CRUSTAL STRUCTURE OF TURKEY FROM RECEIVER FUNCTIONS AND AMBIENT NOISE TOMOGRAPHY

Here we present preliminary results detailing the crustal structure of Turkey from a combination of receiver function and ambient seismic noise tomography analysis. We use over 250 3-component broadband stations from permanent and temporary networks in Turkey and surrounding regions to image structure in Turkey from a combination of receiver function and ambient seismic noise tomography from crust to upper-mantle.

Receiver functions for teleseismic events during period between 2008 and 2010 have been calculated using frequency domain deconvolution. Using the methodology of Niu and James (2002), the receiver functions are analyzed to joint solve for Vp/Vs ratio and Moho conversion depth. The resulting maps show a highly variable Moho with depths ranging between ~35 km and 58 km depth as well as a variable but generally high average Vp/Vs ratio with median values closer to 1.8 rather than 1.73.

Rayleigh and Love wave group velocities extracted from the cross-correlations of ambient seismic noise are used in a nonlinear iterative tomographic inversion. Then the velocity models from the tomographic inversions are used in a joint inversion to create the Moho depth map of the region. We combine the receiver function results with results from ambient noise tomography to generate a comprehensive interpretation of the Moho and crustal structure of Turkey.

The results mark the complex structure of the region. The seismic images from western Turkey show low velocities possibly linked to the elevated temperatures or fluid content. The images for central Turkey show low velocities for shallow depths but seismic velocity increases with depth; this also coincides with the geothermal potential of the region. The complex wavespeed images for eastern Turkey marks the effects of the ongoing geological processes such as the active collision of Anatolian block and Arabian plate.