高密度电阻率法在城市活断层调查中的应用

目的 在城市活断层调查中应用高密度电阻率层析成像测量方法。资料和方法 利用电阻率层析成像测量方法，在北京某地的活断层、郑州老鸦陈断层、安阳南断裂等处理进行了地震活断层调查，采用正、反演处理软件进行资料处理和解释。结果 取得了较理想的勘探效果。结论 在城市活断层调查中，电阻率层析成像测量方法是一种十分有效的勘探方法。     

沿河开发建筑场地之隐伏沙洞的电阻率层析成像

采用电阻率层析成像二维测量的方法,对河南省三门峡市沿河开发的建筑场地进行了勘探,获取了地下隐伏沙洞的准确位置、埋藏深度、含水情况、尺寸大小等。说明电阻率层析成像二维测量的方法在地下隐伏沙洞的探测中是行之有效的;地下隐伏沙洞在没有水体存在时,电阻率层析成像二维测量成果图中反映的一般都是高阻异常封闭圈。如果有水体存在,其异常则表现为低阻异常封闭圈。     

乌鲁木齐碗窑沟断层电阻率成像探测与探槽剖面的对比研究

利用电阻率二维层析成像方法对碗窑沟断层进行了试验探测,获得了该断层典型的电阻率成像异常特征:地层电性结构存在强间断面,呈现明显的"二分"现象,高、低阻间的梯度界线倾向低阻区。在对乌鲁木齐地区其它具有类似构造特征的断层进行探测时,电阻率成像剖面呈现出相似的异常特征,说明这一异常特征可以作为乌鲁木齐地区判定断层的重要标志和依据。乌鲁木齐地区多为高角度的逆冲断层,此类构造电阻率成像剖面中高、低阻之间的界线与断层并不重合,断层处于高阻区域,倾向与视电阻率衰减梯度线倾向相反,断层的真实位置与图像最上部高、低电阻转折的拐点部位最接近     

福州八一水库-尚干断裂的高密度电法和瞬变电磁法试验探测

为了检验高密度电法和瞬变电磁法在城市活断层探测中的有效性 ,在福州市区及周围进行了试验探测① ,文中主要介绍对八一水库尚干断裂的探测结果。八一水库尚干断裂是一条穿过福州市区的主要断裂带 ,其主断裂在八一水库测区位于一条由新店通往古城的水泥马路东侧 ,在横向上表现为东西宽几十米的电阻率低异常带 ,在纵向上从盖层底部向下延伸到基底深处。试验表明 ,高密度电法和瞬变电磁法可以互相补充和验证 ,从而提高整体探测效果     

应用电阻率层析成像探测采空区、斜风井巷道稳定性计算

采用电阻率层析成像二维测量的方法,对河南省义马市义马煤业(集团)2×50MW跃进电厂采空区和斜风井巷道进行了勘探,获取了采空区、影响区以及斜风井巷道的准确位置.说明,电阻率层析成像二维测量的方法在采空区和斜风井巷道的探测中是行之有效的;煤矿采空区和斜风井巷道内在没有水体存在时,电阻率层析成像二维测量成果图中反映的一般都是高阻异常封闭圈.如果有水体存在,其异常则表现为低阻异常封闭圈.同时,根据该区的地质构造、地层结构、地面建筑的有关参数等资料,分析和计算了斜风井巷道的稳定性和安全性.结果表明,①主控楼受斜风井巷道的影响较大,是不稳定的,也是不安全的,必须采取妥善的加固措施;②主厂房不受斜风井巷道的影响,是稳定的,可以不采取加固措施.     

福州八一水库—尚干断裂的高密度电法和瞬变电磁法试验探讨

为了检验高密度电法和瞬变电磁法在城市活断层探测中的有效性，在福州市区及周围进行了试验探测，文中主要介绍对八一水库-尚干断裂的探测结果。八一水库-尚干断裂是一条穿过福州市区的主要断裂带，其主断裂在八一水库测区位于一条由新店通往古城的水泥马路东侧，在横向上表现为东西宽几十米的电阻率低异常带，在纵向上从盖层底部向下延伸到基底深处。试验表明，高密度电法和瞬变电磁法可以互相补充和验证，从而提高整体探测效果。     

电阻率层析成像在沈阳市地震活断层探测中的应用

本文介绍了在沈阳市活断层探测中应用电阻率层析成像方法取得的结果。,认为应用该方法在目标区可以较准确地探测断层的几何结构和物理特征,为沈阳市活断层探测与地震危险性评价研究提供了准确可靠的物探依据。     

