Seismic Hazard Implications in and Around the Yedisu Seismic Gap (Eastern Türkiye) Based on Coulomb Stress Changes, B-Values, and S-Wave Velocity

Abstract

The Yedisu Seismic Gap is one of the most important seismic gaps throughout the North Anatolian Fault Zone since it has not produced destructive earthquakes for a long time. To analyze the characteristics of future seismic hazards, the interrelationships between seismotectonic b-values, Coulomb stress changes, and S-wave velocity models of crust are presented in and around the Yedisu Seismic Gap located northwest of the Karliova Triple Junction. For this purpose, the most up-to-date earthquake catalog and the focal mechanism solutions of recent earthquakes are used to image the different depth intervals. Results show that the relatively positive stresses are accumulating along the Varto Fault Zone and Kargapazari and Yedisu Segments between 5 and 15 km depth intervals. At the same time, the lower b-values between 0.6 and 1.0 are found in the same segments. However, in the volcanic regions around the Karliova Triple Junction, the low S-wave velocity zones may be related to high b-values, negative stress changes, and volcanic structures. The region between the Turnadag? volcano and the Varto caldera shows scattered stress and b-value changes in the upper crust. Moreover, the probability of earthquakes for Mw = 6.0, 7.0, and 7.7 in the intermediate term (10 years) is estimated as -65%, -17%, and -5%, respectively. Recurrence of earthquakes with Mw = 6.0, 7.0, and 7.7 are calculated as -10, -55, and -187 years, respectively. Con-sequently, the regions characterized by low strong b-values and positive stress loading reveal high earthquake hazard potential on the whole in the next decade.