A Quantitative Estimate of Modern Deformations of the Earth's Crust in the Mongolian Block (Based on GPS-Geodesy and Seismotectonic Data)

摘要

Based on measurements carried out using the method of GPS-geodesy and the calculation of seismotectonic deformations in the source zones of the strongest earthquakes, we have obtained the first estimates of the velocity of horizontal deformations of the Earth's crust in western Mongolia. The velocities of the displacements of large blocks, which contact by seismoactive faults, have been calculated. This has allowed us to obtain a first approximation of the recurrence periods of the strongest earthquakes in these zones. The increased attention that has been given to the modern geodynamics and seismicity of the Mongolian Block (Fig. 1) is related to the fact that five earthquakes with magnitudes exceeding 7.5 occurred along its periphery in the 20th century: Tsetserleg (July 9, 1905; M_S = 7.8), Bolnai (July 23, 1905; M_S = 8.2), Fuyun (August 10, 1931; M_S = 8.0), Gobi Altai (December 4, 1957; Ms = 8.1), and Mogod (January 5, 1967; M_S = 7.5), as well as the last strong earthquake in the Altai-Chuya area (September 27, 2003, M_S= 7.5).