玉溪盆地内普渡河断裂的电阻率层析成像探测

玉溪盆地是云南地区地震活动频度高、强度大的高潜在危险区之一。为了建立直接服务于该区域防震减灾的"标准"结构模型,利用电阻率层析成像技术探测了玉溪盆地盆山过渡带的电性结构以及隐伏并穿过玉溪盆地西缘的普渡河断裂。在数据采集中,作为地震浅层反射勘探的重要补充,共布设了6条电阻率层析成像测线来控制该断裂。使用的观测装置为Wennerα,电极间距为6m,最大隔离系数为30～75,每个排列的电极数目为112～288个。探测结果表明,玉溪盆地内的普渡河断裂分为NNE走向的东西两支;断裂带的宽度由南向北先从温泉镇到黑村附近逐渐变宽,经莲池小学、梅园村到玉昆钢厂附近后逐渐变窄;断裂的上盘为低阻破碎带,下盘为较均匀的高阻结构。东支(F1-2)的视倾向在梅园村及以北为SE/S,在莲池小学及以南为NW,视倾角为56°～73°;西支(F1-1)的视倾向为SE/E/S,视倾角为38°～66°。地震勘探结果认为普渡河断裂的东西两支的倾向在整个玉溪盆地内均为SE/E,视倾角为75°～80°,这与我们的结果略有差异。     

福州市活断层探测与地震危险性评价

大量震例研究表明，活动断层产生的直下型地震对城市的破坏非常严重，应用先进有效的地质与地球物理探测技术，准确地探明城市之下及附近活动断层分布，确定直下型地震的震源和危害性是我国城市减灾工作面临的一个非常急迫的实际问题。《福州市活断层探测与地震危险性评价》项目作为中国地震局全国城市活动断层探测的试点与示范项目于2001年初开始实施，2004年8月通过中国地震局的验收。项目围绕解决城市范围内的断裂定位、定年、定性、深部背景、地震危险性和危害性及防震减灾对策等一系列科学问题，通过“初查与目标区主要活断层鉴定”、“深部地震构造环境探测”、“地震活断层鉴定与危险性评价”、“地震活断层的详细探测”、“地震活断层危害性评价”和“活断层地理信息系统建设”等阶段的探测和评价工作，同时在福州市城、郊区全面开展壤中气汞、土壤汞、气氡、地质雷达、多道直流电法、瞬变电磁法、浅层地震折射法、浅层地震反射法、勘探震源效果对比、用于建立福州盆地埋藏第四系(标准)剖面的钻探等多种手段的试验探测，总结各种试验探测的技术指标和实践经验，在活断层的综合试验探测、定位定年、地震危险性和危害性评价等方面取得了下列成果与结论：(1)福州市活断层综合试验探测成果表明，在充分收集、整理与分析相关地质、地球物理、钻孔等资料的基础上，以地球化学探测为先导“侦察机”，确定了活断层的可能位置；以浅层地震勘探为主要探测方法，辅以电磁勘探作为补充，并利用钻探建立的第四系(标准)剖面或地层层序及测井获得的各种地球物理参数进行必要的校正和验证，结合裸露地表断层或埋深较浅断层的槽探及古地震调查或隐伏断层两侧钻孔岩芯岩性、层序、绝对年龄或孢粉等相对年龄的测定与对比等，是进行城市活断层探测(定位)与地震危险性、危害性评价(定年、定性)的最佳组合方法。(2)福州盆地位于具有发生中等强度地震的区域地震构造环境中，“台湾动力触角”对其影响相对较弱。(3)福州盆地主要断裂的活动性较弱，经鉴定的6条目标断裂都不是全新世断裂。其中，八一水库-尚干断裂和闽侯-南屿断裂至少为晚更新世中期以来的不活动断裂，其它为晚更新世以来不活动断裂。(4)福州盆地深部不存在发生直下型强烈破坏性地震的构造环境，其邻近的长乐-诏安断裂带是未来可能会发生对福州市有影响的地震震源区。(5)福州盆地主要断裂存在发生中等-中强地震的危险性，但发震概率较小。(6)福州盆地地震危害性较弱，地面发生地震地表破裂带的可能性不大。(7)开发建立了全国第一个活断层地理信息系统，具备信息查询显示、数据管理、数据的分析处理和咨询服务等功能。     

