Remote Sensing Applications comprising geological and geophysical Data for neotectonic Investigations: A Case Study in South-Central-Egypt

The analysis of the complex, neotectonic movements in the investigation area in southern-central Egypt and the specific dynamics of the moving units with different sizes and velocities is a difficult task. It requires an interdisciplinary approach, especially the integration of remote sensing, geological, geodetical and geophysical data. Geostructural mapping is essential for understanding the structural architecture and tectonic evolution in the study area. Thus, a prerequisite for the detection of neotectonic activity is a systematic inventory of structural features, fault and fracture zones, traces of magmatic activity, and of seismic and geodetic data. Satellite data support the detailed, structural 2D inventory to a large extent. When combing and merging optical and radar satellite images with DEM data, the morphologic properties at the surface can be determined, especially based on 3D perspective views with vertical exaggeration up to 20 x. Thus, fault related structures like push-up ridges or pull-apart depressions along fault zones can be detected. Based on the digitized structural features and traces of fault zones density calculations were carried out. Those areas with the highest densities of prominent fault zones and fault related structures can be assumed to be susceptible to relatively higher geodynamic activity in the past and, when reactivated, up to recent times. Neotectonic movements affect the present day geomorphology. High-resolution satellite images help to differentiate various traces and types of neotectonic activities and to study kinematic processes along larger fault zones, even influencing recent morphodynamic processes such as the drainage pattern or slope failure. Linear courses and parallel arrangements of dry riverbeds, their meanders, and terraces clearly reveal a recent tectonic influence on their development. The identification of the geomorphic signatures of tectonic activity can be supported by the evaluation of morphometric properties of the surface. When calculating the difference between an original digital elevation model (DEM) and the filled DEM in ArcGISPro software, depressions can be identified that might lead to the identification of pull-apart depressions, basins or of rift zones. By extracting steep slope degrees from slope gradient maps and digitizing traces of mass movements based on satellite images, it can be derived where areas are more likely to be prone to slope failure in case of increasing geodynamic activity such as earthquakes with magnitudes > 5.