InSAR time-series results of the 2025 Santorini unrest, using Sentinel-1A data

Le résumé fourni par la source

Santorini Island is of volcanic origin and has historically faced repeated volcanic and seismic activity. In early 2025, increased volcanism and intensified earthquake activity, similar to 2011-2012, caused residents’ concern. This study aims to characterize ground deformation on Santorini Island during its volcanic unrest in 2025 using InSAR observations. For this purpose, 74 synthetic aperture radar (SAR) images of Sentinel-1A satellites in descending and ascending orbits were acquired from early January 2024 to late March 2025. Line-Of-Sight (LOS) velocity values of the descending and ascending orbits were decomposed to determine the east-west and vertical displacement velocities. According to the results obtained, uplifts up to +60 mm/year velocity values were detected in the central parts of the island called Caldera, and subsidence up to –30 mm/year velocity values were detected in the outer regions. In addition, eastward horizontal movements reaching velocities of +60 mm/year and westward horizontal movements reaching velocities of –50 mm/year were also detected throughout the island. In the second stage of the study, a total of 4 points were selected on the islands of Thira, Thirasia, Nea Kameni, and Palea Kameni, considering the Kameni and Kolumbo fault zones. For these points on the island of Santorini, the displacements occurring over 15 months were analysed by time series analysis, and the temporal behaviour of the deformation (increasing/decreasing trend) was monitored. The analysed data indicate that the ongoing horizontal and vertical movements on the island could be caused by volcanic rather than seismic effects, which is consistent with previous studies. This situation shows that volcanic risk assessments in the region should be monitored for the upcoming processes.

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