Neotectonics and active tectonics of the Dahra- Lower Cheliff Basin (Tell Atlas, Algeria): Seismotectonic implication

Abstract

Neotectonics and active tectonics in the Dahra region (northern Algeria) are investigated using morpho-structural analysis and field study. This work allowed us to identify several geological structures that exhibit characteristics of typical NE-SW active folds; dissymmetric folds underlined by reverse faults with extrados normal faults. Five “en–echelon” structures were identified, namely, the Djebel Benzekri, the Djebel Semouda, the Abreuvoir, the Bouassas and the Belhacel folds. The determined stress axis from field measurements is comparable to that derived from focal mechanisms solutions of recent earthquakes. The surveyed faults and folds are comparable to that known as seismogenic structures such as the Abou El Hassan and Oued Fodda fault-related folds reactivated during the 1922 (Mw = 6.0) and in 1980 (Ms = 7.3) destructive earthquakes, respectively. As results the offset and the slope determined for these structures could indicate an important rate of deformation. Using the obtained faults parameters the seismic potential is indicated by the capability of these structures to produce Mw > 6.0 earthquakes.