能动断层的概念及其演化

对能动断层概念史的研究,可以揭示出能动断层的核心意义以及与活动断层的区别和联系。能动断层的鉴定以确定未来地表或近地表断层错断可能性为目的,与地震地面运动相比是一种不可设计的厂址评价要素。因此,在厂址适宜性评价中意义重大。     

能动断层和地表断层的概念及其调查

提出并研究了能动断层与地表断层这两个概念的形成与基本含意,强调了在实际核工程厂址选择时所必须进行的调查内容与要求,并进一步研究了能动断层的鉴别标准问题     

能动构造源及其在核动力工程选址中的意义

能动构造源是源于能动断层的一个新概念，在核工程的厂址评价中有决定性作用，研究认为，能动构造源序判标志中的时间约定方法强调了以地质观测为主的综合判定法，明确规定了地震活动的鉴别中的作用。提出“晚更新世Ｑ３（约１０万年）以来”在我国具有特殊的活动构造意义，即喜马拉雅运行进入最活跃的时期波及全国并持续至今，能动构造源的判定在近场区以评价地表或近地表破裂为主，在远场区则是为了划分潜在震源区。     

锦屏水电站工程区活动断层的遥感分析与调查

应用卫星遥感高分辨率ETM彩色合成影像和SPOT-4全色黑白影像,对四川省雅砻江锦屏水电站工程场地及其外围地区进行地质构造的解译调查,其中重点对厂址区附近的锦屏山断层、青纳-民胜乡断层、沃底-干海子断层等断裂构造进行详细判读,并结合野外现场勘查和断层测年结果进行分析,初步认为,锦屏水电站及其周边地区活动断层的最晚活动时代为晚更新世晚期,没有发现全新世活动的直接证据.     

隐伏和出露地表断层近断层地表运动特征的研究进展

本文介绍了在强震地震学研究方面国内外目前所关注的重要问题：隐伏断层和出露地表断层在地震发生时近断层地表运动特征存在着明显的差异。根据近几十年全球发生的中强地震的地表运动参数的统计分析所得的结果表明,由隐伏断层所造成的近断层地表运动强度（速度、加速度）大于出露地表断层所产生的地表运动强度,虽然发生在出露地表断层的地震往往可造成较大的近断层地表位移,但是当地震矩震级（MW）达到 7.5 级以上的时候,近断层地表加速度和速度在近源区却出现了饱和现象。对该问题的深入研究有着十分重要的科学意义和工程应用价值。本文着重介绍了当前国际上对该问题的研究现状,并且建议在此基础上利用三维有限差分断层动力学模型,模拟断层的动态破裂过程以及近断层地表运动的特征。     

日本横手盆地东缘陆羽逆断层系的同震地表破裂特征及其分段性

通过对陆羽逆断层系上１８９６年同震地表破裂特征、长期活动习性和断错地貌等的研究，给出了可识别的逆断层型段落边界的标志，它们是断层崖形态持久性变化的过渡地段、断层抬升盘山地分水岭高程明显变化的转折部位、剖面几何结构转换区和断层下降盘盆地内的隐伏横向基岩脊等；指出逆断层上公里量级的空缺和阶区不能有效地终止或延缓逆断层型同震地表破裂的横向扩展，因此，不能作为逆断层型段落的边界，最后对陆羽逆断层系的千屋段和横手段的地震危险性进行了简要评估     

浅层断层对场地地震动影响的有限元分析

应用动接触理论模拟断层的滑移问题，用有限元方法计算浅层断层对场地地震动的影响．计算结果表明，在地表断层出露的周围地区，断层下盘地表地震动放大效应较大，断层上盘地表地震动放大作用有明显的降低．这一结果说明，在有浅层断层的场地建设重大工程时需要考虑断层对地震动的影响．      

核电厂地震安全性评价中的断裂构造调查与评价

本文针对当前工作中存在的问题，对核电厂地震安全性评价工作中断裂构造调查与评价的技术思路、发震构造鉴定、能动断层鉴定与调查、地表断裂影响评价、发震构造与能动断层的关系等方面的问题，从核安全法规的层面进行了分析和讨论。认为对核安全法规的正确认识和理解，是较好地解决当前问题的重要途径。     

