Abstract: The NE-trending central segment of the Longmenshan thrust belt is composed of 3 major thrust or reverse faults. Geomorphic evidence and earthquake activity indicate that Quaternary activity is stronger on the southwest and weaker on the northeast along the central segment of the Longmenshan thrust belt. The segmentation of faulting is probably produced by the activity on the NS-trending Minshan uplift on the north of the Longmenshan thrust belt. Because deformation is dispersed on 3 faults, only moderate(M≤6)earthquakes have occurred along the central segment of the Longmenshan thrust belt.

Key words: Longmenshan Montains, Thrust belt, Tectonlc geomorphology, Seismicity

摘要： 龙门山逆断裂带中段由3条主要的逆断裂带组成,根据构造地貌学特征和地震活动性推测,其第四纪活动性自南西向北东方向递减,表现出明显的分段性。其中灌县-江油断裂控制了山地与平原或山地与丘陵区的分界以及第四系的厚度,根据这一特征可知该断裂的活动性自南向北,在大邑、灌县和彭县一带最强,绵竹次之,安县至江油最弱。断裂活动的分段性可能受龙门山北部南北向岷山隆起的控制。由于新构造活动分布在3条断裂上,所以区内以6级以下的中小地震活动为主。

关键词: 龙门山, 逆断裂带, 构造地貌, 地震活动性