Location of the southern boundary of the Okhotsk plate based on a set of seismic characteristics
N.A. Bushenkova, T.A. Stupina, O.A. Kuchay
Trofimuk Institute of Petroleum Geology and Geophysics, Siberian Branch of the Russian Academy of Sciences,
Novosibirsk, Russia
Keywords: the Okhotsk plate southern boundary, features of the seismic focal zone, lithospheric plate boundary, subduction in the P-wave velocity anomalies field, the seismotectonic deformation main axes directions, Hokkaido, Honshu, Sea of Japan
Abstract
The study is devoted to determining the position of the southern boundary of the Okhotsk Plate based on the analysis of the seismicity distribution in the area of the Hokkaido, Honshu and adjacent territories according to a local data from Japanese catalogs (JMA) for the period 1998-2022. And comparing them with regional seismic tomography models, as well as with the distributions of the seismotectonic deformations main axes directions according to the focal mechanisms of strong (Mw> 4.7) earthquakes based on the International Seismological Center catalogs data (ISC) for the period 1976-2022 and other relevant geological and geophysical characteristics (gravitational field heterogeneities, crustal thickness, volcanic manifestations, etc.). It was found that the southern boundary of the Okhotsk Plate passes along the southern tip of the Hokkaido Island. Namely through the Oshima Peninsula and Uchiura Bay, and not along the Hidaka Ridge or through Honshu Island, as was assumed in previous constructions by other authors.
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