电阻率图像中的地下水和断层

目的：将电阻率层析成像应用于探测潜伏断层的研究中，本文发现了断层和地下水的一些基本电阻率分布特征，这对于工程物探意义重大，一般情况下，断层两侧具有不同的电阻率特征，但是，根据电阻率层析图像中的电阻率分布，通常难以区分断层和地下水层，这是因为两者不仅都具有低电阻率值，而且还具有非常相似的电阻率异常特征。资料和方法：运用电阻率层析图像的数据，电阻率层析图像中的断层会呈现如下特征：1）由于孔隙度的加大和地下水的存在，使得断层表现出高角度的低阻线性结构。它们既可以出现在浅部盖层中，也可以存在于深部基岩中，特别是在深部区域，它们尤为明显；2）它们还呈现出高角度的线性梯度带，在该梯度带两边的电阻率结构出现整体性的差异，通常情况下，正断层的上盘表现出低阻或／和班驳状的高阻和低阻扰动区，而下盘则为完整的高阻区，这与逆冲断层正好相反；3）与断层有关的电阻率异常区常常具有良好的大尺度水平连续性，并且可以追瞎异常区附近的精细电性结构。而地下水的电阻率特征为：1）如果没有裂隙，地表水所引起的低阻区非常浅，即使存在丰富的水源以及高孔隙度的砾岩和中粗砂。一般情况下，其底端深度不超过强风化区；2）地下水的电阻率值非常低，特别在高矿化度的地区。地下水，包括岩溶水和砂岩水，的电阻率总显示出局部水平延伸或／和面团状特征；3）地下水层的深度朝某个固定方向逐渐增加，并且其电阻率图像会随季节而变；4）一般情况下，在水下渗的地区，会出现降水漏斗，其上部为高阻，而下部为低阻，从而便形成了“Y”或“V”字型的典型结构。结果：利用上述的基本特征一般可以区分断层和地下水。结论：仅依靠电阻率层析图像，可能极难准确地区分断层和裂隙水，这是因为裂隙水不但可能具有高角度的低阻线性结构，而且在一定尺度上具有很好的水平连续性，还有，由于电阻率层析成像较差的垂直分辨率，难以精确确定断层的上端点位置，所以结合其它的物探手段如钻探和浅层地震勘探是非常必要的。     

CORRELATION BETWEEN GAS GEOCHEMICAL EMISSION AND FAULT ACTIVITY OF THE YUXIAN-GUANGLING AND KOUQUAN FAULTS

Soil gas emission is closely related to tectonic and seismic activity and has been widely used to track active faults and monitor seismicity in the upper crust. Because active fault plays an important role as the channel of the earth's deep gas upward migration due to its high permeability and porosity, the geochemical characteristics of soil gas in fault zone is a good indicator of tectonic fracture and activity. In order to study the soil gas geochemical emission intensities and its correlation to fault activity, fluxes of Rn, Hg and CO₂ in soil gas and the ground resistivity were surveyed across the Yuxian-Guangling Fault and Kouquan Fault which are both Quaternary active faults in the border area of Shanxi Province, Hebei Province and Inner Mongolia Autonomous Region. In 2017, soil gas fluxes were measured in 2 profiles consisting of 10 and 9 wells of depth of 3.0m across the fault scarps in Yuxian-Guangling Fault and Kouquan Fault, respectively. Resistivity tomography sections were attained by ground resistivity survey with electrode spacing of 5.0m along the profiles of soil gas measurement. The gas geochemical data show that there exist two abnormal flux peaks across the Yuxian-Guangling Fault and one in the Kouquan Fault. The high density resistivity measurement shows that fault breccia and fractured rocks zones are developed under the measured faults, where higher values of soil gas flux are also observed. Fractures with high gas permeability in the strata favor the transfer and migration upward of soil gases, which results in the anomalies of gas flux value. In addition, the anomalies of gas flux values are spatially identical with the occurrence of the fault scarps. The soil gas degassing rate of Yuxian-Guangling Fault is higher than that of Kouquan Fault. The research results of high density electrical prospecting and previous tectonic activity show that low-resistance bodies are more developed and the fault activity is stronger with higher slip rate, which leads to the more intense emission of soil gas in Yuxian-Guangling Fault. The conclusions can be made that soil gas geochemical characteristics and degassing rate in fault zone is closely correlated to the tectonic activity and fracture degree. Combination of geochemical and geophysical methods is an efficient way for the monitoring and study of fault activity to estimate the possible earthquake hazards.     

