Abstract: A large number of observed data about the widths of earthquake surface ruptures produced on diverse types of active faults, as well as the widths of intense deformation zones in trench logs across active faults are presented in this paper. Combining these data with the close relation between the damage zone of surface construction and the spatial position of active fault, the authors propose that a minimum distance(safety distance)of 30m away from active fault is essentially required for constructions to prevent the effect of faulting. The more accurate safety distance required for various types of active faults can be tested and modified through the analysis of the deformation features of strata in trench logs across the fault. The required safety distance in some specific sites, such as the step-overs of active faults, as well as the area defined by sub-parallel secondary faults on both sides, should be the sum of the width of the area and 15m from area boundaries. It is suggested that this "safety distance" should be taken as a legal regulation for constructions and buildings. In addition, further attention should be paid to the identification of active fault and precise determination of the geometric structures of the surface fault strand, so that earthquake hazards can be positively and effectively reduced.

Key words: active fault, earthquake surface rupture zone, safety distance

摘要： 基于不同类型活断层产生的地震地表破裂带宽度和跨断层探槽地质剖面的地层强变形带宽度等观测事实,结合地面建筑设施毁坏带与活断层密切的空间位置关系,采用统计分析方法,确定了活断层"避让带"宽度为30m.各活断层更为准确的避让带宽度可通过分析跨断层探槽地质剖面上地层的变形特征加以验证或修订;活断层斜列阶区、平行次级断层围限区、走向弯曲区等特殊地域的避让带宽度为这些地域宽度与两外侧各15m之和.建议有关部门进行活断层"避让带"立法与执法管理,并加强活断层鉴定及其地表活动线几何结构形态的准确定位工作,积极而有效地减轻地震灾害.

关键词: 活断层, 地震地表破裂带, 避让带宽度