In magnetotelluric (MT) inversion, when the used grid is not uniform or the positions of observation sites in the grid are not appropriate, site shift will occur which can affect the accuracy of inversion. Besides, in order to ensure accuracy and stability of forward modeling, spacing of the inversion grid cannot vary too much, requiring smoothness of some degree. To solve these issues, this paper suggests several methods of automatic constructing a site-centered grid to eliminate site shift and using regularization constraints to control the smoothness of the grid. To realize this object this paper also proposes a set of test indexes for grid quality. Comparison of case calculations indicates that different site sets may require varied methods to construct optimal grids. Among them the “optimized dynamic allocation under flattest model constraint”, and “optimized dynamic allocation under smoothest model constraint” are most adaptive, by which the constructed grids have fairly smooth grid spacing and smaller site shifts. The comparison also shows that using a grid of high quality (smooth, little site shift) can enhance the reliability of inversion as well as efficiency of inversion calculation. The methods proposed in this paper provide a simple and effective approach to produce a proper grid for 2D MT inversion.

在大地电磁二维反演中，如果网格不均匀或者测点在网格中的位置不恰当，则将出现测点偏离现象，影响反演的精度.此外，由于正演精度和稳定性的需要，反演中网格间距不能差别太大，需要具有一定的光滑性.本文提出了几种自动构建测点中心网格的方法来消除测点偏离现象，并以正则化约束条件来保证网格的光滑程度.本文还提出了一套网格质量检验指标.算例对比研究表明，对于不同的测点集，最佳网格构建的方法可能不相同，但其中“最平模型约束动态配点法”、“最光模型约束动态配点法”拥有最强的适应能力，它们在各种情况下所构建的网格一般同时具备较光滑的网格间距变化和较小的测点偏离程度.此外，采用高质量（光滑性好、测点偏离程度低）网格在一定程度上不仅可提高反演结果的可靠性，还能提高反演的计算效率.本文的方法为获得高质量的大地电磁二维反演网格提供了简单有效的途径.

In this paper, a new inversion method, Adaptive Regularized Inversion Algorithm (ARIA), is presented to overcome the difficulty in determination of regularized factors for magnetotelluric (MT) inversion. In ARIA, first a new data variance disposing method, data variance normalization method, is put forward. This method uses a new way to calculate the influence matrix of data variance in inversion. Thus, the data variance only influences data fitting, and has no influence on the weight between the data object function and the model constraint object function. So the influence factors in determination of the regularized factor are reduced. Second, the definition of roughness kernel matrix is presented in the course of constructing the model constraint object function, and a concise equation of it is derived. Thus the construction of the model object function becomes very simple and direct. Third two adaptive methods of regularized factors are put forward based on the relations of data object function, model constraint object function, and regularized factor. ARIA is used to solve the one_dimensional inversion by MT data by the constraint of the flattest model. Several examples are given to illustrate the effectiveness of ARIA.

针对大地电磁正则化反演中正则化因子的选取困难问题提出了自适应正则化反演算法（Adaptive Regularized Inversion Algorithm, ARIA）. 在该算法中， ①提出了一种新的数据方差处理方法：数据方差规范化，使得数据方差的大小只对数据的拟合发生影响，不对数据目标函数和模型约束目标函数的权重产生影响，从而减少了正则化因子取值的影响因素；②提出了粗糙度核矩阵的概念，并给出了由基本结构插值基函数计算粗糙度核矩阵的公式，使得模型目标函数的构建更为简便、直接；③根据数据目标函数、模型约束目标函数和正则化因子之间的关系，提出了两种正则化因子自适应调节方法. 本文详细阐述了最平缓模型约束下的大地电磁一维连续介质反演的ARIA实现，以几个算例的分析比较来说明ARIA的有效性.

本文论述了采用Delphi和FORTRAN语言混合编程实现的大地电磁资料处理与解释的Windows可视化集成系统--大地电磁测深数据管理器(MTDATAMNG)的一些主要特性。首先简单介绍了MTDATAMNG的设计思想和主要的程序框架,并对程序设计过程中的两个关键技术(面向对象编程技术和Delphi／FOR-TRAN混合编程技术)做了简单的说明;然后重点阐述了MTDATAMNG的主要功能,展示了该系统具有较为完备的数据备档存储方式、多种数据处理方式和图形显示格式、强大的正反演模拟功能(一维、二维正演,三维正演的数据接口,一维、二维反演,二维带地形反演)和多样的数据输入输出接口,表明该可视化系统整合了数据处理的各种技术,并具有三维数据处理能力;文章最后对MTDATAMNG的图形显示的主要功能做了进一步的图示说明。

