Geomorphic signature of active tectonics in European foreland basins: morphometric analysis of drainage network systems of Western Alps and Romanian Carpathians

Mechanisms and processes that have led to the formation of curved orogenic belts are widely studied and still discussed around the world. Europe has witnessed the formation and evolution of a few cases, among which are the Western Alps (and Alps-Apennines inference zone) and the curvature zone of Romanian Carpathians, both formed during Alpine orogeny. Despite the differences regarding the tectonic evolution between these two different ranges, foreland basins are present in both cases as the result of the geodynamic processes related to deformation during the collisional phases. These subsurface features, filled with deposits of material eroded from the surrounding mountain ridges, often turn into flat surfaces resulting from the deposition of sediments. Under such conditions, any signature or features of tectonic activity are not easily recognized in the visible landscape. However, anomalous changes in fluvial geomorphology, characteristics of drainage patterns and topographic setting along drainage network systems are among the elements that can provide relevant information of recent tectonic activity in areas where the main signatures and tectonic features might be buried by thick layers of sediment eroded from the adjacent mountain ranges. This study aims is to analyze topographic features in these mountain ranges through a morphometric approach using GIS techniques. This approach enables evidence of active tectonics to be identified and, consequently, potential seismic hazard for those areas where knowledge of seismogenetic sources is still limited. In addition, certain aspects of the tectonic evolution of these areas might be more clearly understood with the new information obtainable from such study. Morphometric analysis based on 5 m and 10 m resolutions DEM supported by geological and geomorphological field investigations provided evidence of compressive tectonics activity referable to recent times. Stream-Length Gradient (SL) and Normalized Steepness index (K_sn) are some of the indices that have been calculated using open-source QGIS software.