Digital elevation model with the ground-based SAR IBIS-L as basis for volcanic deformation monitoring

Within the project Exupéry, a hybrid deformation observation system is developed, which is part of a Volcano Fast Response System (VFRS). The VFRS shall be a mobile, robust, real-time, easy to use early warning system, which, in case of a volcanic crisis, will support the locale authorities in their decisions about hazard mitigation provisions, especially about the evacuation of people.The hybrid deformation observation system combines a ground-based Synthetic Aperture Radar named IBIS-L with a network of GPS receivers and will allow the continuous, weather independent determination of areal 3D displacements.In this paper we present the results of first tests with IBIS-L in an active quarry near Dieburg, Germany. A Digital Elevation Model (DEM) was determined with IBIS-L and compared with a DEM derived by terrestrial laser scanning and photogrammetry. The ability to determine accurate DEMs with IBIS-L is the basis for the combination of different observation techniques, as without a DEM the displacements observed with IBIS-L cannot be georeferenced.The standard deviation of the differences between the DEM by IBIS-L and the DEM by laser scanning and photogrammetry depends on the surface characteristics. We found a standard deviation of 0.8 m at a slope of rocks and debris, 2.0 m at mining terraces with low vegetation and 3.0 m in a vegetation covered area.