Towards Early Warning for Damages to Cultural Heritage Sites: The Case of Palmyra

The intentional damage to local cultural heritage sites carried out in recent months by the Islamic State has received wide coverage from the media worldwide, raising the awareness for the need of prompt, safe, non-invasive damage detection and assessment surveys. Earth observation data represents the only reliable, non-invasive information source in areas which are not accessible due to conflicts or natural disasters. In order to provide a fast response, automated image processing techniques are needed to speed up the analysis. This chapter shows a comprehensive case of study for damage detection and monitoring in time through a series of satellite images acquired over the city of Palmyra, Syria, which suffered huge losses related to its cultural heritage in a time span longer than a year. Maps highlighting potential damages are derived from robust change detection techniques, based on changes in the textural features characterizing pre- and post-disaster satellite data. Such information could help experts at timely assessing the damages to cultural heritage sites of interest, and a chronological study of the different damages can be produced if a satellite image time series is available on the site of interest. Furthermore, the idea of marking sensitive areas characterized by different criticality is introduced: early damage detection routines could thus be restricted to the most important or threatened sites or expanded to larger areas or surrounding urbanizations. For this purpose, a pair of images acquired on the city of Sirwah, Yemen, are analysed, and the change detection results are discussed in this frame.