大型变电站厂址的地震地质条件研究——四川省石棉地区变电站遴选实例

地震灾害对工程场地的影响主要体现在3个方面，一是地震断层直接造成地面的断错：二是强烈的地面地震动；三是地震引起的地质灾害如滑坡、泥石流或砂土液化等。本文结合在四川省石棉地区大型变电站厂址的遴选实例，说明详细研究厂址附近断层的活动习性及其空间分布位置是研究大型变电站厂址地震地质条件的关键性因素。     

跨断层长输油(气)管道抗震研究与实践

概述了输油（气）管道跨断层抗震研究与实践的现状，总结了判断地表断裂位移的两种经验统计方法和覆盖土层场地地表断裂的分析判断方法，评述了用这些方法得到的结果。对常用的跨断层管道抗震分析方法进行了评述，并列举了我国管道工程中可行的抗震措施。     

绰尔河断裂对文得根水库坝址区稳定性的影响

通过地质调查、物化探测量、地震活动性分析，研究了绰尔河断裂的位置、地质特征和活动性，以及该断裂对文得根水库坝址区稳定性的影响。结果表明，绰尔河断裂总体沿绰尔河河谷呈NW向展布，形成于中生代，经历了多期活动，表现为先压扭后引张。断裂北段宽而深，南段窄而浅。晚更新世末期以来不活动。绰尔河断裂对坝址稳定性影响不大。     

辽宁瓦房店温坨子原核电站场址东岗断裂的活动性

位于辽宁瓦房店温坨子的东岗断裂是一条隐伏断层 ,靠近该地区原曾选定的核电站场址。通过详细的野外地质工作 ,查明了该断裂的地理位置、几何形态 ,发现断裂带东延至尉屯就转向北去 ,并确定它没有与金州断裂相接。经系列探槽的开挖 ,断层构造岩及有关地层样品作绝对年龄测定 ,证明东岗断层错断了中更新世地层 ;但约 5万年以来断层的上覆地层没有被错断 ,因此认为东岗断层不是能动断层     

珠海市鸡啼门大桥桥址区断层的勘查研究

本文叙述了鸡啼门大桥桥址区断层勘查研究的内容、方法和结论。指出斜穿大桥轴线的F_3断层,破碎带宽约28m,垂直落差约6m,规模较大,在晚更新世时期重复活动,活动方式粘滑为主。但在距今22000多年以来,已逐渐趋于稳定,全新世时期的活动迹象不明显。     

新疆阿克苏大石峡水电站附近活动断层的基本特征

通过对大石峡水电站附近的多条活动断层研究表明:库车坳陷西段的乌什坳陷区内,主要发育有两排新隆起的活动褶皱,由北向南依次为沙依拉木背斜带和苏尔滚背斜带;区内的活动断层主要以NE向为主,其中较大的断层有阔克沙勒断层、迈丹—沙依拉木断层和库齐隐伏断层。研究区中对场地影响较大的断层为迈丹—沙依拉木断层和大石峡口山前断层,它们均表现为东西分段特性,断层整体活动程度西强东弱。库齐隐伏断层是一条晚更新世末期的活动断层,最新的活动时代为距今1.4万年左右。     

熊坡背斜构造变形与蒲江-新津断裂活动特征

熊坡背斜位于龙门山构造带东南端的成都盆地内,是龙门山逆冲推覆构造向前推挤进入盆地内部的一个主要变形区域,与其配套发育的断裂为蒲江-新津断裂,断裂与背斜褶皱之间在构造变形模式上表现出明显的一致性。在褶皱和断裂的构造变形和活动特征上,熊坡背斜南段表现为一种不对称的褶皱,向NE方向发展表现为较为宽缓的对称褶皱形态,卷入的地层主要是中生代及其以前的地层,对蒲江-新津断裂的地貌调查结果表明,断裂没有对该区域内广泛发育的冲沟Ⅰ级阶地产生影响,而对山前发育的相当于南河(岷江Ⅰ级支流)Ⅳ级阶地的洪积台地有明显的控制作用,说明断裂活动时间应该为第四纪早期,到第四纪晚期活动减弱或是趋于静止     

