SOME FEATURES OF THE RECENT TECTONIC STRESS FIELD OF CHINA AND ENVIRONS
Yan Jia-quan Shi Zhen-liang Wang Su-yun Huan Wen-lin (Institute of Geophysics, State Seismological Bureau)
Based on the results of focal mechanism solutions for 173 shallow earthquakes occurred during the past 40 years (1937-1977) in China and its environs and some other data, the predominantly horizontal eompressive character of the recent tectonic field existing in this part of the world has been discussed. It shows that:(1) In south China, the prevailing horizontal eompressive stress field is NWW;(2) In North China, Korea and Southwest Japan, NEE horizontal eompressive stress field and NNW horizontal tensional stress field prevail;(3) For the main part of the Chinghai-Tibet Plateau extending as far as West Mongolia, it is under the horizontal compressive stress field, NS to NE in directions. East of the Lanzhou-Chayu line, the stress field deviates toward the SE. In the West Tianshan region, the eompressive stress becoms NW. The intraplate tectonic stress field is thought to be related to the movement of the surrounding lithosphere and that of the upper mantle.