The constructed model for a deep structure of the lithospere under the Neftegorsk earthquake region shows that North Sakhalin consists of the North Sakhalin sedimentary basin, the Deryugin basin and the ophiolite complex located between them. The ophiolite complex composed of the the ultrabasic rocks, fixes the position of the ancient subduction zone which was active about 100-60 million years ago. On a surface the subduction zone manifests itself as deep faults running along Sakhalin. The center of the Neftegorsk earthquake was directly formed by burst of activity of this ancient subduction zone.