浅层地震勘探在沿海地区隐伏断层探测中的应用
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摘要
中国沿海地区的第四系厚度变化较大,在大部分地区存在淤泥、黏土和砂层的多重互层情况,这种地层结构对地震波的传播十分不利,容易造成对高频信号能量的强烈耗散。沿海地区又具有人口密度大、工业干扰强烈的特点,地震波的激发、接收条件较差。文中给出了在粤东、天津和唐山覆盖层厚度变化较大的地区,利用浅层地震勘探开展隐伏断层探测的应用实例。较系统地介绍了野外工作、资料处理和解释方法。阐述了在强干扰环境下提高信噪比和分辨率的有效技术途径。所给实例中的反射波组能量强,隐伏断层的反应明显,经跨断点钻探验证,结果证实地震勘探确定的界面深度、断点位置和基岩错距等参数都是可靠的。所述技术方法对类似地区的城市活断层探测和工程物探工作都有较重要的参考价值。
The depth of Quaternary in China coastal zone varies greatly.In most areas,silt,clay and sand are always multiply interbedded.This kind of formation can attenuate greatly the high frequency signal,and is unfavorable to propagation of seismic wave.At the same time,the density of population in the area is much higher and the industrial noise is strong,so the trigger and receiver conditions are not ideal.The paper presents some application examples of detecting buried faults with near-surface seismic methods in east Guangdong,Tianjin and Tangshan where the thickness of overburden varies greatly,and systemically introduces the methods of fieldworks,data processing and explanation approaches.It also illustrates the effective methods of how to improve SNR and resolution in environment with strong noise.In the application,the signal of refection is strong and the buried faults can be reflected evidently.Proofs of drilling at both sides of the faults approve that the depth of interface,location of fault point and throw of basement determined by seismic exploration are all reliable.The techniques and methods mentioned in this paper are of important reference value in urban active fault detection and engineering geophysical prospecting in similar areas.
The depth of Quaternary in China coastal zone varies greatly.In most areas,silt,clay and sand are always multiply interbedded.This kind of formation can attenuate greatly the high frequency signal,and is unfavorable to propagation of seismic wave.At the same time,the density of population in the area is much higher and the industrial noise is strong,so the trigger and receiver conditions are not ideal.The paper presents some application examples of detecting buried faults with near-surface seismic methods in east Guangdong,Tianjin and Tangshan where the thickness of overburden varies greatly,and systemically introduces the methods of fieldworks,data processing and explanation approaches.It also illustrates the effective methods of how to improve SNR and resolution in environment with strong noise.In the application,the signal of refection is strong and the buried faults can be reflected evidently.Proofs of drilling at both sides of the faults approve that the depth of interface,location of fault point and throw of basement determined by seismic exploration are all reliable.The techniques and methods mentioned in this paper are of important reference value in urban active fault detection and engineering geophysical prospecting in similar areas.
引文
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何正勤,叶太兰,丁志峰,等.2001.城市活断层探测中的浅层地震勘探方法[J].国际地震动态,265:1—6.HE Zheng-qin,YE Tai-lan,DING Zhi-feng,et al.2001.The method of shallowseismic exploration for surveying of ur-ban active faults[J].Recent Developments in World Seismology,265:1—6(in Chinese).
王振东.1988.浅层地震勘探[M].北京:地质出版社.120—132.WANG Zhen-dong.1988.Shallow Seismic Exploration[M].Geological Press,Beijing.120—132(in Chinese).
姚姚.2006.地震波场与地震勘探[M].北京:地质出版社.75—189.YAO Yao.2006.Seismic Field and Seismic Exploration[M].Geological Press,Beijin
俞寿朋.1993.高分辨率地震勘探[M].北京:石油工业出版社.20—33.YU Shou-peng.1993.High-resolution Seismic Exploration[M].Petroleum Industry Press,Beijing.20—33(in Chi-nese).
中国地震局.2005.中华人民共和国地震行业标准:活动断层探测方法(DB/T152005)[S].北京:地震出版社.11.China Earthquake Administration.2005.The People s Republic of China Trade Standard for Seismology:Method forSurveying and Prospecting of Active Fault(DB/T152005)[S].Seismological Press,Beijing.11(in Chinese).
Robert B H,Cyntyia L P and Jeffrey E C.2000.Shallowseismic reflection profiling over Brevard Zone South Caroline[J].Geophysics,65(5):1388—1401.
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