Neotectonics of the Malatya Basin, SE Türkiye; implications of the reactivations of the faults of the basin during 6 February 2023 earthquakes of the East Anatolian Fault System

The Malatya Basin (MB) is a fault-controlled superimposed sedimentary basin situated in the SE of Anatolia, near and to the north of the East Anatolian Fault System (EAFS). The rock units ranging from the Permo–Carboniferous to the Upper Miocene form the basin’s basement. The thickening of the Upper Cretaceous–Upper Miocene sequence toward the Malatya Fault (MF), the basin’s northwestern boundary, indicates a dip-slip-dominated character for the MF and its control on the first-step sedimentation of the basin. The MF changes its character from dip-slip normal to the strike-slip in the Late Pliocene, and today presents a 1700-m left lateral offset, which points to a 0.56-mm/y slip rate and a recurrence period of 3571 years. It should be noted that there is no genetic relation to the Ovacık Fault (OF). The dip-slip normal Çöşnük Fault (ÇF), which is the basin’s southern boundary and was reactivated during the 6 February earthquakes, led to the development of the region as a limnic environment during the second depositional step, as in the Pliocene. In the late Pliocene, the limnic basin turned into a fluvial regime. This fluvial system is the third step in the basin’s depositional period. The ÇF later developed a strike-slip character and caused a left-lateral offset of the Fırat River of about 4000 meters. The MF, as the basin’s northwest boundary, was active from the beginning of the Pliocene with a left-lateral strike-slip character, causing earthquakes; however, it was not activated during the 6 February earthquakes. As for the ÇF, it began moving in a strike-slip mode in the late Pliocene, causing earthquakes at depths of 4–6 km. It is suggested that an earthquake could have occurred on the EAFS, which also activated this fault zone. This could have happened during the 6 February 2023 earthquakes.