Impact of the 2020 Elazığ and 2023 Kahramanmaraş Earthquakes on the Palu–Ilıca–Karlıova Segments using InSAR, GNSS, and Seismotectonic Analyses

The left-lateral East Anatolian Fault (EAF) is one of the most active intracontinental plate-boundary faults, along with the right-lateral North Anatolian Fault (NAF), accommodating the westward movement of the Anatolian plate in the Eastern Mediterranean Region. The historical seismic records, indicating the large-magnitude earthquakes caused by the East Anatolian Fault Zone (EAFZ), conflict with the region’s relative tectonic silence during the instrumental period. The largest known historical earthquakes along the EAFZ occurred in 995 (Ms 7 - 7.8), 1114 (M > 7.8), 1408 (Ms 7.2), 1513 (M > 7.4), 1789 (Ms > 7), 1822 (Ms > 7.4), 1872 (Ms > 7.2), 1874 (Ms > 7.1), 1893 (M > 7.1), 1905 (Ms 6.8), 1971 (Ms 6.8), 2020 (Mw 6.75) and 2023 (Mw 7.5). The 24 January 2020 Mw 6.7 Doğanyol-Sivrice Earthquake and the 6 February 2023 Mw 7.8 Kahramanmaraş Earthquake Doublet have shown that the EAFZ, located in the middle of the continental collision zone, poses a significant potential to generate catastrophic earthquakes despite its long quiescence-period. Following the 2020 Mw 6.7 Doğanyol-Sivrice earthquake, studies that particularly focusing Coulomb stress change distribution indicated that the stress transfer along the EAF towards the northeast of Lake Hazar, in particular to the Palu, Ilıca, and Karlıova segments. Similarly, stress transfer following the February 6, 2023 Kahramanmaraş earthquakes was towards both southwest, i.e., to the Amanos and Hacıpaşa segments, and to the northeast of the EAF. Although M<4 aftershocks from both activities extended to the end of the Karlıova segment where the Karlıova triple junction joins the NAF, there have been no M>5 earthquakes in the Palu, Ilıca, and Karlıova segments since 2010. Therefore, we selected the region covering these segments for the investigation since it is the relatively seismically inactive area of the EAF. Our major objective is to understand the impact of the 2020 Doğanyol-Sivrice and 2023 Kahramanmaraş earthquakes and subsequent post-seismic deformation period on the silent region through the analyses of InSAR (SBAS) and GNSS time series, incorporated with analyses of coseismic deformation, Coulomb Stress Change, and b-value variation. To achieve this aim, ISCE2 and Mintpy utilities were used in the calculation of the InSAR time-series and GAMIT/GLOBK is used to construct GNSS time-series. The results from multiple-data analyses enable a comprehensive understanding of the tectonic setting as well as to understand whether the segments in the region are locked or experiencing any creep activity.