论文部分内容阅读
对近十年来发展起来的海底电磁法作了综述，重点放在可控源时间域上。类似于航空电磁法可对陆地上的经济带进行电导率填图一样，可控源海底电磁法也可在数十米的范围内对海底进行电导率填图。海底的电导率通常远小于海水的电导率，理论研究表明可控源时域水平电偶极子及水平磁偶极子系统能用来精确地确定海底的电导率。这两种装置对两个半空间的响应会在时间轴上出现两个峰值。早期的第一个峰值在时间轴上的位置可以直接用来确定海底的电导率，代表了电磁波在海底的传播；而晚期的第二个峰值代表电磁波在海水中的传播，亦可用来确定海水的电导率。该文概述了可控源时域海底电磁法理论方面的主要研究成果，同时也讨论了海底电磁法的仪器设备，特别介绍了多伦多大学物理系研制的时域水平磁偶极子及水平电偶极子海底观测系统。这些设备在浅海及洋中脊附近深海中的试验结果也在文中作了讨论
A review of the submarine electromagnetic method developed over the past decade has been made, focusing on the controllable source time domain. Similar to the aeronautical electromagnetism method which can conduct conductivity mapping on the economic belt on land, the controlled source seafloor electromagnetic method can also conduct conductivity mapping on the seabed within the range of several tens of meters. The conductivity of the seabed is usually much less than the conductivity of seawater. Theoretical studies show that the controllable source time-domain horizontal dipole and horizontal dipole subsystems can be used to accurately determine the seafloor conductivity. The response of the two devices to the two half-spaces shows two peaks on the time axis. The position of the first peak on the time axis of the early stage can be directly used to determine the conductivity of the sea floor and represents the propagation of electromagnetic waves on the sea floor. The second peak of the late stage represents the propagation of electromagnetic waves in seawater and can also be used to determine seawater Conductivity. This paper summarizes the main research results on the theory of submarine electromagnetic fields in controllable time-domain, and also discusses the instruments and equipment of the submarine electromagnetic method. In particular, the time-domain horizontal magnetic dipole and horizontal galvanic dipole developed by the Department of Physics, University of Toronto Pole submarine observation system. The test results of these devices in the deep sea near shallow ocean and mid-ocean ridge are also discussed in this paper