Characteristics of present-day active strain field of Chinese mainland |
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| Authors: | GUO Liang-qian LI Yan-xing YANG Guo-hua HU Xin-kang First Crust Monitoring Application Center China Earthquake Administration Tianjin China |
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| Institution: | (1) First Crust Monitoring and Application Center, China Earthquake Administration, Tianjin, 300180, China |
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| Abstract: | On the basis of the GPS data obtained from repeated measurements carried out in 2004 and 2007, the horizontal principal strain
of the Chinese mainland is calculated, which shows that the direction of principal compressive strain axis of each subplate
is basically consistent with the P-axis of focal mechanism solution and the principal compressive stress axis acquired by geological method. It indicates that
the crustal tectonic stress field is relatively stable in regions in a long time. The principal compressive stress axes of
Qinghai-Tibet and Xinjiang subplates in the western part of Chinese mainland direct to NS and NNE-SSW, which are controlled
by the force from the collision of the Eurasia Plate and India Plate. The principal compressive strain axes of Heilongjiang
and North China subplates in the eastern part direct to ENE-WSW, which shows that they are subject to the force from the collision
and underthrust of the Eurasia Plate to the North America and Pacific plates. At the same time, they are also affected by
the lateral force from Qinghai-Tibet and Xinjiang subplates. The principal compressive strain axis of South China plate is
WNW-ESE, which reflects that it is affected by the force from the collision of Philippine Sea Plate and Eurasia Plate and
it is also subject to the lateral force from Qinghai-Tibet subplate. It is apparent from the comparison between the principal
compressive strain axes in the periods of 2004∼2007 and 2001∼2004 that the acting directions of principal compressive stress
of subplates in both periods are basically consistent. However, there is certain difference between their directional concentrations
of principal compressive stress axes. The surface strain rates of different tectonic units in both periods indicate that the
events predominating by compressive variation decrease, while the events predominating by tensile change increase.
Foundation item: Project of State Science and Technology in the Eleventh “Five-year Plan” (2006BAC01B02-02-03). |
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| Keywords: | GPS strain field compressive strain axis stress tectonic motion |
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