乌鲁木齐地区N倾断层系的构造特征

乌鲁木齐地区发育有5条N倾的断层,这些断层晚更新世以来均有较为明显的活动迹象,并在地表形成了较为显著的构造标志。通过沿断层大比例尺地质地貌填图、探槽开挖和年代测定,较为准确地获得了断层的最新活动时代、运动性质和特征等问题,并确定出这些断层都是在距今20万年~30万年以来快速翘升形成的。结合深地震反射资料,对乌鲁木齐地区的深部结构进行了分析讨论,从而对N倾断层系的深部构造特征也有了更加清晰的认识,为准确评价这些断层的孕震模式和发震能力提供了可靠的依据。     

海河隐伏活断层探测中土壤气氡和气汞测量及其结果

在海河隐伏断裂的探测中,利用FD-3017RaA测氡仪和XG-4型测汞仪开展了土壤气氡和土壤气汞的测量工作。根据12条断层气测线的测量结果,结合人工地震探测资料,对断层气异常位置与断层位置的关系进行了分析;运用断层气异常强度与断层活动性的关系对海河断裂的活动性进行了研究,给出了海河断裂天津段的位置和活动性分段。研究结果表明,断层气方法不仅能给出断层的初步位置,而且能够用于断层的活动性初步分段,但断层气方法所给出的断层位置应是一个条带。经与人工地震探测结果对比分析,断裂位于这个条带内;根据土壤气氡测量结果,可将海河断裂分为东、西两段,且东段的活动性要强于西段。这种强、弱之分仅是一种相对结果,在判定断层是否为活断层方面还存在一定困难     

DISCUSSION ON THE SEISMOGENIC STRUCTURE OF ZHAN-JIANG BAY AREA FROM THE VIEW OF DEEP FAULT SYSTEM INTERPRETED BASED ON THE GRAVITY DATA

The neotectonics in Zhanjiang Bay area is almost the inferred faults and there are not any active faults seen on the ground surface. So it is difficult for research on the seismogenic structure. This paper analyzes and interpretes the gravity data that can reflect the feature of deep faults and then discusses the seismogenic structure of Zhanjiang Bay area in combination with its geology and earthquake activity. There is a huge NEE-trending high gravity gradient belt lying in the coastal region among Guangdong, Guangxi, and Hainan, and Zhanjiang Bay is located in this gravity gradient belt. We analyzed and interpreted more than eighty images obtained with many different methods one by one, then, got the result that Zhanjiang Bay area is embraced by two giant fault belts trending in the NEE and NW direction respectively, and its interior is crossed over by the NE-trending fault belt. These three fault belts are well shown in the gravity images, especially the NEE-trending fault belt and NW one. The gravity isolines and gradient belts or the thick black stripes of the NEE-and NW-trending fault belts are displayed apparently. Also, these gravity structures are good in continuity, extend vastly and cut deeply. What is more, the NEE-trending fault belt plays a leading and region-controlling part. It shows good continuity, and cuts off the NW-and NE-trending faults frequently and intensively. The NW-trending fault belt also is good in continuity and cuts the NEE-and NE-trending faults relatively frequently and strongly, but it is restricted by the NEE-trending one. Last, the continuity of the NE-trending fault is worse and the strength cutting off NE-and NW-trending faults is significantly weak, just in some segments and in the shallow positions. According to the characteristics above and combined with the analyses of geological structure and earthquake activity, the conclusion can be drawn that the NEE-trending fault is the controlling structure and the main seismogenic structure in Zhanjiang Bay area, and the NW-trending fault is the second one. They conjugate and act together. Therefore, Zhanjiang Bay has the tectonic condition for generating M_S=6.5 earthquakes.     

