Azimuthal Elastic Anisotropy of the Upper Mantle under the Central Part of the Voronezh Uplift

The azimuthal elastic anisotropy of the upper mantle of the Voronezh uplift is estimated from the data of three three-component broadband stations of the Voronezh seismic network: "Storozhevoe" (VSR), "Novokhopersk" (VRH), and "Galichia Gora" (LPSR) from SKS/SKKS splitting. Two parameters were calculated-the time shift between two quasi-shear waves (delta t), which are formed when a shear wave (for example, SKS) passes through an anisotropic medium, and the azimuth of the axis of maximum speed alpha (axis of symmetry), along which a "fast" quasi-shear wave propagates. According to the data from different station, the anisotropic parameters are alpha = 40 degrees, delta t = 0.6 s (VSR); alpha = 40 degrees, delta t = 0.1 s (VRH); alpha = 40 degrees, delta t = 0.4 s (LPSR). Taking into account the relatively close location of the stations, all the data were summed up to yield alpha = 40 degrees, delta t = 0.4 s. As all obtained results are similar to each other and coincide with the direction of movement of the Eurasian plate, it is concluded that the anisotropy of the upper mantle in the region is relatively weak, has a northeast azimuth, and is caused by modern tectonic processes.