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Abstract:
On June 14, 2020, Mw 5.9 Kaynarpınar earthquake occurred in the easternmost part of the North Anatolian Fault Zone, along the Yedisu Seismic Gap near the Karlıova Triple Junction. Following the event, various agencies reported different epicenter locations. This issue and the complex fault pattern around the triple junction caused uncertainties about the ruptured fault and the rupture mechanism. To define the geometry of the ruptured fault, we (1) held a field survey within a week of the mainshock, (2) correlated our field data with the multitrack InSAR data, (3) relocated the epicenter of the mainshock, and its aftershocks, and (4) implemented moment tensor inversion analyses to the earthquakes larger than M 3.3. We defined a ~ N70E-striking surface rupture and measured the average co-seismic dextral slip magnitude as ~ 16 ± 1 cm in the field which is compatible with the horizontal displacement magnitude measured by InSAR (13–15 cm). Since no ~ N70E-striking faults were reported in the existing active fault database, we examined the prominent geomorphological structures along the rupture area. We determined two dextral fault families along the eastern part of the Yedisu Seismic Gap; (1) NW–SE-striking faults of the North Anatolian Fault Zone, and (2) N70E-striking faults forming the Kaynarpınar–Yuvaklı Fault Zone. This fault zone, defined and named in this study, is a part of the N70E-striking faults of the Turkish–Iranian High Plateau and the North Anatolian Fault Zone. The fault zone must have carried some, if not most, of the dextral sense-of-slip in the easternmost part of the North Anatolian Fault Zone during the Quaternary
