The recent tectonic stress districts and strong earthquakes in China

According to the stress state and force source character, the recent tectonic stress field of China is preliminary divided into four classes. Among them, there are two first order districts, four second order districts, five third order districts and twenty-six fourth order districts. By analyzing those tectonic stress districts and strong earthquakes, the close relation between them is mainly summarized as follows: (1) The boundary of stress districts especially the first or second order boundary controlled by the interaction of tectonic plates has strong earthquakes very easily and frequently. (2) Stress districts with stress direction, regime type and stress value transformation are concentrative zones of strong earthquakes. (3) Stress districts with local stress differentiation but in the homogeneous stress background are the places where strong earthquakes are rela-tively concentrated. On the basis of these research work, we discuss the present dynamic environment in China from force source and plates movement.