Basic characteristics of recent tectonic stress field in southwest China |
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Authors: | Fu-Ren Xie Jing-Zhong Zhu Hai-Qing Liang and Guang-Xun Liu |
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Affiliation: | (1) Institute of Crustal Dynamics, State Seismological Bureau, 100085 Beijing, China |
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Abstract: | Direction and structure characteristics of 58 tectonic stress tensors have been determined in 41 surveyed areas (points) in
the southwestern district of China through a calculation method for inversion of tectonic stress tensors from sliding direction
of faults, and, in combination with seismic mechanism solution andin-situ stress measurements, the following characteristics of the recent tectonic stress fields in the southwestern district of China
have been defined: (1) the stress fields in this district have remained stable since the end of early to mid-Pleistocene;
(2) the effect of such tectonic stresses is mainly horizontal; (3) the orientation of the maximum principal stress axis shows
a trend of regular rotation from north to south, i. e. from NEE-SWW in northern Songpan and Longmen Shan areas to sub-EW in
the central part of western Sichuan, and further to NNW-SWW or sub-SN in Yunnan; (4) the regional tectonic stress fields are
of distinct division character; (5) there is well concordance between the main direction and type of stress structures in
the stress tate both in deep and shallow parts of the crust. In addition, studies of staged tectonic stress tensors preliminarily
show that in early Quaternary the southwestern district was mainly affected by lateral compression of Indian plate, under
which the regional tectonic stress fields mainly display NE-sub-EW compression.
The Chinese version of this paper appeared in the Chinese edition ofActa Seismologica Sinica,15, 407–417, 1993. |
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Keywords: | southwestern district of China recent tectonic stress field stria stress tensor |
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