Combined Squee-SARTM and GPS ground deformation study of Nisyros-Yali volcanic field (Greece) for period 2002-2012

This study presents the spatial and temporal grounddeformation pattern of the Nisyros-Yali volcanic field after the period of the seismic crisis (1996-1998) based on the local GPS network remeasurement and the analysis of Interferometric data (2003-2010) applying the SqueeSAR technique. The GPS results indicated intense subsidence in the northern and central parts of Nisyros that caused the western and eastern flanks of the island to “collapse” towards its center. The observed LOS velocity field of the SqueeSAR analysis revealed a nearly linear type of ground deformation, exhibiting values ranging between -3 to +3mm/yr with small standard deviations. The interferometric results have also shown subsidence along the northern and central parts of the island, and an inherent eastward horizontal component at its southeastern part. The overall pattern of the observed subsidence in the area after 2000 is consistent with decrease of pressure in the associated magma chambers and hydrothermal system. Index Terms — Radar Interferometry, Geophysical measurements, Geodesy