活动断裂探测的高分辨率地震数据采集技术

高分辨率浅层地震勘探技术能够较准确地探测活动断层的位置、性质,并初步研究断裂的活动性。作者在夏垫断裂上采用不同激发震源、不同道间距、不同观测系统参数的探测方法,获得了多条高质量叠加时间剖面图,图中清晰地显示了从几米到几百米深度范围内的地层结构和构造特征。通过对这些叠加时间剖面的分析,获得了不同激发震源、不同道间距、不同观测系统参数时间剖面的分辨率。给出了对于不同的探测目标层埋深和精度要求所适用的探测方法和工作参数,为提高断层探测的分辨率和活动断层最新活动时代的确定精度奠定了良好的基础。     

夏垫断裂浅部特征高分辨反射地震探测研究

在夏垫断裂上采用浅层纵、横波相结合的联合探测方法,获得了多条反映不同深度的高质量叠加时间剖面图,这些图像清晰地显示了夏垫断裂的浅部构造特征和地表以下浅至几米的地层结构和断裂特征信息,使得采用人工地震方法探测地表下10m以内的断裂成为可能。本次探测工作中,还在夏垫断裂的南侧发现了1条倾角较缓、呈铲型向下延伸的断裂,表明夏垫断裂是由2条断裂组成的断裂带。     

The Best Combination Methods and Applied Research of Seismic Prospecting for Active Faults in Urban Areas

This paper introduces briefly the basic principles of various seismic prospecting techniques and working methods according to nationwide practices of seismic prospecting of active faults beneath big cities in recent years.Furthermore,it analyzes the application range of different seismic prospecting methods,main achievements and solved problems,and discusses the best combination of seismic exploration methods for detecting crustal structures and locating the faults used in the present stage,that is,to trace faults which are at depths of hundred of meters underground using shallow seismic investigation,to detect the faults which are above basement(at a depth of kilometers) using high resolution refraction sounding,and the deep crustal faults using combined seismic prospecting methods of reflection seismic sounding and wide-angle reflection/refraction sounding,and furthermore,to use the 3-D deep seismic sounding method to obtain 3-D velocity structures beneath urban areas.Thus,we can get information about fault attitude and distribution at different depths and a complete image of faults from their shallow part to deep part using the combined seismic exploration method.Some application examples are presented in the article.     

The characteristics of Quaternary activity of faults in the sea area near the Yangtze River mouth

Introduction As far as the frequency and magnitude are concerned, the earthquakes in the sea area to the east of Shanghai are far more strong than in land area with the largest one in the sea area near the Yangtze River mouth being MS=436, while in land, only MS=434 occurred on Sept. 1, 1624. As a moderately strong earthquake active area, the sea area near the Yangtze River mouth, may cause a potential risk to Shanghai. In 1971 and 1996, earthquakes with MS=5~6 occurred in this area. Geo…     

Geological Observations of Damage Asymmetry in the Structure of the San Jacinto, San Andreas and Punchbowl Faults in Southern California: A Possible Indicator for Preferred Rupture Propagation Direction

We present new in situ observations of systematic asymmetry in the pattern of damage expressed by fault zone rocks along sections of the San Andreas, San Jacinto, and Punchbowl faults in southern California. The observed structural asymmetry has consistent manifestations at a fault core scale of millimeters to meters, a fault zone scale of meters to tens of meters and related geomorphologic features. The observed asymmetric signals are in agreement with other geological and geophysical observations of structural asymmetry in a damage zone scale of tens to hundreds of meters. In all of those scales, more damage is found on the side of the fault with faster seismic velocities at seismogenic depths. The observed correlation between the damage asymmetry and local seismic velocity structure is compatible with theoretical predictions associated with preferred propagation direction of earthquake ruptures along faults that separate different crustal blocks. The data are consistent with a preferred northwestward propagation direction for ruptures on all three faults. If our results are supported by additional observations, asymmetry of structural properties determined in field studies can be utilized to infer preferred propagation direction of large earthquake ruptures along a given fault section. The property of a preferred rupture direction can explain anomalous behavior of historic rupture events, and may have profound implications for many aspects of earthquake physics on large faults.     

