Multi-Temporal InSAR Techniques Used to Detect Large Slope Instabilities Along the National Road 7, Mendoza, Argentina
Michoud, Clément1; Derron, Marc-Henri1; Baumann, Valérie2; Jaboyedoff, Michel1; Lauknes, Tom Rune3
1University of Lausanne, SWITZERLAND; 2Geological Survey of Argentina, ARGENTINA; 3Norut, NORWAY
In average 2'230 vehicles use every day the National Road 7 to reach Santiago de Chile from Buenos Aires. In the Mendoza Province, where the road crosses elevated passes along the Andes Cordillera, this extremely essential corridor is exposed to several natural hazards, such as snow avalanches, debris flows or rockfalls, which endanger infrastructures and populations. Indeed, the diversity of soil and rock conditions, the active geomorphological processes associated to post-glacial debuttressing, seasonal freeze and thaw and severe storms along the road corridor, increase the risk to natural hazard.
This study, initiated by Baumann et al. (2005), aims to produce regional susceptibility maps merging modern remote sensing and numerical modeling approaches with classical field checking. In order to detect active large instabilities, we have for this study processed a large number of ERS and Envisat ASAR scenes with the support of the European Space Agency (ESA Category-1 Project 7154), covering the period from 1995 to 2000. We applied both the persistent scatterer (PSI) and the small-baseline (SB) multi-temporal interferometric SAR (InSAR) techniques. As the study area contains sparse vegetation, and the SB InSAR method is therefore well suited to map the area containing mainly distributed scatterers. Furthermore, PSI algorithms are also used for comparison for selected landslides in the inventory.
Both approaches show a relatively good coherence within mountain areas, which is a key point for the large instability detections closed to the N7. Indeed, several large slope instabilities and even active scree deposits were identified. This inventory is finally compared with field observations already performed in subset areas and with existing susceptibility maps regarding debris-flows and rockfalls.
The final objective of this project is to develop a risk strategy that will help local authorities to manage the risk along this highway and also to provide guidelines.