The precursor observations, such as electromagnetism, underground fluid, geodesy, etc., for earthquake monitoring and prediction have been internationally implemented for decades. However, nowadays it is highly debatable whether the earthquake-related precursory anomalies can be observed or not, owing to the lack of both the reproducibility and similarity of these anomalies. The anomalies of direct current apparent resistivity (AR, for short; denoted as ρ s ) recorded by station Chengdu before the M S 8.0 Wenchuan quake on May 12, 2008, and the M S 7.0 Lushan quake on Apr. 20, 2013 provide examples to address this issue. The reasons for this are as follows. First, this station is only 35 km from the epicenter in Wenchuan and 99 km from that in Lushan. Second, both the two events happened along the NE-strike Longmen Shan fault zone west of the station. Third, the two focal mechanisms and depths are almost the same. Whether did the reproducibility and similarity of the AR anomalies appeared before the two great shocks? The primary curve of AR observation data and the annual-variation-free curve from which the annual variation of AR is eliminated by using the moving Fourier method (MFM, for short) are traditionally adopted to analyze the anomalies in China. As for the traditional approaches, it is reliable for identifying the relative AR change with the amplitude of no less than 1% because the measurement accuracy is much better than 0.3% in the observation of AR. But, it is sometimes difficult to distinguish the normal and anomalous changes using the traditional approaches, which will result in the uncertainty of anomalies. To solve this problem, the normalized variation rate method (NVRM) is put forward and its principle is briefly described as follows. The long-term decreasing or decreasing variation in the AR time series { ρ s } (with the length N ), if any, is eliminated by the linear regression and the annual variation in it is also removed by using the MFM. The ξ continuous data in { ρ s } are selected to form the i th time sub-series and the variation rate is calculated from ρ si · '=K i ×R i (where K i is its slope coefficient and R i is linear correlation coefficient). Like this, the initial variation rate time series ρ s ·' is generated with the step length ξ fixed. Finally, the NVRM time series ρ s · (dimensionless) with its mean value m →0 and RMSE σ n -1 →1 is obtained from ρ si ·' after the processing such as the normalization, centralization, and noise reduction. The index of anomalies is consistently defined as ±2.4 on ρ s · for each station or channel. In this paper the traditional approaches and the NVRM are applied to process the AR data observed by station Chengdu. At station Chengdu, two measurement channels are respectively in N58°E and N49°W orientations at the same location and each channel employs the fixed Schlumberger array. Before the M S 8.0 Wenchuan and M S 7.0 Lushan events, the two orthogonal channels recorded pre-seismic anomalies with the repeatability, similarity and difference. (1) The two anomalies recorded by each channel showed the repeatability and similarity. The AR anomalies of channel NE, with the relative amplitude of ~-7.0% on the daily mean curve, before the Wenchuan event persistently decreased for 19 months, and then started a recovery (increasing) change about 3.5 months before the shock. Another decrease anomaly, -5.9%, before the M S 7.0 Lushan event continued for 8 months and started a recovery change immediately following the maximum drop. The earlier decreasing and then increasing changes had distinctly exhibited the reproducibility in their changing forms and processes, which tallied with the change process of the electrical resistivity within the focal area predicted by the dilatancy-diffusion model. Furthermore, they also exhibited the similarity in the large-amplitude decrease in the medium-term before the two events. The two anomalies recorded by channel NW in the medium-term clearly showed their reproducibility of the two positive anomalies on the NVRM curves. Their change forms were identical, their starting times were nearly the same, and only the amplitude was larger before the near-distance and greater event in Wenchuan than that before the slightly farther and smaller shock in Lushan. (2) Before each quake the two anomalies recorded by the two channels showed differences in their change forms, amplitudes and starting times. The channel NE recorded the two prominent decreasing anomalies in the medium-term while channel NW recorded two NVRM positive anomalies that indicated the increasing changes of AR, which manifested as the anisotropic changes in the reverse directions. The two anomalies on the monthly and daily mean curves of channel NE were larger in amplitude while those of channel NW appeared only on the NVRM curves that indicated the small-amplitude changes of AR, which showed the apparent anisotropic changes in amplitude. The two medium-term anomalies of channel NE started earlier while those on channel NW started later. Furthermore, the channel NE is obviously superior to channel NW in the responsiveness to the two quakes. (3) The possible reasons for the anomalies of AR is theoretically explained based on the anisotropic medium as follows. During the later preparation of the two great earthquakes, there occurred such the processes as the nonlinear growth and development of the micro cracks within the medium below the station, with the micro-crack strikes in the dominant arrangement roughly along the NW—SE direction and the penetration of low-resistance water within the medium. As a result, the processes brought about the anisotropic changes in electrical resistivity within the medium, with the change in the direction being larger in amplitude than that perpendicular to direction. It resulted in the apparent anisotropic changes, with the AR change of channel NE being larger than that of channel NW. Furthermore, the anisotropic changes in the electrical resistivity were rather strong due to the near distance and large magnitude, so the reverse changes of AR appeared; and before the Wenchuan quake the underground medium below this station had undergone the process mostly characterized by the NW—SE direction compression since August 2006 at latest, and before the Lushan quake the compression had been formed since August 2012. The M S 8.0 Wenchuan and M S 7.0 Lushan earthquakes all occurred on the Longmen Shan fault, very near to station Chengdu. Their focal characters and depths are almost the same, and the two measuring channels in the station record the AR anomalies with the following features: (1) Before the two events, the two anomalies recorded by each channel clearly exhibited the repeatability in the medium-term feature and changing form, and the similarity in the amplitude. Especially, the two anomalies recorded by channel NE show the repeatability in the "earlier decreasing and then recovery (increasing) change" process. (2) Before each quake, the two anomalies recorded by the two channels show the differences in the change form, amplitude and starting time. The repeatability and similarity prove the anomalies to be directly associated with the two great earthquakes, and the differences show that the anisotropic AR changes are directly related to the two source characters.

