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本文基于1970年以来的地震目录及四川地区4.0级以上地震的震源机制解资料,分析鲜水河断裂带分段(炉霍段、道符段、康定段、石棉段)的地震活动特征及研究区现代构造应力场,结合深部速度结构,探讨鲜水河断裂带上地震活动频度与龙门山断裂带地震活动的关系及康定地段6.3级地震的孕震环境。结果发现:(1)鲜水河断裂带北段和南段地震活动性存在差异,炉霍段和道孚段的地震活动频度1981年前要高于2000年后,康定段和石棉段的地震活动频度2000年以后高于1981年前;(2)分析地壳P波速度结构发现康定震区西侧川滇块体表现出低速异常,东侧表现出高速异常;(3)对构造应力场的分析结果表明龙门山断裂带主要以NW-SE向挤压为主,鲜水河断裂带构造应力场以NWW-SEE向为主。综合鲜水河断裂带应力场特征、深部速度结构、断层间的相互作用等信息推断,康定M6.3地震的发生与该地区应力积累及深部孕震环境相关,同时由于龙门山断裂带地震活动性影响,导致鲜水河断裂带康定段的能量释放。
Based on the catalogs of earthquakes since 1970 and the focal mechanism solutions of earthquakes of magnitude 4.0 above the Sichuan area, this paper analyzes the seismic activity characteristics of the Xianshuihe fault zone (Huohuode, Daoluntuan, Kangding and Shimian) Based on the modern tectonic stress field combined with the deep velocity structure, the relationship between the frequency of seismic activity on the Xianshuihe fault zone and the seismic activity of the Longmenshan fault zone and the seismogenic environment of the Kangding 6.3 earthquake are discussed. The results show that: (1) there is difference in seismicity in the northern segment and the southern segment of the Xianshuihe fault zone, and the frequency of seismic activity in the Luhuo section and the Daofu section before 1981 was higher than that in 2000 after Kangding section and Shimian section The frequency of seismic activity is higher than that before 1981 after 2000; (2) By analyzing the velocity structure of the P wave in the crust, it is found that the Sichuan-Yunnan block on the west side of the Kangding earthquake area shows a low-speed anomaly and the east side shows high-speed anomalies. (3) Field analysis results show that the Longmenshan fault zone is dominated by NW-SE extrusion, and the tectonic stress field of the Xianshuihe fault zone is dominated by NWW-SEE. Based on the information of stress field, deep velocity structure and the interaction between faults in the Xianshuihe fault zone, the occurrence of Kangding M6.3 earthquake is related to the stress accumulation and deep seismogenic environment in the area. Meanwhile, due to the seismic activity of the Longmenshan fault zone Sexual influence, resulting in energy release Kangding section of Xianshuihe fault zone.