﻿ 基于地磁垂直分量反相位现象的地下畸变电流正演计算
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 大地测量与地球动力学  2019, Vol. 39 Issue (6): 596-601  DOI: 10.14075/j.jgg.2019.06.009

### 引用本文

ZHANG Xin, FENG Zhisheng, YUAN Guiping. Calculating the Distortion Current Based on the Anti-Phase Phenomena of the Geomagnetic Vertical Component[J]. Journal of Geodesy and Geodynamics, 2019, 39(6): 596-601.

### Foundation support

The Spark Program of Earthquake Technology of CEA, No. XH18034Y; Seismic Regime Tracking Project of CEA, No.2018010403.

### 第一作者简介

ZHANG Xin, assistant researcher, majors in crustal deformation observation and electromagnetism, E-mail: zxdqwl@163.com.

### 文章历史

1. 广东省地震局，广州市先烈中路81号，510070;
2. 江苏省地震局，南京市卫岗路3号，210014

1 地磁观测背景和垂直分量反相位现象

 图 1 甘东南及邻区构造及台站分布 Fig. 1 Structure and station distribution of southeast Gansu and adjacent areas

 图 2 地磁Z分量的反相位现象 Fig. 2 Anti-phase phenomenon of geomagnetic Z components

 图 3 反相位现象的电流畸变效应 Fig. 3 Current distortion effect of anti- phase phenomenon
2 正演模型的理论基础

 $B = \frac{{{\mu _0}I}}{{4\pi a}}\left( {\cos {\theta _1} - \cos {\theta _2}} \right)$ (1)

 图 4 线电流和面电流模型 Fig. 4 Line current and surface current model
 $B = \frac{{{\mu _0}I}}{{4\pi \sqrt {{h^2} + {b^2}} }}$ (2)

 ${B_{{\rm{s}}1}} = \frac{{{\mu _0}I}}{{2\pi (b - d)}}\ln \left( {\frac{{b - d + \sqrt {{b^2} + {c^2}} }}{{\sqrt {{b^2} + {c^2}} }}} \right)$ (3)

 ${B_{s2}} = \frac{{{\mu _0}I}}{{2\pi a}}\ln \frac{{\sqrt {{{(b - a/2)}^2} + {h^2}} }}{{\sqrt {{{(b + a/2)}^2} + {h^2}} }}$ (4)

 图 5 线电流的感应磁场分布 Fig. 5 The geomagnetic field induced by line current

 图 6 竖直面电流的感应磁场 Fig. 6 The geomagnetic field induced by vertical surface current

 图 7 线电流和面电流叠加的感应磁场 Fig. 7 The geomagnetic field induced by line current and surface current superposition
3 电性结构约束下的正演结果

 图 8 基于实际电性结构的电流模型(黑色数字为模型1距离，红色为模型2距离) Fig. 8 The current model based on actual electric structure

 图 9 倾斜面电流的感应磁场空间分布 Fig. 9 The spatial distribution of geomagnetic field induced by the tilting current

4 讨论与结论

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Calculating the Distortion Current Based on the Anti-Phase Phenomena of the Geomagnetic Vertical Component
ZHANG Xin1     FENG Zhisheng2     YUAN Guiping2
1. Guangdong Earthquake Agency, 81 Middle-Xianlie Road, Guangzhou 510070, China;
2. Jiangsu Earthquake Agency, 3 Weigang Road, Nanjing 210014, China
Abstract: We simulate and calculate the spatial distribution and the time dependent characteristics of the induced geomagnetic under different depths, intensities and changes. In addition, the distortion current intensity and distribution depth before the Minxian-Zhangxian MS6.6 earthquake in 2013 are calculated based on the electrical structural results of magnetotelluric sounding in the southeast of Gansu province. The difference between the superposition effect on the Z component and the measured data is very small. The model explains the site of a large range low point displacement before the earthquake, and the method may also be used in other areas with low point displacement with clear electrical structure.
Key words: geomagnetic low point displacement; distortion current; earthquakes; electrical structure