浅层人工地震P波和S波资料揭示的郑州老鸦陈断层特征

断层活动性的探测研究是城市防震减灾的基础性工作。为了查明郑州老鸦陈断层的位置、性质及其活动性,2006年底跨老鸦陈断层进行了高分辨率的浅层地震P波和S波探测,通过采用不同的地震波激发源、不同的观测系统参数相结合的工作方法,获得了沿剖面不同深度的地下细结构图像,揭示了老鸦陈断层的形态和特征。结果表明,老鸦陈断层为一条倾向NE、走向NW的正断层,该断层错断了新近系(N)以前的地层,在Q+N地层内部没有发现断层引起的地层错断现象     

浅层人工地震的断层识别

在工程地质问题中,用浅层地震折射法识别断层,是地震勘探为工程地质服务的主要项目之一.本文讨论了通过正确设计观测系统,合理控制炸药量,正确掌握地震折射资料的解释方法,是正确识别断层的有效途径.     

浅层地震勘探在沿海地区隐伏断层探测中的应用

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     

昌都城区浅层地震勘探分析

为了查明昌都市城区第四系覆盖区厚度、隐伏断裂带的位置和隐伏断裂带的上断点埋深及断裂带活动性,在昌都市城区布设4条浅层反射波法地震勘探测线,总勘探长度3 km。CX-1线位于国道317,探测出两条断层,F11和F12;CX-2线位于昌都中路,探测出三条断层,F21、F22和F23;CX-3线位于马草坝路,探测出四条断层F31、F32、F33和F34;CX-4线位于昌都西路,探测出五条断层F41、F42、F43、F44和F45均为,以上14条断层都为非活动性断裂,每条断裂均位于基岩内部,没有错断第四系覆盖层,均为前第四纪断层。下一步将通过后期收集到的深部钻孔资料、断层排钻勘探资料以及地表地震地质调查资料对解释结果进行补充完善。     

浅层地震勘探方法在活动断层中的应用——以邯郸市活动断层探测为例

浅层地震勘探方法在城市活动断层探测中发挥着重要作用,实践表明,浅层地震反射波法可以获取深度十米至几十米的浅层地层反射信号,且大部分反射剖面均可较清楚地揭示出浅部断层位置和断层特征,地震数据处理是准确识别近地表活动断层的重要环节,也是提高资料分辨率和信噪比的有效途径。本文应用邯郸市活动断层浅层地震资料,运用多途径、分步骤的去噪技术和方法,压制干扰,极大地提高了资料的分辨率和信噪比,并对活动断层的典型剖面进行重点研究和验证。     

地震勘探资料揭示郑州老鸦陈断层特征

断层活动性的探测研究是城市地震预测和防震减灾的基础性工作。为了查明郑州老鸦陈断层的位置、性质及其活动性,2006年底,在郑州市北郊横跨老鸦陈断层进行了不同探测深度的浅层地震勘探,通过采用爆破震源和可控震源相结合、不同观测系统参数相结合的工作方法,获得了探测深度30—6000m范围内的地下结构与构造图像。结果表明,老鸦陈断层为一条倾向NE、走向NW的正断层,该断层错断了新第三纪(N)以前的地层,在Q N地层内部没有发现断层引起的地层错断现象。     

城市活动断层探测中的浅层地震勘探数据库建设——以石嘴山市活动断层探测为例

浅层人工地震勘探是城市活断层探测工程中的重要部分。浅层地震勘探数据库记录测点位置、测线分布图、断点位置等详细信息。本文以宁夏石嘴山市活动断层探测为例,重点介绍了针对石嘴山市内四条隐伏断裂所布设的33条浅层地震勘探测线数据库建设的数据库模型、技术方法、操作技巧及注意事项,为城市活断层探测中基于 ArcGIS等平台系统建立浅层地震勘探数据库提供借鉴。     

