Electromagnetic Study of the Stagnant Slab

本项目旨在研究由地震层析成像证实存在的静止板的电学特征，该项目于2003年至2005财政年度在俄罗斯中国东北地区和普里莫尔斯基地区进行了三年的研究。在中国东北部分的吉林和辽宁两省，与中国地震局地质研究所赵国章教授合作，利用电话线观测了电场变化。我们成功地获得了吉林3条线路和辽宁4条线路的高质量电场数据。长春地磁观测站也记录到了地磁场变化的三个分量，海洋半球磁强计系统自1998年以来一直在该观测站运行。我们还研究了我国以往的大地电磁测量成果，绘制了研究区近地表电导图，用于校正电偶效应对长周期电感…的影响。更多关于陆地-海洋分布或近地表电导率结构的响应。在俄罗斯远东的Primorski区，我们与V.A.Nikiforov教授和他的团队合作。尽管我们花费了比预期更多的时间来获得联邦当局的许可，但我们最终使用了两对相距约30公里的电极，获得了地电变化的记录。当地电话线被用来连接这些电极，使我们能够几乎在N-S和E-W方向进行测量。我们还得到了俄罗斯方面的一些大地电磁结果，我们仔细分析了所获得的数据，研究了研究下地幔电导率的一维分布和横向变化，一直到过渡带。结合电导率研究、P波层析成像和高压实验的结果，我们估计了该地区地幔中水的分布。本研究的成果发表在下列国际期刊上。较少

This project aimed to study electrical signature of the stagnant slab whose presence was well established by seismic tomography, and was carried out in the Northeaster district of China and the Primorski region of Russia for three years from 2003 to 2005 fiscal year.In Jilin and Liaoning provinces of the NE part of China, observations of electric field variations were made by using telephone lines collaborating with Professor G.Z.Zhao of Institute of Geology, China Earthquake Administration. We successfully obtained high-quality electric field data from 3 lines in Jilin and 4 lines in Liaoning provinces. Three components of geomagnetic field variations were also recorded at Changchun magnetic observatory where an Ocean Hemisphere Magnetometer System has been operating since 1998. We also investigated past results of magnetotelluric surveys done by Chinese, and made a map of near-surface conductance in the study area which is useful for correcting galvanic effects on long period inducti … More on responses by land-ocean distribution or near-surface conductivity structure.In the Primorski district of Far-east Russia, we collaborated with Professor V.A.Nikiforov and his group. Though we spent much time to get permissions from federal authorities more than expected, we finally obtained a record of geo-electric variations, by using two pairs of electrodes that were installed about 30km apart from each other. Local telephone lines were used to connect these electrodes that enabled us to make measurements nearly in N-S and E-W directions. We also obtained some magnetotelluric results that had been done by Russian side.We carefully analyzed data thus obtained, and studied the one-dimensional distribution and lateral variation of the electrical conductivity in the mantle beneath the study are down to the transition zone. Combining results from this conductivity study, P-wave tomography, and high pressure experiments, we estimated the distribution of water in the mantle of this region. Results obtained in the present study were published in international journals as listed below. Less