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First results of ground displacement monitoring in Paris (France) with Sentinel 1 A/B time series / Matthias Jauvin (2017)

Public Titre : First results of ground displacement monitoring in Paris (France) with Sentinel 1 A/B time series Type de document : Article/Communication Auteurs : Matthias Jauvin, Auteur ; Yajing Yan, Auteur ; Bénédicte Fruneau , Auteur ; Emmanuel Trouvé, Auteur ; Pierre Gusmano, Auteur Editeur : Paris : Agence Spatiale Européenne ASE / European Space Agency ESA Année de publication : 2017 Conférence : Fringe 2017, 10th International Workshop on Advances in the Science and Applications of SAR Interferometry and Sentinel-1 InSAR 05/06/2017 09/06/2017 Helsinki Finlande programme sans actes Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image radar et applications [Termes IGN] image Sentinel-SAR [Termes IGN] Paris (75) [Termes IGN] surveillance géologique Résumé : (auteur) SAR differential interferometry represents an efficient tool to spatially monitor small ground deformations. During the last fifteen years, methods based on image time series, such as Persistent Scatterers technique, have shown their capabilities for monitoring finer displacements with millimeter precision. With the launch of Sentinel 1A and 1B in April 2014 and 2016, it is now possible to work with free time series of medium resolution images. The rapid revisit time (6 days) of this new constellation limits the temporal decorrelation, which makes it possible to have a high PS density, especially in urban areas. This reduction of the distance between PSs would then reduce the dispersion of the displacement measurements, so that the main source of error in deformation measurement will be due to the variation of the atmospheric composition.Major cities such as the city of Paris are experiencing constant changes that involve major construction works, both on the surface and underground. Paris for instance has started a new project called “Grand Paris”, which aims at transforming the Parisian metropolitan area with in particular major developments in transport network (subway, train and tramway). Such projects usually come with important pumping of groundwater or large excavations, whose surface impacts must be monitored with precision during and after the operations. In this context, Sentinel 1 data is a promising alternative of precedent radar satellite images, which guarantees the continuous availability of data for all applications and offers a good opportunity to develop operational monitoring applications. Even with a medium resolution, it is still possible to consider a use of this technique for monitoring displacements related to human activity (pumping of groundwater, construction of underground structures...) in urban areas. In this paper, we will present our first results obtained with a stack of Sentinel 1A and 1B images (29 images from S1-A and S1-B already processed, probably 45 for the Fringe workshop) acquired in IW mode. The PS processing is performed by using Gamma software. Some specific areas where construction works have already started are currently investigated to try to identify meaningful displacement patterns. In order to avoid limitations such as difficult PS identification and wrong interpretation of the deformation, we consider integrating PS results in processes of monitoring with others geodetic measurements (GPS, tachometry or leveling) acquired by companies specialized in high-precision topography, in order to better analyze and understand the deformations, their related processes and risks. Numéro de notice : C2017-055 Affiliation des auteurs : UPEM-LASTIG+Ext (2016-2019) Thématique : IMAGERIE Nature : Poster nature-HAL : Poster-avec-CL DOI : sans Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=96652

Present-day deformation in Taiwan mountain belt as monitored by InSAR / Bénédicte Fruneau (2017)

Public Titre : Present-day deformation in Taiwan mountain belt as monitored by InSAR Type de document : Article/Communication Auteurs : Bénédicte Fruneau , Auteur ; Erwan Pathier, Auteur ; Marie-Pierre Doin, Auteur ; Jyr-Ching Hu, Auteur ; Hsin Tung, Auteur Editeur : Paris : Agence Spatiale Européenne ASE / European Space Agency ESA Année de publication : 2017 Conférence : Fringe 2017, 10th International Workshop on Advances in the Science and Applications of SAR Interferometry and Sentinel-1 InSAR 05/06/2017 09/06/2017 Helsinki Finlande programme sans actes Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image radar et applications [Termes IGN] déformation de la croute terrestre [Termes IGN] interféromètrie par radar à antenne synthétique [Termes IGN] surveillance géologique [Termes IGN] Taïwan Résumé : (auteur) Taiwan Island, resulting from oblique collision between Philippine sea plate and Eurasian plate converging at a rate of about 8 cm per year, is one of the most active tectonic region in the world. With a subtropical environment, it is faced to different hazards, including earthquakes, debris flow, landslides, and flooding. The precise measurement of the present-day ground displacements at the scale of the whole Taiwan Island is thus essential in several domains of Earth Sciences, in particular for earthquake cycle study and earthquake hazard assessment, for subsidence and landslide monitoring, and also to better understand the kinematics and mechanics of mountain building. In the framework of our complete mapping of Taiwan Island with InSAR, we use in this study the full archive of SAR data acquired by ALOS-1 satellite on the 2007-2011 period. ALOS L-band data are very effective in the vegetated and hilly Taiwan environment. SAR images are processed through a small baseline approach with NSBAS interferometric chain (Doin et al., 2015). It includes several corrections applied before unwrapping, in particular correction of atmospheric delays predicted from the global atmospheric re-analysis ERA-Interim model, and local DEM error correction. These corrections are of particular importance as they reduce the variance of the phase across regions with high topographic gradients, hence preventing unwrapping errors. Unwrapping process is also performed using a specific scheme, taking into account the information of colinearity. Thanks to this careful processing, we are able to unwrap across the Central Range, a challenging area with more than 3000m of topographic ranges. InSAR offers an unprecedented continuous view of deformation field of a large part of the Central Range. LOS velocity map obtained on track 446 shows a clear pattern of deformation, consistent with a rapid uplift of the Central Range South of the island. This uplift, already partially documented by GPS and leveling, is clearly mapped here and seems to show overall continuity. However, details of this map should be analyzed with caution.This is a real contribution of InSAR with respect to GPS, with a dramatic increase of the spatial information: even if the density of GPS stations is high in Taiwan, they are mostly distributed around the Central Range, and do not offer such spatial sampling.On this track, InSAR results allow also to connect spatially south western part of Taiwan, mapping the deformations of the Foothills and the Coastal Plain, and the southern end of the Longitudinal Valley, showing aseismic creep. Numéro de notice : C2017-054 Affiliation des auteurs : UPEM-LASTIG+Ext (2016-2019) Autre URL associée : vers HAL Thématique : IMAGERIE Nature : Poster nature-HAL : Poster-avec-CL DOI : sans Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=96651