城市活断层探测中的浅层地震勘探方法

对大量地震灾害的研究表明，地震发生时，位于地表活动断层上的房屋或构筑物的破坏最严重，尤其是20世纪90年代后期美国北岭地震，日本阪神地震和中国台湾集集大地震等的发生后，世界许多国家的政府和地震科学家都清楚地认识到城市活断层探测与研究的重要性和急迫性，城市活断层的探测对于城市规划，抗震设防，减轻地震对城市设施的破坏都具有重要的现实意义，浅层高分辨地震勘探是城市活断层探测手段中最有效，最可靠的方法之一，可以在地表探测到地下活断层的位置，埋深，产状和空间展布情况，但由于城市环境的强干扰背景和场地条件的复杂性，必须针对实际情况，在观测系统，震源，数据采集环境的强干扰背景和场地条件的复杂性，必须针对实际 情况，在观测系统，震源，数据采集和处理方法等环节中，采用一系列提高分辨率， 提高信噪比的有效方法，才能取得可靠的探测成果，本文对城市活断层探测中的浅层地震勘探方法的技术难点和相应的解决方法进行了讨论，并结合我们近几年来在城市开展浅层地震勘探的一些经验，介绍一些实用性的浅层地震勘探工作方法。     

老鸦陈断层和地震勘探

本文扼要介绍了围绕老鸦陈断层开展的几次地震勘探工作，认为由此得出“老鸦陈断层是第四纪活动断层”的结论值得商榷。     

STUDY ON TANGSHAN-HEJIAN-CIXIAN EARTHQUAKE FAULT ZONE BY SHALLOW SEISMIC EXPLORATION METHOD

The location of the buried faults, the fault broken layers and the depth of breakpoints in the Tangshan-Hejian-Cixian seismotectonic zone are not clear. We implemented 4 shallow seismic exploration profiles on the Daming Fault, Cangxi Fault, and Dachengdong Fault. Line DZ1 is located on the Daming Fault in the southeast of Daming County. Five breakpoints were dectectd, which are all normal faults, with depths of 95~125m and displacements about 6~12m, offsetting late Pleistocene but not the Holocene. Line DZ2 is located in the east of Xianxian County to dectect the Cangxi Fault. Three breakpoints were detected, all are normal faults, with depths of 170~190m and displacements about 7~10m. The upper breakpoints of the three faults cut the middle Pleistocene. The lines DZ3 and DZ4 are located in the west of Litan Town, Dacheng County. Four breakpoints were detected, with the upper breakpoint depth of 120~130m and displacements about 5~15m. They are all normal faults, and the upper breakpoints of the faults cut the Pleistocene strata.
The result of the exploration of Cixian-Daming Fault is not consistent with the buried depth 1 200m proposed by XU Hua-ming. It is proved that the activity of the fault is also consistent with the overall activity of the Cixian-Daming Fault, which is an active fault since late Pleistocene.
The Dachengdong Fault and Cangxi Fault offset the middle Pleistocene strata. Although the late Pleistocene active faults are generally defined as active faults in the practice of active tectonics research in China, strong earthquakes in eastern China have shorter recurrence period, and earthquakes of magnitude 6 or so may also occur in some middle Pleistocene active faults.
During the compilation of GB18306-2015 “Seismic ground motion parameter zonation map of China”, there were no late Pleistocene active faults in the M6~6.5 potential source areas in eastern China. Therefore, we believe that the Dachengdong and Cangxi faults still have the ability to generate earthquake of magnitude 6 or so, and the faults have some similarities with the seismogenic structures of Xingtai earthquake swarm. Under the action of the latest tectonic stress field, the “deep faults” tearing ruptured successively and expanded upwards, resulting in stress migration and loading between two neighbouring en-echolon concealed faults, so, the Dachengdong and Cangxi faults are the product of this three-dimensional rupture process. The Dachengdong Fault is a “newly-generated” fault resulting from the tearing rupturing and upward expanding of the pre-existing concealed “deept faults” in the middle and lower curst.     