Potential of Electrical Resistivity Tomography to Detect Fault Zones in Limestone and Argillaceous Formations in the Experimental Platform of Tournemire, France

The Experimental platform of Tournemire (Aveyron, France) developed by IRSN (French Institute for Radiological Protection and Nuclear Safety) is located in a tunnel excavated in a clay–rock formation interbedded between two limestone formations. A well-identified regional fault crosscuts this subhorizontal sedimentary succession, and a subvertical secondary fault zone is intercepted in the clay–rock by drifts and boreholes in the tunnel at a depth of about 250 m. A 2D electrical resistivity survey was carried out along a 2.5 km baseline, and a takeout of 40 m was used to assess the potential of this method to detect faults from the ground surface. In the 300 m-thick zone investigated by the survey, electrical resistivity images reveal several subvertical low-resistivity discontinuities. One of these discontinuities corresponds to the position of the Cernon fault, a major regional fault. One of the subvertical conductive discontinuities crossing the upper limestone formation is consistent with the prolongation towards the ground surface of the secondary fault zone identified in the clay–rock formation from the tunnel. Moreover, this secondary fault zone corresponds to the upward prolongation of a subvertical fault identified in the lower limestone using a 3D high-resolution seismic reflection survey. This type of large-scale electrical resistivity survey is therefore a useful tool for identifying faults in superficial layers from the ground surface and is complementary to 3D seismic reflection surveys.     

高密度电阻率法在西藏日喀则地区隐伏断裂探测中的应用

以跨谢通门—青都断裂的两条高密度电阻率法探测资料为基础, 对高密度电阻率法在青藏高原日喀则地区隐伏断裂探测中的首次应用进行了详细介绍． 所获取的高密度电法剖面显示, 该断层的电阻率异常特征清晰, 其上断点埋深可达20—30 m, 较浅层人工地震探测所揭示的断层上断点埋深(50 m)更浅, 结合地层年代资料推测该断裂的最新活动时期为早—中更新世． 探测结果表明: 高密度电法剖面清晰地显示了断层在浅部松散层的延伸, 适用于日喀则地区的隐伏断层探测; 相较于浅层人工地震探测, 该方法对浅部松散层的探测具有明显优势, 一定条件下能够更好地揭示断层上断点埋深, 可与浅层人工地震探测形成互补． 需要指出的是, 在应用中需重视测区水文地质及地层发育情况对探测的影响．      

技术应用综合物探方法在张家口某工程场地地震安全性评价中的应用研究

结合地质和遥感图像解译资料,以物探方法查找活断层是行之有效的方法。针对单一的物探方法在反演解释中具有多解性的弊端,本文提出以高密度电阻率法为主,浅层地震反射波法为辅的综合物探勘察组合模式。经实际钻探证明,这种综合物探模式对隐伏活断层的勘察是完全可行的,并具有较强的实用推广性。     

