High Vp/Vs ratio in the crust and uppermost mantle beneath volcanoes in the Central and Eastern Anatolia.

In this paper, I analyse Vp, Vs and Vp / Vs ratio for the crust and uppermost mantle of Anatolia in $$\rm EU_{60}$$, a recently developed 3-D tomographic model for the European continent. Beneath volcanic fields in the Central and Eastern Anatolia, pronounced reductions in isotropic Vs are observed in the crust and uppermost mantle, reflecting high temperature associated with Neogene–Quaternary magmatism in the study region. These slow wave speed anomalies correlate well with high Vp / Vs ratio in model $$\rm EU_{60}$$. By analysing relative perturbations in Vp and Vs at different depths, I observe a distinct pattern for grid points associated with volcanic and non-volcanic regions. The linear regression results of volcanic grid points are characterized by high δlnV_s/δlnV_p slopes in comparison with non-volcanic grid points. Grid points with linear fitting slopes greater than 2.2 are observed around 50–60 km beneath volcanic provinces. These observations suggest the presence of partial melt in the crust and uppermost mantle beneath volcanoes in the Central and Eastern Anatolia. Comparisons between seismic observations with theoretical single phase partial melting calculations suggest the presence of cracks filled with a few volume per cent of melt in the upper and lower crust. Less than $$1\,{per\,cent}$$ melt-filled inclusions with aspect ratio smaller than 0.001 might exist in the uppermost mantle. [ABSTRACT FROM AUTHOR]