影响城市隐伏活断层探查与评价的两个重要问题

实践证明, 对于有厚层第四纪沉积层覆盖的城市活断层探查, 存在二个问题。一是上断点层位作为活动性指标的局限性; 二是探测手段有效深度范围和分辨率的有限性。二个问题共同点都是使探测的上断点深度大于真实上断点深度, 结果就是漏掉活断层, 低估断层的地震危险性, 这与近年来许多地方“意外”发生破坏性地震有密切关系。须在探查与评价实践中积累经验, 深入讨论, 予以解决。

Tow important problems of influence in the survey and evaluation of the buried active fault in city

The comprehensive study based on combining geophysical prospecting with geological data indicates that there are two problems in the survey of active fault in city with the Quaternary deposit cover layer. One is the limitation of the stratigraphic position of the upper faulted point for active index. The other is the finiteness of the effective depth and resolution of exploration method. Since the upper fa ul ted point depth o f prospecting is greater than the actual depth, as a result, some active fault may fail to detect and underestimate seismic risk of fault, it is concerned with the damage earthquake occurring in some area in recent years. It is necessary to solve the above- mentioned problems in the survey of active fault in city.