STUDY ON THE ELECTRICAL STRUCTURE OF THE ANQIU AND JUXIAN ELECTROMAGNETIC STATIONS IN THE TANLU FAULT ZONE

The Yishu fault zone is one of the branch faults of the Tanlu fault zone in its central part. Moderate and strong earthquakes occurred in the Yishu fault zone repeatedly. Due to its complex structure, the Yishu fault zone attracts much attention from earthquake researches. The Anqiu and Juxian electromagnetic stations in Shandong Province locate near the Anqiu-Juxian Fault and Changyi-Dadian Fault, which are branches of the Yishu fault zone, respectively. Geoelectric field and geomagnetic field observation were carried out in these two stations. The Wudi electromagnetic station is in the west of Tanlu fault zone in the Jidong-Bohai block and 230km from Anqiu electromagnetic station. This paper firstly describes the crustal structure near the electromagnetic stations by using magnetotelluric(MT)method. By processing the data carefully, we obtain the MT data in good quality near the stations. The MT data of each electromagnetic station and its nearby area suggests that the electrical structure and geological structure of the station are comparable. This paper applied 1-D and 2-D inversion for MT data and obtained the crustal electrical structure model beneath the Anqiu and Juxian seismic station. The shallow electrical structure from the MT method was compared with the results of symmetrical quadrupole electrical sounding. The model suggests that the electrical structure beneath the Anqiu and Juxian electromagnetic stations is complex and shows the feature of block boundary. The Wudi electromagnetic station is located inside a basin, the crustal structure shows layered feature typical for the stable blocks. Beneath the Anqiu electromagnetic station, there is a 1km-thick relative low resistivity layer in the shallow crust and a high resistivity body beneath it with a depth of 13km. There is a high resistivity structure in the crust beneath the Juxian electromagnetic station. The crustal structures are divided into two different parts by Anqiu-Juxian Fault and Changyi-Dadian Fault, respectively. More conductive layers appear to the west of the two faults. Plenty of fluid possibly exists within the conductive body to the west of Changyi-Dadian Fault, which plays important role in the earthquake generation. There is a relative low resistivity layer in the crust within 1~2km beneath the Wudi electromagnetic station. Beneath the relatively low resistivity layer, a relatively high resistivity layer extends to a depth of around 15km, and the resistivity value decreases with the increase of depth. The electrical resistivity model suggests the seismic activity of the Yishu fault zone around the Anqiu and Juxian electromagnetic stations should be taken into account seriously, and monitoring and research on it need to be strengthened. The results of this paper provide a certain reference value for the crustal structure research to similar stations.     

1920年海原8.5级地震震中区地电阻率各向异性研究

通过海原8.5级地震震中区环行电测深研究,发现在断层破碎带有明显的电阻率各向异性,垂直断层走向呈现明显的高电性,断层走向呈现明显的低电性.根据电性差异讨论了断层地表的变形特征.研究结果表明：环形电测深工作,对研究地面附近地层物性变化有重要意义.     

代县盆地可控音频大地电磁浅层电性结构探测

为研究代县盆地及其断裂的空间展布以及深部的延展情况,东南跨过五台山北麓断裂带,西北至恒山山前黄土丘陵区,布置了一条NW向穿过代县盆地的可控音频大地电磁(CSAMT)测深剖面,全长12.55km.共完成可控源音频大地电磁测点246个,观测频率为8533.333 ～1.333333Hz.视电阻率、相位曲线具有明显的分段特征...     

安丘—莒县断裂小店—大店段断层活动证据及断层泥分布特征初步研究

郯庐断裂带最新活动的断层分布于潍坊至嘉山一带, 而安丘—莒县断裂是郯庐断裂带的重要活动断裂之一。 基于地质考察、 高密度电法探测和钻孔联合剖面, 对安丘—莒县断裂小店—大店段断层活动证据及断层泥分布特征进行研究。 地质考察发现紫红色砂砾岩逆冲到全新世耕植土上方, 两者之间发育断层泥带, 断层泥内含少量角砾岩, 为全新世活动逆断层。 高密度电法探测结果表明断层通过位置电阻率差异明显。 钻孔联合剖面揭露的地层: 全新世耕植土、 全风化砂质泥岩、 强风化砂质泥岩、 碎裂岩、 断层泥带及中风化砂质泥岩。 钻孔K1和K2揭露深灰色断层泥带, 倾向西, 倾角约为74°, 厚度约为13.9 m, 与南侧出露的断层泥带产状相协调。 工作区范围内, 发育多处褶皱、 破碎带和断层泥带, 断层表现为全新世逆断层性质。     

Coseismic Damage at an Archaeological Site in Sicily,Italy: Evidence of Roman Age Earthquake Surface Faulting

Archaeoseismology can provide a useful chronological tool for constraining earthquakes and documenting significant evidence that would otherwise be lost. In this paper, we report a case of surface faulting on ancient man-made structures belonging to the archaeological site of Santa Venera al Pozzo situated along the eastern flank of Mt. Etna volcano in eastern Sicily (southern Italy), which is affected by well-developed tectonic faults. Geological surveys highlight a set of fractures affecting the archaeological ruins, suggesting the occurrence of a capable fault zone across the area. An integrated geophysical survey was carried out in order to identify the main subsurface tectonic discontinuity ascribable to the fault zone. The information derived from different geophysical techniques, such as electrical resistivity tomography, seismic refraction tomography, ground-penetrating radar, and magnetic surveys allowed us to infer that the fractures observed at the surface could have been produced by coseismic rupture. They are conceivably linked to a strong earthquake that probably occurred in the Roman period, around mid-end of the third-century AD; time constraints are inferred through the dating of buildings of the archaeological site.