Geoelectromagnetics charges on

Abstract

A continued resurgence of the use of electromagnetic (EM) methods in remarkably diverse geologic applications has occurred in the last four years (1991–1994). During this time EM methods in the United States have found a permanent place in major multidisciplinary continental dynamic projects, airborne EM has been successfully used by U.S. companies for diamond exploration in Canada's Northwest Territories, EM methods are now routinely used in environmental assessment, and renewed interest has occurred in seismoelectromagnetic monitoring. These activities have been accompanied by added emphasis on borehole EM, better on‐site processing and data presentation, improved inversion including fast (but lower resolution) imaging, and increased understanding of the possible causes of conductivity variations in the inaccessible regions of the Earth. This review is not meant to catalogue all EM geophysical efforts in the past four years. The emphasis will be on developments in the U.S.; however, the geophysics EM community is highly connected world‐wide. Many U.S. academic researchers and exploration companies have particularly close relations (e.g., joint research projects and exploration contracts) with Canadian and Mexican counterparts. Thus, it has been unavoidable, in fact necessary, to include references to many works published by our nearest North American neighbors. EM workshops held every two years under the sponsorship of the International Association of Geomagnetism and Aeronomy (IAGA) Working Group 1–3 strongly foster international cooperation. The workshop was held in Wellington, New Zealand in 1992 and it was in Brest, France in 1994. A pre‐meeting hands‐on, magnetotelluric (MT) data interpretation workshop was inaugurated prior to the Wellington meeting. All participants discussed analyses of common data sets distributed prior to the workshop. The success of this format prompted an equally successful activity in Cambridge, England before the Brest meeting.