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Apport de l'interférométrie radar satellitaire pour le suivi des évolutions environnementales en Amazonie, Brésil

Abstract : During the past decade, successive satellites launches for Earth observation with SAR (Synthetic Aperture Radar) sensors onboard have shown its potential, once these systems are able to cover large areas with high resolution, which represents an advantage for surface monitoring. The mass of data generated has enabled the development of radar interferometry and its relevance to the study of small deformations in urban areas or in fault zones, showing that the technique was able to focus on different spatial scales of deformation, as well as temporal scales ranging from a few weeks to more than a decade. Usually, these types of applications have been limited to non-equatorial regions of the world due to the presence of atmospheric disturbances that affect the radar signal. Given the large size and the remote location of tropical basins such as the Amazon, satellite observations remain as a viable approach to validate existing geophysical models. In this context, this thesis proposes to extend conventional applications, taking care to investigate the potential and limitations of SAR interferometry for the measurement of ground deformation in the Amazon region, not yet studied in this specific context. The research aim is to estimate the displacement at the surface of the Earth on the urban area of Manaus, the largest city in the state of Amazonas in Brazil, which is an important site for oil and gas exploration and the transport. This site is surrounded by fragile ecosystems, which make it very sensitive to the presence of the oil industry. Considering this, an understanding of the temporal dynamics and spatial distribution of neotectonic phenomena is fundamental to the development of best practice environmental management. At the methodological level, to overcome the major challenges of the application of differential interferometry on the data stack Radarsat-1, a multi-scale and "model free" strategy, based on the information of a non-linear deformation over time is passed successfully. The essential feature of this process is the separation of the phase signal into small and large scale spatial contributions to simplify the separation of the three phase components (topography, atmosphere and movement). This leads to a more robust processing and allows the phase component inversion for small piles of images. In the geophysical level, the application of interferometry to investigate the ground movement is performed for the first time in the middle of the Amazon, complementing previous studies of structural geology based on measurements from the correlation of optical images and field measurements. In addition to prior knowledge, this study provides accurate information on the hypothesis of recent crustal movements associated with neotectonic activities of the Amazon basin. The results indicate a range of motion of the adjacent crust structure circular drainage in the city of Manaus. The Radarsat-1 and 2 acquired in this region provide a better understanding of geological activity and crustal movement in the Amazon basin.
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Fernanda Ledo Gonçalves Ramos. Apport de l'interférométrie radar satellitaire pour le suivi des évolutions environnementales en Amazonie, Brésil. Sciences de la Terre. Université de Grenoble; Universidade federal do Rio de Janeiro, 2013. Français. ⟨NNT : 2013GRENA019⟩. ⟨tel-01069825⟩

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