高分辨折射和浅层反射地震方法在活断层探测中的联合应用
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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.
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.
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.
引文
邓起东,徐锡伟,张先康,王广才.2003.城市活动断裂探测的方法和技术[J].地学前缘,10(1):93-103.
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徐朝繁,张先康,张建狮,胡修奇.2006b.射线数分布分析法及其在地壳上部复杂结构探测中的应用[J].地震学报,28(2):167-175.
徐明才,高景华,荣立新,柴明涛,吕庆田,史大年.2005.地面地震层析成像和高分辨地震联合勘探技术[J].地质与勘探,41(4):83-87.
杨卓欣,袁道阳,段永红,徐朝繁,嘉世旭,酆少英.2009.高分辨折射勘探技术在浅层反射勘探失效地区的应用:兰州市活断层浅层勘探实例[J].地震地质,31(1):57-68.
Zhang J,Toks z M N.1998.Nonlinear refraction travelti me tomography[J].Geophys,63(5):1726-1737.
邓起东,卢造勋,杨主恩.2007.城市活断层探测和断层活动性评价问题[J].地震地质,29(2):189-199.
侯贺晟,高锐,卢占武,贺日正,李秋生,管烨,李朋武,熊小松.2009.青藏高原羌塘盆地中央隆起近地表速度结构的初至波层析成像试验[J].地质通报,28(6):738-745.
吴怡,嘉世旭,段永红,徐朝繁,杨卓欣.2006.地震折射波法在郑州市西区浅层勘探中的应用[J].地震地质,28(1):84-92.
徐朝繁,张先康,刘保金,酆少英,胡修奇.2005.高分辨折射地震资料处理及应用[J].地球物理学进展,20(4):1052-1058.
徐朝繁,张先康,段永红,杨卓欣,酆少英,胡修奇.2006a.新疆伽师强震群区上部地壳细结构的高分辨折射地震探测研究[J].地震学报,28(1):60-69.
徐朝繁,张先康,张建狮,胡修奇.2006b.射线数分布分析法及其在地壳上部复杂结构探测中的应用[J].地震学报,28(2):167-175.
徐明才,高景华,荣立新,柴明涛,吕庆田,史大年.2005.地面地震层析成像和高分辨地震联合勘探技术[J].地质与勘探,41(4):83-87.
杨卓欣,袁道阳,段永红,徐朝繁,嘉世旭,酆少英.2009.高分辨折射勘探技术在浅层反射勘探失效地区的应用:兰州市活断层浅层勘探实例[J].地震地质,31(1):57-68.
Zhang J,Toks z M N.1998.Nonlinear refraction travelti me tomography[J].Geophys,63(5):1726-1737.
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