TECTONIC STRESS FIELD AT INTERMEDIATE DEPTHS OF THE SOUTHERN FLANK OF THE KURIL-KAMCHATKA SEISMIC ZONE

• Main Authors: D. A. Safonov, Д. А. Сафонов
• Other Authors: The work was funded from the government budget for the IMGG FEB RAS, Работа выполнена в рамках государственного задания ИМГиГ ДВО РАН
• Format: Article in Journal/Newspaper
• Language: Russian
• Published: Institute of the Earth's crust of the Russian Academy of Sciences, Siberian Branch 2021
• Subjects: промежуточные глубины; double seismic focal zone; tectonic stress field; slab; intermediate depth; двойная сейсмофокальная зона; поле тектонических напряжений; слэб; Kamchatka
• Online Access: https://www.gt-crust.ru/jour/article/view/1374; https://doi.org/10.5800/GT-2021-12-4-0564

The study has been done on the orientation of the principal axes of tectonic stress field at intermediate depths of earthquakes of the southern flank of the Kuril-Kamchatka subduction system separately for the upper and lower double seismic focal zones. Use has been made of the NIED and GlobalCMT catalogue data. The computation-based results are presented on schemes of the stressed state of the investigated areas and in tables. In the context of the southern Kuril Islands, evidence has been provided for predominance of the maximum compressive stresses along the slab plane in the upper layer and minimal compressive stresses (deviation extension) in the lower layer. However, the principal axes of maximum and minimum compression are displaced in direction relative to the slab dip: by 30–40° counterclockwise for the compression axis in the upper layer, which coincides with the direction of plate movement, and clockwise for the extension axis in the lower layer. This might be caused by the right-lateral strike-slip component of the Pacific Plate subduction. Unlike the general trend, the orientation of the principal axes of the stress field beneath the central Hokkaido-related segments in the upper layer is almost identical to that in the lower layer. There have also been found the segments exposed to shear stress, with the most extensive located opposite the northern Kunashir Island and beneath the southern Hokkaido Island. The results obtained for major large groups of clusters show good accordance with those published by other authors. The discrepancies relate primarily to small groups of isolated clusters showing local stress field heterogeneities. Исследовано поле ориентаций осей главных тектонических напряжений на участке промежуточных глубин землетрясений южного фланга Курило-Камчатской субдукционной системы отдельно для верхнего и нижнего слоя двойной сейсмофокальной зоны. Привлечены данные каталогов NIED и GlobalCMT. Результаты расчетов представлены в виде схем напряженного состояния изучаемых областей и ...