Highlights of current activity along EAF-Palu, NAF-Yedisu segments and Karlıova Triple Junction:Following the 2020 (Mw 6.8 Sivrice) and 2023 (Mw 7.8-7.6 Kahramanmaras) earthquakes

Recent studies have shown that large earthquakes can induce deformation at distances significantly greater than those predicted by simple elastic half-space models. This observation indicates that regional-scale effects must be considered when assessing post-earthquake deformation and seismic hazard. Several studies have demonstrated that the 6 February 2023 Kahramanmaraş earthquake doublet (Mw 7.8 and Mw 7.6) affected distant regions in addition to the immediately ruptured faults.

Within the scope of our project, supported by TÜBİTAK 1001 (Project No. 123Y350), we investigate the current fault activity and seismic hazard of fault segments located north of the 2020 Mw 6.8 Sivrice earthquake and the 2023 Mw 7.8–7.6 Kahramanmaraş earthquakes. Our approach integrates multidisciplinary datasets, including seismology, geodesy (GNSS, InSAR, and creepmeters), and geology (morphometric analyses). The study area comprises the East Anatolian Fault (EAF)–Palu segment, the North Anatolian Fault (NAF)–Yedisu segment, and the Karlıova Triple Junction (KTJ).

Following the 2020 Mw 6.8 Sivrice earthquake, seismicity increased along several sections of the EAF. Initially, aftershocks were concentrated within the rupture zone and subsequently migrated southwestward, while no significant increase in seismicity was observed along the Palu segment to the north. Approximately three years later, the Kahramanmaraş earthquake sequence (Mw 7.8 and Mw 7.6) occurred on 6 February 2023, after which seismic activity expanded over a broad region along the EAF. Compared to the ruptured areas and their immediate surroundings, seismicity remained relatively sparse along the northern sections of the EAF, where our study area is located.

The Palu segment lies adjacent to the NE the Sivrice earthquake rupture zone and forms part of the EAF, whereas the Yedisu segment, located on the NAF, is characterized by a long-term slip deficit and is considered a seismic gap. The Karlıova Triple Junction represents the intersection of the North and East Anatolian faults and exhibits a complex faulting system resulting from active continental collision. Each of these fault segments displays distinct kinematic characteristics and has been affected by the 2020 and 2023 earthquakes to varying degrees.

The current seismicity distribution within the study area (Palu, Yedisu, and KTJ) indicates that earthquake clusters observed prior to these large events remain active, with no anomalous seismic behavior identified to date. Despite the relatively low level of seismicity along the Palu segment compared to the main rupture zones, geodetic observations suggest that its well-known creep velocity has accelerated following the 2020 and 2023 earthquakes. In addition, we investigate the relationship between long-term and present-day geodetic deformation rates, morphological indicators, and slip deficits along active fault branches using continuous and campaign GNSS measurements together with InSAR data. These multidisciplinary datasets, currently under preparation, will be integrated intofault interaction modeling and seismic hazard assessments for the region at the conclusion of the project.