Abstract: In this paper, the average slip rates of the western branch of the Xiaojiang fault zone are estimated as 6.7 mm/yr, 7.0 mm/yr and 6.4 mm/yr during the Quaternary period, the late Pleistocene epoch and the Holocene epoch respectively according to the offsets of the geomorphic and geologic features and their ages. Furthermore, the recurrence intervals of strong earthquakes and the activity of the fault zone are discussed on the basis of the estimate of the slip rates and the research on both prehistorical and historical seismicity. The results indicate that the western branch of the Xiaojiang fault zone is characterized by repeated activity which leads to the periodical occurrences of strong earthquakes. The average recurrence interval at the same site of the fault is about 900 years and that on the whole fault zone is more than 330 years.

Key words: Yunnan, Xiaojiang fault zone. Slip rate. Earthquake, Recurrence interval

摘要： 本文通过对各种断错地质地貌现象及被错体年龄的分析,估算出小江西支断裂在第四纪、晚更新世及全新世以来的滑动速率分别为6.7毫米/年、7.0毫米/年及6.4毫水/年。在此基础上,结合历史地震及古地震活动讨论了强震的重复周期和断裂的活动特征,结果表明小江西支断裂的活动以重复错动发生强烈地震为主要特征,强震在断裂带上同一地段的平均重复周期为900年左右,沿整个断裂带的重复周期大于330年。

关键词: 云南, 小江断裂带, 滑动速率, 地震, 重复周期