Spaceborne and airborne DInSAR products generation and analysis to support Civil Protection activities in volcanic and seismic regions

Abstract

In the last decades, Differential Synthetic Aperture Radar Interferometry (DInSAR) has demonstrated to be an effective tool to detect and follow Earth surface deformations with a centimeter to millimeter accuracy in different hazard scenarios. In particular, the DInSAR techniques are nowadays playing an important role to study ground deformation phenomena, such as volcanic eruptions and seismic events, thanks to their capability to provide dense measurements over wide areas and at relatively low cost. The increasing diffusion of the use of DInSAR is also due to the large availability of huge and easily accessible SAR data archives, as those acquired, since late 2014, by the Copernicus Sentinel-1 constellation, which is routinely providing C-band SAR data with a defined repeat-pass frequency at a rather global scale. Therefore, such a constant and reliable availability of data allowed us to move from single event analysis to monitoring tasks, particularly in natural hazard prone areas. In this work we present the DInSAR related activities that are carried out at the Institute of Electromagnetic Sensing of Environment of National Research Council of Italy (IREA-CNR) to support the Italian Department of Civil Protection (DPC) for volcanoes and seismic areas studying and monitoring. First, by exploiting the Sentinel-1 data archives and the publicly accessible earthquake catalogues, we implemented an automatic service that generates the DInSAR co-seismic displacement maps, once an earthquake that likely produces ground deformation occurs. Although originally developed to monitor the Italian territory, the service has been extended to operate at global scale and the generated products are made freely available to the scientific community through the European Plate Observing System Research Infrastructure (EPOS-RI). Furthermore, by also exploiting Sentinel-1 data, we developed a second service which is devoted to volcano ground displacement monitoring. The designed system is fully automatic and the process is triggered by the availability of a new SAR data in the Sentinel-1 catalogues acquired from both ascending and descending passes, for every monitored volcano site. The data, per each orbit, are automatically ingested and then processed through the well-known Parallel Small BAseline Subset (P-SBAS) DInSAR technique that allows generating the displacement time series and the corresponding mean displacement velocity maps relevant to the overall observation period. The so-retrieved Line of Sight (LOS) measurements are then combined to compute the Vertical and East-West components of the retrieved deformation, which are straightforward understandable by most of the end users. This service is currently operative for the main active Italian volcanoes (Campi Flegrei caldera, Mt. Vesuvius, Ischia, Mt. Etna, Stromboli and Vulcano), but it can be easily extended to include other volcanic areas on Earth. Finally, thanks to the availability of an airborne platform which is equipped with a X-band and L-band SAR sensor, we implemented a pre-operative infrastructure that, in conjunction with the already mentioned spaceborne systems, allows us to provide further information on the areas under study, particularly during emergency scenarios. This work is supported by the CNR-IREA and Italian DPC agreement, the CNR-IREA/MiTE-DGISSEG agreement, the H2020 EPOS-SP (GA 871121), the ASI DInSAR-3M project.