Deep structure of the Vostok Basin, East Antarctica as deduced from seismological observations

Seismological observations using the earthquake converted-wave method were carried out from December 7, 2002 to January 23, 2003 (season 48 of the Russian Antarctic Expedition) in the southern part of Vostok Subglacial Lake for the purpose of studying the structure of the Earth’s crust. Three observation points were placed. One of them was located at the Vostok Station and the other two were located at distances of 8.7 and 12.02 km to the east and to the west of the station, respectively. The performed investigation showed that the thickness of the Earth’s crust in the studied area is 34–36 km. The crust is subdivided into three blocks of different ranks. The low-velocity block is situated immediately beneath the Vostok Basin. Seven interfaces of mode conversion were detected. The results obtained allow us to suggest an increase in heat flow in the Vostok Basin and to the east of this basin. The seismic layering of the ice cover is correlated with the results of radioecho sounding and the structure of the glacier documented in cores of 5G-1 Borehole. The interfaces within the glacier near the Vostok Station are located at depths of 700 ± 100 m, 1600 ± 100 m, and 2200 ± 100 m.