本文评价了四川汶川 M S 8.0、芦山 M S 7.0地震前后成都台地电观测环境,研究了该台视电阻率变化.结果为:(1)两次大震发生在该台以西的龙门山断裂带、震源机制和震源深度接近,是近距离大震,相应地,在两次地震前该台两个正交测道中的每一测道视电阻率变化均显示了中期异常及其变化过程的重现性和异常幅度的相似性;(2)在每次地震前,两个测道表现了异常变化形态、幅度和起始时间的差异性.其重现性、相似性证明这些异常与两次大震晚期孕育有关;差异性主要展示了与震源机制有直接联系的视电阻率各向异性变化,揭示了震前该台地下介质经历了强烈的电性各向异性变化的过程.

郯城-庐江断裂带(简称郯庐断裂)是中国东部一条古老的而今仍在活动着的巨型断裂带,它经历了长期复杂的形成演化过程,对区域构造、沉积古地理、岩浆活动、成矿作用和地震活动等曾起过重要控制作用。

We adopted the spectrum analysis method and the BAYTAP_G method to analyze the geoelectric potential data at the Niijima station during 1998～2000 After the quantitative analysis of the tide response of geoelectric potential changes at the above station, we obtained some main characteristics of the tide response. Besides the tidal components with various periods such as diurnal tide, semidiurnal tide, and so on, semimonthly and semiyearly variations of tide response were also detected from the geoelectric potential data at the Niijima station. Further quantitative analysis showed that some anomalous tide response for the surveying dipoles associated with the Wakago site occurred prior to the earthquake swarm in the summer of 2000, while no clear anomalous tide response for another surveying dipole at the same station. The above result may become a kind of new evidence of the so-called “selectivity" phenomena of seismic electromagnetic signals.

本文通过采用频谱分析和BAYTAP-G方法对位于日本伊豆群岛的新岛台跨度达三年（1998～2000年）的地电场的观测资料进行了分析研究，对该台地电场的潮汐响应进行了定量提取与分析，得到了地电场潮汐响应的一些主要特征，例如除了存在全日分潮、半日分潮等不同周期的潮汐成分外，还呈现出明显的半月、半年等不同周期的活动规律.进一步的定量分析显示与新岛台若乡（Wakago）关联的测线的潮汐响应在2000年夏季的群发地震前呈现出不同程度的异常变化，而在所分析的另一条测线中并未检测到类似的异常，这也许可以成为地震电磁信号的“选择性”现象的一种新的证据.

Magnetotelluric (MT) measurement has been carried out at 7 sites along a profile in NNW direction in Arxan active volcanic area. The data were processed and analyzed by using a two-dimensional (2-D) inversion. The obtained 2-D result shows that two volcanic zones, the older and younger volcanic zones with their magma conduits down to depth, exist in the study area. Of them a newly found younger active volcanic zone still maintains its higher temperature state at depth of 10-12 km, where may exists an abundant fluid, and a conduit for supplying heat from the mantle to the crust exists at depth of 30~50 km. But a magma conduit being in cooling may exist down to depth of 30 km beneath the older volcanic zone. The two volcanic zones may have the same resource at depth.

