ASSESSMENT OF RELATIVE-ACTIVE TECTONICS IN RHUMEL-SMENDOU BASIN (NE ALGERIA) - OBSERVATIONS FROM THE MORPHOMETRIC INDICES AND HYDROGRAPHIC FEATURES OBTAINED BY THE DIGITAL ELEVATION MODEL.

The eastern Tell Atlas of Algeria is characterized by a complex neotectonic system including lateral strike-slips, and normal and reverse faults. The landscape of the Neogene basin of Mila-Constantine acquired its shape due to the perpetual action of tectonic activity, and erosion processes. Neo-tectonics in this basin have affected the geometry of the stream network and the contemporary landscape topography. Our methodology evaluates the active tectonics in this mountainous region by a combination of drainage network and geomorphic indices, namely, the basin-shape index (Bs), stream-length gradient (SL), hypsometric integral (HI), mountain front sinuosity (Smf), basin asymmetry factor (AF), and valley-floor ratio (Vf). The calculated values of the six measured geomorphic indices were used to differentiate the distribution of faults function as well as the relative tectonic activity in the study area. The obtained results from the GIS-based multi-criteria analysis of these indices consist of the index of active tectonics (IAT). Hence, we defined four hierarchic degrees of IAT, namely, very high (VH), high (H), moderate (M), and low (L). The relative active tectonics represents an obvious correlation between morpho-structural features, tectonic activities, and uplift rates. It selects the morphotectonic features and landforms that interpret the tectonic events in the study area. Our results prove that this approach discerns the most active regions related to the neo-tectonic action in the Rhumel-Smendou drainage basin. The combination of geomatics and field surveys highlights the cliffs which are still rising by using the drainage patterns, the landform model, and the mountain range shape. [ABSTRACT FROM AUTHOR]