Three Dimensional Electromagnetic Prospecting System for Deep Crust Structure

地壳深部结构三维电磁勘探系统

• 批准号: 11555268
• 负责人: MOGI Toru
• 金额: $ 5.18万
• 依托单位: HOKKAIDO UNIVERSITY
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B)
• 财政年份: 1999
• 资助国家: 日本
• 起止时间: 1999 至 2001
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-11555268/
• 关键词: EM Survey; 3D modeling; 3D inversion; 電磁気探査; 地殻構造探査; 地質構造探査

The purpose of this study was constructing an appropriate survey system to image three dimensional (3D) subsurface resisitivity structure using the magnetotelluric (MT) method.We developed the data processing scheme involving the robust stacking method based on the "M parameter" estimation, the impedance estimation method using Singular Value Decomposition of the data matrix and impedance smoothing method based on the Hirbert transformation between phase and impedance. We have verified the effectiveness of these techniques.We also developed a high accuracy 3D EM modeling scheme based on the staggered grid finite difference method. We tried to improve the condition of a large size coefficient matrix to easily solve and have overcome the problem of high resistivity contrast model and topography model in this scheme. The 3D inversion scheme based on the ABIC constrained smoothness least square method was modifying to apply a actual field data.We carried out MT survey at 25 sites distributed like a grid in the Nakatonbetsu area, Northern Hokkaido as a demonstrative research for the survey system developed in this research. We used MTU5 wide band MT survey machine and obtained electric and magnetic field data at 40 frequencies in the range of 380-0.00055 Hz. To obtain lower frequency data, we carried out MT observation using the fluxgate type magnetometer over two months. A reasonable 3D resistivity structure was imaged but the result suggested that we need further study to improve the resolution at deeper part

为建立大地电磁（MT）三维电阻率结构成像系统，提出了基于“M参数”估计的稳健叠加方法，利用数据矩阵的奇异值分解和基于相位和相位之间的希尔伯特变换的阻抗平滑方法，阻抗本文还提出了一种基于交错网格有限差分法的高精度三维电磁建模方法。该方案对系数矩阵的大尺寸条件进行了改进，使其易于求解，克服了高电阻率对比度模型和地形模型的问题。本文对基于ABIC约束平滑最小二乘法的三维反演方法进行了改进，使之适用于实际的野外数据，并在北方北海道中屯别地区的25个网格状测点进行了大地电磁测量，作为本研究开发的测量系统的示范性研究。我们使用MTU 5宽频带MT测量机，获得了380-0.00055 Hz范围内40个频率的电场和磁场数据。为了获得低频数据，我们用磁通门型磁力仪进行了两个多月的MT观测。三维电阻率结构成像合理，但仍需进一步研究，以提高深部分辨率

项目成果

Fomenko, E., Mogi, T.: Proceedings of 105SEGJ conference. 32-35 (2001)

Fomenko, E.，Mogi, T.：105SEGJ 会议记录。

梶原竜哉: "MT法データによる森地熱地域の比抵抗構造"物理探査学会第100回学術講演会講演論文集. 202-206 (1999)

梶原龙也：《基于MT法数据的森地热区电阻率结构》物理勘探学会第100届学术会议论文集202-206（1999）。

Elena Y.Fomenko, Toru Mogi: "A new computation method for staggered grid of 3D EM field conservative modeling"Earth, Planets and Space. 54・4(In press). (2002)

Elena Y.Fomenko、Toru Mogi：“3D 电磁场保守建模的交错网格的新计算方法”地球、行星和空间 54・4（印刷中）。

Elena Y. Fomenko, Toru Mogi: "A new computation method for staggered grid of 3D EM field conservative modeling"Earth, Planets and Space. 54-3(In press). (2002)

Elena Y. Fomenko、Toru Mogi：“3D 电磁场保守建模交错网格的新计算方法”地球、行星和空间。

Hendra Grandis, Toru Mogi, Djedi S.Widarto: "Thin-Sheet Electromagnetic Modelling Example from two Exteme Scales."物理探査学会第103回学術講演会講演論文集. 192-196 (2000)

Hendra Grandis、Toru Mogi、Djedi S.Widarto：“两个极端尺度的薄板电磁建模示例”，物理探索学会第 103 届学术会议论文集（2000 年）。