Abstract: Displacements along active faults buried directly beneath major cities create devastating earthquakes that seriously threaten the safety of human lives and properties. Exploration and seismic hazard assessment of active faults in urban areas are thus an important systematic engineering for disaster mitigation in major cities. It is also a new field for active tectonic studies. The kernel of this work includes determining of the exact location of active faults, dating the ages of last tectonic activity, relating the shallow level faults to structures in the crustal depth, assessing seismic hazard and potential for surface offsets, and formulating countermeasures for disaster mitigations. We use the following simple phrases to express these key scientific problems: Where are the faults? Are they active? How deep are they? Will they create earthquake? Will they form surface offsets? What are the countermeasures? This paper explains these key scientific problems in detail.

Key words: active fault, seismic hazard assessment, urban areas

摘要： 城市范围内直下型活动断裂突发错动产生的直下型大地震,直接威胁城市和人民生命财产的安全.城市活动断裂探测和地震危险性评价是为城市减灾服务的一项系统工程,也是活动构造研究面临的一项新的工作.这一工作的核心是要解决城市范围内的断裂定位、断裂最新活动、断裂的深部背景、断裂的地震危险性和地面错动危险性及减灾对策.为了更好地理解这一问题,作者用"有没有、活不活、深不深,震不震,错不错,好对策"这6句话来表示其核心内容.文中对这些问题作了具体的说明.

关键词: 活动断裂, 地震危险性, 城市