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DInSAR analysis of ALOS PALSAR images for the assessment of very slow landslides: the Tena Valley case study |
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| Authors: | Juan Carlos García-Davalillo Gerardo Herrera Davide Notti Tazio Strozzi Inmaculada Álvarez-Fernández |
| Institution: | 1. Valencia Unit, Geo-Hazard InSAR Laboratory Geological Risk Group, Instituto Geológico y Minero de Espa?a (IGME), c/ Cirilo Amorós 42 Entresuelo, 46004, Valencia, Spain 2. Geo-Hazard InSAR Laboratory Geological Risk Group, Instituto Geológico y Minero de Espa?a (IGME), c/ Ríos Rosas 23, 28003, Madrid, Spain 3. Department of earth and environmental science, University of Pavia, Via Ferrata 1, 27100, Pavia, Italy 4. Gamma Remote Sensing, Worbstrasse 225, 3073, Gümligen, Swizerland 5. Department of Mining Engineering, University of Oviedo, c/ Independencia 13, 33004, Oviedo, Spain |
| Abstract: | In this work we analyse the performance of advanced land observing satellite (ALOS) phased array type L-band syntetic aperture radar (PALSAR) images for mapping and monitoring of very slow landslides using conventional differential interferometry in the Tena Valley (Central Pyrenees, Spain). These results are compared with those retrieved in previous works where multi-band advanced differential interferometric synthetic aperture radar (DInSAR) analysis was performed for the same area using PSI techniques. The study area is largely underlain by slates (ca. 80 %) where large deep-seated very slow earth flows are dominant. The results reveal that DInSAR analysis is able to measure displacements of landslides with a greater spatial coverage than PSI analysis, but for a lower amount of them (nine against 51). Overall, the combination of the DInSAR and multi-band PSI analysis permitted to map and monitor 68 % of the landslides in Tena Valley. From this amount, 63 landslides are considered as active. The main advantage of DInSAR with respect to PSI analysis is the capability to detect faster movements (up to 145 cm?year?1) derived from the 46 days interferograms. That is the case of Sextas and La Selva landslides where an acceleration of the moving mass was measured after intense rainfall periods producing major damages to linear infrastructures. The combination of measured displacement from ALOS interferograms, with the observed damages on the A-136 road, was useful to assess the potential damage that could cause these slow movements. In general, it is demonstrated that even though PSI analysis provides a better performance in terms of landslide mapping, L-band DInSAR analysis provides an added value for landslide hazard assessment through radar remote sensing. For this reason it is necessary to encourage the launch of new satellite missions similar to ALOS PALSAR that could operate with shorter revisiting time periods. |
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