Comment on “Electromagnetic geophysics: Notes from the past and the road ahead” (Michael S. Zhdanov, 2010, GEOPHYSICS, 75, no. 5, 75A49–75A66)

Abstract

The direct current and electromagnetic methods have been around for almost 180 years and have been applied successfully in mining, petroleum, geotechnical, engineering, environmental, groundwater, and tectonic studies. Over such a long period of time, it is possible to lose track of who the pioneers were that developed the various techniques in current use and who wrote the seminal papers on these techniques. As such, a historical review paper is most welcome and, in the past, there were only few attempts to undertake this task (e.g., Rust, 1938; Ward, 1980; Fountain, 1998). Each of these historical reviews covered only a limited number of topics and I was glad to see the recent attempt by Zhdanov to undertake a similar task in his 2010 paper entitled “Electromagnetic geophysics: Notes from the past and the road ahead.” I was eagerly looking forward to reading this paper because I have been practicing geophysics for almost six decades and have witnessed the birth and successful development of most modern techniques. I was also encouraged by the fact that in the abstract Zhdanov wrote “This paper describes the evolution of the conceptual and technical foundations of EM methods.” Upon reading the paper, however, I have found a number of improper or missing citations of seminal papers and discrepancies between the sequence of events as stated in Zhdanov’s review paper and my recollections corroborated by the many published papers by many authors and also by the review chapters in the two-volume book “Electromagnetic methods in applied geophysics,” which I edited. Some of these omissions and discrepancies are shown below. On page 75A52, Zhdanov writes: “Berdichevsky was the first to realize the importance of accounting for the effects of horizontal geoelectrical inhomogeneities on MT data. Berdichevsky’s work on the distortion theory resulted in the method …