Straightforward inversion scheme (SIS) for one-dimensional magnetotelluric data     

P. K. Gupta  Sri Niwas  V. K. Gaur 《Journal of Earth System Science》1996,105(4):413-429

This paper presents a Straightforward Inversion Scheme (SIS) for interpreting one-dimensional magnetotelluric sounding data. The basic steps of SIS are (i) parameterization of the layered model such that the layer thickness, expressed in units of its skin depth, is a constant (α); (ii) expansion of the reflection function at each interface as a power series in parameter u = exp(-2(1 +j)α√f);(iii) development of a recurrence relation between the coefficients of the same powers ofu in the power series of reflection functions of any two successive layers; (iv) estimation of the impedance power series coefficients using regressed minimum norm estimator; and (v) evaluation of layer resistivities and thicknesses using the inverse recurrence relation. The power of SIS is established by inverting four synthetic data sets and two field data sets. The effect of noise is extensively studied on a synthetic data set, deliberately corrupted with increasing levels of Gaussian random noise up to 25%. It is found that the scheme can retrieve broad features of the true model even with noise levels as high as 25%. On the basis of findings of different experiments conducted on SIS, it is concluded that SIS is an efficient, robust algorithm with high resolving power. Further, being linear, it is non-iterative and it dispenses with the requirement of having to choose an initial guess model.  相似文献   

Study on new optimum parameters in MT repeated survey     

张云琳  刘晓玲  安海静  司玉兰  蒋梅  张五四  李志雄 《地震学报(英文版)》1994,7(4):603-610

（张云琳,刘晓玲,安海静,司玉兰,蒋梅,张五四,李志雄）ＳｔｕｄｙｏｎｎｅｗｏｐｔｉｍｕｍｐａｒａｍｅｔｅｒｓｉｎＭＴｒｅｐｅａｔｅｄｓｕｒｖｅｙ￥Ｙｕｎ－ＬｉｎＺＨＡＮＧ;Ｘｉａｏ－ＬｉｎｇＬＩＵ;Ｈａｉ－ＪｉｎｇＡＮ;ＭｅｉＪＩＡＮＧ;Ｚｈｉ－Ｘ...  相似文献   

Electrical Structure and Fault Features of Crust and Upper Mantle beneath the Western Margin of the Qinghai-Tibet Plateau： Evidence from the Magnetotelluric Survey along Zhada-Quanshui Lake Profile   总被引：1，自引：0，他引：1  

金胜叶高峰  魏文博邓明 景建恩 《中国地质大学学报(英文版)》2007,18(4):326-333

The magnetotelluric (MT) survey along the Zhada (札达)-Quanshui (泉水) Lake profile on the western margin of the Qinghai (青海)-Tibet plateau shows that the study area is divided into three tectonic provinces by the Yalung Tsangpo and Bangong (班公)-Nujiang (怒江) sutures. From south to north these are the Himalayan terrane, Gangdise terrane, and Qiangtang (羌塘) terrane. For the study area, there are widespread high-conductivity layers in the mid and lower crust, the top layers of which fluctuate intensively. The high-conductivity layer within the Gangdise terrane is deeper than those within the Qiangtang terrane and the Himalaya terrane, and the deepest high-conductivity layer is to the south of the Bangong-Nujiang suture. The top surface of the high-conductivity layer in the south of the Bangong-Nujiang suture is about 20 km lower than that in the north of it. The high-conductivity layer within the Gangdise terrane dips toward north and there are two high-conductivity layers within the crust of the southern Qiangtang terrane. In the upper crust along the profile, there are groups of lateral electrical gradient zones or distortion zones of different scales and occurrence indicating the distribution of faults and sutures along the profile. According to the electrical structure, the structural characteristics and space distribution of the Yalung Tsangpo suture,Bangong-Nujiang suture, and the major faults of Longmucuo (龙木错) and Geerzangbu are inferred.  相似文献   

Magnetotelluric resistivity modeling for 3D characterization of geothermal reservoirs in the Western side of Mt. Aso, SW Japan   总被引：1，自引：1，他引：1  

Hisafumi Asaue  Katsuaki Koike  Toru Yoshinaga  Shinichi Takakura   《Journal of Applied Geophysics》2006,58(4):296

Geothermal reservoirs are usually located at a depth range of 2 to 5 km, so to efficiently utilize such resources an advanced prospecting method is needed to detect these deep geologic structures. This study aimed to three-dimensionally characterize geothermal reservoirs by a combination of Magnetotelluric (MT) survey, inversion analysis of apparent resistivity, and interpolation of the resistivity data obtained. The western side of Mt. Aso crater, southwest Japan, was chosen as the case study area. Three hot springs exist there and a fault is assumed to go in the direction connecting them. A MT survey was carried out at 26 sites and the data processed by a remote reference method to reduce artificial noises. Based on skewness and Mohr circle analyses of the impedance tensor, the local geologic structure at each site could be approximated as horizontally layered and therefore, a one-dimensional inversion analysis was applied to the MT raw data. The resultant resistivity column data were then interpolated by the three-dimensional optimization principle method. The resistivity distributions obtained clarified continuous conductors with especially low resistivity (less than 10 Ω·m) at the hot springs along the fault. Because the resistivity decreases largely with an abundance of clay minerals, the conductors could be considered to correspond with the cap rocks. Thus, two geothermal reservoirs, whose shapes were estimated to be pillar, were detected under the cap rocks in an elevation range of − 1000 to − 3000 m. By comparing the resistivity distributions with the temperature distributions based on fluid-flow calculations at a steady state using FEM, the validity of the location and dimension of the estimated reservoirs were confirmed.  相似文献   