宁波育王山山前断层几何结构及新活动时代

根据1：10000条带状地质填图所获资料,分析了育王山山前断层的几何结构和新活动时代。断层北起岙张水库大坝东北,向南经河头蕉-竺家-陈家-钱家-俞家-王家一线以西,止于詹家西南,由2条次级段呈羽列式展布,北段为岙张水库-红岩水库段,南段为红岩水库东南-詹家段。剖面上断层地貌显示清楚,西侧为侏罗系构成的育王山低山,东侧为大楔盆地。各条断层皆由多个断面构成宽几米-几十米的断层带。根据探槽、天然剖面特征和OSL、ESR样品年龄测试结果综合分析,断层至少有两期活动,早期活动性质为逆断层,时间为早更新世,晚期活动性质为右旋走滑兼正断或逆断层,时间为中更新世,最新活动时代为中更新世晚期。通过探槽揭露,确定育王山山前洪积扇陡坎是人类活动造成,而非断层陡坎。     

新疆乌什地震带断裂研究的综合地球物理方法

本文介绍了重力、磁力、大地电磁测深、地震等地球物理资料与地震相关的活动断裂的识别标志,并以新疆乌什地震带为例分析了综合各种物探资料研究活动断裂的方法。结果显示根据不同的研究目的选择合适的针对性方法可以较好的获得断裂的展布、深部或者活动性等特征。     

东辛油田地震勘探历程——一个复杂断块构造的三维地震解释实例

东辛油田是一个典型的断块复杂构造。在这个油田上,地震精查的方法在搞清断裂系统方面,取得了较好的成效。本文简述了在该油田早期所采用的一套三维地震解释（立体归位）方法,其中有些方法对当前搞三维地震勘探,及断层面的地质解释方面都还有着参考价值。近年来,又用数字地震方法,在此浅层的复杂构造的下面,发现了比较简单的深层构造,在几张附图中展示了深浅层构造之间的关系。     

交城断裂交城县城段的位置及其与地裂缝的关系

交城断裂为太原盆地西界的主控边界断裂,为查明交城断裂在这一地区的确切位置和地裂缝与交城断裂的关系,采用地震地质调查和人工地震勘探对在此范围内交城断裂的具体位置和地层错断情况进行了详细研究。结果表明,交城断裂交城县城段并不是位于基岩隆起区与盆地倾斜平原的分界处,而是位于距该分界东南约200 m处。交城县城西北侧的地裂缝与地震勘探在这一带所探查到的交城断裂的位置相当吻合,由此可以推断地裂缝的产生与交城断裂有关,属构造地裂缝。指出,在进行活动断裂附近的城市规划或重大工程建设时应对“山根”的倒退现象予以高度重视。     

应用三分量浅层地震反射方法探测隐伏活动断裂

多波多分量地震勘探方法在油气田勘探开发中日益受到重视,但在工程和活动断裂探测中过去还没有开展多波多分量地震勘探的先例.本文简要介绍了在北京黄庄—高丽营断裂上开展的三分量浅层地震反射试验数据采集和资料处理方法,以及取得的初步结果.试验结果表明,采用纵波震源或横波震源激发、三分量接收的浅层地震勘探方法,可获得较高信噪比的浅层地震纵波、横波和转换波剖面,特别是水平分量采集的横波和转换波可提供很有意义的地下结构和构造信息.综合利用纵波、横波和转换波剖面特征进行的地质分层和断层解释结果取得了与跨断层的钻孔联合地质剖面结果较好的一致性.     

