Structural and geological study of the zone of influence of the central part of the West Sakhalin fault

Structural and geological studies were carried out as part of a comprehensive field research for studying the geological and structural characteristics in the area of the village of Boshnyakovo – the town of Shakhtyorsk (the Uglegorsky district, Sakhalin Island). It is shown that the change of the structural-facies zones of the Cenozoic section (from the Middle Eocene to the Lower Miocene) occurs in the Onnai – Goncharovka interfluve. Large slickensides have been documented in the supposed zone of the Lesogorsk-Uglegorsk earthquake of 1924 with MLH = 7.0. Detailed measurements of the spatial orientation of slickensides were carried out in order to reconstruct tectonic stresses by tectonophysical methods. There is a predominance of horizontal extension in the structure of the studied slickensides, less often horizontal extension in combination with shear.