Long-Term Post-Earthquake Monitoring of Urban Areas Based on Time Series Analysis of Sentinel-2 Spectral Reflectance Data

Post-disaster analysis is an important challenge in disaster risk management during the recovery phase. This study focuses on the benefits of the use of multispectral images by Copernicus Sentinel-2 to assess long-term urban change and to monitor the progress of reconstruction after earthquakes. The innovative and straightforward methodology aims at monitoring changes in urban areas, and more specifically related to buildings, after a seismic event. It is based on the analysis of extended time series of the spectral reflectance values in the Red-Green-Blue (RGB) bands and the resulting Perceived Lightness (PL) values, as well as the Normalized Difference Vegetation Index (NDVI). This procedure is effective and reproducible, with the advantage that Sentinel-2 observations, unlike commercial Very High Resolution (VHR) images, are free and regularly available on a wide scale. Based on a rich set of multispectral data, this research provides valuable insights into urban dynamics, and aims to optimize post-disaster risk management.