在阿尔山活火山区一条北北西向测线上进行了7个大地电磁测深点的观测。2-D解释结果表明，研究区内新、老两条火山带可能存在通往深部的岩浆通道。其中，新发现的活火山带地下在10~12km还保持着较高的热状态，很可能富含流体，在30~50km处可能是地幔向上的供热通道；而老火山带30km以上可能存在一个正在冷却的岩浆通道，两条火山条带的深部可能是同源的。

The measurement of electromagnetic field at two sites in Hanwang and Chouziba for monitoring aftershock series has been done in continuous observation after the M s 8.0 Wenchuan earthquake on May 12, 2008. The measurement was done in two periods. Recorded data covered 35 aftershocks with magnitude more than M s 4.0. Comparing with the seismic data recorded at Hanwang station for 15 events, the coseismic signal of aftershocks exists on all components of the magnetic and electric fields at two different sites. The EM coseismic signals arrived simultaneously with the seismic waves,but not at the origin time of the earthquake. The signal produced at the origin time of the earthquake is much smaller than coseismic signal of the waves. It can′t be identified from the time series. In addition, the generation of coseismic electromagnetic signals can be explained by earthquake dynamo mechanism. Analysing and comparing the relationship between the seismic displacement and EM coseismic signals，the mechanism of EM coseismic signal generation appear to be driven by seismic waves. That is，the EM observation system set up in geomagnetic field moved with the ground motion so that the EM coseismic signals were produced. The observations of seismic displacement and electromagnetic signals verified it.

汶川5.12大地震发生后，在武都汉王地震台及其附近地区布置了2个大地电磁测深点，进行了两期余震序列的地震电磁效应连续监测，共观测到 M s 4.0及以上的余震事件35次.通过与汉王强震台的地震记录数据中15个强震记录比较发现，与地震波相对应的地震同震电磁信号存在于所有的电场和磁场记录分量中，它们与地震波到达同步.地震破裂发生时的电磁辐射信号在记录数据中相比地震波达到观测点的电磁信号幅度要小得多，无法从观测数据识别出来.通过分析对比地震位移和同震电磁信号的关系，提出了地震电磁同震信号产生的地震波驱动机理，认为观测系统在地球基本磁场中随地面运动产生了地震同震电磁信号，并从观测的地震振动位移和电磁信号进行了验证.

The Anqiu-Juxian Fault is a major branch fault and an active prominent fault of the Yishu Fault belt. The spatial distribution, geometric features and the latest activities of the Anqiu-Juxian Fault are studied by field survey and mapping in this study. The northern segment of the Anqiu-Juxian Fault between Juxian and Changyi can be divided into four segments, namely from north to south, the Changyi-Nanliu segment, the Anqiu-Mengtuan segment, the Qingfengling segment and the Mengyan segment. These segments are left-step en echelon arranged, and each of the fault segments consists of right-step en echelon arranged sub-segments. The Changyi-Nanliu segment is about 31km long and composed of 4 sub-segments in right-step en-echelon arrangement, namely, Wenshan sub-segment, Zhuli sub-segment, Shuangguan-Meicun sub-segment and Nanliu sub-segment, from north to south. The length of these sub-segments is 5km, 7km, 10km and 9km, respectively. The width of the stepover between them is about 2～3km. The Changyi-Nanliu segment generally strikes～15°, and the fault plane dips both west and east with dip angle 70°～80°. This segment offsets the widely distributed eolian yellow or orange fine sand and silt that were formed in the latest late Pleistocene, and it also offsets the mid-Holocene grey-yellow clay. The latest active age of the Changyi-Nanliu segment is the middle and late Holocene. This segment is characterized by right-lateral strike-slip motion with thrust and normal fault component, and the normal faulting activity is usually younger than the reverse faulting activity. The Anqiu-Mengtuan segment is about 50km long and exposes～21km. It strikes 15°～20°with the major fault plane dipping NWW with dip angle 70°～80°. This fault segment is characterized by right-lateral strike-slip motion with west-to-east thrust component. The segment can also be divided into two sub-segments, namely, the 13km long Anqiu-Guangong sub-segment and the 8km long Anshang-Mengtuan sub-segment, as in right-step en echelon arrangement, with a stepover of about 3km in width. The youngest offset stratum along the Anqiu-Mengtuan segment is the late Pleistocene, so, its latest active age is the late Paleocene and early Holocene. The Qingfengling segment is about 32km long, striking 15°～20°, dipping mainly southeast and partly west with dip angles more than 60° generally. This segment is characterized by right-lateral strike-slip motion with minor thrust component. It is composed of 4 sub-segments, which are the Xiaodianzi-Henhushan sub-segment, Kushan-Chezhuang, Maobu and Wangtaizi sub-segment, respectively from north to south. The length of these sub-segments is 6km, 8km, 14km and 4km, respectively. The former three sub-segments are aligned right-laterally. The Qingfengling segment offsets the upper late Pleistocene and the early Holocene strata; its latest active age is the early Holocene. The Mengyan segment exposes about 20km, striking 20° and dipping northwest with dip angle ～70°. It is also characterized by right-lateral strike-slip motion with thrust component, and its latest active age is the early Holocene. The only historical earthquake that occurred on the north segment of the Anqiu-Juxian Fault between Juxian and Changyi is the 70BC Anqiu M 7 earthquake. However, paleo-earthquake researches show that several strong earthquakes occurred along the Qingfengling segment and the Mengyan segment between the latest late Pleistocene to early Holocene. The time of the latest strong earthquake is ～3 500a BP, 2 084a BP (-70BC), ～10 000a BP, ～10 000a BP on the Changyi-Nanliu segment, Anqiu-Mengtan segment, Qingfengling segment, and Mengyan segment, respectively. Since the strong earthquake recurrence interval is still not known for each segment, the exact time for the next strong earthquake can't be predicted. However, according to the geometric features, latest active age, latest activity features, historic earthquake data and paleoearthquake documents of this active fault, the 4 segments do have seismotectonic conditions for generating M≥7 earthquake, and the potential earthquake risk does exist and may be rather high and imperative. Thus, the fault activities and the potential earthquake hazard should be considered during future earthquake hazard prevention and prediction.

