海水层对海洋大地电磁勘探的影响研究  

The effect of seawater in the marine magnetotelluric sounding

作　　者：杨进[1] 魏文博[1] 王光锷[1] 

机构地区：[1]地下信息探测技术与仪器教育部重点实验室中国地质大学(北京)

出　　处：《地学前缘》2008年第1期217-221,共5页Earth Science Frontiers

基　　金：国家高技术研究发展计划“863”项目“海底大地电磁探测技术”课题(820-03-04);北京市重点学科资助项目“地球探测与信息技术”(XK104910598)

摘　　要：为了研究海水层对大地电磁测深的影响,建立了一维层状模型并进行计算。结果表明,海水层对电磁场的影响特征主要表现为高频段的影响大于低频段,磁场的影响大于电场,相位的影响大于振幅。针对海洋大地电磁测深中使用远参考道问题,设计了三种二维地电模型(取参考点位于陆地或海底,测点位于海底),并对三种模型的大地电磁响应进行了有限单元法数值模拟,通过异常对比研究表明,在海洋大地电磁测深中可以使用远参考道,获得海底深部介质的地电信息。In order to study the effect of conductive seawater on the telluric electric field and magnetic field and the attenuation characteristic of the fields with different depths of seawater and different conductivities of sea floor, we have set up a one-dimensional layered model to carry out the numerical computation of the MT response. The computation results show that the field attenuation of high frequency is more than that of low frequency, that the attenuation of magnetic field is more than that of electric field, and that the decay rate of phase is faster than that of amplitude. In order to study the feasibility of the remote marine MT sounding, the apparent resistivity in TE mode （E field parallel to the strike） is computed with finite element method and a comparison is made between the results obtained from three models, The comparison results show that the apparent resistivity anomalies at low frequency have little difference in the two cases （using and not using remote field）. Therefore, the electric information of medium below the sea floor can be acquired by using remote MT sounding.

关 键 词：海洋 大地电磁测深 有限单元法 数值模拟 

分 类 号：P736.12[天文地球—海洋地质]