Neotectonics and Stressed State Patterns of the Sakhalin Island

Abstract

The study of neotectonics, neotectonic and modern stress of the Sakhalin has been performed by the set of methods. The scheme of modern geodynamics of the island has been constructed by the data of neotectonic activation of the faults. Three types of zones with dissimilar geodynamic conditions have been distinguished: transtension, transpression, and strike-slip (simple shift). The results of Sakhalin modern stress reconstruction based on focal mechanisms of earthquakes allowed to characterize the distribution of the stress state parameters over the island surface: the Lode-Nadai factor and the direction of axes of deviatoric compression and tension. The changes in characteristics of modern tectonic stress field have been noticed at the boundaries of regions with different regimes of modern faulting. Specific orientations of compression axes of the neotectonic stress field are proper for North Sakhalin. Therein, the directions of compression axes become northeast in contrast to the predominant sublatitude orientation on the island as a whole. The obtained data on neotectonics and inherited modern stress field are applicable to the problems of engineering geological support of oil and gas projects’ realization in the Sakhalin (new wells construction, control of the pipelines stability, accompanying urban planning, etc.).