安丘-莒县断裂是沂沭断裂带的主要分支之一, 也是最主要的一条活动断裂。通过断裂活动性调查和地质填图, 查明了安丘-莒县断裂北段的空间展布、几何结构以及最新活动特征。在莒县至昌邑一带, 安丘-莒县断裂自北向南大致可划分为昌邑—南流段、安丘—孟疃段、青峰岭段和孟堰段等4个段落。它们以左阶斜列形式展布, 而每个断层段又由更次一级的段落以右阶斜列的形式组成。昌邑—南流断层段的最新活动时代为全新世中晚期, 除右旋走滑断层活动外, 还观察到逆冲和正断运动分量, 其中正断运动分量的发生时代较新。安丘—孟疃和青峰岭2个断层段以右旋走滑运动为主, 兼有逆冲运动分量, 最新活动时代分别为晚更新世和全新世早期。孟堰断层段也以右旋为主兼具逆冲分量, 最新活动时代为全新世早期。安丘—孟疃断层段公元前70年曾发生过安丘7级地震, 结合断层活动性质和最新活动时代综合判断, 山东莒县以北的安丘-莒县断裂的未来地震危险性较大, 在今后的地震灾害防御和地震预测工作中应予以重视。

Magnetotelluric data along a profile in the East Dabie Mountains has been collected along the profile across the ultra_high pressure metamorphic belt of NNE direction. According to the two_dimensional electrical structure of crust_upper mantle of the Dabie orogen, the North Huaiyang tectonic belt and Dabie block are different tectonic units in electrical structure. They are separated by the Xiaotian_Mozitan fault, which dips north and shows decoupling at the mid_upper crust level. Four electrical layers can be determined from surface to depth, which are the surficial weathering layer, the mid_upper crust high resistivity layer, the inner_crust relatively high conductive layer and the mantle layer. In the Dabie block, the mid_upper crust is mainly of high resistivity, corresponding to the distribution area of high_ultrahigh pressure metamorphic rock, its thickest place is between Yuexi and Yingshan. In the Dabie block, theremaybe exist channels of granitic magma activity of the Yanshan Period, which make further uplift of the ultra_high pressure metamorphic rocks and affect the distribution of inner_crust high conductive layers and cause great difference in depth of the high conductive layer.

通过在大别造山带东部横穿超高压变质带的一条NNE向剖面大地电磁测深资料的分析解释，获得了关于沿剖面的地壳上地幔二维电性结构，显示北淮阳与大别地块是电性差异显著的构造单元，它们之间的界面与晓天—磨子潭断裂对应；晓天—磨子潭断裂倾向北，在中上地壳层位出现错动解耦现象；从地表向深处可划分出4个主要电性层：地表风化层、中上地壳高阻层、壳内相对高导层以及上地幔层；大别地块内中、上地壳层位以高阻层为主，与高压-超高压变质岩分布区对应，高阻层最厚处在岳西—英山之间；在大别地块内，推测存在燕山期花岗质岩浆活动的通道，它们造成了超高压变质岩的进一步抬升，同时影响了大别地块内存在的壳内相对高导层的分布，壳内相对高导层在层位上相差较大.

