Abstract: On the basis of the obtained focal mechanism solutions of 77 small and moderate earthquakes with the Snoke method, we used Gephart stress tensor inversion method to obtain the characteristics of tectonic stress field of the Shandong—Jiangsu—Anhui segment of the Tancheng—Lujiang Fault zone. The results show that the maximum and minimum principal compressive stress orientation angles are 80°and 172° respectively. Besides, the maximum, medium and minimum principal compressive stress dip angles are 15°, 65°and 19° respectively, which reflect that the study area is under the circumstance of horizontal action in EW and horizontal tensile action in NS. According to seismic activity, geological structure and the difference of focal mechanism solutions, we divided the Shandong—Jiangsu—Anhui segment of Tancheng—Lujiang Fault zone into 5 parts, and the study result indicates that there is local difference in stress among the 5 parts, the maximum principal compressive stress orientation angle is in the range of 63°～88°, and there is a deflection trend in the clockwise direction from north to south overall. The result of study on stress field along the both sides of the Tancheng—Lujiang Fault zone shows, that the maximum principle stress direction existes a deflection trend in counter-clockwise direction from west to east, which is closer to EW on the west side and closer to NW on the east side, and the Tancheng—Lujiang Fault zone is in the transition area between the two sides.

Key words: Tectonic stress field, Focal mechanism solution, Shandong—Jiangsu—Anhui segment of Tancheng—Lujiang Fault zone