PRIMARILY STUDY ON FEATURES OF SURFACE RUPTURES INDUCED BY THE 2016 MW7.8 KARKOURA EARTHQUAKE,NEW ZEALAND

The surface ruptures produced by the 2016 M_W7.8 Karkoura earthquake, New Zealand are distributed in a belt with~170km long and~35km wide, trending generally in the NE-SW direction. There are at least 12 faults on which meter-scale displacements are identified and they were formed across two distinct seismotectonic provinces with fundamental different characteristics(Hamling et al., 2017; Litchfield et al., 2017). Although the trending directions of the seismic surface ruptures vary greatly at different locations, the ruptured faults can be generally divided into two groups with the NE to NEE direction and the NNW to N direction, respectively. The faults in the NNW-near NS direction are nearly parallel with 40~50km apart and featured by reverse movement with the maximum displacement of 5~6m. The faults in the NE-NNE direction, with the maximum of 25~30km apart are not continuous and featured by the dextral strike slip with the largest displacement of 10~12m. Even if some faults along the NE-NEE direction are end to end connected, their strikes differ by about 30°. The combination styles of the strike-slip fault surface ruptures along the NE-NEE direction can be merged into 3 categories, including en-echelon, bifurcation and parallel patterns. The scales of the fault surface ruptures with the same structural style could be obviously different in different areas, which results in significant changes in the widths of deformation zone, from tens of meters to hundreds of meters. En-echelon distributed surface rupture(section)can appear as a combination belt of meter-scale to dozens of meter-scale shear fracture with bulge and compressional shear fractures, and also can be characterized by the combination of the left-step en-echelon tensile shear fractures with a length of more than one hundred meters. The step-overs between surface rupture sections are clearly different in sizes, which can be dozens of meters, hundreds of meters to several kilometers. The spacing between parallel surface ruptures can be several meters, dozens of meters to several kilometers. Besides, as one of the prominent characteristics, the seismic surface ruptures caused by the Karkoura earthquake broke through the known distribution pattern of active faults. The surface ruptures can occur either on the previously thought inactive or unmapped faults, or break through the distribution range of previously realized active faults in the striking or lateral direction. The basic features about the distribution and widths of the surface ruptures induced by the 2016 M_W7.8 Karkoura earthquake, New Zealand presented in this paper might be helpful for understanding some seismic problems such as complex corresponding relationship between the active faults and the deep seismogenic structure, and the necessary measurements for engineering crossing active faults.     

陕南汉中盆地西部梁山南缘断裂隐伏段的活动性鉴定

汉中盆地是青藏高原、 秦岭与大巴山—龙门山差异隆升区中间的新生代断陷盆地, 是重要的地质体连结点. 通过新近开展的汉中市活断层探测工作中的地面地质调查、 浅层地震勘探与钻孔联合地质剖面分析等工作认为, 汉中盆地内部存在一条活动断裂, 即梁山南缘断裂. 浅层地震勘探资料显示, 梁山南缘断裂错断多套第四纪以来的地层, 错距自下而上逐渐减小. 钻孔联合地质剖面显示, 梁山南缘断裂错断晚更新世中晚期以来的砾砂及卵石层, 距今58 ka的砾砂层错距约为6 m. 这些现象首次揭示了汉中盆地内部梁山南缘断裂的最新活动时代和活动性质.      

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。     

煤矿井巷间地质构造及其异常多波联合探测技术与应用

影响煤矿层安全高效开采的最主要的地质因素是断层构造及其异常,特别是落差在3~5m的中小断层构造对生产影响最大.为了保证开采工作的顺利进行,通常需在工作面回采前对面内地质条件进行探测与评价.利用地震波CT多波联合探测反演与解释,可精确确定工作面内的地质构造及异常范围.其弯曲射线追踪SIRT法反演可获得收敛性好的探测区域波速结果,以纵波波速结果为主,高速区代表断层构造迹线,低速区代表煤层增厚,同时结合其它参量成图,可有效识别各种地质构造及其特征.3241工作面的探测与回采实例有效地说明了,多波联合探测技术可为面内生产解决大量的实际地质问题.     

地震折射和反射方法研究郯庐断裂带宿迁段的浅部构造特征

郯庐断裂带是中国东部最大的一个活动构造带,其内部结构非常复杂,不同区段表现出不同特征的构造样式.本文采用浅层地震反射波成像技术对郯庐断裂带宿迁段的近地表结构进行了高分辨率成像,利用该区已有的深地震反射剖面数据,采用初至波层析成像方法获得了郯庐断裂带的浅层P波速度结构.结果表明,郯庐断裂带宿迁段是一个由多条断裂以及凹陷和隆起构成的复杂构造带,且新生代地层厚度和地震波速分布明显受到断裂的影响与控制.郯庐断裂带的东、西两侧为基底隆起区,近地表速度结构呈现为明显的高速特征,新生代地层厚度小于200m.郯庐断裂带总体显示为低速凹陷结构,新生代地层厚度在300～600m之间变化,最厚处位于宿迁市的陵城镇附近.郯庐断裂带宿迁段主要由5条断裂构成,从这些断裂的上断点埋深和第四纪活动特征来看,郯庐断裂带的东边界断裂F_1和西边界断裂F_4的活动性相对较弱,为第四纪早期活动断裂.断裂F_2和F_3控制了郯庐断裂带内部的新生代凹陷,两者的活动时代分别为中更新世和晚更新世.安丘—莒县断裂F_5位于断裂F_1和F_2之间,由2条相向而倾的分支断层F_5和F_(5-1)构成,其活动时代分别为全新世和晚更新世.研究结果为进一步认识郯庐断裂带宿迁段的近地表特征及其活动性提供了新证据.     