The contact area between the West Qinling orogen zone and North-South seismic tectonic zone (31 degrees N-36 degrees N; 104 degrees E-108 degrees E) represents a special conjunction between the large-scale NS and EW trending tectonic zones in China mainland. Two magnetotelluric (MT) sounding profiles (LMS-L3 and DBS-L1), located on either side of 106 degrees E, cross through this area. They also pass through the Qingchuan section, that was ruptured by strong aftershocks of the Wenchuan M8 event in 2008, as well as the unruptured Ningqiang section of the northeastern Longmenshan fault. Using the MT data collected on these two profiles, this work attempts to reveal the deep electric structure beneath this area. Data processing and analysis include calculation of the electric strike and 2D skewness of the area using MT phase vector decomposition, and NLCG 2D inversion on apparent resistivity and phase data of TE + TM modes. The results from inversion show that the Chenxian basin northern fault and Kangxian fault, both lie in the West Qinling orogen zone, extend downward by several tens kilometers, and the Kangxian fault dips toward north at a bigger angle than that of the Chenxian basin northern fault. In the study area, mutual connection of high-resistivity bodies at depth characterizes the southern section of the West Qinling orogeny zone, Bikou block and northeastern Longmenshan fault, of which the angles becomes steeper to south, resulting in electric boundaries. The two MT profiles reveal that low-resistivity layers are present at depth west of 106 degrees E, while no such character appears on the east side, instead a high-resistivity body exists there. The difference of deep electric structure on opposite side of 106 degrees E is consistent with the seismic velocity structure, likely associated with differential distributions of middle-sized and major earthquakes in this region. Besides, within the Qingchuan section (ruptured) and Ningqiang section (unruptured) of the northeastern Longmenshan fault, deep electric structure beneath the Pingwu-Qingchuan fault exhibits various features, i.e. electric property changes much in the Qingchuan section while changes little in the Ningqiang section. An intact high-resistivity body is found at depth below the Ningqiang section, and the aftershocks of the 2008 Wenchuan event terminated near the Qingmuchuan town, closely related to the, eastward extension depth and distance of the Pingwu-Qingchuan fault, meanwhile an intact high-resistivity body in the Ningqiang section blocks the aftershocks development of the 2008 Wenchuan event to the northeast along Longmenshan.

西秦岭造山带与南北地震构造带接触区是中国大陆最重要的南北向和东西向构造转化的接合部位之一.本文介绍了分别位于该区106°E东、西两侧的LMS-L3和DBS-L1两条大地电磁剖面的探测结果，两条剖面分别跨过了龙门山构造带东北段的青川段和宁强段.采用大地电磁相位张量分解技术对两条剖面上各测点的电性走向、二维偏离度等进行了计算和分析，采用NLCG二维反演方法对TE+TM模式的视电阻率和阻抗相位数据进行了二维联合反演.反演得到二维电性结构，在经度106°西侧LMS-L3剖面的深部电性结构自北向南揭示出，西秦岭北缘、成县盆地北缘、康县（即勉略构造带）和平武-青川断裂带都表现为明显的电性梯度带，深部延伸可达几十公里；西秦岭造山带、碧口地块与龙门山构造带东北段3个构造单元整体表现为高电阻体、呈现往南叠合且角度逐渐变陡的趋势.在106°E西侧西秦岭造山带区域的深部存在壳内低阻层，而东侧区域表现为高电阻体，深部电性结构在106°E东、西两侧的差异与该区深部速度结构特征一致，东、西两侧深部结构差异可能是该区中强地震分布差异的深层原因.LMS-L3和DBS-L1两条剖面南段的深部电性结构图像揭示出龙门山构造带东北部的青川段和宁强段内的平武-青川断裂带具有明显不同的深部结构特征，平武-青川断裂带在青川段为明显的电性梯度带，在宁强段不再表现为电性梯度带，而是完整的高电阻块体.汶川强余震向东北发展止于青川青木川附近，与平武-青川断裂带延伸深度和向北东方向的延伸长度密切相关，同时高电阻块体的宁强段对汶川强余震东北发展起到了阻挡作用.

The earthquake precursors are related to various geophysical observational techniques and their metric units are also different. Therefore, the direct quantitative comparistion among various precursory anomalies is impossible. This brings difficulty to predict earthquake. Aimed at this technical difficulty, anomaly subordinate function μ(non\|dimensional value) is used to normalize precursory anomalies of different property and metric units. Based on the calculation of subordinate function with the geomagnetic data Cangshan earthquake of Ms5.2 (sept.20,1995) has obvious precursory anomalies. The recognition of true anomalies is improved. Some questions are proposed and must be paid attention in applying magaetic precursors for eaithquke predition.

地震前兆涉及到多种地球物理观测方法，且计量单位各不相同，因此，各类前兆异常之间无法进行直接的定量对比，这给地震预报研究带来了困难.应用异常从属函数值（无量纲量）可统一规划不同性质、不同计量单位的地震前兆异常.本文通过研究地磁资料从属函数，发现1995年9月20日山东苍山Ms5.2级地震前有明显的前兆异常.增强了对地震前兆异常的识别能力，文中提出该方法在地磁场研究中应注意的问题.

