Sentinel-1 InSAR data applied to surface deformation in Macaronesia (Canaries and Cape Verde)

Abstract

The Macaronesia islands (Canary and Cape Verde archipelagos) have experienced intense seismic and volcanic activity that may in the near future put in risk people and goods. It is important to implement measurement strategies to monitor the seismic activity and the surface deformation. Synthetic Aperture Radar interferometry (SAR) has proven to be a useful technique to monitor the surface deformation in wide and remote areas, warning pre-eruption displacements and large-scale mass-wasting, so helping civil protection authorities. In this project, we investigate the applicability of SAR Interferometry (InSAR) for long time deformation monitoring in La Palma and Tenerife (Canary archipelago) and Fogo islands (Cape Verde archipelago). We have applied the advanced interferometric SAR processing based on Persistent Scatterers (PS). The small number of manmade structures on the volcanic areas reduces the density of Persistent Scatterers. Furthermore, the different ascending and descending acquisition geometries give different sets of PSs, with complementary spatial coverage and different line-of sight velocities. The strategy used to overcome the aforementioned problem is based on the combination of 3D GPS velocities with two sets of PS determined from ascending and descending passes. A data set of hundreds of SAR images acquired by Sentinel-1 were interferometrically processed and two sets of PSs, determined from ascending and descending passes, were computed for each island. The images were acquired between 2015 and 2018. In each island, the two PS datasets, were combined to derive the vertical deformation map and further be calibrated with GNSS velocities provided by EUREF continuous operating GNSS stations. The results are analysed and compared with previous results and studies of DInSAR techniques and GPS campaigns.