Simulation and Observations of Audio Magnetotelluric Measurements over Water-Covered Areas

Abstract

Electromagnetic (EM) surveys play a significant role in mineral exploration. However, the EM method often faces limitations when investigating minerals in areas covered by rivers, lakes, or other water bodies. This paper introduces audio magnetotelluric (AMT) observation technology that utilizes separated electric and magnetic channels to deal with this challenge over water-covered areas. The study analyzes and discusses the characteristics of the relative error of the magnetic field through forward simulation. The observation and profile experiments were conducted at the estuary of a river in Liaoning Province, China, and high-quality data in the river and the pseudo-geoelectric section of the underwater space were successfully obtained. The results demonstrate the feasibility and effectiveness of the AMT observation technology over water-covered areas, emphasizing the importance of locating the magnetic channel in a quiet zone at a certain distance from the shore. This configuration helps reduce the influence of resistivity differences between water and shore, ultimately improving data quality and accuracy. The research suggests that the AMT observation technology, utilizing separated electric and magnetic channels, has the potential for further improvement and can serve as a valuable guide for mineral exploration over water-covered areas.