Magnetotelluric(MT) data along about 150km profile has been collected along the profile across the central Tan-Lu fault zone(Yi-Shu fault zone,36°N ).The observational data of this survey are processed by using the Robust method and remote reference technique. Apparent resistivity, impedance phase curves, Skewness and regional strike were anylysed. By means of the NLCG method,2D inversion modeling is performed with the data of two modes TE and TM. The 2D electrical structure along the profile is obtained. The target area can be divided into four electrical conductivity blocks, which separately correspond to the Lu-Xi uplift, Tan-Lu fault zone, Jiao-Lai depression, and Lu-Dong uplift. There is high resistivity in the uplift area of Lu-Xi and Lu-Dong and low resistivity in the depression of Jiao-Lai. The development and occurrence the earthquakes are closely related to the deep electric structure. The earthquake focus area of three earthquakes around the MT profile are significantly heterogeneous, and the high conductivity layer existed near the hypocenter region.

穿过郯庐断裂带中段（沂沭断裂带，36°N）所做的大地电磁测深（MT）剖面长约150km.使用Robust技术和远参考道大地电磁方法处理观测数据.通过分析视电阻率、阻抗相位、Swift二维偏离度和区域走向，定性确定测区的电性结构.二维反演解释中选择非线性共轭梯度（NLCG）方法，使用TE、TM两种模式资料联合反演，沿剖面的二维电性结构显示：自西向东，鲁西隆起、郯庐断裂带、胶莱坳陷及鲁东隆起4个电性区块分别对应，鲁东和鲁西隆起区为高阻，郯庐断裂带电性结构复杂，高、低阻相间，胶莱坳陷为低阻（高导）区.沿MT剖面附近曾发生3个地震，其震源区处在电性变化剧烈部位，并在震源区附近存在高导体.

Wenchuan earthquakes occurred on May 12, 2008 is not an independent tectonic event confined in a local regions. It is reasonable to study the deep structure of the crust, upper mantle and mantle transition zone combining between the local and regional observation data for understanding the preparation and development of Wenchuan earthquakes. The analysis on Wenchuan earthquake generation in this paper is on basis of electromagnetic measurement data obtained recent years with considering the other data e.g., seismic data, which are relative to three level of tectonic movements, Pacific plate subduction and penetration, collision of India plate with Tibet plateau and pressure of Songpan-Garzê block upon Sichuan block. The stagnant slabs formed by Pacific plate subduction exist generally in the mantle transition zones under eastern China continent of North-South seismic belts, which can not be ignored when the generation of Wenchuan earthquakes are investigated. Both northward and eastward movements of different blocks in the Tibet caused by collision of India plate appear. Their eastward movements act on the eastern margin of Tibet i.e., mid- and south- sections of North-South seismic belt and affect the shocks occurred there including Wenchuan earthquakes. The south-east-east direction along which Songpan-Garzê block moves is approximately normal to Longmenshan faults and formed a T-geometry structure by both of them. The Longmenshan faults are represented by a large steep electric boundary in the resistivity profile. This kind of pattern of deep structure is prone to accumulate the stress before Wenchuan earthquakes and is a direct factor for generation of the earthquakes.

2008年5月12日汶川 M S 8级地震的发生不是局部地区孤立的构造事件，研究汶川地震的孕震机制，应该把局部分析和区域分析相结合，关注地壳上地幔直至地幔过渡带的深部结构.基于近年来在东北、华北和汶川地震附近地区进行的深部结构电磁探测结果，结合地震学等其他资料，从太平洋板块的俯冲、印度板块的碰撞和松潘甘孜地块的推挤三个“层次”探讨分析汶川特大地震的成因.太平洋板块向亚洲大陆的俯冲作用，导致中国大陆东部地幔过渡带深度较普遍地存在着停滞的板片，它对汶川地震的影响不可忽视.印度板块与青藏高原的碰撞，使组成高原的各地块发生向北和向东的运动，各地块向东的运动作用于南北地震带中南段，影响到该区域的地震活动.松潘甘孜地块向四川地块的推挤，使松潘甘孜地块运动方向和龙门山断裂带形成“丁”字形结构，龙门山断裂带显示为较陡直的电性边界，加剧了汶川地震前的应力积累，可能是汶川地震发生的最直接的诱因.

