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Imprint of the Bering Plate in Chukotka, East Siberia, from Regional GPS Observationsтезисы доклада
- Авторы: Kogan M.G., Frolov D.I., Steblov G.M., Gabsatarov Y.V., Vladimirova I.S., Freymueller J.T.
- Сборник: American Geophysical Union (AGU) 2009 Fall Meeting
- Серия: Eos, Transactions American Geophysical Union
- Том: 90
- Тезисы
- Год издания: 2009
- Место издания: San Francisco. Calif. USA. 14-18 December 2009 USA
- Первая страница: G23D-04
- Аннотация: The Bering Sea is bordered by Chukotka and Kamchatka on the west, Alaska on the east, and the Aleutians on the south. The Bering plate (BER), distinct from the North American plate (NAM), was earlier hypothesized judging from seismicity [Mackey et al., 1997]. Recent analysis of GPS observations in western Alaska, on islands in the Bering Sea interior, and on the Aleutians confirmed the existence of BER rotating clockwise around the pole in east Asia [Cross and Freymueller, 2008]. However, the confirmation of BER was lacking on the western margin. Here we augment the data base with the GPS survey of Chukotka performed at four epochs in 2004-2009 and analyze implications of velocities in Chukotka for the motion of BER. To strengthen reference to NAM in this region remote from the interior of NAM, we evaluated station velocities by the method adopted in the PBO processing: in each daily solution, we combined observations in Chukotka and at 25-30 well-determined global stations over a hemisphere centered on Chukotka. The data spanning five years showed two contrasting patterns of motion of stations in Chukotka. In general, whole Chukotka slowly moves relative to NAM at a speed not exceeding 3 mm/a. While velocities over most of the region point to ESE, velocities over northeastern Chukotka point nearly to the south agreeing with the motion of St Lawrence Island and Seward Peninsula on Alaska, located to the east of Chukotka. The change in direction of motion over Chukotka indicates existence of a right-lateral fault that agrees with focal mechanisms of events over the seismic belt along the western margin of the Bering Sea. Movement of northeastern Chukotka confirms the sense and angular rate of rotation of BER as estimated by Cross and Freymueller from observations over the eastern part of BER. The slow motion of most of Chukotka to ESE indicates that this wedge-like extremity of NAM deforms being jammed between the Eurasian and Pacific plates, or, alternatively, it belongs to another rigid block located farther to the north.
- Добавил в систему: Стеблов Григорий Михайлович