Relationships between some key segments of the Pacific Plate collision with the Okhotsk Plate in connection with the strongest earthquakes of 1952 and 2025 in southeastern Kamchatka

The seismicity of the Central Sakhalin Fault (CSF) segment in southern Sakhalin (as an extension of the Hidaka collisional domain) and the adjacent areas of the Sea of Okhotsk is considered in connection with the severe earthquakes of 1952 and 2025 in southeastern Kamchatka. The catalogs include the strongest crustal (M>5) earthquakes in the Anivsko-Bykovskaya zone of possible earthquake sources of the Central Sakhalin Fault (also known as the Aprelovsky Fault) from 1905 to 2025. In addition, the study includes the strongest deep-focus earthquakes (M>6) in the marine zone in the southeast of Sakhalin. The Hidaka Pacific Plate thrusting zone is considered to be a southern analogue of the same zone in the Kuril and Aleutian Island arc systems, which suggests that there is a synchronization of significant events. It is shown that the segment of the CSF under consideration is in interaction with the West Sakhalin and Hokkaido-Sakhalin faults (which brings the key events on these faults closer in time), while the Sakhalin part of the continuation of the Hidaka zone manifested itself in the strongest deep-focus earthquakes several years before both Kamchatka megaearthquakes, and in the first case, it was also the most powerful crustal earthquake on the segment of the CSF under consideration.