It is shown that the structure of the crust and upper mantle (thickness,geothermal field etc.) beneath the Zhangbei Shangyi earthquake area,which belongs to Inner Mongolia geo axes,has the nature of a transition zone as compared to its surrounding regions,Yanshan mountain fold belt,rifting basin of North China,rift system of Shanxi province and Erdos block.The Zhangbei Shangyi earthquake area is located near the Zhangjiakou Bohai Sea Penglai tectonic belt (ZPB) which is a significant tectonic boundary.Along the ZPB a relative low resistivity zone appears in the whole lithosphere.The width of ZPB is about 40km and becomes bigger with increasing depth.The structure of seismic velocity similar to electricity also occurrs along the ZPB.A NNW trending tectonic belt in the crust is newly detected beneath Zhangbei Shangyi earthquake area.The NNW trending tectonic belt and ZPB are postulated to play an important role in a combining way for pregnancy and genesis of the earthquake.The recent results of magnetotelluric observation indicate that there is a low resistivity layer at the depth of about 15km beneath earthquake area,which is deeper and thinner than that to the south of Shangyi Chongli fault,which is tectonic boundary between Inner Mongolia geo axes and other southern tectonic units.The foci of main shock and most aftershocks are located above the low resistivity layer in the crust.

对张北-尚义地震区及其邻区的深部结构的研究表明,张家口-蓬莱构造带与其两侧的山西裂谷系、华北裂谷盆地和燕山褶皱带相比,具有低阻性质,地壳内的速度界面及莫霍面的深度分布显示出明显的不同。以延怀盆地为界,把张家口-蓬莱构造带分成西北和东南两段。最新的大地电磁观测研究表明,张北-尚义地震区电性结构与周围有一定差别,壳内有一近北北西向构造,主震和绝大多数余震都发生在壳内低阻带以上。

The new experiment of 30 days was carried out at twelve earthquake monitoring stations and a few mobile observatories located in North，South，NE，NW and SW China using Control Source Extremely Low Frequency (CSELF) electromagnetic technique in 2009. The measurement indicates that the artificial electromagnetic signals can be recorded at stations as far as 1700km from the transmitter. The measured electric and magnetic fields and apparent resistivity using CSELF signals have much more powerful ability to resist the interference of cultural noise in comparison to natural electromagnetic signals. They are much more stable than those using natural signals, which is favorable to identifying the anomalous phenomena caused by earthquake. The experiment shows that CSELF is potentially valuable for earthquake research and prediction. It is also found that the recorded electric and magnetic component amplitude of CSELF signal varies depending on the distance and azimuth of the observatories relative to the transmitter. These amplitudes decline with increasing distance between observatory and transmitter faster within some space extent than those outside the extent. It may be easier for magnetic components to have higher ratio of signal to noise than for electric component.

2009年利用大功率人工源极低频电磁技术(CSELF)在位于华北、华南、东北、西北和西南的12个地震台站和几个流动观测点进行了连续30天新的观测试验.结果表明，利用CSELF技术可以在1700 km之外测量到人工源电磁场信号，计算得到的电、磁场功率谱密度和视电阻率与天然源信号相比，抗干扰能力更强，观测信号更稳定，特别有利于识别和捕捉地震等诱发的电磁异常现象，在地震预测监测中具有很大的研究应用潜力.试验还发现，各地震台站和流动测点观测的CSELF信号的强度，与台站或者测量的电、磁场分量相对于发射源的距离、方位有明显的关系；发现在离开发射源的相对近区，场强随距离的衰减，比在相对远区更快；发现接收磁场信号比电场信号较易获得更高信噪比的数据.

The Ordos fault block is a stable block since the Cenozoic time.Whether low-resistivity layers exist in the middle and lower crust of this kind block is an open question.This work attempts to reveal the entire crustal structure of the Ordos fault block based on interpretation of magnetotelluric data collected along the profile across this region.The result shows that a layered structure characterizes the crust of the Ordos fault block,with a low-resistivity layer at depth of about 20km,presumably associated with fluids there.On contrast,in the areas of active tectonics in the east and west of the fault block,there is no such layered electric structure in crust,while the low-resistivity zones may be related with the detachments(or ductile-shear zones) in crust.The difference in electric structure of crust between the Ordos fault block and neighboring areas is of significance to the analysis of activity and deformation in varied blocks.

鄂尔多斯断块作为新生代以来的稳定块体,其中下地壳内是否存在低阻层一直受到关注。基于穿过鄂尔多斯断块大地电磁剖面的观测资料,利用新的数据处理和解释技术,对鄂尔多斯断块的地壳结构进行了整体研究,发现鄂尔多斯断块的地壳具有成层性结构特点,并在约20km深度存在低阻层,推测它是由流体引起的电阻率降低。在断块东、西两侧的构造活动区,其地壳内不存在成层性电性结构,其中的低阻带可能与地壳内的滑脱带(或韧性剪切带)有关。鄂尔多斯断块和周围地区地壳电性结构的不同特点,对于分析不同地块的变形和地震活动性等有一定价值。