Ground deformation monitoring of the Santorini volcano using satellite radar interferometry

The island complex of Santorini is located at the central part of the Hellenic Volcanic Arc in the Southern Aegean Sea. This volcano complex basically consists of five islands, Thera, Therassia, Palea Kammeni, Nea Kammeni and Aspronisi forming a caldera of 83 km² with 390 m depth. The last significant volcanic activity took place between 1925 and 1950. However, the volcano is at a rest state during the last 50 years. The present work refers to the ground deformation monitoring of the area using ERS1, ERS2 and Envisat radar scenes from 1993 to 2004. A total number of four ERS1&2 SLC radar images covering the period 1993 to 1999, and two ENVISAT ASAR images for the period 2003-2004 were used. The method applied was the two-passes interferometry with a contribution of a high resolution Digital Elevation Model. The interferometric results show that although the volcano is at a rest phase, in the two volcanic centers of Pales and Nea Kammeni ground deformation (subsidence) of 62 mm along the line of sight of the satellite was detected.