Crust and Uppermost Mantle Velocity Structure beneath the East Anatolian Fault Zone from Joint Inversion of P-Receiver Functions and Rayleigh Wave Group Velocities

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Alkan H.

European Journal of Science and Technology, cilt.21, sa.21, ss.285-300, 2021 (Hakemli Dergi)

Özet

The East Anatolian Fault Zone (EAFZ) is an active plate boundary where an intense earthquake activity has occurred from past to present. This activity is highly related to the geodynamic structure of the region. Because of the northward motion of Arabian plate and southward motion of the Eurasian plate, the Anatolian plate has attempted to escape westward with anticlockwise rotation. This tectonic movement cause the development of important tectonic structures. In relation to these active plate motions, the S-wave velocity structure of the EAFZ intersecting the North Anatolian Fault Zone (NAFZ) in the northeast and the Dead Sea Fault Zone (DSFZ) in the southwest is very important in interpretation the tectonic structure of the region. In this study, it was applied on the joint inversion technique of P-wave receiver functions and Rayleigh wave group velocities by using the data collected from eight broadband stations along the EAFZ. The P-receiver functions were obtained by using approximately eighty teleseismic events seperately for each station, recorded by the three-component broadband seismometers. On the other hand, for the Rayleigh wave group velocity dispersion curves, twenty-one local earthquakes which have focal depth less than 50 km and bigger than moment magnitude Mw=5.0 were used. The results obtained from these two techniques for each station was jointly inverted to determine the 1-D S-wave velocity structure of crust and uppermost mantle. S-wave velocity models along the EAFZ indicate the presence of the low-velocity layers in the upper crust, within the approximately depths of 4-12 km. However, the Conrad discontinuity along the seismic stations was around a depth of ~22 km. Furthermore, the crust-mantle boundary along the EAFZ is about ~44 km depth. Consequently, this study yields the crustal and uppermost mantle S-wave velocity structure compatible with the tectonics of the studied region.