【摘要】 浅层反射地震方法是城市活断层探测常用的技术,但在基岩埋深比较浅的地区,往往只能识别出基岩顶面的反射波,而仅根据反射地震剖面上单个同相轴的变化很难准确判定断层是否存在.浅层地层的错断往往会引起速度的横向变化,利用高分辨折射地震方法采集的数据,应用层析成像方法获得的速度剖面,能够反映地下速度结构的变化,可以从另一方面揭示浅层断层存在的可能性.在四川某地,将这两种方法同时应用于活断层浅层地震勘探中.结果表明,两种方法联合应用可在一定程度上弥补浅层反射地震勘探方法在基岩埋深较浅地区的不足.更多还原

【Abstract】 Shallow reflection seismic exploration is a commonly used technique in urban active fault survey. Usually,however,we can not identify the presence of faults solely based on the offset of co-phase axis on seismic reflection profiles,because the effective reflection layers are few and only the reflection from the shallow top bedrock can be recognized. The stagger in shallow strata may cause lateral velocity variation. On the other hand,the tomographically imaged velocity profiles deduced from the high-resolution seismic refraction profile data can reflect the change of crustal velocity structure and indicate the existence of a fault. In a region in Sichuan,the two approaches were applied to shallow seismic exploration for active fault survey along the same profile. The experimental results indicate that the joint application of the two methods can,to some extent,remedy the defect of the shallow reflection seismic exploration performed in the region with shallowly buried bedrock.更多还原