Researchers from CNR and INGV have detected the ground deformations caused by the last seismic event of 30 October through the radar images of the sensors of the Sentinel-1 constellation of the European Copernicus Programme. The results, albeit preliminary, show a deformation that extends over an area of about 130 square kilometers and whose maximum displacement is at least 70 cm, located near the Castelluccio area
The activity relating to the study of ground deformations and seismic sources continues, now focused on the new event of 30 October which hit the provinces of Macerata and Perugia. This activity is coordinated by the Civil Protection Department (DPC) and is carried out by a team of researchers from the Institute for Electromagnetic Sensing of the Environment National Research Council (CNR-IREA of Naples) and the National Institute of Geophysics and Volcanology (INGV), centers of expertise in the fields of satellite radar data processing and seismology, with the support of the Italian Space Agency (ASI).
Thanks to the use of radar data acquired by the satellites of the Sentinel-1 constellation of the European Copernicus Programme, the CNR-IREA and INGV research team was able to analyze the ground movements caused by the earthquake of 30 October. In particular, exploiting the Differential SAR Interferometry technique, it was possible to detect ground deformations through the generation of the co-seismic deformation map, obtained from the images acquired from descending orbits on 25 October (pre-event) and 31 October (post-event).
"These analyses", explains Riccardo Lanari, director of the CNR-IREA, "although they are quite critical for the Sentinel-1 radar data (C band), since we are dealing with areas characterized by thick vegetation, show a deformation that extends over an of about 130 square kilometers and whose maximum displacement is at least 70 cm, located near Castelluccio. These results will be refined in the coming days thanks to further analyses, this time with radar data acquired by the Japanese satellite ALOS2 which, operating in L-band, guarantees more accurate estimates of the extent of surface movements in areas with vegetation cover".
"From the interferogram obtained from Sentinel-1 data (attached figure) it is possible to delimit the area (40 x 15 km) in which the ground subsided following the earthquakes of 26 and 30 October of magnitude 5.9 and 6.5", declares Stefano Salvi, INGV technologist manager. “The complexity of the ground movements can be clearly seen, essentially due to two categories of effects: the sliding of the opposite edges of the earth's crust along the deep fault planes is due to the concentric pattern of the colored fringes (lines of equal sag), while discontinuities, thickenings or acute-angled folds of the fringes are due to very superficial phenomena such as fault scarps, reactivations of landslides, sinkholes in karst formations. It is the contribution of earthquakes to the construction of the Apennine landscapes”.