b'Member recollections ASEG newsThe first magnetotelluric survey in Australiaas witnessed by RogerHenderson in 1968.Roger Henderson rogah@tpg.com.auAfter receiving my MSc in deep resistivity from Sydney University and becoming the foundation lecturer in exploration geophysics at Macquarie University in 1968, my wish was to start a PhD inmagnetotellurics. Figure 1.Part of the featureless 150 km of track leading to the camp. Source: the authors 35mm slide.Magnetotellurics (MT) is a passivein the Terry Range1 (see Figure1). AfterThefollowing specifications are from electromagnetic method that usesa long, hot day, upon arrival at this mostnotes that I made of the trip.natural time variations of the Earthsremote place. I was offered any amount of ice cream from the refrigeratedThe telluric electrodes were 40 cm long magnetic and electric fields to measurelead rods with up to three placed in the electrical resistivity of the sub- van that also contained fresh lobsters flown in from Darwin. Being a Frenchparallel. The magnetic measurements surface. were made with 2 m long induction coils company, as well as the usual cook in The principles of MT are based on thethe crew of seven, they also had a Chef. of 30 000 turns on a mu-metal core. Both theory expounded by Cagniard (1953).electrodes were buried to avoid wind The method was in its infancy in 1968,As MT has now been practiced for overnoise, as usual (see Figure2). Measured and the only text book, just newly50 years and is currently at a highlycomponents were filtered and recorded on published, was Keller and Frischknechtsophisticated level, I wont explaina two-channel chart recorder and played (1966). I had also just read a paper onthe technique any further except to the subject by Vozoff (1963) and, inhighlight the differences between the addition, an account of some Russian1968 and modern surveys. This may activity in Siberia (Alexeyev etal., 1967).be of particular interest to current Keeva Vozoff subsequently becamepractitioners of the method. A webinar an expert in MT while Professor ofgiven recently by Wenping Jiang from Geophysics at Macquarie UniversityGeoscience Australia, titled Application from 1972-94. of multi-scale MT data to mineral exploration acquainted me with the As preparation for my studies I arrangedlatest developments in the method to visit the first MT survey in Australia,(https://www.aseg.org.au/search/node/which was taking place at that time.Wenping%20Jiang).It was located in the Canning Basin,The crew of seven included two WA and operated by Societe Nationaleengineers from SNPA. This meant that des Petroles dAquitaine (SNPA) ofPau, who had developed the equipment, Pau, France, for its affiliated company,were able to modify and maintain it. One Australian Aquitaine Petroleum P/L. of the engineers was Marcel Waeselynck The field camp was 750 km WNW ofwho had published full details of the Alice Springs in the northern Gibsonmethod internally (Waeselynck, 1967). Desert, and was reached by me in 1968 by flying from Sydney to Alice Springs, 1 Another description of the survey location taking the 5-seater aircraft servicingis; east of Well No. 27 of the Canning Stock Wilson Cliffs No. 1 oil well (at: 126.5 E,route along which a magnetometer survey 22.3 S) and driving 150 km south overwas conducted by Edward Kidson in 1914,Figure 2.An induction coil part buried. Source: never-ending sand dunes to the campasdescribed by Doug Morrison (2005). the authors 35 mm slide.OCTOBER 2021 PREVIEW 12'