| 大地电磁测深数据处理——4元素和6元素阻抗张量元素的比较研究(英文) |
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| 作者姓名： | M.Shireesha T.Harinarayana |
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| 作者单位： | 印度国家地球物理研究所 |
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| 摘 要： | 阻抗张量元素的计算是在大地电磁测深数据处理的重要一步。按照常规,阻抗张量被定义为以Zxx,Zxy,Zyx,和Zyy为元素的2×2矩阵。在本次研究中,6个元素的阻抗张量的计算使用了一个含有Zxx,Zxy,Zyx,Zyy,Zxz和Zyz分量的2x3矩阵。对上述两类阻抗张量元素的属性进行了分析。利用由印度古吉拉特邦卡奇沉积盆地采集的5个分量大地电磁数据测试了文中的方法。从视电阻率和相位的计算中我们是观察到在大部分的频带范围内4个元素阻抗和6个元素阻抗Zxy和Zyx两类元素区别不大。然而,较长周期时间的数据,如超过100秒,观察到视电阻率的增加和相位的减少。我们还注意到,倾子幅度在大部分时间几乎是零,但较长周期(超过100秒),逐渐呈增加的趋势。卡奇沉积盆地的地电断面表明在较长的周期内浅层近水平层和深层异常高电导性的不均质层都可能是引起大的Hz分量的原因。这表明,磁场垂直分量Hz对在大的2D/3D结构区域内的电场参数估计发挥的重要作用。
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| 关 键 词： | 大地电磁 阻抗张量 电场 |
Processing of magnetotelluric data - a comparative study with 4 and 6 element impedance tensor elements |
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| M.Shireesha,T.Harinarayana.Processing of magnetotelluric data - a comparative study with 4 and 6 element impedance tensor elements[J].Applied Geophysics,2011,8(4):285-292. |
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| Authors: | M Shireesha T Harinarayana |
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| Institution: | 1. National Geophysical Research Institute, Hyderabad, 500007, India
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| Abstract: | Computation of impedance tensor elements is one of the important steps in magnetotelluric data processing. Conventionally,
the impedance tensor is defined as a 2 × 2 matrix with Zxx, Zxy, Zyx, and Zyy as elements. In the present study, the six-element
impedance tensor is computed with a 2 × 3 matrix using Zxx, Zxy, Zyx, Zyy, Zxz, and Zyz. The properties of the impedance tensor
elements have been analyzed for these above two types. The methodology has been tested with five component magnetotelluric
data from the Kutch sedimentary basin, Gujarat, India. From the computation of apparent resistivity computation and phase
we observed that there is small difference between the four and six impedance elements of Zxy and Zyx for most of the frequency
band. However for longer period data, more than 100 sec, an increase in the apparent resistivity and decrease in the phase
is observed. We also note that the tipper magnitude is nearly zero for most of the periods, but gradually shows an increasing
trend for longer periods (>100 sec). The Kutch sedimentary basin geoelectric section shows near horizontal layers at shallow
depths and anomalous high conductivity heterogeneous layers at deeper depths may be responsible for the large Hz component
at longer periods. This indicates that the vertical component of the magnetic field, Hz, does play an important role in the
estimation of electric field parameters in the region with large 2D/3D structures. |
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| Keywords: | magnetotelluric data impedance tensor |
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