Long-and Short-Term Deformation Monitoring of Santorini Volcano: Unrest Evidence by DInSAR Analysis

Abstract

Santorini Volcano is an active strato volcano, located at the central part of the Hellenic Volcanic Arc, developing ad retro of the Hellenic Arc and Trench. The explosive history of the volcano dates back to 1645 BC with the Minoan eruption, while it is documented to have produced at least ten eruptions until 1950 AD. The most recent volcanic unrest began in early 2011. Multi-reference Synthetic Aperture Radar (SAR) Interferometric techniques were applied to study the evolution of ground deformation during 1992-2011, with the use of ERS-1 and -2 and ENVISAT radar imagery. Datasets of common acquisition geometry were added into a single stack so as to obtain the linear deformation rates by means of phase averaging. However, to reveal the deformation history of the volcano, Singular Value Decomposition (SVD) method was implemented. This allowed retrieving ground deformation time-series on a pixel basis over regions with high temporal coherence levels. Results from independent tracks, agreeing with each other, suggest a deformation rate of approximately 5 mm/yr of subsidence at the southern part of Nea Kammeni Volcano, for the period 1992-2010. For the unrest period of 2011, intense uplift of 4.8 cm was observed throughout Nea Kammeni. Global Positioning System (GPS) observations from a local geodetic network confirm the DInSAR findings.