Implementation of DInSAR methods for the monitoring of heritage sites: Hera Lacinia in Crotone (Southern Italy)

Abstract

Deformation and generally ground displacement can also affect cultural and archeological heritage sites: the monitoring of such ancient witnesses results to be very significant for the preservation and the conservation of the structures present within the sites. The Differential SAR interferometry is here applied to investigate the displacements occurring in Capo Colonna area (Crotone municipality, Southern Italy), a site which name derives from the only remaining column of the old Hera Lacinia temple, belonging to the Magna Graecia city of Kroton. The processing and the interpretation of SAR images has been carried out thanks to the availability of stacks of TerraSAR-X imagery, in the time span 2008-2010 and of COSMO Sky-Med acquired between 2014-2015. The results obtained show the protraction of a well-known subsiding trend, probably caused by a mix of natural causes (lithostratigraphic setting, seismic activity, eustatic sea-level changes), and anthropic causes, represented by the on-shore and off-shore gas extraction active in the area, identifying displacement velocities up to 15 mm/yr along the Line of Sight of the satellite, both in the ascending and in the descending orbits. These two contributions have been assembled in order to obtain the total vertical displacement, which has been calculated in 3 cm in two years of analysis. Moreover, the installation of 80 corner reflectors in October 2014 provided an improvement of the SAR interpretation, allowing also to focus in the future also on the coastal erosion affecting the site and the ruins and to further investigate about the relationship between gas extraction, performed by ENI, and the vertical motion.