NEW EVIDENCES OF THE HOLOCENE FAULT IN SUQIAN SEGMENT OF THE TANLU FAULT ZONE DISCOVERED BY SHALLOW SEISMIC EXPLORATION METHOD

The fault F₅ is considered as the most active fault in the Tanlu fault zone(Yi-Shu fault zone), which is located from Weifang of Shandong Province to Jiashan of Anhui Province, with a length of 360km. It has always been a focus of concern to many geoscientists because of its complexity and importance. But, for a long period of time, there exists biggish indetermination in the accurate position and active ages of the fault F₅ in Suqian section of Tanlu fault zone. Seismic reflection exploration is the main technique in present urban active faults detecting. In order to investigate the spatial distribution, characteristics and activities of the fault F₅ in covered terrains, we carried out a systematic survey to the fault with shallow seismic prospecting method and obtained the accurate position and development characteristics of the fault. The results show that the fault F₅ continues to develop toward south rather than ending at the Huancheng South Road of Suqian City. F₅ is mainly composed of two main faults, which dip in opposite directions and almost vertically. Near the Sankeshu town, F₅ is composed of three faults with right-stepping, forming a small pull-apart basin with length of 6km, width of 2.5km, controlling the deposition of Neogene and Quaternary strata. By combining the results of composite drilling section and trenching, we make a conclusion that the western branch of fault F₅ is a Holocene active fault, and the eastern branch is a Pleistocene active fault. Our general view is that fault F₅ is a Holocene active fault.     

拉萨市附近刘吾大佛寺间断裂的浅层地震勘探

简要介绍了在青藏高原拉萨市附近刘吾 -大佛寺间断裂的浅层地震勘探工作 ,并进行了初步的地质解释。结果表明 ,刘吾 -大佛寺间断裂所在区域的速度模型为 5层结构。第 1层至第 4层的介质深度从 0m变化到 2 6 0m ,P波速度 80 0～ 2 0 0 0或 2 80 0m/s,介质为第四纪或第三纪覆盖层 ;第 5层的介质P波速度在 30 0 0～ 4 0 0 0m/s以上 ,其CDP图像分布零散、没有形成较强的反射界面 ,推测该区域为花岗岩类的基岩区。根据反射波组的连贯性、间断性及位置 ,判定在浅层地震勘探剖面 32 0m处存在着刘吾 -大佛寺间断裂 ,它是 1条逆断层 ,倾向NE ,倾角 80°左右 ,其上端点出现在深约 10 0m处     

北京市立水桥附近黄庄-高丽营隐伏断裂的浅层地震勘探

利用高精度的浅层地震勘探手段,探测出北京市立水桥附近的黄庄-高丽营隐伏断裂,并进行了地质解释。结果表明北京市立水桥附近区域的浅部速度模型为4层结构。第1层至第2层的介质深度从0～150m,P波速度从800～2000m/s,介质为第四纪或古-新近纪覆盖层;第3层至第4层的介质深度为130～300m,P波速度在2000～2500m/s以上,推测为泥岩、砂岩类的基岩区。黄庄-高丽营隐伏活断裂其浅部由东西2条近似平行、相距1300m、走向N23°E、倾向SE的断裂所组成,西断裂F2倾角22°,东断裂F1倾角67°,在634m深度归结成单条断层,构成分叉状结构;断层上盘埋深101m,下盘埋深109m,断距为8m,为断错T2,T3地层界面、带走滑分量的正断层型     

