The Use of Sentinel-1 Synthetic Aperture Radar (SAR) Images and Open-Source Software for Cultural Heritage: An Example from Paphos Area in Cyprus for Mapping Landscape Changes after a 5.6 Magnitude Earthquake

Abstract

Active satellite remote sensors have emerged in the last years in the field of archaeology, providing new tools for monitoring extensive cultural heritage landscapes and areas. These active sensors, namely synthetic aperture radar (SAR) satellites, provide systematic datasets for mapping land movements triggered from earthquakes, landslides, and so on. Copernicus, the European program for monitoring the environment, provides continuous radar datasets through the Sentinel-1 mission with an almost worldwide coverage. This paper aims to demonstrate how the use of open-access and freely distributed datasets such as those under the Copernicus umbrella, along with the exploitation of open-source radar processing software, namely the sentinel applications platform (SNAP) and SNAPHU tools, provided respectively by the European Space Agency (ESA) and the University of Stanford, can be used to extract an SAR interferogram in the wider area of Paphos, located in the western part of Cyprus. The city includes various heritage sites and monuments, some of them already included in the UNESCO World Heritage list. The interferogram was prepared to study the effects of an earthquake to the buildings and sites of the area. The earthquake of a 5.6 magnitude on the Richter scale was triggered on 15 April 2015 and was strongly felt throughout the whole island. The interferogram results were based on Differential Synthetic Aperture Radar Interferometry (D-InSAR) methodology, finding a maximum uplift of 74 mm and a maximum subsidence of 31 mm. The overall process and methodology are presented in this paper.

Detecting Displacements Within Archaeological Sites in Cyprus After a 5.6 Magnitude Scale Earthquake Event Through the Hybrid Pluggable Processing Pipeline (HyP3) Cloud-Based System and Sentinel-1 Interferometric Synthetic Aperture Radar (InSAR) Analysis

“…In the light of the above, it becomes evident that relative displacements have occurred in the areas of the UNESCO Heritage sites. The displacements retrieved from the current interferometric analysis are also supported by the findings of a similar study, emanated from the same seismic event [16]. Table IV below reproduces the quantification of the displacements detected.…”

“…As it is evident, the coherence map is different for both orbits. A threshold of around the 0.60 coherence value is usually used to exclude areas with noise [16].…”

“…Several studies exist in the literature whereas these sensors, as well as other radar satellites, are used for a rapid response to natural hazards, providing a rapid damage mapping [11,12,13] In [14] pairs of Sentinel-1 images have been used to study the deformation analysis in Mindanao, the Philippines after four strong earthquakes of magnitude >6.4 occurred successively in 2019, while high coherence Sentinel-1 images processing were implemented for dam monitoring in [15]. The use of Sentinel-1 blended with freely distributed image software analysis were proposed as a solution for monitoring archaeological sites [16]. In [17], radar high-resolution satellite images were able to detect small displacements over the Historical Centre of Rome.…”

SAR Sentinel 1 Imaging and Detection of Palaeo-Landscape Features in the Mediterranean Area

“…All the Sentinel missions were released under an open data policy to foster knowledge, innovative applications, and advanced developments. In particular, S-1 data were used for the monitoring of cultural heritage (CH) [12], and recent pioneering studies have highlighted that S-1 can be useful to extract information regarding the contemporary and past…”

Detecting Looting Activity through Earth Observation Multi-Temporal Analysis over the Archaeological Site of Apamea (Syria) during 2011–2012

“…Increased interest from the scientific community for monitoring archaeological areas through satellite imagery has been reported in the recent past (Luo et al 2019 Agapiou & Lysandrou 2015). These studies have shown the benefits of using Earth Observation as a systematic tool for monitoring natural and man-made hazards (Tzouvaras et al 2019), including also looted areas (Cigna et al 2014;Tapete et al 2013).…”