电磁法在新疆干旱区找水效果及适应性探讨   总被引：1，自引：0，他引：1  

王卫江  兰险  刘学清 《新疆地质》2004,22(3):265-270

运用加拿大PHOENIX公司V5系统MT大地电磁法、美国GEOMETRICS公司EH-4系统电导率成像法、加拿大PHOENIX公司V5(2000)系统CSAMT可控源音频磁大地电流法、V5(2000)系统TDEM瞬变电磁法及法国IRIS公司NUMIS系统NMR核磁共振法，住新疆典型干旱水类型已知条件区开展找水试验研究工作，探讨新疆典型干旱水类型区几种先进的电磁法及其有效性、适应性，对今后在新疆干旱区开展电磁法找水工作提供参考．  相似文献   

二维倾斜地形对大地电磁资料的影响与地形校正   总被引：4，自引：0，他引：4       下载免费PDF全文

晋光文  赵国泽 《地震地质》1998,20(4):167-458

二维倾斜地形影响,主要使ＴＭ极化模式的视电阻率降低。数值模拟结果证明,倾角小于１０°时,地形影响可以忽略,随着倾角的增大,地形影响急剧加强。同时,倾斜地形影响与周期有关,周期愈长,影响愈甚,而且,当倾角增大时,开始出现显著影响的周期提前。利用带地形均匀半空间与水平均匀半空间的电磁响应,计算出校正系数,进而可以消除或降低地形影响  相似文献   

Shallow crustal structure of Chicxulub impact crater imaged with seismic, gravity and magnetotelluric data: inferences about the central uplift     

J. O. Campos-Enríquez  F. J. Chávez-García  H. Cruz  J. G. Acosta-Chang  T. Matsui  J. A. Arzate  M. J. Unsworth  J. Ramos-López 《Geophysical Journal International》2004,157(2):515-525

  相似文献   

MT剖面透视新方法与托来6．0级地震     

张云琳  刘伟  安海静  陈运平  李志雄  刘晓玲 《中国地震》2001,17(1):82-91

在近10余年观测研究的基础上，采用高精度MMSO2E系统，在青藏高原北缘祁连山地震危险区，建立了国内外第一个初具规模的MT透视剖面，研究区不仅电磁干扰背景较弱，而且地震活动性较强，自1986年以来，我们已经获得了11次5－7级地震前后的宝贵资料，在研究这些资料的基础上，提出了一些有意义的认识和结论，对观测资料进行了全定量化的误差分析，评估了MT响应参数和复合二元相关度和可信限，论述了MT剖面透视资料的可靠性和可信性，对介质导电性和电性横向非均匀性动态变化的原因进行了讨论，研究表明，MT剖面透社为大陆坡坏地性地震的中短期预测及震源物理发展过程提供了定量化的多参数指标体系。  相似文献   

Identification and Correction for MT Static Shift Using TEM Inversion Technique     

Yang ChangfuDepartment of Earth Science  Nanjing University  Nanjing Lin ChangyouLanzhou Institute of Seismology  China Seismological Bureau  Lanzhou 《中国地质大学学报(英文版)》2001,12(3)

ＩＮＴＲＯＤＵＣＴＩＯＮＴｈｅｆｉｅｌｄａｎｄｔｈｅｏｒｅｔｉｃａｌｓｔｕｄｉｅｓｓｈｏｗｔｈａｔｉｎｔｈｅｐｒｅｓｅｎｃｅｏｆｎｅａｒ ｓｕｒｆａｃｅｉｎｈｏｍｏｇｅｎｅｉｔｉｅｓ ,ＭＴａｐｐａｒｅｎｔｒｅｓｉｓｔｉｖｉｔｙｃｕｒｖｅｓｏｎｔｈｅｌｏｇａｐｐａｒｅｎｔ ｒｅｓｉｓｔｉｖｉｔｙｖｅｒｓｕｓｌｏｇｆｒｅｑｕｅｎｃｙｄｉｓｐｌａｙａｒｅａｌｗａｙｓｓｈｉｆｔｅｄｉｎｌｉｎｅｗｉｔｈａｆａｃｔｏｒ ,ｃｏｎｓｔａｎｔｉｎａｌｌｆｒｅｑｕｅｎｃｉｅｓ ,ｗｉｔｈｔｈｅｉｍｐｅｎｄｅｎｃｅｐｈａ…  相似文献   

四川大足-福建泉州深部地电特征   总被引：8，自引：3，他引：8       下载免费PDF全文

蒋洪堪  战双庆 《地球物理学报》1992,35(2):214-222

根据四川大足-福建泉州剖面的大地电磁测深结果,划分了低阻的中新生界、高阻的三叠系-古生界以及相对低阻的浅变质的元古界板溪群等;了解了一些岩体的底界深度,推断沅麻盆地5 km以下出现岩脉群. 武陵山重力梯度带附近,中下地壳至上地幔岩石层有很高的电阻率,它和梯度带的形成有关.华南褶皱系普遍存在壳内高导层,它和爆破地震所反映的壳内低速层的位置相近. 深部电性证明,华蓥山断裂带、茶陵断裂带和福安-南靖断裂带等是深、大断裂带. 上地幔岩石层在横向上具有不同的电阻率.软流层深度自西向东由120-150kin变化到76km,衡阳以东最深可达240km. 由软流层变化及断裂分布,认为扬子准地台和华南褶皱系两大构造单元的分界位于茶陵-永兴断裂附近.  相似文献