郯庐断裂带鲁苏皖段构造应力场及分段特征研究

Tectonic Stress Field and Segmention Characteristics in the Shandong—Jiangsu—Anhui Segment of the Tancheng—Lujiang Fault Zone

利用Snoke方法求解和收集得到的77次中小地震的震源机制解资料，采用Gephart应力张量反演方法，获得了郯庐断裂带鲁苏皖段构造应力场，最大主压应力方位角为80°最小主压应力方位角为172°，最大、中等和最小主压应力倾角分别为15°、65°和19°，反映了研究区处于近EW向水平作用和近NS向的水平拉张作用环境下。根据地震活动、地质构造及震源机制解差异，我们将郯庐断裂带鲁苏皖段分5个区段开展研究，结果显示：5个分区应力场存在局部差异，最大主压应力方位角处于63°～88°之间，从北往南总体方向成顺时针偏转的趋势。跨郯庐断裂带两侧的应力场研究结果显示，从西到东最大主压应力方向有一个逆时针偏转的趋势，西侧最大主压应力方向更接近EW向，东侧更接近NE向，郯庐断裂带内处于两侧的过渡地段．

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 seg- ment of the Tancheng--Lujiang Fault zone. The results show that the maximum and mini- mum 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 hori- zontal action in EW and horizontal tensile action in NS. According to seismic activity, geo- logical structure and the difference of focal mechanism solutions, we divided the Shan- dong--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 maxi- mum 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 di- rection 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.