Joint Inversion of Rayleigh Wave Phase Velocities and P-Receiver Functions Along the East Anatolian Fault Zone

Abstract

The detailed crustal and uppermost mantle structure along the East Anatolian fault zone is investigated from the joint inversion data set recorded in 30 broadband seismic stations. Inter-station Rayleigh wave phase velocities are retrieved 5-50 s periods for all stations, whereas radial receiver functions are calculated beneath 17 stations. Firstly, the H-k stacking analysis of receiver functions is applied to calculate the average Moho depth and V-p/V-s ratio, used in the initial model parameters for joint inversion. Then, the joint inversion is performed to develop a new 3-D S-wave velocity model. The findings obtained from these different algorithms show that the Moho discontinuity reaches similar to 42 km and the Conrad discontinuity appears in the depth of similar to 17 km. The low-velocity zones with a minimum S velocity of similar to 2.5 km/s are identified in the upper crust beneath many of the seismic stations and correlate well with the upper crust-lower crust boundary. Combined with previous studies, the high V-p/V-s ratio of the crust and low shear wave velocities interpreted the presence of partial melting and high heat flow. On the other hand, the current seismicity in the region presents that the earthquakes occurred in the depth of 10-20-km depths and major earthquakes (Mw >= 5.0) intensified to the northwest, corresponding exactly to the brittle-ductile transition zone, which may contribute to the occurrence of the earthquakes in shallow depths towards the southwest especially. In conclusion, the new model produced in this study can serve as a reference model for Earth crust studies in the near future.