3-D upper crustal velocity structure of the Inner Gulf of Izmir from ambient noise tomography

This study aims to reveal upper-crustal velocity structure of İzmir Gulf and surroundings using ambient noise tomography. One-year vertical component ambient noise data have been used from 17 stations which belong to the İzmirNET accelerometric network. Rayleigh wave group velocities which present good S/N ratio have been obtained from dispersion curves by using multiple filter technique. Results have been mapped by performing a surface wave tomography algorithm for 2, 4 and 6 s periods. Then, shear wave velocities have been computed from the inversion of group velocities which are obtained from local dispersion curves at different periods. Low velocity areas belong to alluvial units in Inner Gulf and surroundings, have been precisely observed down to 3 km at group and Vs maps. Added to this, it is detected not only low velocities but also high Vs values in the depth slices of inner parts of the Gulf.