Very High Resolution Photogrammetric DSMs and True-Orthoimages: 3D-Fault Zone Mapping in Northern Chile

Kurzfassung

Both Digital Surface Models (DSM) and aerial imagery are commonly used to map and assess geologic structures from remote sensing data. Here we present a high-resolution topographic and visual data set from the Atacama fault system (AFS) near Antofagasta, Chile. The data were acquired with the Modular Airborne Camera System – MACS – (Lehmann et al. 2011) developed by the DLR (German Aerospace Center) in Berlin, Germany. Photogrammetric processing including dense image matching with SGM (Hirschmueller, 2008) and orthorectification was conducted using the processing chain at DLR. The data show a very high geometric accuracy which is the basis for multitemporal analysis. The DSM and the co-registered True Ortho Images with 5cm ground resolution permit the identi­cation of very small-scale geomorphic features. The data used are part of an ongoing study on the geologic history of the AFS in Northern Chile in the context of earthquake prediction. A primary step towards assessing time and size of future earthquakes is the identi­cation of earthquake recurrence patterns in the existing seismic record. Geologic and geomorphic data are commonly analyzed for this purpose, reasoned by the lack of sufficiently long historical or instrumental seismic data sets. Until recently, those geomorphic data sets encompassed field observation, local total station surveys, and aerial photography. Over the last decade, LiDAR-based high-resolution topographic data sets (e.g. Zielke et al. 2010) became an additional powerful mean, contributing distinctly to a better understanding of earthquake rupture characteristics (e.g., single-event along-fault slip distribution, along-fault slip accumulation pattern) and their relation to fault geometric complexities. Compared to typical LiDAR-DEM (with ~0.5m grid size), ground resolution of the MACS-DSM is increased by an order of magnitude while the spatial extend of these data set is essentially the same. We present examples of the 5cm resolution data set and further explore resolution capabilities and potential with regards to the aforementioned tectono-geomorphic questions.