Abstract: The authors make the width of surface rupture caused by 2008 Ms 8.0 Wenchuan earthquake as the object, characterize the width of surface rupture by the thrust fault scarps, flexure-slip folds, and mole tracks, and check out characteristics of the width of the surface rupture along the Beichuan-Yingxiu fault and Hanwang-Bailu fault. The conclusion suggests that there is difference about the width between the Beichuan-Yingxiu fault and Hanwang-Bailu fault and about the width in different section along the same Beichuan-Yingxiu fault. Both of the faults have obvious hanging wall effect. The safety distance away from the fault in the hanging wall in rebuilding is 70 m at least and 23.5 m in the foot wall, and the total safety distance along the fault in rebuilding should be more than 108 m about the Beichuan-Yingxiu fault. The safety distance away from the fault in the hanging wall in rebuilding is 35 m at least and 20 m in the foot wall, and the total distance should be more than 58 m about the Hanwang-Bailu fault. In addition, the width and hanging wall effect of co-seismic surface rupture zone is in accordance with the hight of fault scarp, intensity isoseismal map, and strong earthquake ground motions.

Key words: Wenchuan earthquake, width of surface rupture, hanging wall effect, setback distance

摘要： 以汶川地震产生的地表破裂宽度为研究对象, 以地表微变形、裂隙和鼓包、叠瓦状断层及反冲断层等为标志界定破裂的宽度, 查明中央破裂带和前山破裂带宽度的分布。结果表明, 中央断裂带与汉旺?白鹿断裂带的地表破裂宽度不同, 中央断裂带不同段落的地表破裂宽度也不相同。断层还表现出明显的断层上盘效应, 北川?映秀断裂上盘最小避让距离为70 m, 下盘最小避让距离为23.5 m, 断层两侧避让总宽度不应小于108 m; 汉旺?白鹿断裂上盘最小避让距离为35 m, 下盘最小避让距离20 m, 总避让宽度不应小于58 m。地表破裂宽度及断层上盘效应与破裂带陡坎高度、地震烈度分布、强震记录具有较好的一致性。

关键词: 汶川地震, 地表破裂宽度, 断层上盘效应, 避让距离