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Foumelis, Michael
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Foumelis, Michael
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- PublicationOpen AccessSENTINEL-1 TOPS INTERFEROMETRIC TIME SERIES RESULTS AND VALIDATION(2016-07-10)
; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; This paper presents results of the Sentinel-1 sensor in the interferometric wide-swath (IW) mode encompassing the first one and a half years of operation of the mission. The paper focuses on persistent scatterer interferometric results and their validation. Further applications and investigations are also addressed, e.g., earthquakes, glaciers, or the exploitation of the overlap areas for the measurement of the along-track motion in the scene.32 17 - PublicationRestrictedMonitoring Santorini volcano (Greece) breathing from spaceSince its last eruption in 1950, Santorini volcano (Greece) remained in a dormant state. This is also evidenced for the period 1992–2010 by the gradual deflation signal over Nea Kameni as measured by satellite Synthetic Aperture Radar Interferometry (InSAR) with lowrates of about 5–6mmyr–1 as well as by the absence of seismic activity within the caldera. However, at the beginning of 2011 the volcano showed signs of unrest with increased microseismic activity and significant ground uplift, reaching 14 cm within a year (2011 March–2012 March), according to InSAR time-series. ALOS PALSAR data indicate the onset of the phenomenon in early 2010 where an aseismic pre-unrest phase of increased subsidence (1–3 cm) preceded the uplift. Joint inversions of SAR and GPS velocities using spherical and spheroidal magmatic source types indicate their location offshore at about 1 km north of Nea Kameni and between 3.5 and 3.8 km depth. The estimated volume variation rate is 6 × 106 m3 yr-1 to 9 × 106 m3 yr-1. A gradual slowing in the rate of inflation within the first quarter of 2012 is apparent by ENVISAT data, while subsequent observations from RADARSAT-2 confirm the observed trend.
801 2 - PublicationOpen AccessMulti-Sensor SAR Geodetic Imaging and Modelling of Santorini Volcano Post-Unrest Response(2019-01)
; ; ; ; ; ; ; ; ; ; ; Volcanic history of Santorini over recent years records a seismo-volcanic unrest in 2011–12 with a non-eruptive behavior. The volcano deformation state following the unrest was investigated through multi-sensor Synthetic Aperture Radar Interferometry (InSAR) time series. We focused on the analysis of Copernicus Sentinel-1, Radarsat-2 and TerraSAR-X Multi-temporal SAR Interferometric (MT-InSAR) results, for the post-unrest period 2012–17. Data from multiple Sentinel-1 tracks and acquisition geometries were used to constrain the E-W and vertical components of the deformation field along with their evolution in time. The interpretation of the InSAR observations and modelling provided insights on the post-unrest deformation pattern of the volcano, allowing the further re-evaluation of the unrest event. The increase of subsidence rates on Nea Kameni, in accordance with the observed change of the spatial deformation pattern, compared to the pre-unrest period, suggests the superimposition of various deformation sources. Best-fitting inversion results indicate two deflation sources located at southwestern Nea Kameni at 1 km depth, and in the northern intra-caldera area at 2 km depth. A northern sill-like source interprets the post-unrest deflation attributed to the passive degassing of the magma intruded at 4 km during the unrest, while an isotropic source at Nea Kameni simulates a prevailing subsidence occurring since the pre-unrest period (1992–2010).1056 87 - PublicationOpen AccessINTERFEROMETRIC INVESTIGATIONS WITH THE SENTINEL-1 CONSTELLATION(2017-07-23)
; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; The contribution focuses on the current status of the ESA study entitled “INSARAP Sentinel-1 Constellation Study”, which investigates the interferometric performance of the S1A/S1B units. General aspects like the interferometric compatibility in terms of common range and Doppler bandwidth and the burst synchronization are addressed. Besides the first interferometric results with both units, time series results over the pilot sites combining both satellites are also shown, as well as some investigations with fast moving (i.e., glaciers) scenarios.36 16