THE COSEISMIC VERTICAL DISPLACEMENTS OF SURFACE RUPTURE ZONE OF THE 1556 HUAXIAN EARTHQUAKE

Coseismic displacement plays a role in earthquake surface rupture, which not only reflects the magnitude scale but also has effect on estimates of fault slip rate and earthquake recurrence intervals. A great historical earthquake occurred in Huaxian County on the 23^rd January 1556, however, there was lack of surface rupture records and precise coseismic vertical displacements. It's known that the 1556 Huaxian earthquake was caused by Huashan front fault and Weinan plateau front fault, which are large normal faults in the east part of the southern boundary faults in Weihe Basin controlling the development of the basin in Quaternary. Here, we made a study on three drilling sites in order to unveil the coseismic vertical displacements. It is for the first time to get the accurate coseismic vertical displacements, which is 6m at Lijiapo site of Huashan front fault, 7m at Caiguocun site, and 6m at Guadicun site of Weinan plateau front fault. These coseismic displacements measured based on same layers of drilling profiles both at footwall and hanging wall are different from the results measured by former geomorphological fault scarps. It's estimated that some scarps are related with the nature reformation and the human beings' activities, for example, fluviation or terracing field, instead of earthquake acticity, which leads to some misjudgment on earthquake displacements. Moreover, the vertical displacements from the measurement of geomorphological scarps alone do not always agree with the virtual ones. Hence, we assume that the inconsistency between the results from drilling profiles and geomorphological scarps in this case demonstrates that the fault scarp surface may have been demolished and rebuilt by erosion or human activities.     

RESEARCH ON THE CHARACTERISTICS OF QUATERNARY ACTIVITIES OF SU-XI-CHANG FAULT

Running across the urban areas of Changzhou, Wuxi and Suzhou, the NW-trending Su-Xi-Chang Fault is an important buried fault in Yangtze River Delta. In the respect of structural geomorphology, hilly landform is developed along the southwest side of the Su-Xi-Chang Fault, and a series of lakes and relatively low-lying depressions are developed on its northeast side, which is an important landform and neotectonic boundary line. The fault controlled the Jurassic and Cretaceous stratigraphic sedimentary and Cenozoic volcanic activities, and also has obvious control effects on the modern geomorphology and Quaternary stratigraphic distribution. Su-Xi-Chang Fault is one of the target faults of the project "Urban active fault exploration and seismic risk assessment in Changzhou City" and "Urban active fault exploration and seismic risk assessment in Suzhou City". Hidden in the ground with thick cover layer, few researches have been done on this fault in the past. The study on the activity characteristics and the latest activity era of the Su-Xi-Chang Fault is of great significance for the prevention and reduction of earthquake disaster losses caused by the destructive earthquakes to the cities of Changzhou, Wuxi and Suzhou. Based on shallow seismic exploration and drilling joint profiling method, Quaternary activities and distribution characteristics of the Su-Xi-Chang Fault are analyzed systematically. Shallow seismic exploration results show that the south branch of the Su-Xi-Chang Fault in Suzhou area is dominated by normal faulting, dipping to the north-east, with a dip angle of about 60° and a displacement of 3~5m on the bedrock surface. The north branch of the Su-Xi-Chang Fault in Changzhou area is dominated by normal faulting, dipping to the south, with a dip angle of about 55°~70° and a displacement of 4~12m on the bedrock surface. All breakpoints of Su-Xi-Chang Fault on the seismic exploration profiles show that only the bedrock surface was dislocated, not the interior strata of the Quaternary. On the drilling joint profile in the Dongqiao site of Suzhou, the latest activity of the south branch of Su-Xi-Chang Fault is manifested as reverse faulting, with maximum displacement of 2.9m in the upper part of Lower Pleistocene, and the Middle Pleistocene has not been dislocated by the fault. The fault acts as normal fault in the Pre-Quaternary strata, with a displacement of 3.7m in the Neogene stratum. On the drilling joint profile in the Chaoyang Road site of Changzhou, the latest activity of the north branch of Su-Xi-Chang Fault is manifested as reverse faulting too, with maximum displacement of 2.8m in the bottom layer of the Middle Pleistocene. The fault acts as normal fault in the Pre-Quaternary strata, with a displacement of 10.2m in the bedrock surface. Combining the above results, we conclude that the latest activity era of Su-Xi-Chang Fault is early Middle Pleistocene. The Su-Xi-Chang Fault was dominated by the sinistral normal faulting in the pre-Quaternary period, and turned into sinistral reverse faulting after the early Pleistocene, with displacement of about 3m in the Quaternary strata. The maximum magnitude of potential earthquake on the Su-Xi-Chang Fault is estimated to be 6.0.