Characteristics of the Zhengzhou Laoyachen Fault Revealed by Seismic Exploration Data

Exploration and research of fault activities are the fundamentals of earthquake prediction and prevention and disaster reduction. In order to determine the location, characteristics and activities of the Zhengzhou-Laoyachen fault, shallow seismic prospecting with different exploration depth across the Laoyachen fault was carried out in the northern suburbs of Zhengzhou city in 2006. The images of the subterranean structure and tectonics at depths of 30m～6000m have been available by applying the combined methods of explosive seismic sources and vibrator seismic sources, as well as the combination of diverse observation systems with different parameters. The outcome indicates that the Laoyachen fault is a normal fault running NW and dipping NE, which offsets stratums ahead of Neogene (N). However, no fault displacements are found in the interior stratums of Q+N.     

地震正演模拟在高分辨率隐伏断层地震勘探中的应用

应用波动方程有限差分方法人工合成地震记录进行城市隐伏断层的地震勘探.采用适当的差分算法、震源子波以及有效地边界条件和频散消除方法来提高正演模拟的精度和分辨率.结果表明地震数值模拟可以用来分析地层厚度、断层倾角、断层深度以及断裂带宽度等参数对地震记录的影响;通过实际试验数据和正演模拟的合成单炮地震记录的对比,可以快速判断断层的大致位置和断裂带的大致范围以及目标地层的大致深度.该方法能有效辅助实际野外工作中的数据采集参数的估计,提高勘探效率和精度.     

黎城盆地北缘黎城断裂的地球物理特征及活动性分析

黎城断裂是晋获断裂构造带上的重要构造单元,查明其构造特征具有重要意义。在黎城盆地北缘针对黎城断裂进行了地球物理勘探和地质考察,对黎城断裂的活动性进行研究。浅层地震勘探和高密度电法勘探的结果表明,黎城断裂是一条第四系活动断裂,倾角较陡。地质剖面考察的结果表明晋获断裂受黎城断裂的影响明显,南北段存在巨大差异。综合以上研究成果,判断黎城断裂为第四系活动断裂,其对晋获断裂的控制作用明显。     

关于兰州市“刘家堡断裂”的地震勘探研究

各种地质调查方法的综合研究证明,兰州市所谓的“刘家堡断裂”实际上应该是兰州七里河向斜盆地的北部边界.采用适合于百米以内地震勘探的观测系统,主要探测“刘家堡断裂”沿线浅部岩层变化情况,通过分析4个场地的浅层地震剖面,阐述了勘探场地附近地震图像的特征及其所反映的七里河向斜盆地西北边缘的构造趋势.地震勘探认为,向斜构造界线两侧岩层物理性质差异明显,地震反射剖面对比反映出“刘家堡断裂”与“深沟桥断裂”交汇的部位褶皱变形非常剧烈.总之,兰州盆地内部地质构造复杂,地震勘探的正确解释是建立在对地质构造正确认识的基础上的.     

A Review on Researches of Active Tectonics——History, Progress and Suggestions1

This paper reviews the history and progress of research on active tectonics in China and overseas. By giving a brief introduction on the history of active tectonic research in China and other countries, the paper sums up the process and development of quantitative investigation of active tectonics since the 1980s. The focus is on the main efforts and progress made in China on certain aspects of research, such as basic surveys and applied investigation of active tectonics, the study of theories related to regional active tectonics and their kinematics and geodynamics, surveys on coupling relations between deep and shallow structures, active fault surveys and prospecting and seismic hazard assessment in urban areas, as well as the efforts made using Quaternary geochronology. Furthermore, the paper looks back on Chinese quantitative investigation of active tectonics in China and sums up cognitions derived from studies on the determination of several basic and measurable parameters of active tectonics. These parameters include the length of fault and fault segmentation, coseismic slip and cumulative slip, fault slip rate, the sequence of paleoearthquake events and the time elapsed since the most recent event. At the same time, efforts and progress made in China on assessing the long-term seismic potential for active faults and evaluating the risk from potential active fault movement have been reviewed by summarizing research on developing theories, models, methods and the application of time-dependent seismic potential to prohabilistic assessment, magnitude estimation for potential earthquakes on active faults, and the forecast of potential risk caused by active fault movement. Finally, in consideration of the realities and problems in the research of active tectonics in China, the authors put forward several suggestions for issues worthy of more attention for further investigation in the future.