Proceedings of the 12th International INQUA meeting on paleoseismology, active tectonic and archaeoseismology

332 1 2 T H I N T E R N AT I O N A L I N Q U A M E E T I N G O N PA L E O S E I S M O L O G Y , A C T I V E T E C T O N I C S A N D A R C H A E O S E I S M O L O G Y ( PATA ) , O C T O B E R 6 T H - 1 1 T H , 2 0 2 4 , L O S A N D E S , C H I L E PATA Days 2024 K E Y W O R D S Oranie, Fault-related fold, SARF, Algeria, Active Tectonics, Seismic Hazard (1) Faculté des sciences de la Terre de Géographie et de l’Aménagement du Territoire, University of Science and Technology Houari Boumedienne. Bab Ezzouar, Algiers, Algeria (2) Centre de Recherche en Astronomie, Astyrophysique et Géophysique, Bp 63 Route de l’Observatoire,Bouzarèah, Algiers. *Email: yahyouhe@yahoo.fr Yahia Mohammedi (1,2) Abdelkarim Yelles-Chaouche (2) Nassim Hallal (2) Abderezzak Tizeraoui (2) Hamoud Beldjoudi (2) Mohamed-Said Guettouche (1) NEOTECTONIC OVERVIEW OF THE ARZEW SALLINE FAULT-RELATED FOLD IN NW ALGERIA: EVIDENCE OF ACTIVE TECTONICS THROUGH FIELD OBSERVATIONS AND GEOMORPHOLOGY A B S T R A C T The Oranie region (NW Algeria), located at the active junction between the Tell-Rif System, Algerian Basin, and Alboran domain, exhibits relative seismic quiescence compared to nearby regions. This study investigates the potential link between the previously undocumented Arzew Saline Fault-related Fold (SARF) and the region's historical seismicity. Utilizing remote sensing, geomorphology, and detailed fieldwork, we reveal compelling evidence for ongoing tectonic activity along the 40-km-long, NE- SW trending SARF. Field observations confirm active faulting with a reverse component, evidenced by meter-scale preserved fault scarps. Additionally, extrados normal faults affecting Holocene deposits provide further evidence for recent, potentially large, seismic events. Analysis of folded Quaternary terraces suggests a preliminary upper Pleistocene slip rate of 0.7–0.9 mm/yr. These results position the SARF as a significant contributor to the Oranie region's seismic hazard and highlight the need for future paleoseismic investigations. I N T R O D U C T I O N The Oranie region, situated along the northwestern Algerian margin, occupies a tectonically active zone at the diffuse transpressional boundary between the Eurasian and African plates (Mustapha Meghraoui & Pondrelli, 2012). This boundary converges at a rate of approximately 5 mm/year in a NW-SE direction (Bougrine et al., 2019). The Oranie basin forms the westernmost extension of the Lower Chelif Quaternary Basin.