Abstract: Based on analysis of distribution of 2 660 earthquake focal mechanism solutions from “Database of Crustal Stress of China and Adjacent Area” (updated to December, 2003), the regional characteristics of focal mechanism solutions are studied. In the Northeast and North China stress regions, the orientations of maximum horizontal stress mostly are in the near EW direction and NEE-SWW direction. The strike-slip focal mechanism is predominant in Northeast and North China stress regions. In the South China stress region, the predominant orientation of maximum horizontal stress is in NE-SW direction. The focal mechanisms mainly include thrust faulting and strike-slip faulting. In the Xinjiang stress region, the predominant orientation of maximum horizontal stress is in near N-S direction. There is a significant number of thrust faulting events and strike-slip faulting events in Xinjiang stress region. In the south Tibetan stress region, the predominant orientation of maximum horizontal stress is in near N-S direction, and the focal mechanism solutions are of strike-slip and normal faulting. In the stress region of north Tibet plateau and in the northeastern edge, the predominant orientation of maximum horizontal stress is not concentrated, and the focal mechanisms mostly are of strike-slip faulting, with some normal faulting and thrust faulting.

Key words: focal mechanism solutions, stress field, stress region

摘要： 利用《中国大陆地壳应力环境基础数据库》收录的中国及邻区2660个地震震源机制解资料(数据截止到2003年底),在分析中国及邻区震源机制解及其分布特征的基础上,重点分析探讨了中国境内6级以上地震的震源机制解的分区特征:东北-华北应力区震源机制解水平最大主应力的优势分布方位为近EW向和NEE向,震源机制解类型相对较为单一,以走滑型为主。华南应力区水平最大主应力的优势分布方位为NW-SE向,震源机制解类型主要是逆断型和走滑型。新疆应力区水平最大主应力的优势分布方位为近SN向,类型也主要是逆断型和走滑型。在青藏高原南部应力区,震源机制解水平最大主应力方位的分布相对比较集中,优势方位为近SN向,类型基本上只有走滑型和正断型2类。而在青藏高原北部及北东边缘应力区,水平最大主应力方位变化较大,震源机制解类型以走滑型为主,同时还有一定数量的正断型和逆断型震源机制解。

关键词: 震源机制解, 构造应力场, 分区