Abstract:

The offshore of China mainland includes the Bohai Sea, Yellow Sea and East China Sea. Using data of focal mechanism solutions, borehole breakouts and hydraulic fractures, there have been various degree studies  on the recent tectonic stress field of this region and adjacent areas. Based on these previous work, in combination with analyses of neotectonic movements of marine area and land and dynamic conditions, we attempt to make a further research on this subject. Our result shows that the recent tectonic stress field of this region is characterized by nearly horizontal compression, which is in NE direction in the north and gradually turns to NEE, EW, SEE and SE in the south, exhibiting a fan shape of diverging toward east. The intensity of tectonic stress is not uniform, relatively strong in the north and weak in the south. The marine and continental areas share a common recent tectonic stress field, which can be divided into Northeast China, North China and South China stress provinces. The generation of such a stress field is associated with the extrusion toward northeast and southeast at the eastern margin of the Tibetan plateau due to the continued northward indentation of the India plate, as well as the effect of the westward subduction of the Pacific and Philippine Sea plates in the east. And the eastward extrusion by the Tibetan plateau seems to be the dominant driving force.

Key words: offshore of eastern China, focal mechanism solution, borehole breakout, recent tectonic stress field, horizontal compression