Analysis of Sentinel-1 and Sentinel-2 data for post-earthquake reconstruction monitoring: a case study of the 2024 Noto Peninsula earthquake

Sentinel-1 and Sentinel-2 have been widely used for earthquake damage detection; however, their use in monitoring long-term recovery activities remains largely unexplored. This study evaluates the effectiveness of Sentinel-1 and Sentinel-2 satellite observations for monitoring post-earthquake recovery processes. Focusing on the 2024 Noto Peninsula earthquake, indices were used to assess the detectability of surface changes associated with two key recovery activities: debris removal and temporary housing construction. A detailed analysis of the long-term Sentinel-1 backscatter time-series monitoring was conducted. Public demolition sites exhibited characteristic temporal changes in the vertical transmit–horizontal receive polarization: an initial increase associated with debris generation, followed by a gradual decrease, and then a sharp decline corresponding to the commencement of demolition. At the temporary housing construction sites, the vertical transmit–vertical receive polarization values increased rapidly during construction and remained elevated. The findings revealed that different recovery activities produce distinct backscatter signatures, suggesting that synthetic aperture radar time-series analysis can serve as an effective tool for characterizing post-disaster recovery. Applying these temporal patterns across wider areas enables the identification of collapsed structures and newly constructed temporary housing. This study demonstrated the potential of freely available satellite data to systematically monitor reconstruction processes.