NEW EVIDENCE ON NE-SEGMENT OF JINTAN-RUGAO FAULT DISCOVERED BY SHALLOW SEISMIC EXPLORATION METHOD

The NE-trending regional deep fault, i.e. the Jintan-Rugao Fault, is a boundary fault between the Subei depression and Nantong uplift, and its research has always received broad attention because of its importance and complexity. For the absence of definite proof, there is little consensus regarding the structure and spatial distribution of the fault among geoscientists, and its latest active time is ambiguous. The study of Quaternary activity characteristics of the Jintan-Rugao Fault is of great significance for earthquake trend prediction and engineering safety evaluation, and for earthquake prevention and disaster reduction in Jiangsu Province. In order to investigate the spatial location, characteristics and tectonic features and redefine the activity of the NE-segment of the Jintan-Rugao Fault, and on the basis of likely location and marker beds derived from petroleum seismic exploration sections, we collect and arrange 4 shallow seismic exploration profiles crossing the fault to conduct high-resolution seismic reflection imaging, following the working concept of ‘from known to unknown, from deep to shallow’. In this study, an observation system with trace intervals of 4~6m, shot intervals of 12~18m, and channels of 90~256 and 15~36 folds is used. In addition, by introducing different tonnage vibroseis to suppress the background noise, the raw data with high SNR(signal-noise ratio)can be obtained. By using the above working method and spread geometry, we obtained clear imaging results of the subsurface structure and fault structure in the coverage area of the survey lines. This exploration research accurately locates the NE-segment of Jintan-Rugao Fault, and further shows that it is not a single fault but a fault zone consisting of two normal faults with N-dipping and NE-striking within the effective detection depth. The shallow seismic profiles reveal that the up-breakpoint on the south branch with stronger activity is at depth of 235~243m, which offsets the lower strata of lower Pleistocene. Combining drilling data around the survey lines, we infer the activity time of this fault is early Pleistocene. The results of this paper provide reliable seismological data for determining the location and activity evaluation of the NE-segment of Jintan-Rugao Fault. In eastern China, where the sedimentary layer is thicker, the latest active age of faults can not be determined entirely according to the latest faulted strata. For a fault passing through the thicker area of new deposits, its latest active age should be based on the tectonic background, seismic activity, present tectonic stress field, topographic deformation, structural micro-geomorphological characteristics, sedimentary thickness of new strata, controlling effect of faults on new strata and the latest strata of faults, and combined with upper breakpoints, morphology, structure and occurrence of faults, the active state of the target concealed faults should be analyzed. If the activity of the fault is judged only by the upper faulted point, it may lead to overestimating the age of the fault activity.     

济南市区内千佛山断裂的地表探测研究

本文论述了影响城市工程物探探测效果的主要因素,并根据实际工作条件,为最大程度提高采集精度,采用浅层地震勘探和地震映像两种方法探测了千佛山断裂在济南市区内同一地点的隐伏位置及产状。并且在断层两盘布置钻孔,验证探测结果的可靠性。综合分析认为,物探结果表现了较高的信噪比和分辨率,充分说明这两种方法在城市工程物探中有较好的适用性。     

浅地层剖面仪在水域工程勘察中的应用

扼要介绍了水上浅地层剖面仪的方法技术，列举了该法在浅海，内河和湖泊减种典型环境及相应的地质条件下勘测所得到的剖面记录及地质解释结果，指出了运用该方法所能解决的工程地质问题。     

浅层地震勘探资料处理中的速度分析参数选取

浅层人工地震勘探是当前城市地震活断层探测的主要方法,勘探精度不仅受激发、接收等因素的影响,还与地震数据处理的精度密切相关。速度分析是地震勘探资料处理中的关键环节,它的准确与否对动校正、共深度点叠加、叠后偏移及时深转换等都将产生影响。针对浅层地震资料目的层较浅、叠加次数少和城市背景干扰大等特点,文中对速度分析的参数选取问题进行了研究。首先通过对相邻CDP道集内各接收道炮检距的分析,以及单个和多个CDP道集的对比,提出了用于速度分析的CDP大道集的抽取原则。并通过对不同的CDP大道集、速度扫描间隔、计算时窗长度、动校切除比例等所获得的速度谱的对比分析,对速度谱扫描过程中各参数的选取提出了建议,并对速度分析及时深转换过程中值得注意的问题进行了讨论