The article analyses the results of geophysical studies of rift structures in East Antarctic, direct geological surveying of which is impossible due to a thick ice sheet. A model is proposed for the formation of Lake Vostok depression suggesting its emplacement within the regional transtensional zone. The Lake basin includes the southern longitudinal graben forming along the main shear and the northwestern basin, which is estimated as a pull-apart structure. Based on results of the gravity and magnetic field interpretation proposed in the article, the identification and parameters of the interblock suture zone in the basement of the coastal part of the subglacial Lake Vostok are substantiated. Similarities in the structure of the Earth’s crust of regional and local structures containing Lakes Vostok and Baikal have been recorded for a large number of features: spatial correlation with position of regional shear zones; geniculate morphology of lake basins composed of linear longitudinal depressions parallel to direction of the shear zone and depressions controlled by diagonal fault displacements; relief of adjacent structures; steepness of coasts; high seismicity with earthquakes localized along the main axes of fault displacements as well as the Earth’s crust structure of geostructures controlling these basins. The formation model of rift structures of East Antarctic localized along subparallel shear zones is presented. To explain the geodynamic nature of rift systems, the model of the upper mantle convective cell is used. The Vostok, Scott, Aurora, Concordia, Adventure, Wilkes, and Astrolabe depressions form an extensive tectonic zone approximately 2,000 km long and 1,500 km wide. Tectonic schemes showing localization of the East Antarctic rift system as well as depressions of the Mesozoic West Transbaikal rift area and the Cenozoic Baikal-Stanovoi rift zone are presented.